Bump version to 5.1.5 for release

See discussion #266

.github/workflows/automerge_dependabot.yml

@@ -15,7 +15,7 @@ jobs:
       # Note: this is directly from GitHub's example for using data from a triggering workflow:
       # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#using-data-from-the-triggering-workflow
       - name: 'Download artifact'
-        uses: actions/github-script@v6
+        uses: actions/github-script@v7
         with:
           script: |
             let allArtifacts = await github.rest.actions.listWorkflowRunArtifacts({
@@ -42,12 +42,12 @@ jobs:
           echo "PR_NUMBER=$(cat pr_number)" >> "$GITHUB_ENV"
 
       - name: Approve
-        uses: hmarr/auto-approve-action@v3.2.1
+        uses: hmarr/auto-approve-action@v4.0.0
         with:
           github-token: "${{ secrets.GITHUB_TOKEN }}"
           pull-request-number: "${{ env.PR_NUMBER }}"
       - name: Merge
-        uses: pascalgn/automerge-action@v0.15.6
+        uses: pascalgn/automerge-action@v0.16.4
         env:
           GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
           MERGE_LABELS: "dependencies,java"

.github/workflows/ci.yml

@@ -3,9 +3,11 @@ name: OpenInv CI
 on:
   push:
     branches:
-      - '**'
+      - 'master'
     tags-ignore:
       - '**'
+    paths-ignore:
+      - resource-pack/**
   # Enable running CI via other Actions, i.e. for drafting releases and handling PRs.
   workflow_call:
 
@@ -13,12 +15,12 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
-      - uses: actions/setup-java@v3
+      - uses: actions/setup-java@v4
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
           cache: 'maven'
 
       # Install Spigot dependencies if necessary.
@@ -31,13 +33,13 @@ jobs:
       # Upload artifacts
       - name: Upload Distributable Jar
         id: upload-final
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: dist
-          path: ./target/OpenInv.jar
+          path: ./target/*.jar
       - name: Upload API Jar
         id: upload-api
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: api
           path: ./api/target/openinvapi*.jar

.github/workflows/draft_release.yml

@@ -13,22 +13,28 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       # Fetch all history - used to assemble changelog.
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
       - name: Set Release Variables
         run: bash ./scripts/set_release_env.sh
 
-      - name: Download Artifact
-        uses: actions/download-artifact@v3
+      - name: Download build
+        uses: actions/download-artifact@v4
         with:
           name: dist
           path: dist
 
+      - name: Package resource pack
+        run: |-
+          pushd resource-pack
+          zip -r ../dist/openinv-legibility-pack.zip .
+          popd
+
       - name: Create Release
         id: create-release
-        uses: softprops/action-gh-release@v0.1.15
+        uses: softprops/action-gh-release@v2.2.1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
@@ -36,4 +42,4 @@ jobs:
           body: ${{ env.GENERATED_CHANGELOG }}
           draft: true
           prerelease: false
-          files: ./dist/OpenInv.jar
+          files: ./dist/**

.github/workflows/external_release.yml

@@ -9,12 +9,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout Code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
       - name: Fetch Github Release Asset
-        uses: dsaltares/fetch-gh-release-asset@1.1.1
+        uses: dsaltares/fetch-gh-release-asset@1.1.2
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           version: ${{ github.event.release.id }}

.github/workflows/pull_request.yml

@@ -16,7 +16,7 @@ jobs:
         run: |
           mkdir -p ./pr
           echo ${{ github.event.number }} > ./pr/pr_number
-      - uses: actions/upload-artifact@v3
+      - uses: actions/upload-artifact@v4
         with:
           name: pr_number
           path: pr/

.github/workflows/resource_pack_ci.yml

@@ -0,0 +1,24 @@
+name: Resource Pack CI
+
+on:
+  push:
+    branches:
+      - 'master'
+    tags-ignore:
+      - '**'
+    paths:
+      - resource-pack/**
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build resource pack
+        id: upload-resource-pack
+        uses: actions/upload-artifact@v4
+        with:
+          name: openinv-legibility-pack
+          path: ./resource-pack/
+          compression-level: 9

README.MD

@@ -1,16 +1,17 @@
 ## About
-OpenInv is a [Bukkit plugin](https://dev.bukkit.org/bukkit-plugins/openinv/) which allows users to open and edit anyone's inventory or ender chest - online or not!
+OpenInv is a [Bukkit plugin](https://dev.bukkit.org/projects/openinv) which allows users to open and edit anyone's inventory or ender chest - online or not!
 
 ## Features
 - **OpenInv**: Open anyone's inventory, even if they're offline.
-  - Read-only mode! No edits allowed! Don't grant the permission `OpenInv.editinv`
-  - Cross-world support! Don't grant `OpenInv.crossworld`
-  - No self-opening! Don't grant `OpenInv.openself`
-  - Drop items as the player! Place items in the unused slots to the right of the armor to drop them
+  - Read-only mode! Don't grant edit permission.
+  - Cross-world support! Allow access only from the same world.
+  - No duplicate slots! Only armor is accessible when opening self (if allowed at all)!
+  - Drop items as the player! Place items in the dropper slot in the bottom right. Can be disabled via permission!
+  - Allow any item in armor slots! Configurable via permission.
 - **OpenEnder**: Open anyone's ender chest, even if they're offline.
-  - Read-only mode! No edits allowed! Don't grant `OpenInv.editender`
-  - Cross-world support! Don't grant `OpenInv.crossworld`
-  - No opening others! Don't grant `OpenInv.openenderall`
+  - Allow access only to own ender chest! Don't grant permission to open others.
+  - Read-only mode! Don't grant edit permission.
+  - Cross-world support! Allow access only from the same world.
 - **SilentContainer**: Open containers without displaying an animation or making sound.
 - **AnyContainer**: Open containers, even if blocked by ocelots or blocks.
 
@@ -18,88 +19,7 @@ OpenInv is a [Bukkit plugin](https://dev.bukkit.org/bukkit-plugins/openinv/) whi
 See [the wiki](https://github.com/Jikoo/OpenInv/wiki/Commands).
 
 ## Permissions
-<table>
-  <tr>
-    <th>Node</th>
-    <th>Description</th>
-  </tr>
-  <tr>
-    <td>OpenInv.*</td>
-    <td>Gives permission to use all of OpenInv.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.openinv</td>
-    <td>Required to use /openinv.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.openself</td>
-    <td>Required to open own inventory.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.editinv</td>
-    <td>Required to make changes to open inventories.</td>
-  </tr>
-  <tr>
-      <td>OpenInv.openonline</td>
-      <td>Allows users to open online players' inventories. For compatibility reasons this is granted by the nodes OpenInv.openinv and OpenInv.openender.</td>
-  </tr>
-  <tr>
-      <td>OpenInv.openoffline</td>
-      <td>Allows users to open offline players' inventories. For compatibility reasons this is granted by the nodes OpenInv.openinv and OpenInv.openender.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.openender</td>
-    <td>Required to use /openender.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.editender</td>
-    <td>Required to make changes to open ender chests.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.openenderall</td>
-    <td>Allows users to open others' ender chests. Without it, users can only open their own.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.exempt</td>
-    <td>Prevents the player's inventory being opened by others.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.override</td>
-    <td>Allows bypassing of the exempt permission.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.crossworld</td>
-    <td>Allows cross-world usage of /openinv and /openender.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.search</td>
-    <td>Required to use /searchinv and /searchender.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.searchenchant</td>
-    <td>Required to use /searchenchant.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.anychest</td>
-    <td>Required to use /anychest.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.any.default</td>
-    <td>Cause AnyContainer to be enabled by default.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.silent</td>
-    <td>Required to use /silentcontainer.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.silent.default</td>
-    <td>Cause SilentContainer to be enabled by default.</td>
-  </tr>
-  <tr>
-    <td>OpenInv.spectate</td>
-    <td>Allows users in spectate gamemode to edit inventories.</td>
-  </tr>
-</table>
+See [the wiki](https://github.com/Jikoo/OpenInv/wiki/Permissions)
 
 ## For Developers
 
@@ -129,11 +49,9 @@ As OpenInv is compiled against Mojang's mappings, you must run BuildTools with t
 `java -jar BuildTools.jar --remapped --rev $serverVersion`  
 `$serverVersion` is the version of the server, i.e. `1.18.1`
 
-To compile for a single version, specify the module you are targeting:  
-`mvn -pl $moduleName -am clean install`  
-`$moduleName` is the name of the module, i.e. `internal/v1_18_R1`.
+To compile just the API, execute Maven as usual:  
+`mvn clean package`  
 
-To compile for a set of versions, use a profile. Select a profile using the `-P` argument:  
+To compile the full plugin, use the provided profile with `-P all`:  
 `mvn clean package -am -P all`  
-The only provided profile is `all`. The final file is `target/OpenInv.jar`  
 For more information, check out the [official Maven guide](http://maven.apache.org/guides/introduction/introduction-to-profiles.html).

addon/togglepersist/pom.xml

@@ -0,0 +1,72 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <artifactId>openinvparent</artifactId>
+        <groupId>com.lishid</groupId>
+        <relativePath>../../pom.xml</relativePath>
+        <version>5.1.5</version>
+    </parent>
+
+    <artifactId>openinvtogglepersist</artifactId>
+
+    <dependencies>
+        <dependency>
+            <artifactId>annotations</artifactId>
+            <groupId>org.jetbrains</groupId>
+        </dependency>
+        <dependency>
+            <groupId>org.spigotmc</groupId>
+            <artifactId>spigot-api</artifactId>
+        </dependency>
+        <dependency>
+            <artifactId>openinvapi</artifactId>
+            <groupId>com.lishid</groupId>
+            <scope>provided</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <finalName>OITogglePersist</finalName>
+        <resources>
+            <resource>
+                <directory>src/main/resources</directory>
+                <filtering>true</filtering>
+            </resource>
+        </resources>
+
+        <plugins>
+            <plugin>
+                <artifactId>maven-compiler-plugin</artifactId>
+            </plugin>
+            <plugin>
+                <artifactId>maven-resources-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>copy-final-jar</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>copy-resources</goal>
+                        </goals>
+                        <configuration>
+                            <outputDirectory>${project.parent.build.directory}</outputDirectory>
+                            <resources>
+                                <resource>
+                                    <directory>${project.build.directory}</directory>
+                                    <includes>
+                                        <include>${project.build.finalName}.jar</include>
+                                    </includes>
+                                </resource>
+                            </resources>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+
+    </build>
+
+</project>

addon/togglepersist/src/main/java/com/github/jikoo/openinv/togglepersist/TogglePersist.java

@@ -0,0 +1,143 @@
+package com.github.jikoo.openinv.togglepersist;
+
+import com.google.errorprone.annotations.Keep;
+import com.lishid.openinv.event.PlayerToggledEvent;
+import com.lishid.openinv.util.setting.PlayerToggle;
+import com.lishid.openinv.util.setting.PlayerToggles;
+import org.bukkit.configuration.Configuration;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.plugin.java.JavaPlugin;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+import java.util.logging.Level;
+
+public class TogglePersist extends JavaPlugin implements Listener {
+
+  private final Map<UUID, Set<String>> enabledToggles = new HashMap<>();
+
+  @Override
+  public void onEnable() {
+    getServer().getPluginManager().registerEvents(this, this);
+
+    File file = new File(getDataFolder(), "toggles.yml");
+
+    // If there's no save file, there's nothing to load.
+    if (!file.exists()) {
+      return;
+    }
+
+    Configuration loaded = YamlConfiguration.loadConfiguration(file);
+
+    // For each toggle, enable loaded players.
+    for (String toggleName : loaded.getKeys(false)) {
+      PlayerToggle toggle = PlayerToggles.get(toggleName);
+      // Ensure toggle exists.
+      if (toggle == null) {
+        continue;
+      }
+
+      for (String idString : loaded.getStringList(toggleName)) {
+        // Ensure valid UUID.
+        UUID uuid;
+        try {
+          uuid = UUID.fromString(idString);
+        } catch (IllegalArgumentException e) {
+          continue;
+        }
+
+        // Track that toggle is enabled.
+        set(uuid, toggleName);
+      }
+    }
+  }
+
+  private void set(UUID playerId, String toggleName) {
+    enabledToggles.compute(playerId, (uuid, toggles) -> {
+      if (toggles == null) {
+        toggles = new HashSet<>();
+      }
+      toggles.add(toggleName);
+      return toggles;
+    });
+  }
+
+  @Override
+  public void onDisable() {
+    Map<String, List<String>> converted = getSaveData();
+
+    YamlConfiguration data = new YamlConfiguration();
+    for (Map.Entry<String, List<String>> playerToggle : converted.entrySet()) {
+      data.set(playerToggle.getKey(), playerToggle.getValue());
+    }
+
+    File file = new File(getDataFolder(), "toggles.yml");
+    try {
+      data.save(file);
+    } catch (IOException e) {
+      getLogger().log(Level.SEVERE, "Unable to save player toggle states", e);
+    }
+  }
+
+  private @NotNull Map<String, List<String>> getSaveData() {
+    Map<String, List<String>> converted = new HashMap<>();
+
+    for (Map.Entry<UUID, Set<String>> playerToggles : enabledToggles.entrySet()) {
+      String idString = playerToggles.getKey().toString();
+      for (String toggleName : playerToggles.getValue()) {
+        // Add player ID to listing for each enabled toggle.
+        converted.compute(toggleName, (name, ids) -> {
+          if (ids == null) {
+            ids = new ArrayList<>();
+          }
+          ids.add(idString);
+          return ids;
+        });
+      }
+    }
+    return converted;
+  }
+
+  @Keep
+  @EventHandler
+  private void onPlayerJoin(@NotNull PlayerJoinEvent event) {
+    UUID playerId = event.getPlayer().getUniqueId();
+    Set<String> toggleNames = enabledToggles.get(playerId);
+
+    if (toggleNames == null) {
+      return;
+    }
+
+    for (String toggleName : toggleNames) {
+      PlayerToggle toggle = PlayerToggles.get(toggleName);
+      if (toggle != null) {
+        toggle.set(playerId, true);
+      }
+    }
+  }
+
+  @Keep
+  @EventHandler
+  private void onToggleSet(@NotNull PlayerToggledEvent event) {
+    if (event.isEnabled()) {
+      set(event.getPlayerId(), event.getToggle().getName());
+    } else {
+      enabledToggles.computeIfPresent(event.getPlayerId(), (uuid, toggles) -> {
+        toggles.remove(event.getToggle().getName());
+        return toggles.isEmpty() ? null : toggles;
+      });
+    }
+  }
+
+}

addon/togglepersist/src/main/resources/plugin.yml

@@ -0,0 +1,7 @@
+name: OITogglePersist
+main: com.github.jikoo.openinv.togglepersist.TogglePersist
+version: ${project.version}
+author: Jikoo
+description: An OpenInv addon allowing /anycontainer and /silentcontainer to persist across sessions.
+api-version: "1.20"
+depend: [ OpenInv ]

api/pom.xml

@@ -21,7 +21,7 @@
   <parent>
     <artifactId>openinvparent</artifactId>
     <groupId>com.lishid</groupId>
-    <version>4.3.1</version>
+    <version>5.1.5</version>
   </parent>
 
   <artifactId>openinvapi</artifactId>

api/src/main/java/com/lishid/openinv/IOpenInv.java

@@ -17,21 +17,19 @@
 package com.lishid.openinv;
 
 import com.lishid.openinv.internal.IAnySilentContainer;
-import com.lishid.openinv.internal.IInventoryAccess;
 import com.lishid.openinv.internal.ISpecialEnderChest;
 import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.ISpecialPlayerInventory;
-import com.lishid.openinv.util.InventoryAccess;
-import java.util.UUID;
-import java.util.logging.Logger;
 import org.bukkit.Bukkit;
 import org.bukkit.OfflinePlayer;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.InventoryView;
-import org.bukkit.plugin.Plugin;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.util.UUID;
+import java.util.logging.Logger;
+
 /**
  * Interface defining behavior for the OpenInv plugin.
  */
@@ -80,22 +78,6 @@ public interface IOpenInv {
      */
     @NotNull IAnySilentContainer getAnySilentContainer();
 
-    /**
-     * @deprecated Use static {@link InventoryAccess} methods.
-     */
-    @Deprecated(forRemoval = true)
-    default @NotNull IInventoryAccess getInventoryAccess() {
-        return new InventoryAccess();
-    }
-
-    /**
-     * @deprecated Use {@link #getAnyContainerStatus(OfflinePlayer)}. Not all containers are chests.
-     */
-    @Deprecated(forRemoval = true, since = "4.2.0")
-    default boolean getPlayerAnyChestStatus(@NotNull OfflinePlayer offline) {
-        return getAnyContainerStatus(offline);
-    }
-
     /**
      * Get whether a user has AnyContainer mode enabled.
      *
@@ -104,14 +86,6 @@ public interface IOpenInv {
      */
     boolean getAnyContainerStatus(@NotNull OfflinePlayer offline);
 
-    /**
-     * @deprecated Use {@link #setAnyContainerStatus(OfflinePlayer, boolean)}. Not all containers are chests.
-     */
-    @Deprecated(forRemoval = true, since = "4.2.0")
-    default void setPlayerAnyChestStatus(@NotNull OfflinePlayer offline, boolean status) {
-        setAnyContainerStatus(offline, status);
-    }
-
     /**
      * Set whether a user has AnyContainer mode enabled.
      *
@@ -120,14 +94,6 @@ public interface IOpenInv {
      */
     void setAnyContainerStatus(@NotNull OfflinePlayer offline, boolean status);
 
-    /**
-     * @deprecated Use {@link #getSilentContainerStatus(OfflinePlayer)}. Not all containers are chests.
-     */
-    @Deprecated(forRemoval = true, since = "4.2.0")
-    default boolean getPlayerSilentChestStatus(@NotNull OfflinePlayer offline) {
-        return getSilentContainerStatus(offline);
-    }
-
     /**
      * Get whether a user has SilentContainer mode enabled.
      *
@@ -136,14 +102,6 @@ public interface IOpenInv {
      */
     boolean getSilentContainerStatus(@NotNull OfflinePlayer offline);
 
-    /**
-     * @deprecated Use {@link #setSilentContainerStatus(OfflinePlayer, boolean)}. Not all containers are chests.
-     */
-    @Deprecated(forRemoval = true, since = "4.2.0")
-    default void setPlayerSilentChestStatus(@NotNull OfflinePlayer offline, boolean status) {
-        setSilentContainerStatus(offline, status);
-    }
-
     /**
      * Set whether a user has SilentContainer mode enabled.
      *
@@ -152,20 +110,6 @@ public interface IOpenInv {
      */
     void setSilentContainerStatus(@NotNull OfflinePlayer offline, boolean status);
 
-    /**
-     * Get a unique identifier by which the OfflinePlayer can be referenced.
-     *
-     * @deprecated Use {@link OfflinePlayer#getUniqueId()} and {@link UUID#toString()}. This was necessary for non-UUID
-     * versions of Minecraft, but support for them has been dropped for years.
-     * @param offline the OfflinePlayer
-     * @return the identifier
-     * @throws IllegalStateException if the server version is unsupported
-     */
-    @Deprecated(forRemoval = true)
-    default @NotNull String getPlayerID(@NotNull OfflinePlayer offline) {
-        return offline.getUniqueId().toString();
-    }
-
     /**
      * Get an {@link ISpecialEnderChest} for a user.
      *
@@ -229,55 +173,6 @@ public interface IOpenInv {
      */
     @Nullable OfflinePlayer matchPlayer(@NotNull String name);
 
-    /**
-     * @deprecated OpenInv uses action bar chat for notifications. Whether they show is based on language settings.
-     */
-    @Deprecated(forRemoval = true)
-    default boolean notifyAnyChest() {
-        return true;
-    }
-
-    /**
-     * @deprecated OpenInv uses action bar chat for notifications. Whether they show is based on language settings.
-     */
-    @Deprecated(forRemoval = true)
-    default boolean notifySilentChest() {
-        return true;
-    }
-
-    /**
-     * @deprecated see {@link #retainPlayer(Player, Plugin)}
-     */
-    @Deprecated(forRemoval = true, since = "4.2.0")
-    default void releasePlayer(@NotNull Player player, @NotNull Plugin plugin) {}
-
-    /**
-     * @deprecated OpenInv no longer uses an internal cache beyond maintaining copies of currently open inventories.
-     * If you wish to use/modify a player, ensure either {@link IOpenInv#isPlayerLoaded(UUID)} is false or the player
-     * instance is the same memory address as the one in use by OpenInv.
-     * <pre>
-     *  public &#64;NotNull Player savePlayerData(&#64;NotNull Player player) {
-     *     IOpenInv openInv = ...
-     *     if (!openInv.disableSaving() && openInv.isPlayerLoaded(player.getUniqueId())) {
-     *         Player openInvLoadedPlayer = openInv.loadPlayer(myInUsePlayer);
-     *         if (openInvLoadedPlayer != player) {
-     *             // The copy loaded by OpenInv is not the same as our loaded copy. Push our changes.
-     *             copyPlayerModifications(player, openInvLoadedPlayer);
-     *         }
-     *         // OpenInv will handle saving data when the player is unloaded.
-     *         // Optionally, to be sure our changes will persist, save now.
-     *         // openInvLoadedPlayer.saveData();
-     *         return openInvLoadedPlayer;
-     *     }
-     *
-     *     player.saveData();
-     *     return player;
-     * }
-     * </pre>
-     */
-    @Deprecated(forRemoval = true, since = "4.2.0")
-    default void retainPlayer(@NotNull Player player, @NotNull Plugin plugin) {}
-
     /**
      * Forcibly close inventories of and unload any cached data for a user.
      *

api/src/main/java/com/lishid/openinv/event/OpenPlayerSaveEvent.java

@@ -0,0 +1,56 @@
+package com.lishid.openinv.event;
+
+import com.google.errorprone.annotations.RestrictedApi;
+import com.lishid.openinv.internal.ISpecialInventory;
+import org.bukkit.entity.Player;
+import org.bukkit.event.HandlerList;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Event fired before OpenInv saves a player's data when closing an {@link ISpecialInventory}.
+ */
+public class OpenPlayerSaveEvent extends PlayerSaveEvent {
+
+  private static final HandlerList HANDLERS = new HandlerList();
+
+  private final ISpecialInventory inventory;
+
+  /**
+   * Construct a new {@code OpenPlayerSaveEvent}.
+   *
+   * <p>The constructor is not considered part of the API, and may be subject to change.</p>
+   *
+   * @param player the player to be saved
+   * @param inventory the {@link ISpecialInventory} being closed
+   */
+  @RestrictedApi(
+      explanation = "Constructor is not considered part of the API and may be subject to change.",
+      link = "",
+      allowedOnPath = ".*/com/lishid/openinv/event/OpenEvents.java")
+  @ApiStatus.Internal
+  OpenPlayerSaveEvent(@NotNull Player player, @NotNull ISpecialInventory inventory) {
+    super(player);
+    this.inventory = inventory;
+  }
+
+  /**
+   * Get the {@link ISpecialInventory} that triggered the save by being closed.
+   *
+   * @return the special inventory
+   */
+  public @NotNull ISpecialInventory getInventory() {
+    return inventory;
+  }
+
+  @NotNull
+  @Override
+  public HandlerList getHandlers() {
+    return HANDLERS;
+  }
+
+  public static HandlerList getHandlerList() {
+    return HANDLERS;
+  }
+
+}

api/src/main/java/com/lishid/openinv/event/PlayerSaveEvent.java

@@ -0,0 +1,67 @@
+package com.lishid.openinv.event;
+
+
+import com.google.errorprone.annotations.RestrictedApi;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.player.PlayerEvent;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Event fired before a {@link Player} loaded via OpenInv is saved.
+ */
+public class PlayerSaveEvent extends PlayerEvent implements Cancellable {
+
+  private static final HandlerList HANDLERS = new HandlerList();
+
+  private boolean cancelled = false;
+
+  /**
+   * Construct a new {@code PlayerSaveEvent}.
+   *
+   * <p>The constructor is not considered part of the API, and may be subject to change.</p>
+   *
+   * @param player the player to be saved
+   */
+  @RestrictedApi(
+      explanation = "Constructor is not considered part of the API and may be subject to change.",
+      link = "",
+      allowedOnPath = ".*/com/lishid/openinv/event/(OpenPlayerSaveEvent|OpenEvents).java")
+  @ApiStatus.Internal
+  PlayerSaveEvent(@NotNull Player player) {
+    super(player);
+  }
+
+  /**
+   * Get whether the event is cancelled.
+   *
+   * @return true if the event is cancelled
+   */
+  @Override
+  public boolean isCancelled() {
+    return cancelled;
+  }
+
+  /**
+   * Set whether the event is cancelled.
+   *
+   * @param cancel whether the event is cancelled
+   */
+  @Override
+  public void setCancelled(boolean cancel) {
+    this.cancelled = cancel;
+  }
+
+  @NotNull
+  @Override
+  public HandlerList getHandlers() {
+    return HANDLERS;
+  }
+
+  public static HandlerList getHandlerList() {
+    return HANDLERS;
+  }
+
+}

api/src/main/java/com/lishid/openinv/event/PlayerToggledEvent.java

@@ -0,0 +1,71 @@
+package com.lishid.openinv.event;
+
+import com.google.errorprone.annotations.RestrictedApi;
+import com.lishid.openinv.util.setting.PlayerToggle;
+import org.bukkit.event.Event;
+import org.bukkit.event.HandlerList;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.UUID;
+
+/**
+ * Event fired after OpenInv modifies a toggleable setting for a player.
+ */
+public class PlayerToggledEvent extends Event {
+
+  private static final HandlerList HANDLERS = new HandlerList();
+
+  private final @NotNull PlayerToggle toggle;
+  private final @NotNull UUID uuid;
+  private final boolean enabled;
+
+  @RestrictedApi(
+      explanation = "Constructor is not considered part of the API and may be subject to change.",
+      link = "",
+      allowedOnPath = ".*/com/lishid/openinv/event/OpenEvents.java")
+  @ApiStatus.Internal
+  PlayerToggledEvent(@NotNull PlayerToggle toggle, @NotNull UUID uuid, boolean enabled) {
+    this.toggle = toggle;
+    this.uuid = uuid;
+    this.enabled = enabled;
+  }
+
+  /**
+   * Get the {@link PlayerToggle} affected.
+   *
+   * @return the toggle
+   */
+  public @NotNull PlayerToggle getToggle() {
+    return toggle;
+  }
+
+  /**
+   * Get the {@link UUID} of the player whose setting was changed.
+   *
+   * @return the player ID
+   */
+  public @NotNull UUID getPlayerId() {
+    return uuid;
+  }
+
+  /**
+   * Get whether the toggle is enabled.
+   *
+   * @return true if the toggle is enabled
+   */
+  public boolean isEnabled() {
+    return enabled;
+  }
+
+  @NotNull
+  @Override
+  public HandlerList getHandlers() {
+    return HANDLERS;
+  }
+
+  public static HandlerList getHandlerList() {
+    return HANDLERS;
+  }
+
+}

api/src/main/java/com/lishid/openinv/internal/IAnySilentContainer.java

@@ -16,14 +16,11 @@
 
 package com.lishid.openinv.internal;
 
-import org.bukkit.block.Barrel;
 import org.bukkit.block.Block;
 import org.bukkit.block.BlockFace;
 import org.bukkit.block.BlockState;
 import org.bukkit.block.EnderChest;
-import org.bukkit.block.ShulkerBox;
-import org.bukkit.block.data.BlockData;
-import org.bukkit.block.data.type.Chest;
+import org.bukkit.block.data.Directional;
 import org.bukkit.entity.Cat;
 import org.bukkit.entity.Player;
 import org.bukkit.inventory.InventoryHolder;
@@ -50,84 +47,32 @@ public interface IAnySilentContainer {
      */
     void deactivateContainer(@NotNull Player player);
 
-    /**
-     * @param player the player opening the container
-     * @param block  the {@link Block} of the container
-     * @return true if the container is blocked
-     * @deprecated use {@link #isAnyContainerNeeded(Block)}
-     */
-    @Deprecated(forRemoval = true, since = "4.1.9")
-    default boolean isAnyContainerNeeded(@NotNull Player player, @NotNull Block block) {
-        return isAnyContainerNeeded(block);
-    }
-
     /**
      * Check if the container at the given coordinates is blocked.
      *
      * @param block the {@link Block} of the container
      * @return true if the container is blocked
      */
-    default boolean isAnyContainerNeeded(@NotNull Block block) {
-        BlockState blockState = block.getState();
-
-        // Barrels do not require AnyContainer.
-        if (blockState instanceof Barrel) {
-            return false;
-        }
-
-        // Enderchests require a non-occluding block on top to open.
-        if (blockState instanceof EnderChest) {
-            return block.getRelative(0, 1, 0).getType().isOccluding();
-        }
-
-        // Shulker boxes require 1/2 a block clear in the direction they open.
-        if (blockState instanceof ShulkerBox shulker) {
-            if (isShulkerBlocked(shulker)) {
-                return true;
-            }
-        }
-
-        if (!(blockState instanceof org.bukkit.block.Chest)) {
-            return false;
-        }
-
-        if (isChestBlocked(block)) {
-            return true;
-        }
-
-        BlockData blockData = block.getBlockData();
-        if (!(blockData instanceof Chest chest) || ((Chest) blockData).getType() == Chest.Type.SINGLE) {
-            return false;
-        }
-
-        int ordinal = (chest.getFacing().ordinal() + 4 + (chest.getType() == Chest.Type.RIGHT ? -1 : 1)) % 4;
-        BlockFace relativeFace = BlockFace.values()[ordinal];
-        org.bukkit.block.Block relative = block.getRelative(relativeFace);
-
-        if (relative.getType() != block.getType()) {
-            return false;
-        }
-
-        BlockData relativeData = relative.getBlockData();
-        if (!(relativeData instanceof Chest relativeChest)) {
-            return false;
-        }
-
-        if (relativeChest.getFacing() != chest.getFacing()
-                || relativeChest.getType() != (chest.getType() == Chest.Type.RIGHT ? Chest.Type.LEFT : Chest.Type.RIGHT)) {
-            return false;
-        }
-
-        return isChestBlocked(relative);
-    }
+    boolean isAnyContainerNeeded(@NotNull Block block);
 
     /**
-     * Check if a {@link ShulkerBox} cannot be opened under ordinary circumstances.
+     * Check if a shulker box block cannot be opened under ordinary circumstances.
      *
-     * @param shulkerBox the shulker box container
+     * @param shulkerBox the shulker box block
      * @return whether the container is blocked
      */
-    boolean isShulkerBlocked(@NotNull ShulkerBox shulkerBox);
+    default boolean isShulkerBlocked(@NotNull Block shulkerBox) {
+        Directional directional = (Directional) shulkerBox.getBlockData();
+        BlockFace facing = directional.getFacing();
+        // Construct a new 1-block bounding box at the origin.
+        BoundingBox box = new BoundingBox(0, 0, 0, 1, 1, 1);
+        // Expand the box in the direction the shulker will open.
+        box.expand(facing, 0.5);
+        // Move the box away from the origin by a block so only the expansion intersects with a box around the origin.
+        box.shift(facing.getOppositeFace().getDirection());
+        // Check if the relative block's collision shape (which will be at the origin) intersects with the expanded box.
+        return shulkerBox.getRelative(facing).getCollisionShape().overlaps(box);
+    }
 
     /**
      * Check if a chest cannot be opened under ordinary circumstances.
@@ -138,7 +83,7 @@ public interface IAnySilentContainer {
     default boolean isChestBlocked(@NotNull Block chest) {
         org.bukkit.block.Block relative = chest.getRelative(0, 1, 0);
         return relative.getType().isOccluding()
-                || chest.getWorld().getNearbyEntities(BoundingBox.of(relative), entity -> entity instanceof Cat).size() > 0;
+                || !chest.getWorld().getNearbyEntities(BoundingBox.of(relative), Cat.class::isInstance).isEmpty();
     }
 
     /**
@@ -147,9 +92,7 @@ public interface IAnySilentContainer {
      * @param block the potential container
      * @return true if the type is a supported container
      */
-    default boolean isAnySilentContainer(@NotNull Block block) {
-        return isAnySilentContainer(block.getState());
-    }
+    boolean isAnySilentContainer(@NotNull Block block);
 
     /**
      * Check if the given {@link BlockState} is a container which can be unblocked or silenced.
@@ -158,7 +101,8 @@ public interface IAnySilentContainer {
      * @return true if the type is a supported container
      */
     default boolean isAnySilentContainer(@NotNull BlockState blockState) {
-        return blockState instanceof InventoryHolder holder && isAnySilentContainer(holder);
+        return (blockState instanceof InventoryHolder holder && isAnySilentContainer(holder))
+                || blockState instanceof EnderChest;
     }
 
     /**

api/src/main/java/com/lishid/openinv/internal/IInventoryAccess.java

@@ -1,62 +0,0 @@
-/*
- * Copyright (C) 2011-2022 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal;
-
-import com.lishid.openinv.util.InventoryAccess;
-import org.bukkit.inventory.Inventory;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-/**
- * @deprecated Use static {@link InventoryAccess} methods.
- */
-@Deprecated(forRemoval = true)
-public interface IInventoryAccess {
-
-    /**
-     * @deprecated Use static {@link InventoryAccess} methods.
-     */
-    @Deprecated(forRemoval = true)
-    default @Nullable ISpecialEnderChest getSpecialEnderChest(@NotNull Inventory inventory) {
-        return InventoryAccess.getEnderChest(inventory);
-    }
-
-    /**
-     * @deprecated Use static {@link InventoryAccess} methods.
-     */
-    @Deprecated(forRemoval = true)
-    default @Nullable ISpecialPlayerInventory getSpecialPlayerInventory(@NotNull Inventory inventory) {
-        return InventoryAccess.getPlayerInventory(inventory);
-    }
-
-    /**
-     * @deprecated Use static {@link InventoryAccess} methods.
-     */
-    @Deprecated(forRemoval = true)
-    default boolean isSpecialEnderChest(@NotNull Inventory inventory) {
-        return InventoryAccess.isEnderChest(inventory);
-    }
-
-    /**
-     * @deprecated Use static {@link InventoryAccess} methods.
-     */
-    @Deprecated(forRemoval = true)
-    default boolean isSpecialPlayerInventory(@NotNull Inventory inventory) {
-        return InventoryAccess.isPlayerInventory(inventory);
-    }
-
-}

api/src/main/java/com/lishid/openinv/internal/ISpecialEnderChest.java

@@ -16,9 +16,17 @@
 
 package com.lishid.openinv.internal;
 
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
 /**
  * An {@link ISpecialInventory} representing an ender chest.
  */
 public interface ISpecialEnderChest extends ISpecialInventory {
 
+  @Override
+  default @NotNull InventoryType getBukkitType() {
+    return InventoryType.ENDER_CHEST;
+  }
+
 }

api/src/main/java/com/lishid/openinv/internal/ISpecialInventory.java

@@ -18,6 +18,7 @@ package com.lishid.openinv.internal;
 
 import org.bukkit.entity.HumanEntity;
 import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.InventoryType;
 import org.bukkit.inventory.Inventory;
 import org.jetbrains.annotations.NotNull;
 
@@ -33,6 +34,13 @@ public interface ISpecialInventory {
      */
     @NotNull Inventory getBukkitInventory();
 
+    /**
+     * Get the {@link InventoryType} corresponding to this {@code ISpecialInventory}.
+     *
+     * @return the type of Bukkit inventory
+     */
+    @NotNull InventoryType getBukkitType();
+
     /**
      * Set the owning {@link Player} instance to a newly-joined user.
      *

api/src/main/java/com/lishid/openinv/internal/ISpecialPlayerInventory.java

@@ -16,35 +16,17 @@
 
 package com.lishid.openinv.internal;
 
-import java.util.List;
-import org.bukkit.entity.HumanEntity;
-import org.bukkit.inventory.Inventory;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
 
 /**
  * An {@link ISpecialInventory} representing a player inventory.
  */
 public interface ISpecialPlayerInventory extends ISpecialInventory {
 
-    /*
-     * Player inventory usage varies from all other inventories - as the inventory is technically open at all times,
-     * if the player is online or has been online while the inventory is open, they are in the viewer list.
-     */
     @Override
-    default boolean isInUse() {
-        Inventory inventory = getBukkitInventory();
-        List<HumanEntity> viewers = inventory.getViewers();
-
-        if (viewers.size() != 1) {
-            return !viewers.isEmpty();
-        }
-
-        HumanEntity viewer = viewers.get(0);
-
-        if (!viewer.getUniqueId().equals(getPlayer().getUniqueId())) {
-            return true;
-        }
-
-        return viewer.getOpenInventory().getTopInventory().equals(inventory);
+    default @NotNull InventoryType getBukkitType() {
+        return InventoryType.PLAYER;
     }
 
 }

api/src/main/java/com/lishid/openinv/util/InventoryAccess.java

@@ -16,39 +16,23 @@
 
 package com.lishid.openinv.util;
 
-import com.lishid.openinv.internal.IInventoryAccess;
+import com.google.errorprone.annotations.RestrictedApi;
 import com.lishid.openinv.internal.ISpecialEnderChest;
 import com.lishid.openinv.internal.ISpecialInventory;
 import com.lishid.openinv.internal.ISpecialPlayerInventory;
-import java.lang.reflect.Method;
-import org.bukkit.Bukkit;
 import org.bukkit.inventory.Inventory;
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public final class InventoryAccess implements IInventoryAccess {
+import java.util.function.BiFunction;
 
-    private static Class<?> craftInventory = null;
-    private static Method getInventory = null;
+public final class InventoryAccess {
 
-    static {
-        String packageName = Bukkit.getServer().getClass().getPackage().getName();
-        try {
-            craftInventory = Class.forName(packageName + ".inventory.CraftInventory");
-            getInventory = craftInventory.getDeclaredMethod("getInventory");
-        } catch (ClassNotFoundException | NoSuchMethodException ignored) {}
-    }
-
-    /**
-     * @deprecated use {@link #isUsable()}
-     */
-    @Deprecated(forRemoval = true)
-    public static boolean isUseable() {
-        return isUsable();
-    }
+    private static @Nullable BiFunction<Inventory, Class<? extends ISpecialInventory>, ISpecialInventory> provider;
 
     public static boolean isUsable() {
-        return craftInventory != null && getInventory != null;
+        return provider != null;
     }
 
     /**
@@ -69,7 +53,7 @@ public final class InventoryAccess implements IInventoryAccess {
      * @return the backing implementation if available
      */
     public static @Nullable ISpecialPlayerInventory getPlayerInventory(@NotNull Inventory inventory) {
-        return getSpecialInventory(ISpecialPlayerInventory.class, inventory);
+        return provider == null ? null : (ISpecialPlayerInventory) provider.apply(inventory, ISpecialPlayerInventory.class);
     }
 
     /**
@@ -90,34 +74,31 @@ public final class InventoryAccess implements IInventoryAccess {
      * @return the backing implementation if available
      */
     public static @Nullable ISpecialEnderChest getEnderChest(@NotNull Inventory inventory) {
-        return getSpecialInventory(ISpecialEnderChest.class, inventory);
-    }
-
-    private static <T extends ISpecialInventory> @Nullable T getSpecialInventory(@NotNull Class<T> expected, @NotNull Inventory inventory) {
-        Object inv;
-        if (isUsable() && craftInventory.isAssignableFrom(inventory.getClass())) {
-            try {
-                inv = getInventory.invoke(inventory);
-                if (expected.isInstance(inv)) {
-                    return expected.cast(inv);
-                }
-            } catch (ReflectiveOperationException ignored) {}
-        }
-
-        // Use reflection to find the IInventory
-        inv = ReflectionHelper.grabObjectByType(inventory, expected);
-
-        if (expected.isInstance(inv)) {
-            return expected.cast(inv);
-        }
-
-        return null;
+        return provider == null ? null : (ISpecialEnderChest) provider.apply(inventory, ISpecialEnderChest.class);
     }
 
     /**
-     * @deprecated Do not create a new instance to use static methods.
+     * Get a {@link ISpecialInventory} backing an {@link Inventory}. Returns {@code null} if the inventory is not backed
+     * by the correct class.
+     *
+     * @param inventory the Bukkit inventory
+     * @return the backing implementation if available
      */
-    @Deprecated(forRemoval = true, since = "4.2.0")
-    public InventoryAccess() {}
+    public static @Nullable ISpecialInventory getInventory(@NotNull Inventory inventory) {
+        return provider == null ? null : provider.apply(inventory, ISpecialInventory.class);
+    }
+
+    @RestrictedApi(
+        explanation = "Not part of the API.",
+        link = "",
+        allowedOnPath = ".*/com/lishid/openinv/util/InternalAccessor.java")
+    @ApiStatus.Internal
+    static void setProvider(@Nullable BiFunction<Inventory, Class<? extends ISpecialInventory>, ISpecialInventory> provider) {
+        InventoryAccess.provider = provider;
+    }
+
+    private InventoryAccess() {
+        throw new IllegalStateException("Cannot create instance of utility class.");
+    }
 
 }

api/src/main/java/com/lishid/openinv/util/setting/PlayerToggle.java

@@ -0,0 +1,36 @@
+package com.lishid.openinv.util.setting;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.UUID;
+
+/**
+ * A per-player setting that may be enabled or disabled.
+ */
+public interface PlayerToggle {
+
+  /**
+   * Get the name of the setting.
+   *
+   * @return the setting name
+   */
+  @NotNull String getName();
+
+  /**
+   * Get the state of the toggle for a particular player ID.
+   *
+   * @param uuid the player ID
+   * @return true if the setting is enabled
+   */
+  boolean is(@NotNull UUID uuid);
+
+  /**
+   * Set the state of the toggle for a particular player ID.
+   *
+   * @param uuid the player ID
+   * @param enabled whether the setting is enabled
+   * @return true if the setting changed as a result of being set
+   */
+  boolean set(@NotNull UUID uuid, boolean enabled);
+
+}

api/src/main/java/com/lishid/openinv/util/setting/PlayerToggles.java

@@ -0,0 +1,106 @@
+package com.lishid.openinv.util.setting;
+
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.UnmodifiableView;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+import java.util.UUID;
+
+/**
+ * Utility class containing all of OpenInv's {@link PlayerToggle PlayerToggles}.
+ */
+public final class PlayerToggles {
+
+  private static final Map<String, PlayerToggle> TOGGLES = new HashMap<>();
+  private static final PlayerToggle ANY = add(new MemoryToggle("AnyContainer"));
+  private static final PlayerToggle SILENT = add(new MemoryToggle("SilentContainer"));
+
+  /**
+   * Get the AnyContainer toggle.
+   *
+   * @return the AnyContainer toggle
+   */
+  public static @NotNull PlayerToggle any() {
+    return ANY;
+  }
+
+  /**
+   * Get the SilentContainer toggle.
+   *
+   * @return the SilentContainer toggle
+   */
+  public static @NotNull PlayerToggle silent() {
+    return SILENT;
+  }
+
+  /**
+   * Get a toggle by name.
+   *
+   * @param toggleName the name of the toggle
+   * @return the toggle, or null if no such toggle exists.
+   */
+  public static @Nullable PlayerToggle get(@NotNull String toggleName) {
+    PlayerToggle toggle = TOGGLES.get(toggleName);
+    if (toggle == null) {
+      toggle = TOGGLES.get(toggleName.toLowerCase(Locale.ENGLISH));
+    }
+    return toggle;
+  }
+
+  /**
+   * Get an unmodifable view of all toggles available.
+   *
+   * @return a view of all toggles available
+   */
+  public static @UnmodifiableView @NotNull Collection<PlayerToggle> get() {
+    return Collections.unmodifiableCollection(TOGGLES.values());
+  }
+
+  private static @NotNull PlayerToggle add(@NotNull PlayerToggle toggle) {
+    TOGGLES.put(toggle.getName().toLowerCase(Locale.ENGLISH), toggle);
+    return toggle;
+  }
+
+  private PlayerToggles() {
+    throw new IllegalStateException("Cannot create instance of utility class.");
+  }
+
+  private static class MemoryToggle implements PlayerToggle {
+
+    private final @NotNull Set<UUID> enabled;
+    private final @NotNull String name;
+
+    private MemoryToggle(@NotNull String name) {
+      enabled = new HashSet<>();
+      this.name = name;
+    }
+
+    @Override
+    public @NotNull String getName() {
+      return this.name;
+    }
+
+    @Override
+    public boolean is(@NotNull UUID uuid) {
+      return enabled.contains(uuid);
+    }
+
+    @Override
+    public boolean set(@NotNull UUID uuid, boolean enabled) {
+      if (enabled) {
+        return this.enabled.add(uuid);
+      } else {
+        return this.enabled.remove(uuid);
+      }
+    }
+
+  }
+
+}

assembly/pom.xml

@@ -1,58 +0,0 @@
-<!--
-  ~ Copyright (C) 2011-2022 lishid. All rights reserved.
-  ~
-  ~ This program is free software: you can redistribute it and/or modify
-  ~ it under the terms of the GNU General Public License as published by
-  ~ the Free Software Foundation, version 3.
-  ~
-  ~ This program is distributed in the hope that it will be useful,
-  ~ but WITHOUT ANY WARRANTY; without even the implied warranty of
-  ~ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-  ~ GNU General Public License for more details.
-  ~
-  ~ You should have received a copy of the GNU General Public License
-  ~ along with this program. If not, see <http://www.gnu.org/licenses/>.
-  -->
-
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-  <modelVersion>4.0.0</modelVersion>
-
-  <parent>
-    <groupId>com.lishid</groupId>
-    <artifactId>openinvparent</artifactId>
-    <version>4.3.1</version>
-  </parent>
-
-  <artifactId>openinvassembly</artifactId>
-  <name>OpenInvAssembly</name>
-  <packaging>pom</packaging>
-
-  <build>
-    <directory>../target</directory>
-    <finalName>OpenInv</finalName>
-
-    <plugins>
-      <plugin>
-        <artifactId>maven-assembly-plugin</artifactId>
-        <executions>
-          <execution>
-            <id>reactor-uberjar</id>
-            <phase>package</phase>
-            <goals>
-              <goal>single</goal>
-            </goals>
-            <configuration>
-              <appendAssemblyId>false</appendAssemblyId>
-              <descriptors>
-                <descriptor>src/assembly/reactor-uberjar.xml</descriptor>
-              </descriptors>
-            </configuration>
-          </execution>
-        </executions>
-      </plugin>
-    </plugins>
-
-  </build>
-
-</project>

assembly/src/assembly/reactor-uberjar.xml

@@ -1,54 +0,0 @@
-<!--
-  ~ Copyright (C) 2011-2021 lishid. All rights reserved.
-  ~
-  ~ This program is free software: you can redistribute it and/or modify
-  ~ it under the terms of the GNU General Public License as published by
-  ~ the Free Software Foundation, version 3.
-  ~
-  ~ This program is distributed in the hope that it will be useful,
-  ~ but WITHOUT ANY WARRANTY; without even the implied warranty of
-  ~ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-  ~ GNU General Public License for more details.
-  ~
-  ~ You should have received a copy of the GNU General Public License
-  ~ along with this program. If not, see <http://www.gnu.org/licenses/>.
-  -->
-
-<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.1.0"
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.1.0 http://maven.apache.org/xsd/assembly-2.1.0.xsd">
-
-  <id>reactor-uberjar</id>
-
-  <formats>
-    <format>jar</format>
-  </formats>
-
-  <includeBaseDirectory>false</includeBaseDirectory>
-
-  <moduleSets>
-    <moduleSet>
-
-      <useAllReactorProjects>true</useAllReactorProjects>
-
-      <binaries>
-        <outputDirectory>/</outputDirectory>
-        <unpack>true</unpack>
-        <unpackOptions>
-          <excludes>
-            <!--
-              - Exclude existing meta - assembly will write its own manifest, and the rest is maven
-              - details that end users don't need. Ignoring it saves around 7KB after compression
-              - with a single internal module present.
-             -->
-            <exclude>META-INF/**</exclude>
-          </excludes>
-        </unpackOptions>
-        <!-- Exclude dependencies - shade plugin will handle their inclusion as necessary in individual jars. -->
-        <includeDependencies>false</includeDependencies>
-      </binaries>
-
-    </moduleSet>
-  </moduleSets>
-
-</assembly>

common/pom.xml

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>com.lishid</groupId>
+        <artifactId>openinvparent</artifactId>
+        <version>5.1.5</version>
+    </parent>
+
+    <artifactId>openinvcommon</artifactId>
+
+    <dependencies>
+        <dependency>
+            <artifactId>annotations</artifactId>
+            <groupId>org.jetbrains</groupId>
+        </dependency>
+        <dependency>
+            <groupId>org.spigotmc</groupId>
+            <artifactId>spigot-api</artifactId>
+        </dependency>
+        <dependency>
+            <artifactId>openinvapi</artifactId>
+            <groupId>com.lishid</groupId>
+        </dependency>
+    </dependencies>
+
+</project>

common/src/main/java/com/lishid/openinv/event/OpenEvents.java

@@ -0,0 +1,39 @@
+package com.lishid.openinv.event;
+
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.util.setting.PlayerToggle;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.Player;
+import org.bukkit.event.Cancellable;
+import org.bukkit.event.Event;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.UUID;
+
+/**
+ * Construct and call events.
+ */
+public final class OpenEvents {
+
+  public static boolean saveCancelled(@NotNull Player player) {
+    return call(new PlayerSaveEvent(player));
+  }
+
+  public static boolean saveCancelled(@NotNull ISpecialInventory inventory) {
+    return call(new OpenPlayerSaveEvent((Player) inventory.getPlayer(), inventory));
+  }
+
+  public static void notifyPlayerToggle(@NotNull PlayerToggle toggle, @NotNull UUID uuid, boolean state) {
+    Bukkit.getPluginManager().callEvent(new PlayerToggledEvent(toggle, uuid, state));
+  }
+
+  private static <T extends Event & Cancellable> boolean call(T event) {
+    Bukkit.getPluginManager().callEvent(event);
+    return event.isCancelled();
+  }
+
+  private OpenEvents() {
+    throw new IllegalStateException("Cannot create instance of utility class.");
+  }
+
+}

common/src/main/java/com/lishid/openinv/internal/Accessor.java

@@ -0,0 +1,24 @@
+package com.lishid.openinv.internal;
+
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.Inventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public interface Accessor {
+
+  @NotNull
+  PlayerManager getPlayerManager();
+
+  @NotNull IAnySilentContainer getAnySilentContainer();
+
+  @NotNull ISpecialPlayerInventory createPlayerInventory(@NotNull Player player);
+
+  @NotNull ISpecialEnderChest createEnderChest(@NotNull Player player);
+
+  <T extends ISpecialInventory> @Nullable T get(@NotNull Inventory bukkitInventory, @NotNull Class<T> clazz);
+
+  void reload(@NotNull ConfigurationSection config);
+
+}

common/src/main/java/com/lishid/openinv/internal/AnySilentContainerBase.java

@@ -0,0 +1,106 @@
+package com.lishid.openinv.internal;
+
+import org.bukkit.block.Barrel;
+import org.bukkit.block.Block;
+import org.bukkit.block.BlockFace;
+import org.bukkit.block.BlockState;
+import org.bukkit.block.EnderChest;
+import org.bukkit.block.ShulkerBox;
+import org.bukkit.block.data.BlockData;
+import org.bukkit.block.data.type.Chest;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.Method;
+
+public abstract class AnySilentContainerBase implements IAnySilentContainer {
+
+  private static final @Nullable Method BLOCK_GET_STATE_BOOLEAN;
+
+  static {
+    @Nullable Method getState;
+    try {
+      //noinspection JavaReflectionMemberAccess
+      getState = Block.class.getMethod("getState", boolean.class);
+    } catch (NoSuchMethodException e) {
+      getState = null;
+    }
+    BLOCK_GET_STATE_BOOLEAN = getState;
+  }
+
+  private static BlockState getBlockState(Block block) {
+    // Paper: Get state without snapshotting.
+    if (BLOCK_GET_STATE_BOOLEAN != null) {
+      try {
+        return (BlockState) BLOCK_GET_STATE_BOOLEAN.invoke(block, false);
+      } catch (ReflectiveOperationException ignored) {
+        // If we encounter an issue, fall through to regular snapshotting method.
+      }
+    }
+    return block.getState();
+  }
+
+  @Override
+  public boolean isAnyContainerNeeded(@NotNull Block block) {
+    BlockState blockState = getBlockState(block);
+
+    // Barrels do not require AnyContainer.
+    if (blockState instanceof Barrel) {
+      return false;
+    }
+
+    // Enderchests require a non-occluding block on top to open.
+    if (blockState instanceof EnderChest) {
+      return block.getRelative(0, 1, 0).getType().isOccluding();
+    }
+
+    // Shulker boxes require half a block clear in the direction they open.
+    if (blockState instanceof ShulkerBox) {
+      return isShulkerBlocked(block);
+    }
+
+    if (!(blockState instanceof org.bukkit.block.Chest)) {
+      return false;
+    }
+
+    if (isChestBlocked(block)) {
+      return true;
+    }
+
+    BlockData blockData = block.getBlockData();
+    if (!(blockData instanceof Chest chest) || chest.getType() == Chest.Type.SINGLE) {
+      return false;
+    }
+
+    BlockFace relativeFace = switch (chest.getFacing()) {
+      case NORTH -> chest.getType() == Chest.Type.RIGHT ? BlockFace.WEST : BlockFace.EAST;
+      case EAST -> chest.getType() == Chest.Type.RIGHT ? BlockFace.NORTH : BlockFace.SOUTH;
+      case SOUTH -> chest.getType() == Chest.Type.RIGHT ? BlockFace.EAST : BlockFace.WEST;
+      case WEST -> chest.getType() == Chest.Type.RIGHT ? BlockFace.SOUTH : BlockFace.NORTH;
+      default -> BlockFace.SELF;
+    };
+    Block relative = block.getRelative(relativeFace);
+
+    if (relative.getType() != block.getType()) {
+      return false;
+    }
+
+    BlockData relativeData = relative.getBlockData();
+    if (!(relativeData instanceof Chest relativeChest)) {
+      return false;
+    }
+
+    if (relativeChest.getFacing() != chest.getFacing()
+        || relativeChest.getType() != (chest.getType() == Chest.Type.RIGHT ? Chest.Type.LEFT : Chest.Type.RIGHT)) {
+      return false;
+    }
+
+    return isChestBlocked(relative);
+  }
+
+  @Override
+  public boolean isAnySilentContainer(@NotNull Block block) {
+    return isAnySilentContainer(getBlockState(block));
+  }
+
+}

common/src/main/java/com/lishid/openinv/internal/InternalOwned.java

@@ -0,0 +1,7 @@
+package com.lishid.openinv.internal;
+
+public interface InternalOwned<T> {
+
+  T getOwnerHandle();
+
+}

common/src/main/java/com/lishid/openinv/internal/InventoryViewTitle.java

@@ -0,0 +1,48 @@
+package com.lishid.openinv.internal;
+
+import com.lishid.openinv.util.lang.LanguageManager;
+import com.lishid.openinv.util.lang.Replacement;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.entity.Player;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Objects;
+
+public enum InventoryViewTitle {
+
+  PLAYER_INVENTORY("container.player", "'s Inventory"),
+  ENDER_CHEST("container.enderchest", "'s Ender Chest");
+
+  private final String localizationKey;
+  private final String defaultSuffix;
+
+  InventoryViewTitle(String localizationKey, String defaultSuffix) {
+    this.localizationKey = localizationKey;
+    this.defaultSuffix = defaultSuffix;
+  }
+
+  public @NotNull String getTitle(
+      @NotNull LanguageManager lang,
+      @NotNull Player viewer,
+      @NotNull ISpecialInventory inventory) {
+    HumanEntity owner = inventory.getPlayer();
+
+    String localTitle = lang.getLocalizedMessage(
+            viewer,
+            localizationKey,
+            new Replacement("%player%", owner.getName()));
+    return Objects.requireNonNullElseGet(localTitle, () -> owner.getName() + defaultSuffix);
+  }
+
+  public static @Nullable InventoryViewTitle of(@NotNull ISpecialInventory inventory) {
+    if (inventory instanceof ISpecialPlayerInventory) {
+      return PLAYER_INVENTORY;
+    } else if (inventory instanceof ISpecialEnderChest) {
+      return ENDER_CHEST;
+    } else {
+      return null;
+    }
+  }
+
+}

common/src/main/java/com/lishid/openinv/internal/PlayerManager.java

@@ -22,7 +22,7 @@ import org.bukkit.inventory.InventoryView;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public interface IPlayerDataManager {
+public interface PlayerManager {
 
     /**
      * Loads a Player for an OfflinePlayer.
@@ -49,18 +49,6 @@ public interface IPlayerDataManager {
      *`
      * @return the InventoryView opened
      */
-    @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory);
-
-    /**
-     * Convert a raw slot number into a player inventory slot number.
-     *
-     * <p>Note that this method is specifically for converting an ISpecialPlayerInventory slot number into a regular
-     * player inventory slot number.
-     *
-     * @param view the open inventory view
-     * @param rawSlot the raw slot in the view
-     * @return the converted slot number
-     */
-    int convertToPlayerSlot(InventoryView view, int rawSlot);
+    @Nullable InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory, boolean viewOnly);
 
 }

common/src/main/java/com/lishid/openinv/internal/ViewOnly.java

@@ -0,0 +1,4 @@
+package com.lishid.openinv.internal;
+
+public interface ViewOnly {
+}

common/src/main/java/com/lishid/openinv/util/Permissions.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2011-2022 lishid. All rights reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.lishid.openinv.util;
+
+import org.bukkit.permissions.Permissible;
+import org.jetbrains.annotations.NotNull;
+
+public enum Permissions {
+
+    INVENTORY_OPEN_SELF("inventory.open.self"),
+    INVENTORY_OPEN_OTHER("inventory.open.other"),
+    INVENTORY_EDIT_SELF("inventory.edit.self"),
+    INVENTORY_EDIT_OTHER("inventory.edit.other"),
+    INVENTORY_SLOT_HEAD_ANY("inventory.slot.head.any"),
+    INVENTORY_SLOT_CHEST_ANY("inventory.slot.chest.any"),
+    INVENTORY_SLOT_LEGS_ANY("inventory.slot.legs.any"),
+    INVENTORY_SLOT_FEET_ANY("inventory.slot.feet.any"),
+    INVENTORY_SLOT_DROP("inventory.slot.drop"),
+
+    ENDERCHEST_OPEN_SELF("enderchest.open.self"),
+    ENDERCHEST_OPEN_OTHER("enderchest.open.other"),
+    ENDERCHEST_EDIT_SELF("enderchest.edit.self"),
+    ENDERCHEST_EDIT_OTHER("enderchest.edit.other"),
+
+    ACCESS_CROSSWORLD("access.crossworld"),
+    ACCESS_OFFLINE("access.offline"),
+    ACCESS_ONLINE("access.online"),
+
+    SPECTATE_CLICK("spectate.click"),
+
+    CONTAINER_ANY("container.any"),
+    CONTAINER_SILENT("container.silent"),
+    SEARCH_INVENTORY("search.inventory"),
+    SEARCH_CONTAINER("search.container");
+
+    private final String permission;
+
+    Permissions(String permission) {
+        this.permission = "openinv." + permission;
+    }
+
+    public boolean hasPermission(@NotNull Permissible permissible) {
+        return permissible.hasPermission(permission);
+    }
+
+}

common/src/main/java/com/lishid/openinv/util/ReflectionHelper.java

@@ -16,16 +16,15 @@
 
 package com.lishid.openinv.util;
 
-import java.lang.reflect.Field;
 import org.jetbrains.annotations.Nullable;
 
+import java.lang.reflect.Field;
+
 /**
  * A utility for making reflection easier.
  */
 public final class ReflectionHelper {
 
-    private ReflectionHelper() {}
-
     /**
      * Grab an {@link Object} stored in a {@link Field} of another {@code Object}.
      *
@@ -59,8 +58,8 @@ public final class ReflectionHelper {
      */
     public static @Nullable Field grabFieldByType(Class<?> holderType, Class<?> fieldType) {
         for (Field field : holderType.getDeclaredFields()) {
-            field.setAccessible(true);
             if (fieldType.isAssignableFrom(field.getType())) {
+                field.setAccessible(true);
                 return field;
             }
         }
@@ -72,4 +71,8 @@ public final class ReflectionHelper {
         return null;
     }
 
+    private ReflectionHelper() {
+        throw new IllegalStateException("Cannot create instance of utility class.");
+    }
+
 }

common/src/main/java/com/lishid/openinv/util/lang/LanguageManager.java

@@ -16,24 +16,31 @@
 
 package com.lishid.openinv.util.lang;
 
-import com.lishid.openinv.OpenInv;
+import net.md_5.bungee.api.ChatMessageType;
+import net.md_5.bungee.api.chat.TextComponent;
+import org.bukkit.ChatColor;
+import org.bukkit.command.CommandSender;
+import org.bukkit.configuration.Configuration;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.configuration.file.YamlConfiguration;
+import org.bukkit.entity.Player;
+import org.bukkit.plugin.Plugin;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.function.Predicate;
 import java.util.logging.Level;
-import org.bukkit.ChatColor;
-import org.bukkit.configuration.Configuration;
-import org.bukkit.configuration.ConfigurationSection;
-import org.bukkit.configuration.file.YamlConfiguration;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 /**
  * A simple language manager supporting both custom and bundled languages.
@@ -42,14 +49,26 @@ import org.jetbrains.annotations.Nullable;
  */
 public class LanguageManager {
 
-    private final OpenInv plugin;
+    private final Plugin plugin;
+    private final File folder;
     private final String defaultLocale;
     private final Map<String, YamlConfiguration> locales;
 
-    public LanguageManager(@NotNull OpenInv plugin, @NotNull String defaultLocale) {
+    public LanguageManager(@NotNull Plugin plugin, @NotNull String defaultLocale) {
         this.plugin = plugin;
         this.defaultLocale = defaultLocale;
         this.locales = new HashMap<>();
+        this.folder = new File(plugin.getDataFolder(), "locale");
+
+        if (!folder.exists() && !folder.mkdirs()) {
+            plugin.getLogger().warning(() -> "Unable to create " + folder.getPath() + "! Languages may not be editable.");
+        }
+
+        reload();
+    }
+
+    public void reload() {
+        this.locales.clear();
         getOrLoadLocale(defaultLocale);
     }
 
@@ -59,57 +78,86 @@ public class LanguageManager {
             return loaded;
         }
 
-        File file = new File(plugin.getDataFolder(), locale + ".yml");
+        LangLocation lang = bestMatch(locale, null);
+
+        // If a parent was a better match, check if it is already loaded.
+        if (!locale.equals(lang.locale)) {
+            loaded = locales.get(lang.locale);
+            if (loaded != null) {
+                locales.put(locale, loaded);
+                return loaded;
+            }
+        }
 
         // Load locale config from disk and bundled locale defaults.
-        YamlConfiguration localeConfig = loadLocale(locale, file);
+        YamlConfiguration localeConfig = loadLocale(lang);
 
         // If the locale is not the default locale, also handle any missing translations from the default locale.
         if (!locale.equals(defaultLocale)) {
-            addTranslationFallthrough(locale, localeConfig, file);
+            addTranslationFallthrough(lang, localeConfig);
 
             if (plugin.getConfig().getBoolean("settings.secret.warn-about-guess-section", true)
                     && localeConfig.isConfigurationSection("guess")) {
                 // Warn that guess section exists. This should run once per language per server restart
                 // when accessed by a user to hint to server owners that they can make UX improvements.
-                plugin.getLogger().info(() -> "[LanguageManager] Missing translations from " + locale + ".yml! Check the guess section!");
+                plugin.getLogger().info(() -> "[LanguageManager] Missing translations from " + lang.locale + ".yml! Check the guess section!");
             }
         }
 
         locales.put(locale, localeConfig);
+        locales.put(lang.locale, localeConfig);
+
         return localeConfig;
     }
 
-    private @NotNull YamlConfiguration loadLocale(
-            @NotNull String locale,
-            @NotNull File file) {
-        // Load defaults from the plugin's bundled resources.
-        InputStream resourceStream = plugin.getResource("locale/" + locale + ".yml");
+    private @NotNull LangLocation bestMatch(@NotNull String locale, @Nullable LangLocation initial) {
+        File file = new File(folder, locale + ".yml");
+        InputStream bundled = plugin.getResource("locale/" + locale + ".yml");
+
+        if (file.exists() || bundled != null) {
+            return new LangLocation(locale, file, bundled);
+        }
+
+        if (initial == null) {
+            initial = new LangLocation(locale, file, null);
+        }
+
+        int lastSeparator = locale.lastIndexOf('_');
+
+        // Must be at least some content before separator.
+        if (lastSeparator < 1) {
+            return initial;
+        }
+
+        return bestMatch(locale.substring(0, lastSeparator), initial);
+    }
+
+    private @NotNull YamlConfiguration loadLocale(@NotNull LangLocation lang) {
         YamlConfiguration localeConfigDefaults;
-        if (resourceStream == null) {
+        if (lang.bundled == null) {
             localeConfigDefaults = new YamlConfiguration();
         } else {
-            try (BufferedReader reader = new BufferedReader(new InputStreamReader(resourceStream))) {
+            try (BufferedReader reader = new BufferedReader(new InputStreamReader(lang.bundled, StandardCharsets.UTF_8))) {
                 localeConfigDefaults = YamlConfiguration.loadConfiguration(reader);
             } catch (IOException e) {
-                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to load resource " + locale + ".yml");
+                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to load resource " + lang.locale + ".yml");
                 localeConfigDefaults = new YamlConfiguration();
             }
         }
 
-        if (!file.exists()) {
+        if (!lang.file.exists()) {
             // If the file does not exist on disk, save bundled defaults.
             try {
-                localeConfigDefaults.save(file);
+                localeConfigDefaults.save(lang.file);
             } catch (IOException e) {
-                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + locale + ".yml");
+                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + lang.locale + ".yml");
             }
             // Return loaded bundled locale.
             return localeConfigDefaults;
         }
 
         // If the file does exist on disk, load it.
-        YamlConfiguration localeConfig = YamlConfiguration.loadConfiguration(file);
+        YamlConfiguration localeConfig = YamlConfiguration.loadConfiguration(lang.file);
         // Check for missing translations from the bundled file.
         List<String> newKeys = getMissingKeys(localeConfigDefaults, localeConfig::isSet);
 
@@ -135,22 +183,19 @@ public class LanguageManager {
             localeConfig.set("guess", null);
         }
 
-        plugin.getLogger().info(() -> "[LanguageManager] Added new translation keys to " + locale + ".yml: " + String.join(", ", newKeys));
+        plugin.getLogger().info(() -> "[LanguageManager] Added new translation keys to " + lang.locale + ".yml: " + String.join(", ", newKeys));
 
         // Write new keys to disk.
         try {
-            localeConfig.save(file);
+            localeConfig.save(lang.file);
         } catch (IOException e) {
-            plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + locale + ".yml");
+            plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + lang.locale + ".yml");
         }
 
         return localeConfig;
     }
 
-    private void addTranslationFallthrough(
-            @NotNull String locale,
-            @NotNull YamlConfiguration localeConfig,
-            @NotNull File file) {
+    private void addTranslationFallthrough(@NotNull LangLocation location, @NotNull YamlConfiguration localeConfig) {
         YamlConfiguration defaultLocaleConfig = locales.get(defaultLocale);
 
         // Get missing keys. Keys that already have a guess value are not new and don't need to trigger another write.
@@ -166,9 +211,9 @@ public class LanguageManager {
 
             // Write modified guess section to disk.
             try {
-                localeConfig.save(file);
+                localeConfig.save(location.file);
             } catch (IOException e) {
-                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + locale + ".yml");
+                plugin.getLogger().log(Level.WARNING, e, () -> "[LanguageManager] Unable to save resource " + location.locale + ".yml");
             }
         }
 
@@ -190,8 +235,8 @@ public class LanguageManager {
     }
 
     public @Nullable String getValue(@NotNull String key, @Nullable String locale) {
-        String value = getOrLoadLocale(locale == null ? defaultLocale : locale.toLowerCase()).getString(key);
-        if (value == null || value.isEmpty()) {
+        String value = getOrLoadLocale(locale == null ? defaultLocale : locale.toLowerCase(Locale.ENGLISH)).getString(key);
+        if (value == null || value.isBlank()) {
             return null;
         }
 
@@ -214,4 +259,61 @@ public class LanguageManager {
         return value;
     }
 
+    public @Nullable String getLocalizedMessage(@NotNull CommandSender sender, @NotNull String key) {
+        return getValue(key, getLocale(sender));
+    }
+
+    public @Nullable String getLocalizedMessage(
+        @NotNull CommandSender sender,
+        @NotNull String key,
+        Replacement @NotNull ... replacements) {
+        return getValue(key, getLocale(sender), replacements);
+    }
+
+    private @NotNull String getLocale(@NotNull CommandSender sender) {
+        if (sender instanceof Player) {
+            return ((Player) sender).getLocale();
+        } else {
+            return plugin.getConfig().getString("settings.locale", "en");
+        }
+    }
+
+    public void sendMessage(@NotNull CommandSender sender, @NotNull String key) {
+        String message = getLocalizedMessage(sender, key);
+
+        if (message != null && !message.isEmpty()) {
+            sender.sendMessage(message);
+        }
+    }
+
+    public void sendMessage(@NotNull CommandSender sender, @NotNull String key, Replacement @NotNull... replacements) {
+        String message = getLocalizedMessage(sender, key, replacements);
+
+        if (message != null && !message.isEmpty()) {
+            sender.sendMessage(message);
+        }
+    }
+
+    public void sendSystemMessage(@NotNull Player player, @NotNull String key) {
+        String message = getLocalizedMessage(player, key);
+
+        if (message == null) {
+            return;
+        }
+
+        int newline = message.indexOf('\n');
+        if (newline != -1) {
+            // No newlines in action bar chat.
+            message = message.substring(0, newline);
+        }
+
+        if (message.isEmpty()) {
+            return;
+        }
+
+        player.spigot().sendMessage(ChatMessageType.ACTION_BAR, TextComponent.fromLegacy(message));
+    }
+
+    private record LangLocation(@NotNull String locale, @NotNull File file, @Nullable InputStream bundled) {}
+
 }

internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/OpenPlayer.java

@@ -1,74 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_19_R3;
-
-import java.io.File;
-import net.minecraft.Util;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.NbtIo;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.level.storage.PlayerDataStorage;
-import org.apache.logging.log4j.LogManager;
-import org.bukkit.craftbukkit.v1_19_R3.CraftServer;
-import org.bukkit.craftbukkit.v1_19_R3.entity.CraftPlayer;
-
-public class OpenPlayer extends CraftPlayer {
-
-    public OpenPlayer(CraftServer server, ServerPlayer entity) {
-        super(server, entity);
-    }
-
-    @Override
-    public void loadData() {
-        // See CraftPlayer#loadData
-        CompoundTag loaded = this.server.getHandle().playerIo.load(this.getHandle());
-        if (loaded != null) {
-            getHandle().readAdditionalSaveData(loaded);
-        }
-    }
-
-    @Override
-    public void saveData() {
-        ServerPlayer player = this.getHandle();
-        // See net.minecraft.world.level.storage.PlayerDataStorage#save(EntityHuman)
-        try {
-            PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
-
-            CompoundTag playerData = player.saveWithoutId(new CompoundTag());
-            setExtraData(playerData);
-
-            if (!isOnline()) {
-                // Special case: save old vehicle data
-                CompoundTag oldData = worldNBTStorage.load(player);
-
-                if (oldData != null && oldData.contains("RootVehicle", 10)) {
-                    // See net.minecraft.server.PlayerList#a(NetworkManager, EntityPlayer) and net.minecraft.server.EntityPlayer#b(NBTTagCompound)
-                    playerData.put("RootVehicle", oldData.getCompound("RootVehicle"));
-                }
-            }
-
-            File file = File.createTempFile(player.getStringUUID() + "-", ".dat", worldNBTStorage.getPlayerDir());
-            NbtIo.writeCompressed(playerData, file);
-            File file1 = new File(worldNBTStorage.getPlayerDir(), player.getStringUUID() + ".dat");
-            File file2 = new File(worldNBTStorage.getPlayerDir(), player.getStringUUID() + ".dat_old");
-            Util.safeReplaceFile(file1, file, file2);
-        } catch (Exception e) {
-            LogManager.getLogger().warn("Failed to save player data for {}: {}", player.getScoreboardName(), e);
-        }
-    }
-
-}

internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/PlayerDataManager.java

@@ -1,265 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_19_R3;
-
-import com.lishid.openinv.OpenInv;
-import com.lishid.openinv.internal.IPlayerDataManager;
-import com.lishid.openinv.internal.ISpecialInventory;
-import com.lishid.openinv.internal.OpenInventoryView;
-import com.mojang.authlib.GameProfile;
-import java.lang.reflect.Field;
-import java.util.logging.Logger;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.network.chat.Component;
-import net.minecraft.network.protocol.game.ClientboundOpenScreenPacket;
-import net.minecraft.server.MinecraftServer;
-import net.minecraft.server.level.ServerLevel;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.entity.Entity;
-import net.minecraft.world.inventory.AbstractContainerMenu;
-import net.minecraft.world.inventory.MenuType;
-import net.minecraft.world.level.Level;
-import net.minecraft.world.phys.Vec3;
-import org.bukkit.Bukkit;
-import org.bukkit.OfflinePlayer;
-import org.bukkit.Server;
-import org.bukkit.craftbukkit.v1_19_R3.CraftServer;
-import org.bukkit.craftbukkit.v1_19_R3.CraftWorld;
-import org.bukkit.craftbukkit.v1_19_R3.entity.CraftPlayer;
-import org.bukkit.craftbukkit.v1_19_R3.event.CraftEventFactory;
-import org.bukkit.craftbukkit.v1_19_R3.inventory.CraftContainer;
-import org.bukkit.entity.Player;
-import org.bukkit.inventory.InventoryView;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-public class PlayerDataManager implements IPlayerDataManager {
-
-    private @Nullable Field bukkitEntity;
-
-    public PlayerDataManager() {
-        try {
-            bukkitEntity = Entity.class.getDeclaredField("bukkitEntity");
-        } catch (NoSuchFieldException e) {
-            Logger logger = OpenInv.getPlugin(OpenInv.class).getLogger();
-            logger.warning("Unable to obtain field to inject custom save process - players' mounts may be deleted when loaded.");
-            logger.log(java.util.logging.Level.WARNING, e.getMessage(), e);
-            bukkitEntity = null;
-        }
-    }
-
-    public static @NotNull ServerPlayer getHandle(final Player player) {
-        if (player instanceof CraftPlayer) {
-            return ((CraftPlayer) player).getHandle();
-        }
-
-        Server server = player.getServer();
-        ServerPlayer nmsPlayer = null;
-
-        if (server instanceof CraftServer) {
-            nmsPlayer = ((CraftServer) server).getHandle().getPlayer(player.getUniqueId());
-        }
-
-        if (nmsPlayer == null) {
-            // Could use reflection to examine fields, but it's honestly not worth the bother.
-            throw new RuntimeException("Unable to fetch EntityPlayer from provided Player implementation");
-        }
-
-        return nmsPlayer;
-    }
-
-    @Override
-    public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
-        // Ensure player has data
-        if (!offline.hasPlayedBefore()) {
-            return null;
-        }
-
-        // Create a profile and entity to load the player data
-        // See net.minecraft.server.players.PlayerList#canPlayerLogin
-        // and net.minecraft.server.network.ServerLoginPacketListenerImpl#handleHello
-        GameProfile profile = new GameProfile(offline.getUniqueId(),
-                offline.getName() != null ? offline.getName() : offline.getUniqueId().toString());
-        MinecraftServer server = ((CraftServer) Bukkit.getServer()).getServer();
-        ServerLevel worldServer = server.getLevel(Level.OVERWORLD);
-
-        if (worldServer == null) {
-            return null;
-        }
-
-        ServerPlayer entity = new ServerPlayer(server, worldServer, profile);
-
-        // Stop listening for advancement progression - if this is not cleaned up, loading causes a memory leak.
-        entity.getAdvancements().stopListening();
-
-        try {
-            injectPlayer(entity);
-        } catch (IllegalAccessException e) {
-            e.printStackTrace();
-        }
-
-        // Load data. This also reads basic data into the player.
-        // See CraftPlayer#loadData
-        CompoundTag loadedData = server.getPlayerList().playerIo.load(entity);
-
-        if (loadedData == null) {
-            // Exceptions with loading are logged by Mojang.
-            return null;
-        }
-
-        // Also read "extra" data.
-        entity.readAdditionalSaveData(loadedData);
-
-        if (entity.level == null) {
-            // Paper: Move player to spawn
-            // SPIGOT-7340: Cannot call ServerPlayer#spawnIn with a null world
-            ServerLevel level = null;
-            Vec3 position = null;
-            if (entity.getRespawnDimension() != null) {
-                level = entity.server.getLevel(entity.getRespawnDimension());
-                if (level != null && entity.getRespawnPosition() != null) {
-                    position = net.minecraft.world.entity.player.Player.findRespawnPositionAndUseSpawnBlock(level, entity.getRespawnPosition(), entity.getRespawnAngle(), false, false).orElse(null);
-                }
-            }
-            if (level == null || position == null) {
-                level = ((CraftWorld) server.server.getWorlds().get(0)).getHandle();
-                position = Vec3.atCenterOf(level.getSharedSpawnPos());
-            }
-            entity.level = level;
-            entity.setPos(position);
-        }
-
-        // Return the Bukkit entity.
-        return entity.getBukkitEntity();
-    }
-
-    void injectPlayer(ServerPlayer player) throws IllegalAccessException {
-        if (bukkitEntity == null) {
-            return;
-        }
-
-        bukkitEntity.setAccessible(true);
-
-        bukkitEntity.set(player, new OpenPlayer(player.server.server, player));
-    }
-
-    @NotNull
-    @Override
-    public Player inject(@NotNull Player player) {
-        try {
-            ServerPlayer nmsPlayer = getHandle(player);
-            if (nmsPlayer.getBukkitEntity() instanceof OpenPlayer openPlayer) {
-                return openPlayer;
-            }
-            injectPlayer(nmsPlayer);
-            return nmsPlayer.getBukkitEntity();
-        } catch (IllegalAccessException e) {
-            e.printStackTrace();
-            return player;
-        }
-    }
-
-    @Nullable
-    @Override
-    public InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory) {
-
-        ServerPlayer nmsPlayer = getHandle(player);
-
-        if (nmsPlayer.connection == null) {
-            return null;
-        }
-
-        InventoryView view = getView(player, inventory);
-
-        if (view == null) {
-            return player.openInventory(inventory.getBukkitInventory());
-        }
-
-        AbstractContainerMenu container = new CraftContainer(view, nmsPlayer, nmsPlayer.nextContainerCounter()) {
-            @Override
-            public MenuType<?> getType() {
-                return getContainers(inventory.getBukkitInventory().getSize());
-            }
-        };
-
-        container.setTitle(Component.literal(view.getTitle()));
-        container = CraftEventFactory.callInventoryOpenEvent(nmsPlayer, container);
-
-        if (container == null) {
-            return null;
-        }
-
-        nmsPlayer.connection.send(new ClientboundOpenScreenPacket(container.containerId, container.getType(),
-                Component.literal(container.getBukkitView().getTitle())));
-        nmsPlayer.containerMenu = container;
-        nmsPlayer.initMenu(container);
-
-        return container.getBukkitView();
-
-    }
-
-    private @Nullable InventoryView getView(Player player, ISpecialInventory inventory) {
-        if (inventory instanceof SpecialEnderChest) {
-            return new OpenInventoryView(player, inventory, "container.enderchest", "'s Ender Chest");
-        } else if (inventory instanceof SpecialPlayerInventory) {
-            return new OpenInventoryView(player, inventory, "container.player", "'s Inventory");
-        } else {
-            return null;
-        }
-    }
-
-    static @NotNull MenuType<?> getContainers(int inventorySize) {
-
-        return switch (inventorySize) {
-            case 9 -> MenuType.GENERIC_9x1;
-            case 18 -> MenuType.GENERIC_9x2;
-            case 36 -> MenuType.GENERIC_9x4; // PLAYER
-            case 41, 45 -> MenuType.GENERIC_9x5;
-            case 54 -> MenuType.GENERIC_9x6;
-            default -> MenuType.GENERIC_9x3; // Default 27-slot inventory
-        };
-    }
-
-    @Override
-    public int convertToPlayerSlot(InventoryView view, int rawSlot) {
-        int topSize = view.getTopInventory().getSize();
-        if (topSize <= rawSlot) {
-            // Slot is not inside special inventory, use Bukkit logic.
-            return view.convertSlot(rawSlot);
-        }
-
-        // Main inventory, slots 0-26 -> 9-35
-        if (rawSlot < 27) {
-            return rawSlot + 9;
-        }
-        // Hotbar, slots 27-35 -> 0-8
-        if (rawSlot < 36) {
-            return rawSlot - 27;
-        }
-        // Armor, slots 36-39 -> 39-36
-        if (rawSlot < 40) {
-            return 36 + (39 - rawSlot);
-        }
-        // Off hand
-        if (rawSlot == 40) {
-            return 40;
-        }
-        // Drop slots, "out of inventory"
-        return -1;
-    }
-
-}

internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/SpecialEnderChest.java

@@ -1,350 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_19_R3;
-
-import com.lishid.openinv.internal.ISpecialEnderChest;
-import java.util.List;
-import java.util.function.Predicate;
-import java.util.stream.Collectors;
-import net.minecraft.core.NonNullList;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.ListTag;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.ContainerHelper;
-import net.minecraft.world.ContainerListener;
-import net.minecraft.world.entity.player.Player;
-import net.minecraft.world.entity.player.StackedContents;
-import net.minecraft.world.inventory.PlayerEnderChestContainer;
-import net.minecraft.world.item.Item;
-import net.minecraft.world.item.ItemStack;
-import net.minecraft.world.level.block.entity.EnderChestBlockEntity;
-import org.bukkit.Location;
-import org.bukkit.craftbukkit.v1_19_R3.entity.CraftHumanEntity;
-import org.bukkit.craftbukkit.v1_19_R3.inventory.CraftInventory;
-import org.bukkit.entity.HumanEntity;
-import org.bukkit.inventory.InventoryHolder;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-public class SpecialEnderChest extends PlayerEnderChestContainer implements ISpecialEnderChest {
-
-    private final CraftInventory inventory;
-    private ServerPlayer owner;
-    private NonNullList<ItemStack> items;
-    private boolean playerOnline;
-
-    public SpecialEnderChest(final org.bukkit.entity.Player player, final Boolean online) {
-        super(PlayerDataManager.getHandle(player));
-        this.inventory = new CraftInventory(this);
-        this.owner = PlayerDataManager.getHandle(player);
-        this.playerOnline = online;
-        this.items = this.owner.getEnderChestInventory().items;
-    }
-
-    @Override
-    public @NotNull CraftInventory getBukkitInventory() {
-        return inventory;
-    }
-
-    @Override
-    public void setPlayerOffline() {
-        this.playerOnline = false;
-    }
-
-    @Override
-    public void setPlayerOnline(@NotNull final org.bukkit.entity.Player player) {
-        if (this.playerOnline) {
-            return;
-        }
-
-        ServerPlayer offlinePlayer = this.owner;
-        ServerPlayer onlinePlayer = PlayerDataManager.getHandle(player);
-
-        // Set owner to new player.
-        this.owner = onlinePlayer;
-
-        // Set player's ender chest contents to our modified contents.
-        PlayerEnderChestContainer onlineEnderChest = onlinePlayer.getEnderChestInventory();
-        for (int i = 0; i < onlineEnderChest.getContainerSize(); ++i) {
-            onlineEnderChest.setItem(i, this.items.get(i));
-        }
-
-        // Set our item array to the new inventory's array.
-        this.items = onlineEnderChest.items;
-
-        // Add viewers to new inventory.
-        onlineEnderChest.transaction.addAll(offlinePlayer.getEnderChestInventory().transaction);
-
-        this.playerOnline = true;
-    }
-
-    @Override
-    public @NotNull org.bukkit.entity.Player getPlayer() {
-        return owner.getBukkitEntity();
-    }
-
-    @Override
-    public void setChanged() {
-        this.owner.getEnderChestInventory().setChanged();
-    }
-
-    @Override
-    public List<ItemStack> getContents() {
-        return this.items;
-    }
-
-    @Override
-    public void onOpen(CraftHumanEntity who) {
-        this.owner.getEnderChestInventory().onOpen(who);
-    }
-
-    @Override
-    public void onClose(CraftHumanEntity who) {
-        this.owner.getEnderChestInventory().onClose(who);
-    }
-
-    @Override
-    public List<HumanEntity> getViewers() {
-        return this.owner.getEnderChestInventory().getViewers();
-    }
-
-    @Override
-    public boolean stillValid(Player player) {
-        return true;
-    }
-
-    @Override
-    public void setActiveChest(EnderChestBlockEntity enderChest) {
-        this.owner.getEnderChestInventory().setActiveChest(enderChest);
-    }
-
-    @Override
-    public boolean isActiveChest(EnderChestBlockEntity enderChest) {
-        return this.owner.getEnderChestInventory().isActiveChest(enderChest);
-    }
-
-    @Override
-    public int getMaxStackSize() {
-        return this.owner.getEnderChestInventory().getMaxStackSize();
-    }
-
-    @Override
-    public void setMaxStackSize(int i) {
-        this.owner.getEnderChestInventory().setMaxStackSize(i);
-    }
-
-    @Override
-    public InventoryHolder getOwner() {
-        return this.owner.getEnderChestInventory().getOwner();
-    }
-
-    @Override
-    public @Nullable Location getLocation() {
-        return null;
-    }
-
-    @Override
-    public void addListener(ContainerListener listener) {
-        this.owner.getEnderChestInventory().addListener(listener);
-    }
-
-    @Override
-    public void removeListener(ContainerListener listener) {
-        this.owner.getEnderChestInventory().removeListener(listener);
-    }
-
-    @Override
-    public ItemStack getItem(int i) {
-        return i >= 0 && i < this.items.size() ? this.items.get(i) : ItemStack.EMPTY;
-    }
-
-    @Override
-    public ItemStack removeItem(int i, int j) {
-        ItemStack itemstack = ContainerHelper.removeItem(this.items, i, j);
-        if (!itemstack.isEmpty()) {
-            this.setChanged();
-        }
-
-        return itemstack;
-    }
-
-    @Override
-    public ItemStack addItem(ItemStack itemstack) {
-        ItemStack localItem = itemstack.copy();
-        this.moveItemToOccupiedSlotsWithSameType(localItem);
-        if (localItem.isEmpty()) {
-            return ItemStack.EMPTY;
-        } else {
-            this.moveItemToEmptySlots(localItem);
-            return localItem.isEmpty() ? ItemStack.EMPTY : localItem;
-        }
-    }
-
-    @Override
-    public boolean canAddItem(ItemStack itemstack) {
-        for (ItemStack itemstack1 : this.items) {
-            if (itemstack1.isEmpty() || ItemStack.isSameItemSameTags(itemstack1, itemstack) && itemstack1.getCount() < itemstack1.getMaxStackSize()) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
-    private void moveItemToEmptySlots(ItemStack itemstack) {
-        for(int i = 0; i < this.getContainerSize(); ++i) {
-            ItemStack localItem = this.getItem(i);
-            if (localItem.isEmpty()) {
-                this.setItem(i, itemstack.copy());
-                itemstack.setCount(0);
-                return;
-            }
-        }
-    }
-
-    private void moveItemToOccupiedSlotsWithSameType(ItemStack itemstack) {
-        for(int i = 0; i < this.getContainerSize(); ++i) {
-            ItemStack localItem = this.getItem(i);
-            if (ItemStack.isSameItemSameTags(localItem, itemstack)) {
-                this.moveItemsBetweenStacks(itemstack, localItem);
-                if (itemstack.isEmpty()) {
-                    return;
-                }
-            }
-        }
-    }
-
-    private void moveItemsBetweenStacks(ItemStack itemstack, ItemStack itemstack1) {
-        int i = Math.min(this.getMaxStackSize(), itemstack1.getMaxStackSize());
-        int j = Math.min(itemstack.getCount(), i - itemstack1.getCount());
-        if (j > 0) {
-            itemstack1.grow(j);
-            itemstack.shrink(j);
-            this.setChanged();
-        }
-    }
-
-    @Override
-    public ItemStack removeItemNoUpdate(int i) {
-        ItemStack itemstack = this.items.get(i);
-        if (itemstack.isEmpty()) {
-            return ItemStack.EMPTY;
-        } else {
-            this.items.set(i, ItemStack.EMPTY);
-            return itemstack;
-        }
-    }
-
-    @Override
-    public void setItem(int i, ItemStack itemstack) {
-        this.items.set(i, itemstack);
-        if (!itemstack.isEmpty() && itemstack.getCount() > this.getMaxStackSize()) {
-            itemstack.setCount(this.getMaxStackSize());
-        }
-
-        this.setChanged();
-    }
-
-    @Override
-    public int getContainerSize() {
-        return this.owner.getEnderChestInventory().getContainerSize();
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return this.items.stream().allMatch(ItemStack::isEmpty);
-    }
-
-    @Override
-    public void startOpen(Player player) {
-    }
-
-    @Override
-    public void stopOpen(Player player) {
-    }
-
-    @Override
-    public boolean canPlaceItem(int i, ItemStack itemstack) {
-        return true;
-    }
-
-    @Override
-    public void clearContent() {
-        this.items.clear();
-        this.setChanged();
-    }
-
-    @Override
-    public void fillStackedContents(StackedContents stackedContents) {
-        for (ItemStack itemstack : this.items) {
-            stackedContents.accountStack(itemstack);
-        }
-
-    }
-
-    @Override
-    public List<ItemStack> removeAllItems() {
-        List<ItemStack> list = this.items.stream().filter(Predicate.not(ItemStack::isEmpty)).collect(Collectors.toList());
-        this.clearContent();
-        return list;
-    }
-
-    @Override
-    public ItemStack removeItemType(Item item, int i) {
-        ItemStack itemstack = new ItemStack(item, 0);
-
-        for(int j = this.getContainerSize() - 1; j >= 0; --j) {
-            ItemStack localItem = this.getItem(j);
-            if (localItem.getItem().equals(item)) {
-                int k = i - itemstack.getCount();
-                ItemStack splitItem = localItem.split(k);
-                itemstack.grow(splitItem.getCount());
-                if (itemstack.getCount() == i) {
-                    break;
-                }
-            }
-        }
-
-        if (!itemstack.isEmpty()) {
-            this.setChanged();
-        }
-
-        return itemstack;
-    }
-
-    @Override
-    public String toString() {
-        return this.items.stream().filter((itemStack) -> !itemStack.isEmpty()).toList().toString();
-    }
-
-    @Override
-    public void fromTag(ListTag listTag) {
-        for (int i = 0; i < this.getContainerSize(); ++i) {
-            this.setItem(i, ItemStack.EMPTY);
-        }
-
-        for (int i = 0; i < listTag.size(); ++i) {
-            CompoundTag compoundTag = listTag.getCompound(i);
-            int j = compoundTag.getByte("Slot") & 255;
-            if (j < this.getContainerSize()) {
-                this.setItem(j, ItemStack.of(compoundTag));
-            }
-        }
-
-    }
-
-}

internal/v1_19_R3/src/main/java/com/lishid/openinv/internal/v1_19_R3/SpecialPlayerInventory.java

@@ -1,806 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_19_R3;
-
-import com.google.common.collect.ImmutableList;
-import com.lishid.openinv.internal.ISpecialPlayerInventory;
-import java.util.Collection;
-import java.util.Iterator;
-import java.util.List;
-import java.util.function.Function;
-import java.util.function.Predicate;
-import java.util.stream.Collectors;
-import net.minecraft.CrashReport;
-import net.minecraft.CrashReportCategory;
-import net.minecraft.ReportedException;
-import net.minecraft.core.NonNullList;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.ListTag;
-import net.minecraft.network.chat.Component;
-import net.minecraft.network.protocol.game.ClientboundContainerSetSlotPacket;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.tags.DamageTypeTags;
-import net.minecraft.tags.TagKey;
-import net.minecraft.world.Container;
-import net.minecraft.world.ContainerHelper;
-import net.minecraft.world.damagesource.DamageSource;
-import net.minecraft.world.entity.EquipmentSlot;
-import net.minecraft.world.entity.player.Inventory;
-import net.minecraft.world.entity.player.Player;
-import net.minecraft.world.entity.player.StackedContents;
-import net.minecraft.world.item.ArmorItem;
-import net.minecraft.world.item.Item;
-import net.minecraft.world.item.ItemStack;
-import net.minecraft.world.level.block.state.BlockState;
-import org.bukkit.Location;
-import org.bukkit.craftbukkit.v1_19_R3.entity.CraftHumanEntity;
-import org.bukkit.craftbukkit.v1_19_R3.inventory.CraftInventory;
-import org.bukkit.entity.HumanEntity;
-import org.bukkit.inventory.InventoryHolder;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-public class SpecialPlayerInventory extends Inventory implements ISpecialPlayerInventory {
-
-    private final CraftInventory inventory;
-    private boolean playerOnline;
-    private Player player;
-    private NonNullList<ItemStack> items;
-    private NonNullList<ItemStack> armor;
-    private NonNullList<ItemStack> offhand;
-    private List<NonNullList<ItemStack>> compartments;
-
-    public SpecialPlayerInventory(@NotNull org.bukkit.entity.Player bukkitPlayer, @NotNull Boolean online) {
-        super(PlayerDataManager.getHandle(bukkitPlayer));
-        this.inventory = new CraftInventory(this);
-        this.playerOnline = online;
-        this.player = super.player;
-        this.selected = player.getInventory().selected;
-        this.items = this.player.getInventory().items;
-        this.armor = this.player.getInventory().armor;
-        this.offhand = this.player.getInventory().offhand;
-        this.compartments = ImmutableList.of(this.items, this.armor, this.offhand);
-    }
-
-    @Override
-    public void setPlayerOnline(@NotNull org.bukkit.entity.Player player) {
-        if (this.playerOnline) {
-            return;
-        }
-
-        Player offlinePlayer = this.player;
-        Player onlinePlayer = PlayerDataManager.getHandle(player);
-        onlinePlayer.getInventory().transaction.addAll(this.transaction);
-
-        // Set owner to new player.
-        this.player = onlinePlayer;
-
-        // Set player's inventory contents to our modified contents.
-        Inventory onlineInventory = onlinePlayer.getInventory();
-        for (int i = 0; i < getContainerSize(); ++i) {
-            onlineInventory.setItem(i, getRawItem(i));
-        }
-        onlineInventory.selected = this.selected;
-
-        // Set our item arrays to the new inventory's arrays.
-        this.items = onlineInventory.items;
-        this.armor = onlineInventory.armor;
-        this.offhand = onlineInventory.offhand;
-        this.compartments = ImmutableList.of(this.items, this.armor, this.offhand);
-
-        // Add existing viewers to new viewer list.
-        Inventory offlineInventory = offlinePlayer.getInventory();
-        // Remove self from listing - player is always a viewer of their own inventory, prevent duplicates.
-        offlineInventory.transaction.remove(offlinePlayer.getBukkitEntity());
-        onlineInventory.transaction.addAll(offlineInventory.transaction);
-
-        this.playerOnline = true;
-    }
-
-    @Override
-    public @NotNull CraftInventory getBukkitInventory() {
-        return this.inventory;
-    }
-
-    @Override
-    public void setPlayerOffline() {
-        this.playerOnline = false;
-    }
-
-    @Override
-    public @NotNull HumanEntity getPlayer() {
-        return this.player.getBukkitEntity();
-    }
-
-    private @NotNull ItemStack getRawItem(int i) {
-        if (i < 0) {
-            return ItemStack.EMPTY;
-        }
-
-        NonNullList<ItemStack> list;
-        for (Iterator<NonNullList<ItemStack>> iterator = this.compartments.iterator(); iterator.hasNext(); i -= list.size()) {
-            list = iterator.next();
-            if (i < list.size()) {
-                return list.get(i);
-            }
-        }
-
-        return ItemStack.EMPTY;
-    }
-
-    private void setRawItem(int i, @NotNull ItemStack itemStack) {
-        if (i < 0) {
-            return;
-        }
-
-        NonNullList<ItemStack> list;
-        for (Iterator<NonNullList<ItemStack>> iterator = this.compartments.iterator(); iterator.hasNext(); i -= list.size()) {
-            list = iterator.next();
-            if (i < list.size()) {
-                list.set(i, itemStack);
-            }
-        }
-    }
-
-    private record IndexedCompartment(@Nullable NonNullList<ItemStack> compartment, int index) {}
-
-    private @NotNull SpecialPlayerInventory.IndexedCompartment getIndexedContent(int index) {
-        if (index < items.size()) {
-            return new IndexedCompartment(items, getReversedItemSlotNum(index));
-        }
-
-        index -= items.size();
-
-        if (index < armor.size()) {
-            return new IndexedCompartment(armor, getReversedArmorSlotNum(index));
-        }
-
-        index -= armor.size();
-
-        if (index < offhand.size()) {
-            return new IndexedCompartment(offhand, index);
-        }
-
-        index -= offhand.size();
-
-        return new IndexedCompartment(null, index);
-    }
-
-    private int getReversedArmorSlotNum(final int i) {
-        if (i == 0) {
-            return 3;
-        }
-        if (i == 1) {
-            return 2;
-        }
-        if (i == 2) {
-            return 1;
-        }
-        if (i == 3) {
-            return 0;
-        }
-        return i;
-    }
-
-    private int getReversedItemSlotNum(final int i) {
-        if (i >= 27) {
-            return i - 27;
-        }
-        return i + 9;
-    }
-
-    private boolean contains(Predicate<ItemStack> predicate) {
-        return this.compartments.stream().flatMap(NonNullList::stream).anyMatch(predicate);
-    }
-
-    @Override
-    public List<ItemStack> getArmorContents() {
-        return this.armor;
-    }
-
-    @Override
-    public void onOpen(CraftHumanEntity who) {
-        this.player.getInventory().onOpen(who);
-    }
-
-    @Override
-    public void onClose(CraftHumanEntity who) {
-        this.player.getInventory().onClose(who);
-    }
-
-    @Override
-    public List<HumanEntity> getViewers() {
-        return this.player.getInventory().getViewers();
-    }
-
-    @Override
-    public InventoryHolder getOwner() {
-        return this.player.getBukkitEntity();
-    }
-
-    @Override
-    public int getMaxStackSize() {
-        return this.player.getInventory().getMaxStackSize();
-    }
-
-    @Override
-    public void setMaxStackSize(int size) {
-        this.player.getInventory().setMaxStackSize(size);
-    }
-
-    @Override
-    public Location getLocation() {
-        return this.player.getBukkitEntity().getLocation();
-    }
-
-    @Override
-    public boolean hasCustomName() {
-        return false;
-    }
-
-    @Override
-    public List<ItemStack> getContents() {
-        return this.compartments.stream().flatMap(Collection::stream).collect(Collectors.toList());
-    }
-
-    @Override
-    public ItemStack getSelected() {
-        return isHotbarSlot(this.selected) ? this.items.get(this.selected) : ItemStack.EMPTY;
-    }
-
-    private boolean hasRemainingSpaceForItem(ItemStack itemstack, ItemStack itemstack1) {
-        return !itemstack.isEmpty() && ItemStack.isSameItemSameTags(itemstack, itemstack1) && itemstack.isStackable() && itemstack.getCount() < itemstack.getMaxStackSize() && itemstack.getCount() < this.getMaxStackSize();
-    }
-
-    @Override
-    public int canHold(ItemStack itemstack) {
-        int remains = itemstack.getCount();
-
-        for (int i = 0; i < this.items.size(); ++i) {
-            ItemStack itemstack1 = this.getRawItem(i);
-            if (itemstack1.isEmpty()) {
-                return itemstack.getCount();
-            }
-
-            if (this.hasRemainingSpaceForItem(itemstack1, itemstack)) {
-                remains -= (itemstack1.getMaxStackSize() < this.getMaxStackSize() ? itemstack1.getMaxStackSize() : this.getMaxStackSize()) - itemstack1.getCount();
-            }
-
-            if (remains <= 0) {
-                return itemstack.getCount();
-            }
-        }
-
-        ItemStack offhandItemStack = this.getRawItem(this.items.size() + this.armor.size());
-        if (this.hasRemainingSpaceForItem(offhandItemStack, itemstack)) {
-            remains -= (offhandItemStack.getMaxStackSize() < this.getMaxStackSize() ? offhandItemStack.getMaxStackSize() : this.getMaxStackSize()) - offhandItemStack.getCount();
-        }
-
-        return remains <= 0 ? itemstack.getCount() : itemstack.getCount() - remains;
-    }
-
-    @Override
-    public int getFreeSlot() {
-        for(int i = 0; i < this.items.size(); ++i) {
-            if (this.items.get(i).isEmpty()) {
-                return i;
-            }
-        }
-
-        return -1;
-    }
-
-    @Override
-    public void setPickedItem(ItemStack itemstack) {
-        int i = this.findSlotMatchingItem(itemstack);
-        if (isHotbarSlot(i)) {
-            this.selected = i;
-        } else if (i == -1) {
-            this.selected = this.getSuitableHotbarSlot();
-            if (!this.items.get(this.selected).isEmpty()) {
-                int j = this.getFreeSlot();
-                if (j != -1) {
-                    this.items.set(j, this.items.get(this.selected));
-                }
-            }
-
-            this.items.set(this.selected, itemstack);
-        } else {
-            this.pickSlot(i);
-        }
-
-    }
-
-    @Override
-    public void pickSlot(int i) {
-        this.selected = this.getSuitableHotbarSlot();
-        ItemStack itemstack = this.items.get(this.selected);
-        this.items.set(this.selected, this.items.get(i));
-        this.items.set(i, itemstack);
-    }
-
-    @Override
-    public int findSlotMatchingItem(ItemStack itemstack) {
-        for(int i = 0; i < this.items.size(); ++i) {
-            if (!this.items.get(i).isEmpty() && ItemStack.isSameItemSameTags(itemstack, this.items.get(i))) {
-                return i;
-            }
-        }
-
-        return -1;
-    }
-
-    @Override
-    public int findSlotMatchingUnusedItem(ItemStack itemStack) {
-        for(int i = 0; i < this.items.size(); ++i) {
-            ItemStack localItem = this.items.get(i);
-            if (!this.items.get(i).isEmpty() && ItemStack.isSameItemSameTags(itemStack, this.items.get(i)) && !this.items.get(i).isDamaged() && !localItem.isEnchanted() && !localItem.hasCustomHoverName()) {
-                return i;
-            }
-        }
-
-        return -1;
-    }
-
-    @Override
-    public int getSuitableHotbarSlot() {
-        int i;
-        int j;
-        for(j = 0; j < 9; ++j) {
-            i = (this.selected + j) % 9;
-            if (this.items.get(i).isEmpty()) {
-                return i;
-            }
-        }
-
-        for(j = 0; j < 9; ++j) {
-            i = (this.selected + j) % 9;
-            if (!this.items.get(i).isEnchanted()) {
-                return i;
-            }
-        }
-
-        return this.selected;
-    }
-
-    @Override
-    public void swapPaint(double d0) {
-        if (d0 > 0.0D) {
-            d0 = 1.0D;
-        }
-
-        if (d0 < 0.0D) {
-            d0 = -1.0D;
-        }
-
-        this.selected = (int) (this.selected - d0);
-
-        while (this.selected < 0) {
-            this.selected += 9;
-        }
-
-        while(this.selected >= 9) {
-            this.selected -= 9;
-        }
-    }
-
-    @Override
-    public int clearOrCountMatchingItems(Predicate<ItemStack> predicate, int i, Container container) {
-        byte b0 = 0;
-        boolean flag = i == 0;
-        int j = b0 + ContainerHelper.clearOrCountMatchingItems(this, predicate, i - b0, flag);
-        j += ContainerHelper.clearOrCountMatchingItems(container, predicate, i - j, flag);
-        ItemStack itemstack = this.player.containerMenu.getCarried();
-        j += ContainerHelper.clearOrCountMatchingItems(itemstack, predicate, i - j, flag);
-        if (itemstack.isEmpty()) {
-            this.player.containerMenu.setCarried(ItemStack.EMPTY);
-        }
-
-        return j;
-    }
-
-    private int addResource(ItemStack itemstack) {
-        int i = this.getSlotWithRemainingSpace(itemstack);
-        if (i == -1) {
-            i = this.getFreeSlot();
-        }
-
-        return i == -1 ? itemstack.getCount() : this.addResource(i, itemstack);
-    }
-
-    private int addResource(int i, ItemStack itemstack) {
-        Item item = itemstack.getItem();
-        int j = itemstack.getCount();
-        ItemStack localItemStack = this.getRawItem(i);
-        if (localItemStack.isEmpty()) {
-            localItemStack = new ItemStack(item, 0);
-            if (itemstack.hasTag()) {
-                // hasTag ensures tag not null
-                //noinspection ConstantConditions
-                localItemStack.setTag(itemstack.getTag().copy());
-            }
-
-            this.setRawItem(i, localItemStack);
-        }
-
-        int k = Math.min(j, localItemStack.getMaxStackSize() - localItemStack.getCount());
-
-        if (k > this.getMaxStackSize() - localItemStack.getCount()) {
-            k = this.getMaxStackSize() - localItemStack.getCount();
-        }
-
-        if (k != 0) {
-            j -= k;
-            localItemStack.grow(k);
-            localItemStack.setPopTime(5);
-        }
-
-        return j;
-    }
-
-    @Override
-    public int getSlotWithRemainingSpace(ItemStack itemstack) {
-        if (this.hasRemainingSpaceForItem(this.getRawItem(this.selected), itemstack)) {
-            return this.selected;
-        } else if (this.hasRemainingSpaceForItem(this.getRawItem(40), itemstack)) {
-            return 40;
-        } else {
-            for(int i = 0; i < this.items.size(); ++i) {
-                if (this.hasRemainingSpaceForItem(this.items.get(i), itemstack)) {
-                    return i;
-                }
-            }
-
-            return -1;
-        }
-    }
-
-    @Override
-    public void tick() {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            for (int i = 0; i < compartment.size(); ++i) {
-                if (!compartment.get(i).isEmpty()) {
-                    compartment.get(i).inventoryTick(this.player.level, this.player, i, this.selected == i);
-                }
-            }
-        }
-
-    }
-
-    @Override
-    public boolean add(ItemStack itemStack) {
-        return this.add(-1, itemStack);
-    }
-
-    @Override
-    public boolean add(int i, ItemStack itemStack) {
-        if (itemStack.isEmpty()) {
-            return false;
-        } else {
-            try {
-                if (itemStack.isDamaged()) {
-                    if (i == -1) {
-                        i = this.getFreeSlot();
-                    }
-
-                    if (i >= 0) {
-                        this.items.set(i, itemStack.copy());
-                        this.items.get(i).setPopTime(5);
-                        itemStack.setCount(0);
-                        return true;
-                    } else if (this.player.getAbilities().instabuild) {
-                        itemStack.setCount(0);
-                        return true;
-                    } else {
-                        return false;
-                    }
-                } else {
-                    int j;
-                    do {
-                        j = itemStack.getCount();
-                        if (i == -1) {
-                            itemStack.setCount(this.addResource(itemStack));
-                        } else {
-                            itemStack.setCount(this.addResource(i, itemStack));
-                        }
-                    } while(!itemStack.isEmpty() && itemStack.getCount() < j);
-
-                    if (itemStack.getCount() == j && this.player.getAbilities().instabuild) {
-                        itemStack.setCount(0);
-                        return true;
-                    } else {
-                        return itemStack.getCount() < j;
-                    }
-                }
-            } catch (Throwable var6) {
-                CrashReport crashReport = CrashReport.forThrowable(var6, "Adding item to inventory");
-                CrashReportCategory crashReportCategory = crashReport.addCategory("Item being added");
-                crashReportCategory.setDetail("Item ID", Item.getId(itemStack.getItem()));
-                crashReportCategory.setDetail("Item data", itemStack.getDamageValue());
-                crashReportCategory.setDetail("Item name", () -> itemStack.getHoverName().getString());
-                throw new ReportedException(crashReport);
-            }
-        }
-    }
-
-    @Override
-    public void placeItemBackInInventory(ItemStack itemStack) {
-        this.placeItemBackInInventory(itemStack, true);
-    }
-
-    @Override
-    public void placeItemBackInInventory(ItemStack itemStack, boolean flag) {
-        while(true) {
-            if (!itemStack.isEmpty()) {
-                int i = this.getSlotWithRemainingSpace(itemStack);
-                if (i == -1) {
-                    i = this.getFreeSlot();
-                }
-
-                if (i != -1) {
-                    int j = itemStack.getMaxStackSize() - this.getRawItem(i).getCount();
-                    if (this.add(i, itemStack.split(j)) && flag && this.player instanceof ServerPlayer) {
-                        ((ServerPlayer)this.player).connection.send(new ClientboundContainerSetSlotPacket(-2, 0, i, this.getRawItem(i)));
-                    }
-                    continue;
-                }
-
-                this.player.drop(itemStack, false);
-            }
-
-            return;
-        }
-    }
-
-    @Override
-    public ItemStack removeItem(int rawIndex, final int j) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null
-                || indexedCompartment.compartment().get(indexedCompartment.index()).isEmpty()) {
-            return ItemStack.EMPTY;
-        }
-
-        return ContainerHelper.removeItem(indexedCompartment.compartment(), indexedCompartment.index(), j);
-    }
-
-    @Override
-    public void removeItem(ItemStack itemStack) {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            for (int i = 0; i < compartment.size(); ++i) {
-                if (compartment.get(i) == itemStack) {
-                    compartment.set(i, ItemStack.EMPTY);
-                    break;
-                }
-            }
-        }
-    }
-
-    @Override
-    public ItemStack removeItemNoUpdate(int rawIndex) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null) {
-            return ItemStack.EMPTY;
-        }
-
-        ItemStack removed = indexedCompartment.compartment().set(indexedCompartment.index(), ItemStack.EMPTY);
-
-        if (removed.isEmpty()) {
-            return ItemStack.EMPTY;
-        }
-
-        return removed;
-    }
-
-    @Override
-    public void setItem(int rawIndex, final ItemStack itemStack) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null) {
-            this.player.drop(itemStack, true);
-            return;
-        }
-
-        indexedCompartment.compartment().set(indexedCompartment.index(), itemStack);
-    }
-
-    @Override
-    public float getDestroySpeed(BlockState blockState) {
-        return this.items.get(this.selected).getDestroySpeed(blockState);
-    }
-
-    @Override
-    public ListTag save(ListTag listTag) {
-        for (int i = 0; i < this.items.size(); ++i) {
-            if (!this.items.get(i).isEmpty()) {
-                CompoundTag compoundTag = new CompoundTag();
-                compoundTag.putByte("Slot", (byte)i);
-                this.items.get(i).save(compoundTag);
-                listTag.add(compoundTag);
-            }
-        }
-
-        for (int i = 0; i < this.armor.size(); ++i) {
-            if (!this.armor.get(i).isEmpty()) {
-                CompoundTag compoundTag = new CompoundTag();
-                compoundTag.putByte("Slot", (byte)(i + 100));
-                this.armor.get(i).save(compoundTag);
-                listTag.add(compoundTag);
-            }
-        }
-
-        for (int i = 0; i < this.offhand.size(); ++i) {
-            if (!this.offhand.get(i).isEmpty()) {
-                CompoundTag compoundTag = new CompoundTag();
-                compoundTag.putByte("Slot", (byte)(i + 150));
-                this.offhand.get(i).save(compoundTag);
-                listTag.add(compoundTag);
-            }
-        }
-
-        return listTag;
-    }
-
-    @Override
-    public void load(ListTag listTag) {
-        this.items.clear();
-        this.armor.clear();
-        this.offhand.clear();
-
-        for(int i = 0; i < listTag.size(); ++i) {
-            CompoundTag compoundTag = listTag.getCompound(i);
-            int j = compoundTag.getByte("Slot") & 255;
-            ItemStack itemstack = ItemStack.of(compoundTag);
-            if (!itemstack.isEmpty()) {
-                if (j < this.items.size()) {
-                    this.items.set(j, itemstack);
-                } else if (j >= 100 && j < this.armor.size() + 100) {
-                    this.armor.set(j - 100, itemstack);
-                } else if (j >= 150 && j < this.offhand.size() + 150) {
-                    this.offhand.set(j - 150, itemstack);
-                }
-            }
-        }
-
-    }
-
-    @Override
-    public int getContainerSize() {
-        return 45;
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return !contains(itemStack -> !itemStack.isEmpty());
-    }
-
-    @Override
-    public ItemStack getItem(int rawIndex) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null) {
-            return ItemStack.EMPTY;
-        }
-
-        return indexedCompartment.compartment().get(indexedCompartment.index());
-    }
-
-    @Override
-    public Component getName() {
-        return this.player.getName();
-    }
-
-    @Override
-    public ItemStack getArmor(int index) {
-        return this.armor.get(index);
-    }
-
-    @Override
-    public void hurtArmor(DamageSource damagesource, float damage, int[] armorIndices) {
-        if (damage > 0.0F) {
-            damage /= 4.0F;
-            if (damage < 1.0F) {
-                damage = 1.0F;
-            }
-
-            for (int index : armorIndices) {
-                ItemStack itemstack = this.armor.get(index);
-                if ((!damagesource.is(DamageTypeTags.IS_FIRE) || !itemstack.getItem().isFireResistant()) && itemstack.getItem() instanceof ArmorItem) {
-                    itemstack.hurtAndBreak((int) damage, this.player, localPlayer -> localPlayer.broadcastBreakEvent(EquipmentSlot.byTypeAndIndex(EquipmentSlot.Type.ARMOR, index)));
-                }
-            }
-        }
-    }
-
-    @Override
-    public void dropAll() {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            for (int i = 0; i < compartment.size(); ++i) {
-                ItemStack itemstack = compartment.get(i);
-                if (!itemstack.isEmpty()) {
-                    this.player.drop(itemstack, true, false);
-                    compartment.set(i, ItemStack.EMPTY);
-                }
-            }
-        }
-    }
-
-    @Override
-    public void setChanged() {
-        super.setChanged();
-    }
-
-    @Override
-    public int getTimesChanged() {
-        return super.getTimesChanged();
-    }
-
-    @Override
-    public boolean stillValid(Player player) {
-        return true;
-    }
-
-    @Override
-    public boolean contains(ItemStack itemstack) {
-        return contains(itemStack -> itemStack.isEmpty() && itemStack.sameItem(itemstack));
-    }
-
-    @Override
-    public boolean contains(TagKey<Item> tagKey) {
-
-        return contains(itemStack -> !itemStack.isEmpty() && itemStack.is(tagKey));
-    }
-
-    @Override
-    public void replaceWith(Inventory inventory) {
-        Function<Integer, ItemStack> getter;
-
-        if (inventory instanceof SpecialPlayerInventory specialPlayerInventory) {
-            getter = specialPlayerInventory::getRawItem;
-        } else {
-            getter = inventory::getItem;
-        }
-
-        for(int i = 0; i < this.getContainerSize(); ++i) {
-            this.setRawItem(i, getter.apply(i));
-        }
-
-        this.selected = inventory.selected;
-    }
-
-    @Override
-    public void clearContent() {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            compartment.clear();
-        }
-    }
-
-    @Override
-    public void fillStackedContents(StackedContents stackedContents) {
-        for (ItemStack itemstack : this.items) {
-            stackedContents.accountSimpleStack(itemstack);
-        }
-    }
-
-    @Override
-    public ItemStack removeFromSelected(boolean dropWholeStack) {
-        ItemStack itemstack = this.getSelected();
-        return itemstack.isEmpty() ? ItemStack.EMPTY : this.removeItem(this.selected, dropWholeStack ? itemstack.getCount() : 1);
-    }
-
-}

internal/v1_20_R1/src/main/java/com/lishid/openinv/internal/v1_20_R1/OpenPlayer.java

@@ -1,74 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_20_R1;
-
-import com.mojang.logging.LogUtils;
-import java.io.File;
-import net.minecraft.Util;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.NbtIo;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.level.storage.PlayerDataStorage;
-import org.bukkit.craftbukkit.v1_20_R1.CraftServer;
-import org.bukkit.craftbukkit.v1_20_R1.entity.CraftPlayer;
-
-public class OpenPlayer extends CraftPlayer {
-
-    public OpenPlayer(CraftServer server, ServerPlayer entity) {
-        super(server, entity);
-    }
-
-    @Override
-    public void loadData() {
-        // See CraftPlayer#loadData
-        CompoundTag loaded = this.server.getHandle().playerIo.load(this.getHandle());
-        if (loaded != null) {
-            getHandle().readAdditionalSaveData(loaded);
-        }
-    }
-
-    @Override
-    public void saveData() {
-        ServerPlayer player = this.getHandle();
-        // See net.minecraft.world.level.storage.PlayerDataStorage#save(EntityHuman)
-        try {
-            PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
-
-            CompoundTag playerData = player.saveWithoutId(new CompoundTag());
-            setExtraData(playerData);
-
-            if (!isOnline()) {
-                // Special case: save old vehicle data
-                CompoundTag oldData = worldNBTStorage.load(player);
-
-                if (oldData != null && oldData.contains("RootVehicle", 10)) {
-                    // See net.minecraft.server.PlayerList#a(NetworkManager, EntityPlayer) and net.minecraft.server.EntityPlayer#b(NBTTagCompound)
-                    playerData.put("RootVehicle", oldData.getCompound("RootVehicle"));
-                }
-            }
-
-            File file = File.createTempFile(player.getStringUUID() + "-", ".dat", worldNBTStorage.getPlayerDir());
-            NbtIo.writeCompressed(playerData, file);
-            File file1 = new File(worldNBTStorage.getPlayerDir(), player.getStringUUID() + ".dat");
-            File file2 = new File(worldNBTStorage.getPlayerDir(), player.getStringUUID() + ".dat_old");
-            Util.safeReplaceFile(file1, file, file2);
-        } catch (Exception e) {
-            LogUtils.getLogger().warn("Failed to save player data for {}: {}", player.getScoreboardName(), e);
-        }
-    }
-
-}

internal/v1_20_R1/src/main/java/com/lishid/openinv/internal/v1_20_R1/PlayerDataManager.java

@@ -1,249 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_20_R1;
-
-import com.lishid.openinv.OpenInv;
-import com.lishid.openinv.internal.IPlayerDataManager;
-import com.lishid.openinv.internal.ISpecialInventory;
-import com.lishid.openinv.internal.OpenInventoryView;
-import com.mojang.authlib.GameProfile;
-import java.lang.reflect.Field;
-import java.util.logging.Logger;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.network.chat.Component;
-import net.minecraft.network.protocol.game.ClientboundOpenScreenPacket;
-import net.minecraft.server.MinecraftServer;
-import net.minecraft.server.level.ServerLevel;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.entity.Entity;
-import net.minecraft.world.inventory.AbstractContainerMenu;
-import net.minecraft.world.inventory.MenuType;
-import net.minecraft.world.level.Level;
-import org.bukkit.Bukkit;
-import org.bukkit.OfflinePlayer;
-import org.bukkit.Server;
-import org.bukkit.craftbukkit.v1_20_R1.CraftServer;
-import org.bukkit.craftbukkit.v1_20_R1.entity.CraftPlayer;
-import org.bukkit.craftbukkit.v1_20_R1.event.CraftEventFactory;
-import org.bukkit.craftbukkit.v1_20_R1.inventory.CraftContainer;
-import org.bukkit.entity.Player;
-import org.bukkit.inventory.InventoryView;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-public class PlayerDataManager implements IPlayerDataManager {
-
-    private @Nullable Field bukkitEntity;
-
-    public PlayerDataManager() {
-        try {
-            bukkitEntity = Entity.class.getDeclaredField("bukkitEntity");
-        } catch (NoSuchFieldException e) {
-            Logger logger = OpenInv.getPlugin(OpenInv.class).getLogger();
-            logger.warning("Unable to obtain field to inject custom save process - players' mounts may be deleted when loaded.");
-            logger.log(java.util.logging.Level.WARNING, e.getMessage(), e);
-            bukkitEntity = null;
-        }
-    }
-
-    public static @NotNull ServerPlayer getHandle(final Player player) {
-        if (player instanceof CraftPlayer) {
-            return ((CraftPlayer) player).getHandle();
-        }
-
-        Server server = player.getServer();
-        ServerPlayer nmsPlayer = null;
-
-        if (server instanceof CraftServer) {
-            nmsPlayer = ((CraftServer) server).getHandle().getPlayer(player.getUniqueId());
-        }
-
-        if (nmsPlayer == null) {
-            // Could use reflection to examine fields, but it's honestly not worth the bother.
-            throw new RuntimeException("Unable to fetch EntityPlayer from provided Player implementation");
-        }
-
-        return nmsPlayer;
-    }
-
-    @Override
-    public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
-        // Ensure player has data
-        if (!offline.hasPlayedBefore()) {
-            return null;
-        }
-
-        // Create a profile and entity to load the player data
-        // See net.minecraft.server.players.PlayerList#canPlayerLogin
-        // and net.minecraft.server.network.ServerLoginPacketListenerImpl#handleHello
-        GameProfile profile = new GameProfile(offline.getUniqueId(),
-                offline.getName() != null ? offline.getName() : offline.getUniqueId().toString());
-        MinecraftServer server = ((CraftServer) Bukkit.getServer()).getServer();
-        ServerLevel worldServer = server.getLevel(Level.OVERWORLD);
-
-        if (worldServer == null) {
-            return null;
-        }
-
-        ServerPlayer entity = new ServerPlayer(server, worldServer, profile);
-
-        // Stop listening for advancement progression - if this is not cleaned up, loading causes a memory leak.
-        entity.getAdvancements().stopListening();
-
-        try {
-            injectPlayer(entity);
-        } catch (IllegalAccessException e) {
-            e.printStackTrace();
-        }
-
-        // Load data. This also reads basic data into the player.
-        // See CraftPlayer#loadData
-        CompoundTag loadedData = server.getPlayerList().playerIo.load(entity);
-
-        if (loadedData == null) {
-            // Exceptions with loading are logged by Mojang.
-            return null;
-        }
-
-        // Also read "extra" data.
-        entity.readAdditionalSaveData(loadedData);
-
-        if (entity.level() == null) {
-            // Paper: Move player to spawn
-            entity.spawnIn(null);
-        }
-
-        // Return the Bukkit entity.
-        return entity.getBukkitEntity();
-    }
-
-    void injectPlayer(ServerPlayer player) throws IllegalAccessException {
-        if (bukkitEntity == null) {
-            return;
-        }
-
-        bukkitEntity.setAccessible(true);
-
-        bukkitEntity.set(player, new OpenPlayer(player.server.server, player));
-    }
-
-    @NotNull
-    @Override
-    public Player inject(@NotNull Player player) {
-        try {
-            ServerPlayer nmsPlayer = getHandle(player);
-            if (nmsPlayer.getBukkitEntity() instanceof OpenPlayer openPlayer) {
-                return openPlayer;
-            }
-            injectPlayer(nmsPlayer);
-            return nmsPlayer.getBukkitEntity();
-        } catch (IllegalAccessException e) {
-            e.printStackTrace();
-            return player;
-        }
-    }
-
-    @Nullable
-    @Override
-    public InventoryView openInventory(@NotNull Player player, @NotNull ISpecialInventory inventory) {
-
-        ServerPlayer nmsPlayer = getHandle(player);
-
-        if (nmsPlayer.connection == null) {
-            return null;
-        }
-
-        InventoryView view = getView(player, inventory);
-
-        if (view == null) {
-            return player.openInventory(inventory.getBukkitInventory());
-        }
-
-        AbstractContainerMenu container = new CraftContainer(view, nmsPlayer, nmsPlayer.nextContainerCounter()) {
-            @Override
-            public MenuType<?> getType() {
-                return getContainers(inventory.getBukkitInventory().getSize());
-            }
-        };
-
-        container.setTitle(Component.literal(view.getTitle()));
-        container = CraftEventFactory.callInventoryOpenEvent(nmsPlayer, container);
-
-        if (container == null) {
-            return null;
-        }
-
-        nmsPlayer.connection.send(new ClientboundOpenScreenPacket(container.containerId, container.getType(),
-                Component.literal(container.getBukkitView().getTitle())));
-        nmsPlayer.containerMenu = container;
-        nmsPlayer.initMenu(container);
-
-        return container.getBukkitView();
-
-    }
-
-    private @Nullable InventoryView getView(Player player, ISpecialInventory inventory) {
-        if (inventory instanceof SpecialEnderChest) {
-            return new OpenInventoryView(player, inventory, "container.enderchest", "'s Ender Chest");
-        } else if (inventory instanceof SpecialPlayerInventory) {
-            return new OpenInventoryView(player, inventory, "container.player", "'s Inventory");
-        } else {
-            return null;
-        }
-    }
-
-    static @NotNull MenuType<?> getContainers(int inventorySize) {
-
-        return switch (inventorySize) {
-            case 9 -> MenuType.GENERIC_9x1;
-            case 18 -> MenuType.GENERIC_9x2;
-            case 36 -> MenuType.GENERIC_9x4; // PLAYER
-            case 41, 45 -> MenuType.GENERIC_9x5;
-            case 54 -> MenuType.GENERIC_9x6;
-            default -> MenuType.GENERIC_9x3; // Default 27-slot inventory
-        };
-    }
-
-    @Override
-    public int convertToPlayerSlot(InventoryView view, int rawSlot) {
-        int topSize = view.getTopInventory().getSize();
-        if (topSize <= rawSlot) {
-            // Slot is not inside special inventory, use Bukkit logic.
-            return view.convertSlot(rawSlot);
-        }
-
-        // Main inventory, slots 0-26 -> 9-35
-        if (rawSlot < 27) {
-            return rawSlot + 9;
-        }
-        // Hotbar, slots 27-35 -> 0-8
-        if (rawSlot < 36) {
-            return rawSlot - 27;
-        }
-        // Armor, slots 36-39 -> 39-36
-        if (rawSlot < 40) {
-            return 36 + (39 - rawSlot);
-        }
-        // Off hand
-        if (rawSlot == 40) {
-            return 40;
-        }
-        // Drop slots, "out of inventory"
-        return -1;
-    }
-
-}

internal/v1_20_R1/src/main/java/com/lishid/openinv/internal/v1_20_R1/SpecialEnderChest.java

@@ -1,350 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_20_R1;
-
-import com.lishid.openinv.internal.ISpecialEnderChest;
-import java.util.List;
-import java.util.function.Predicate;
-import java.util.stream.Collectors;
-import net.minecraft.core.NonNullList;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.ListTag;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.world.ContainerHelper;
-import net.minecraft.world.ContainerListener;
-import net.minecraft.world.entity.player.Player;
-import net.minecraft.world.entity.player.StackedContents;
-import net.minecraft.world.inventory.PlayerEnderChestContainer;
-import net.minecraft.world.item.Item;
-import net.minecraft.world.item.ItemStack;
-import net.minecraft.world.level.block.entity.EnderChestBlockEntity;
-import org.bukkit.Location;
-import org.bukkit.craftbukkit.v1_20_R1.entity.CraftHumanEntity;
-import org.bukkit.craftbukkit.v1_20_R1.inventory.CraftInventory;
-import org.bukkit.entity.HumanEntity;
-import org.bukkit.inventory.InventoryHolder;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-public class SpecialEnderChest extends PlayerEnderChestContainer implements ISpecialEnderChest {
-
-    private final CraftInventory inventory;
-    private ServerPlayer owner;
-    private NonNullList<ItemStack> items;
-    private boolean playerOnline;
-
-    public SpecialEnderChest(final org.bukkit.entity.Player player, final Boolean online) {
-        super(PlayerDataManager.getHandle(player));
-        this.inventory = new CraftInventory(this);
-        this.owner = PlayerDataManager.getHandle(player);
-        this.playerOnline = online;
-        this.items = this.owner.getEnderChestInventory().items;
-    }
-
-    @Override
-    public @NotNull CraftInventory getBukkitInventory() {
-        return inventory;
-    }
-
-    @Override
-    public void setPlayerOffline() {
-        this.playerOnline = false;
-    }
-
-    @Override
-    public void setPlayerOnline(@NotNull final org.bukkit.entity.Player player) {
-        if (this.playerOnline) {
-            return;
-        }
-
-        ServerPlayer offlinePlayer = this.owner;
-        ServerPlayer onlinePlayer = PlayerDataManager.getHandle(player);
-
-        // Set owner to new player.
-        this.owner = onlinePlayer;
-
-        // Set player's ender chest contents to our modified contents.
-        PlayerEnderChestContainer onlineEnderChest = onlinePlayer.getEnderChestInventory();
-        for (int i = 0; i < onlineEnderChest.getContainerSize(); ++i) {
-            onlineEnderChest.setItem(i, this.items.get(i));
-        }
-
-        // Set our item array to the new inventory's array.
-        this.items = onlineEnderChest.items;
-
-        // Add viewers to new inventory.
-        onlineEnderChest.transaction.addAll(offlinePlayer.getEnderChestInventory().transaction);
-
-        this.playerOnline = true;
-    }
-
-    @Override
-    public @NotNull org.bukkit.entity.Player getPlayer() {
-        return owner.getBukkitEntity();
-    }
-
-    @Override
-    public void setChanged() {
-        this.owner.getEnderChestInventory().setChanged();
-    }
-
-    @Override
-    public List<ItemStack> getContents() {
-        return this.items;
-    }
-
-    @Override
-    public void onOpen(CraftHumanEntity who) {
-        this.owner.getEnderChestInventory().onOpen(who);
-    }
-
-    @Override
-    public void onClose(CraftHumanEntity who) {
-        this.owner.getEnderChestInventory().onClose(who);
-    }
-
-    @Override
-    public List<HumanEntity> getViewers() {
-        return this.owner.getEnderChestInventory().getViewers();
-    }
-
-    @Override
-    public boolean stillValid(Player player) {
-        return true;
-    }
-
-    @Override
-    public void setActiveChest(EnderChestBlockEntity enderChest) {
-        this.owner.getEnderChestInventory().setActiveChest(enderChest);
-    }
-
-    @Override
-    public boolean isActiveChest(EnderChestBlockEntity enderChest) {
-        return this.owner.getEnderChestInventory().isActiveChest(enderChest);
-    }
-
-    @Override
-    public int getMaxStackSize() {
-        return this.owner.getEnderChestInventory().getMaxStackSize();
-    }
-
-    @Override
-    public void setMaxStackSize(int i) {
-        this.owner.getEnderChestInventory().setMaxStackSize(i);
-    }
-
-    @Override
-    public InventoryHolder getOwner() {
-        return this.owner.getEnderChestInventory().getOwner();
-    }
-
-    @Override
-    public @Nullable Location getLocation() {
-        return null;
-    }
-
-    @Override
-    public void addListener(ContainerListener listener) {
-        this.owner.getEnderChestInventory().addListener(listener);
-    }
-
-    @Override
-    public void removeListener(ContainerListener listener) {
-        this.owner.getEnderChestInventory().removeListener(listener);
-    }
-
-    @Override
-    public ItemStack getItem(int i) {
-        return i >= 0 && i < this.items.size() ? this.items.get(i) : ItemStack.EMPTY;
-    }
-
-    @Override
-    public ItemStack removeItem(int i, int j) {
-        ItemStack itemstack = ContainerHelper.removeItem(this.items, i, j);
-        if (!itemstack.isEmpty()) {
-            this.setChanged();
-        }
-
-        return itemstack;
-    }
-
-    @Override
-    public ItemStack addItem(ItemStack itemstack) {
-        ItemStack localItem = itemstack.copy();
-        this.moveItemToOccupiedSlotsWithSameType(localItem);
-        if (localItem.isEmpty()) {
-            return ItemStack.EMPTY;
-        } else {
-            this.moveItemToEmptySlots(localItem);
-            return localItem.isEmpty() ? ItemStack.EMPTY : localItem;
-        }
-    }
-
-    @Override
-    public boolean canAddItem(ItemStack itemstack) {
-        for (ItemStack itemstack1 : this.items) {
-            if (itemstack1.isEmpty() || ItemStack.isSameItemSameTags(itemstack1, itemstack) && itemstack1.getCount() < itemstack1.getMaxStackSize()) {
-                return true;
-            }
-        }
-
-        return false;
-    }
-
-    private void moveItemToEmptySlots(ItemStack itemstack) {
-        for(int i = 0; i < this.getContainerSize(); ++i) {
-            ItemStack localItem = this.getItem(i);
-            if (localItem.isEmpty()) {
-                this.setItem(i, itemstack.copy());
-                itemstack.setCount(0);
-                return;
-            }
-        }
-    }
-
-    private void moveItemToOccupiedSlotsWithSameType(ItemStack itemstack) {
-        for(int i = 0; i < this.getContainerSize(); ++i) {
-            ItemStack localItem = this.getItem(i);
-            if (ItemStack.isSameItemSameTags(localItem, itemstack)) {
-                this.moveItemsBetweenStacks(itemstack, localItem);
-                if (itemstack.isEmpty()) {
-                    return;
-                }
-            }
-        }
-    }
-
-    private void moveItemsBetweenStacks(ItemStack itemstack, ItemStack itemstack1) {
-        int i = Math.min(this.getMaxStackSize(), itemstack1.getMaxStackSize());
-        int j = Math.min(itemstack.getCount(), i - itemstack1.getCount());
-        if (j > 0) {
-            itemstack1.grow(j);
-            itemstack.shrink(j);
-            this.setChanged();
-        }
-    }
-
-    @Override
-    public ItemStack removeItemNoUpdate(int i) {
-        ItemStack itemstack = this.items.get(i);
-        if (itemstack.isEmpty()) {
-            return ItemStack.EMPTY;
-        } else {
-            this.items.set(i, ItemStack.EMPTY);
-            return itemstack;
-        }
-    }
-
-    @Override
-    public void setItem(int i, ItemStack itemstack) {
-        this.items.set(i, itemstack);
-        if (!itemstack.isEmpty() && itemstack.getCount() > this.getMaxStackSize()) {
-            itemstack.setCount(this.getMaxStackSize());
-        }
-
-        this.setChanged();
-    }
-
-    @Override
-    public int getContainerSize() {
-        return this.owner.getEnderChestInventory().getContainerSize();
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return this.items.stream().allMatch(ItemStack::isEmpty);
-    }
-
-    @Override
-    public void startOpen(Player player) {
-    }
-
-    @Override
-    public void stopOpen(Player player) {
-    }
-
-    @Override
-    public boolean canPlaceItem(int i, ItemStack itemstack) {
-        return true;
-    }
-
-    @Override
-    public void clearContent() {
-        this.items.clear();
-        this.setChanged();
-    }
-
-    @Override
-    public void fillStackedContents(StackedContents stackedContents) {
-        for (ItemStack itemstack : this.items) {
-            stackedContents.accountStack(itemstack);
-        }
-
-    }
-
-    @Override
-    public List<ItemStack> removeAllItems() {
-        List<ItemStack> list = this.items.stream().filter(Predicate.not(ItemStack::isEmpty)).collect(Collectors.toList());
-        this.clearContent();
-        return list;
-    }
-
-    @Override
-    public ItemStack removeItemType(Item item, int i) {
-        ItemStack itemstack = new ItemStack(item, 0);
-
-        for(int j = this.getContainerSize() - 1; j >= 0; --j) {
-            ItemStack localItem = this.getItem(j);
-            if (localItem.getItem().equals(item)) {
-                int k = i - itemstack.getCount();
-                ItemStack splitItem = localItem.split(k);
-                itemstack.grow(splitItem.getCount());
-                if (itemstack.getCount() == i) {
-                    break;
-                }
-            }
-        }
-
-        if (!itemstack.isEmpty()) {
-            this.setChanged();
-        }
-
-        return itemstack;
-    }
-
-    @Override
-    public String toString() {
-        return this.items.stream().filter((itemStack) -> !itemStack.isEmpty()).toList().toString();
-    }
-
-    @Override
-    public void fromTag(ListTag listTag) {
-        for (int i = 0; i < this.getContainerSize(); ++i) {
-            this.setItem(i, ItemStack.EMPTY);
-        }
-
-        for (int i = 0; i < listTag.size(); ++i) {
-            CompoundTag compoundTag = listTag.getCompound(i);
-            int j = compoundTag.getByte("Slot") & 255;
-            if (j < this.getContainerSize()) {
-                this.setItem(j, ItemStack.of(compoundTag));
-            }
-        }
-
-    }
-
-}

internal/v1_20_R1/src/main/java/com/lishid/openinv/internal/v1_20_R1/SpecialPlayerInventory.java

@@ -1,806 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv.internal.v1_20_R1;
-
-import com.google.common.collect.ImmutableList;
-import com.lishid.openinv.internal.ISpecialPlayerInventory;
-import java.util.Collection;
-import java.util.Iterator;
-import java.util.List;
-import java.util.function.Function;
-import java.util.function.Predicate;
-import java.util.stream.Collectors;
-import net.minecraft.CrashReport;
-import net.minecraft.CrashReportCategory;
-import net.minecraft.ReportedException;
-import net.minecraft.core.NonNullList;
-import net.minecraft.nbt.CompoundTag;
-import net.minecraft.nbt.ListTag;
-import net.minecraft.network.chat.Component;
-import net.minecraft.network.protocol.game.ClientboundContainerSetSlotPacket;
-import net.minecraft.server.level.ServerPlayer;
-import net.minecraft.tags.DamageTypeTags;
-import net.minecraft.tags.TagKey;
-import net.minecraft.world.Container;
-import net.minecraft.world.ContainerHelper;
-import net.minecraft.world.damagesource.DamageSource;
-import net.minecraft.world.entity.EquipmentSlot;
-import net.minecraft.world.entity.player.Inventory;
-import net.minecraft.world.entity.player.Player;
-import net.minecraft.world.entity.player.StackedContents;
-import net.minecraft.world.item.ArmorItem;
-import net.minecraft.world.item.Item;
-import net.minecraft.world.item.ItemStack;
-import net.minecraft.world.level.block.state.BlockState;
-import org.bukkit.Location;
-import org.bukkit.craftbukkit.v1_20_R1.entity.CraftHumanEntity;
-import org.bukkit.craftbukkit.v1_20_R1.inventory.CraftInventory;
-import org.bukkit.entity.HumanEntity;
-import org.bukkit.inventory.InventoryHolder;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-public class SpecialPlayerInventory extends Inventory implements ISpecialPlayerInventory {
-
-    private final CraftInventory inventory;
-    private boolean playerOnline;
-    private Player player;
-    private NonNullList<ItemStack> items;
-    private NonNullList<ItemStack> armor;
-    private NonNullList<ItemStack> offhand;
-    private List<NonNullList<ItemStack>> compartments;
-
-    public SpecialPlayerInventory(@NotNull org.bukkit.entity.Player bukkitPlayer, @NotNull Boolean online) {
-        super(PlayerDataManager.getHandle(bukkitPlayer));
-        this.inventory = new CraftInventory(this);
-        this.playerOnline = online;
-        this.player = super.player;
-        this.selected = player.getInventory().selected;
-        this.items = this.player.getInventory().items;
-        this.armor = this.player.getInventory().armor;
-        this.offhand = this.player.getInventory().offhand;
-        this.compartments = ImmutableList.of(this.items, this.armor, this.offhand);
-    }
-
-    @Override
-    public void setPlayerOnline(@NotNull org.bukkit.entity.Player player) {
-        if (this.playerOnline) {
-            return;
-        }
-
-        Player offlinePlayer = this.player;
-        Player onlinePlayer = PlayerDataManager.getHandle(player);
-        onlinePlayer.getInventory().transaction.addAll(this.transaction);
-
-        // Set owner to new player.
-        this.player = onlinePlayer;
-
-        // Set player's inventory contents to our modified contents.
-        Inventory onlineInventory = onlinePlayer.getInventory();
-        for (int i = 0; i < getContainerSize(); ++i) {
-            onlineInventory.setItem(i, getRawItem(i));
-        }
-        onlineInventory.selected = this.selected;
-
-        // Set our item arrays to the new inventory's arrays.
-        this.items = onlineInventory.items;
-        this.armor = onlineInventory.armor;
-        this.offhand = onlineInventory.offhand;
-        this.compartments = ImmutableList.of(this.items, this.armor, this.offhand);
-
-        // Add existing viewers to new viewer list.
-        Inventory offlineInventory = offlinePlayer.getInventory();
-        // Remove self from listing - player is always a viewer of their own inventory, prevent duplicates.
-        offlineInventory.transaction.remove(offlinePlayer.getBukkitEntity());
-        onlineInventory.transaction.addAll(offlineInventory.transaction);
-
-        this.playerOnline = true;
-    }
-
-    @Override
-    public @NotNull CraftInventory getBukkitInventory() {
-        return this.inventory;
-    }
-
-    @Override
-    public void setPlayerOffline() {
-        this.playerOnline = false;
-    }
-
-    @Override
-    public @NotNull HumanEntity getPlayer() {
-        return this.player.getBukkitEntity();
-    }
-
-    private @NotNull ItemStack getRawItem(int i) {
-        if (i < 0) {
-            return ItemStack.EMPTY;
-        }
-
-        NonNullList<ItemStack> list;
-        for (Iterator<NonNullList<ItemStack>> iterator = this.compartments.iterator(); iterator.hasNext(); i -= list.size()) {
-            list = iterator.next();
-            if (i < list.size()) {
-                return list.get(i);
-            }
-        }
-
-        return ItemStack.EMPTY;
-    }
-
-    private void setRawItem(int i, @NotNull ItemStack itemStack) {
-        if (i < 0) {
-            return;
-        }
-
-        NonNullList<ItemStack> list;
-        for (Iterator<NonNullList<ItemStack>> iterator = this.compartments.iterator(); iterator.hasNext(); i -= list.size()) {
-            list = iterator.next();
-            if (i < list.size()) {
-                list.set(i, itemStack);
-            }
-        }
-    }
-
-    private record IndexedCompartment(@Nullable NonNullList<ItemStack> compartment, int index) {}
-
-    private @NotNull SpecialPlayerInventory.IndexedCompartment getIndexedContent(int index) {
-        if (index < items.size()) {
-            return new IndexedCompartment(items, getReversedItemSlotNum(index));
-        }
-
-        index -= items.size();
-
-        if (index < armor.size()) {
-            return new IndexedCompartment(armor, getReversedArmorSlotNum(index));
-        }
-
-        index -= armor.size();
-
-        if (index < offhand.size()) {
-            return new IndexedCompartment(offhand, index);
-        }
-
-        index -= offhand.size();
-
-        return new IndexedCompartment(null, index);
-    }
-
-    private int getReversedArmorSlotNum(final int i) {
-        if (i == 0) {
-            return 3;
-        }
-        if (i == 1) {
-            return 2;
-        }
-        if (i == 2) {
-            return 1;
-        }
-        if (i == 3) {
-            return 0;
-        }
-        return i;
-    }
-
-    private int getReversedItemSlotNum(final int i) {
-        if (i >= 27) {
-            return i - 27;
-        }
-        return i + 9;
-    }
-
-    private boolean contains(Predicate<ItemStack> predicate) {
-        return this.compartments.stream().flatMap(NonNullList::stream).anyMatch(predicate);
-    }
-
-    @Override
-    public List<ItemStack> getArmorContents() {
-        return this.armor;
-    }
-
-    @Override
-    public void onOpen(CraftHumanEntity who) {
-        this.player.getInventory().onOpen(who);
-    }
-
-    @Override
-    public void onClose(CraftHumanEntity who) {
-        this.player.getInventory().onClose(who);
-    }
-
-    @Override
-    public List<HumanEntity> getViewers() {
-        return this.player.getInventory().getViewers();
-    }
-
-    @Override
-    public InventoryHolder getOwner() {
-        return this.player.getBukkitEntity();
-    }
-
-    @Override
-    public int getMaxStackSize() {
-        return this.player.getInventory().getMaxStackSize();
-    }
-
-    @Override
-    public void setMaxStackSize(int size) {
-        this.player.getInventory().setMaxStackSize(size);
-    }
-
-    @Override
-    public Location getLocation() {
-        return this.player.getBukkitEntity().getLocation();
-    }
-
-    @Override
-    public boolean hasCustomName() {
-        return false;
-    }
-
-    @Override
-    public List<ItemStack> getContents() {
-        return this.compartments.stream().flatMap(Collection::stream).collect(Collectors.toList());
-    }
-
-    @Override
-    public ItemStack getSelected() {
-        return isHotbarSlot(this.selected) ? this.items.get(this.selected) : ItemStack.EMPTY;
-    }
-
-    private boolean hasRemainingSpaceForItem(ItemStack itemstack, ItemStack itemstack1) {
-        return !itemstack.isEmpty() && ItemStack.isSameItemSameTags(itemstack, itemstack1) && itemstack.isStackable() && itemstack.getCount() < itemstack.getMaxStackSize() && itemstack.getCount() < this.getMaxStackSize();
-    }
-
-    @Override
-    public int canHold(ItemStack itemstack) {
-        int remains = itemstack.getCount();
-
-        for (int i = 0; i < this.items.size(); ++i) {
-            ItemStack itemstack1 = this.getRawItem(i);
-            if (itemstack1.isEmpty()) {
-                return itemstack.getCount();
-            }
-
-            if (this.hasRemainingSpaceForItem(itemstack1, itemstack)) {
-                remains -= (itemstack1.getMaxStackSize() < this.getMaxStackSize() ? itemstack1.getMaxStackSize() : this.getMaxStackSize()) - itemstack1.getCount();
-            }
-
-            if (remains <= 0) {
-                return itemstack.getCount();
-            }
-        }
-
-        ItemStack offhandItemStack = this.getRawItem(this.items.size() + this.armor.size());
-        if (this.hasRemainingSpaceForItem(offhandItemStack, itemstack)) {
-            remains -= (offhandItemStack.getMaxStackSize() < this.getMaxStackSize() ? offhandItemStack.getMaxStackSize() : this.getMaxStackSize()) - offhandItemStack.getCount();
-        }
-
-        return remains <= 0 ? itemstack.getCount() : itemstack.getCount() - remains;
-    }
-
-    @Override
-    public int getFreeSlot() {
-        for(int i = 0; i < this.items.size(); ++i) {
-            if (this.items.get(i).isEmpty()) {
-                return i;
-            }
-        }
-
-        return -1;
-    }
-
-    @Override
-    public void setPickedItem(ItemStack itemstack) {
-        int i = this.findSlotMatchingItem(itemstack);
-        if (isHotbarSlot(i)) {
-            this.selected = i;
-        } else if (i == -1) {
-            this.selected = this.getSuitableHotbarSlot();
-            if (!this.items.get(this.selected).isEmpty()) {
-                int j = this.getFreeSlot();
-                if (j != -1) {
-                    this.items.set(j, this.items.get(this.selected));
-                }
-            }
-
-            this.items.set(this.selected, itemstack);
-        } else {
-            this.pickSlot(i);
-        }
-
-    }
-
-    @Override
-    public void pickSlot(int i) {
-        this.selected = this.getSuitableHotbarSlot();
-        ItemStack itemstack = this.items.get(this.selected);
-        this.items.set(this.selected, this.items.get(i));
-        this.items.set(i, itemstack);
-    }
-
-    @Override
-    public int findSlotMatchingItem(ItemStack itemstack) {
-        for(int i = 0; i < this.items.size(); ++i) {
-            if (!this.items.get(i).isEmpty() && ItemStack.isSameItemSameTags(itemstack, this.items.get(i))) {
-                return i;
-            }
-        }
-
-        return -1;
-    }
-
-    @Override
-    public int findSlotMatchingUnusedItem(ItemStack itemStack) {
-        for(int i = 0; i < this.items.size(); ++i) {
-            ItemStack localItem = this.items.get(i);
-            if (!this.items.get(i).isEmpty() && ItemStack.isSameItemSameTags(itemStack, this.items.get(i)) && !this.items.get(i).isDamaged() && !localItem.isEnchanted() && !localItem.hasCustomHoverName()) {
-                return i;
-            }
-        }
-
-        return -1;
-    }
-
-    @Override
-    public int getSuitableHotbarSlot() {
-        int i;
-        int j;
-        for(j = 0; j < 9; ++j) {
-            i = (this.selected + j) % 9;
-            if (this.items.get(i).isEmpty()) {
-                return i;
-            }
-        }
-
-        for(j = 0; j < 9; ++j) {
-            i = (this.selected + j) % 9;
-            if (!this.items.get(i).isEnchanted()) {
-                return i;
-            }
-        }
-
-        return this.selected;
-    }
-
-    @Override
-    public void swapPaint(double d0) {
-        if (d0 > 0.0D) {
-            d0 = 1.0D;
-        }
-
-        if (d0 < 0.0D) {
-            d0 = -1.0D;
-        }
-
-        this.selected = (int) (this.selected - d0);
-
-        while (this.selected < 0) {
-            this.selected += 9;
-        }
-
-        while(this.selected >= 9) {
-            this.selected -= 9;
-        }
-    }
-
-    @Override
-    public int clearOrCountMatchingItems(Predicate<ItemStack> predicate, int i, Container container) {
-        byte b0 = 0;
-        boolean flag = i == 0;
-        int j = b0 + ContainerHelper.clearOrCountMatchingItems(this, predicate, i - b0, flag);
-        j += ContainerHelper.clearOrCountMatchingItems(container, predicate, i - j, flag);
-        ItemStack itemstack = this.player.containerMenu.getCarried();
-        j += ContainerHelper.clearOrCountMatchingItems(itemstack, predicate, i - j, flag);
-        if (itemstack.isEmpty()) {
-            this.player.containerMenu.setCarried(ItemStack.EMPTY);
-        }
-
-        return j;
-    }
-
-    private int addResource(ItemStack itemstack) {
-        int i = this.getSlotWithRemainingSpace(itemstack);
-        if (i == -1) {
-            i = this.getFreeSlot();
-        }
-
-        return i == -1 ? itemstack.getCount() : this.addResource(i, itemstack);
-    }
-
-    private int addResource(int i, ItemStack itemstack) {
-        Item item = itemstack.getItem();
-        int j = itemstack.getCount();
-        ItemStack localItemStack = this.getRawItem(i);
-        if (localItemStack.isEmpty()) {
-            localItemStack = new ItemStack(item, 0);
-            if (itemstack.hasTag()) {
-                // hasTag ensures tag not null
-                //noinspection ConstantConditions
-                localItemStack.setTag(itemstack.getTag().copy());
-            }
-
-            this.setRawItem(i, localItemStack);
-        }
-
-        int k = Math.min(j, localItemStack.getMaxStackSize() - localItemStack.getCount());
-
-        if (k > this.getMaxStackSize() - localItemStack.getCount()) {
-            k = this.getMaxStackSize() - localItemStack.getCount();
-        }
-
-        if (k != 0) {
-            j -= k;
-            localItemStack.grow(k);
-            localItemStack.setPopTime(5);
-        }
-
-        return j;
-    }
-
-    @Override
-    public int getSlotWithRemainingSpace(ItemStack itemstack) {
-        if (this.hasRemainingSpaceForItem(this.getRawItem(this.selected), itemstack)) {
-            return this.selected;
-        } else if (this.hasRemainingSpaceForItem(this.getRawItem(40), itemstack)) {
-            return 40;
-        } else {
-            for(int i = 0; i < this.items.size(); ++i) {
-                if (this.hasRemainingSpaceForItem(this.items.get(i), itemstack)) {
-                    return i;
-                }
-            }
-
-            return -1;
-        }
-    }
-
-    @Override
-    public void tick() {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            for (int i = 0; i < compartment.size(); ++i) {
-                if (!compartment.get(i).isEmpty()) {
-                    compartment.get(i).inventoryTick(this.player.level(), this.player, i, this.selected == i);
-                }
-            }
-        }
-
-    }
-
-    @Override
-    public boolean add(ItemStack itemStack) {
-        return this.add(-1, itemStack);
-    }
-
-    @Override
-    public boolean add(int i, ItemStack itemStack) {
-        if (itemStack.isEmpty()) {
-            return false;
-        } else {
-            try {
-                if (itemStack.isDamaged()) {
-                    if (i == -1) {
-                        i = this.getFreeSlot();
-                    }
-
-                    if (i >= 0) {
-                        this.items.set(i, itemStack.copy());
-                        this.items.get(i).setPopTime(5);
-                        itemStack.setCount(0);
-                        return true;
-                    } else if (this.player.getAbilities().instabuild) {
-                        itemStack.setCount(0);
-                        return true;
-                    } else {
-                        return false;
-                    }
-                } else {
-                    int j;
-                    do {
-                        j = itemStack.getCount();
-                        if (i == -1) {
-                            itemStack.setCount(this.addResource(itemStack));
-                        } else {
-                            itemStack.setCount(this.addResource(i, itemStack));
-                        }
-                    } while(!itemStack.isEmpty() && itemStack.getCount() < j);
-
-                    if (itemStack.getCount() == j && this.player.getAbilities().instabuild) {
-                        itemStack.setCount(0);
-                        return true;
-                    } else {
-                        return itemStack.getCount() < j;
-                    }
-                }
-            } catch (Throwable var6) {
-                CrashReport crashReport = CrashReport.forThrowable(var6, "Adding item to inventory");
-                CrashReportCategory crashReportCategory = crashReport.addCategory("Item being added");
-                crashReportCategory.setDetail("Item ID", Item.getId(itemStack.getItem()));
-                crashReportCategory.setDetail("Item data", itemStack.getDamageValue());
-                crashReportCategory.setDetail("Item name", () -> itemStack.getHoverName().getString());
-                throw new ReportedException(crashReport);
-            }
-        }
-    }
-
-    @Override
-    public void placeItemBackInInventory(ItemStack itemStack) {
-        this.placeItemBackInInventory(itemStack, true);
-    }
-
-    @Override
-    public void placeItemBackInInventory(ItemStack itemStack, boolean flag) {
-        while(true) {
-            if (!itemStack.isEmpty()) {
-                int i = this.getSlotWithRemainingSpace(itemStack);
-                if (i == -1) {
-                    i = this.getFreeSlot();
-                }
-
-                if (i != -1) {
-                    int j = itemStack.getMaxStackSize() - this.getRawItem(i).getCount();
-                    if (this.add(i, itemStack.split(j)) && flag && this.player instanceof ServerPlayer) {
-                        ((ServerPlayer)this.player).connection.send(new ClientboundContainerSetSlotPacket(-2, 0, i, this.getRawItem(i)));
-                    }
-                    continue;
-                }
-
-                this.player.drop(itemStack, false);
-            }
-
-            return;
-        }
-    }
-
-    @Override
-    public ItemStack removeItem(int rawIndex, final int j) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null
-                || indexedCompartment.compartment().get(indexedCompartment.index()).isEmpty()) {
-            return ItemStack.EMPTY;
-        }
-
-        return ContainerHelper.removeItem(indexedCompartment.compartment(), indexedCompartment.index(), j);
-    }
-
-    @Override
-    public void removeItem(ItemStack itemStack) {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            for (int i = 0; i < compartment.size(); ++i) {
-                if (compartment.get(i) == itemStack) {
-                    compartment.set(i, ItemStack.EMPTY);
-                    break;
-                }
-            }
-        }
-    }
-
-    @Override
-    public ItemStack removeItemNoUpdate(int rawIndex) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null) {
-            return ItemStack.EMPTY;
-        }
-
-        ItemStack removed = indexedCompartment.compartment().set(indexedCompartment.index(), ItemStack.EMPTY);
-
-        if (removed.isEmpty()) {
-            return ItemStack.EMPTY;
-        }
-
-        return removed;
-    }
-
-    @Override
-    public void setItem(int rawIndex, final ItemStack itemStack) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null) {
-            this.player.drop(itemStack, true);
-            return;
-        }
-
-        indexedCompartment.compartment().set(indexedCompartment.index(), itemStack);
-    }
-
-    @Override
-    public float getDestroySpeed(BlockState blockState) {
-        return this.items.get(this.selected).getDestroySpeed(blockState);
-    }
-
-    @Override
-    public ListTag save(ListTag listTag) {
-        for (int i = 0; i < this.items.size(); ++i) {
-            if (!this.items.get(i).isEmpty()) {
-                CompoundTag compoundTag = new CompoundTag();
-                compoundTag.putByte("Slot", (byte)i);
-                this.items.get(i).save(compoundTag);
-                listTag.add(compoundTag);
-            }
-        }
-
-        for (int i = 0; i < this.armor.size(); ++i) {
-            if (!this.armor.get(i).isEmpty()) {
-                CompoundTag compoundTag = new CompoundTag();
-                compoundTag.putByte("Slot", (byte)(i + 100));
-                this.armor.get(i).save(compoundTag);
-                listTag.add(compoundTag);
-            }
-        }
-
-        for (int i = 0; i < this.offhand.size(); ++i) {
-            if (!this.offhand.get(i).isEmpty()) {
-                CompoundTag compoundTag = new CompoundTag();
-                compoundTag.putByte("Slot", (byte)(i + 150));
-                this.offhand.get(i).save(compoundTag);
-                listTag.add(compoundTag);
-            }
-        }
-
-        return listTag;
-    }
-
-    @Override
-    public void load(ListTag listTag) {
-        this.items.clear();
-        this.armor.clear();
-        this.offhand.clear();
-
-        for(int i = 0; i < listTag.size(); ++i) {
-            CompoundTag compoundTag = listTag.getCompound(i);
-            int j = compoundTag.getByte("Slot") & 255;
-            ItemStack itemstack = ItemStack.of(compoundTag);
-            if (!itemstack.isEmpty()) {
-                if (j < this.items.size()) {
-                    this.items.set(j, itemstack);
-                } else if (j >= 100 && j < this.armor.size() + 100) {
-                    this.armor.set(j - 100, itemstack);
-                } else if (j >= 150 && j < this.offhand.size() + 150) {
-                    this.offhand.set(j - 150, itemstack);
-                }
-            }
-        }
-
-    }
-
-    @Override
-    public int getContainerSize() {
-        return 45;
-    }
-
-    @Override
-    public boolean isEmpty() {
-        return !contains(itemStack -> !itemStack.isEmpty());
-    }
-
-    @Override
-    public ItemStack getItem(int rawIndex) {
-        IndexedCompartment indexedCompartment = getIndexedContent(rawIndex);
-
-        if (indexedCompartment.compartment() == null) {
-            return ItemStack.EMPTY;
-        }
-
-        return indexedCompartment.compartment().get(indexedCompartment.index());
-    }
-
-    @Override
-    public Component getName() {
-        return this.player.getName();
-    }
-
-    @Override
-    public ItemStack getArmor(int index) {
-        return this.armor.get(index);
-    }
-
-    @Override
-    public void hurtArmor(DamageSource damagesource, float damage, int[] armorIndices) {
-        if (damage > 0.0F) {
-            damage /= 4.0F;
-            if (damage < 1.0F) {
-                damage = 1.0F;
-            }
-
-            for (int index : armorIndices) {
-                ItemStack itemstack = this.armor.get(index);
-                if ((!damagesource.is(DamageTypeTags.IS_FIRE) || !itemstack.getItem().isFireResistant()) && itemstack.getItem() instanceof ArmorItem) {
-                    itemstack.hurtAndBreak((int) damage, this.player, localPlayer -> localPlayer.broadcastBreakEvent(EquipmentSlot.byTypeAndIndex(EquipmentSlot.Type.ARMOR, index)));
-                }
-            }
-        }
-    }
-
-    @Override
-    public void dropAll() {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            for (int i = 0; i < compartment.size(); ++i) {
-                ItemStack itemstack = compartment.get(i);
-                if (!itemstack.isEmpty()) {
-                    this.player.drop(itemstack, true, false);
-                    compartment.set(i, ItemStack.EMPTY);
-                }
-            }
-        }
-    }
-
-    @Override
-    public void setChanged() {
-        super.setChanged();
-    }
-
-    @Override
-    public int getTimesChanged() {
-        return super.getTimesChanged();
-    }
-
-    @Override
-    public boolean stillValid(Player player) {
-        return true;
-    }
-
-    @Override
-    public boolean contains(ItemStack itemstack) {
-        return contains(itemStack -> itemStack.isEmpty() && itemStack.is(itemstack.getItem()));
-    }
-
-    @Override
-    public boolean contains(TagKey<Item> tagKey) {
-
-        return contains(itemStack -> !itemStack.isEmpty() && itemStack.is(tagKey));
-    }
-
-    @Override
-    public void replaceWith(Inventory inventory) {
-        Function<Integer, ItemStack> getter;
-
-        if (inventory instanceof SpecialPlayerInventory specialPlayerInventory) {
-            getter = specialPlayerInventory::getRawItem;
-        } else {
-            getter = inventory::getItem;
-        }
-
-        for(int i = 0; i < this.getContainerSize(); ++i) {
-            this.setRawItem(i, getter.apply(i));
-        }
-
-        this.selected = inventory.selected;
-    }
-
-    @Override
-    public void clearContent() {
-        for (NonNullList<ItemStack> compartment : this.compartments) {
-            compartment.clear();
-        }
-    }
-
-    @Override
-    public void fillStackedContents(StackedContents stackedContents) {
-        for (ItemStack itemstack : this.items) {
-            stackedContents.accountSimpleStack(itemstack);
-        }
-    }
-
-    @Override
-    public ItemStack removeFromSelected(boolean dropWholeStack) {
-        ItemStack itemstack = this.getSelected();
-        return itemstack.isEmpty() ? ItemStack.EMPTY : this.removeItem(this.selected, dropWholeStack ? itemstack.getCount() : 1);
-    }
-
-}

internal/v1_21_R2/pom.xml

@@ -23,16 +23,16 @@
     <artifactId>openinvparent</artifactId>
     <groupId>com.lishid</groupId>
     <relativePath>../../pom.xml</relativePath>
-    <version>4.3.1</version>
+    <version>5.1.5</version>
   </parent>
 
-  <artifactId>openinvadapter1_20_R1</artifactId>
-  <name>OpenInvAdapter1_20_R1</name>
+  <artifactId>openinvadapter1_21_R2</artifactId>
+  <name>OpenInvAdapter1_21_R2</name>
 
   <properties>
-    <maven.compiler.source>17</maven.compiler.source>
-    <maven.compiler.target>17</maven.compiler.target>
-    <spigot.version>1.20-R0.1-SNAPSHOT</spigot.version>
+    <maven.compiler.system>21</maven.compiler.system>
+    <maven.compiler.release>21</maven.compiler.release>
+    <spigot.version>1.21.3-R0.1-SNAPSHOT</spigot.version>
   </properties>
 
   <dependencies>
@@ -51,10 +51,9 @@
     <dependency>
       <artifactId>openinvapi</artifactId>
       <groupId>com.lishid</groupId>
-      <scope>provided</scope>
     </dependency>
     <dependency>
-      <artifactId>openinvplugincore</artifactId>
+      <artifactId>openinvcommon</artifactId>
       <groupId>com.lishid</groupId>
     </dependency>
     <dependency>
@@ -65,9 +64,6 @@
 
   <build>
     <plugins>
-      <plugin>
-        <artifactId>maven-shade-plugin</artifactId>
-      </plugin>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
       </plugin>

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/InternalAccessor.java

@@ -0,0 +1,81 @@
+package com.lishid.openinv.internal.v1_21_R2;
+
+import com.lishid.openinv.internal.Accessor;
+import com.lishid.openinv.internal.IAnySilentContainer;
+import com.lishid.openinv.internal.ISpecialEnderChest;
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.ISpecialPlayerInventory;
+import com.lishid.openinv.internal.v1_21_R2.container.AnySilentContainer;
+import com.lishid.openinv.internal.v1_21_R2.container.OpenEnderChest;
+import com.lishid.openinv.internal.v1_21_R2.container.OpenInventory;
+import com.lishid.openinv.internal.v1_21_R2.container.Placeholders;
+import com.lishid.openinv.internal.v1_21_R2.player.PlayerManager;
+import com.lishid.openinv.util.lang.LanguageManager;
+import net.minecraft.world.Container;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftInventory;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.Inventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class InternalAccessor implements Accessor {
+
+  private final @NotNull Logger logger;
+  private final @NotNull PlayerManager manager;
+  private final @NotNull AnySilentContainer anySilentContainer;
+
+  public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
+    this.logger = logger;
+    manager = new PlayerManager(logger);
+    anySilentContainer = new AnySilentContainer(logger, lang);
+  }
+
+  @Override
+  public @NotNull PlayerManager getPlayerManager() {
+    return manager;
+  }
+
+  @Override
+  public @NotNull IAnySilentContainer getAnySilentContainer() {
+    return anySilentContainer;
+  }
+
+  @Override
+  public @NotNull ISpecialPlayerInventory createPlayerInventory(@NotNull Player player) {
+    return new OpenInventory(player);
+  }
+
+  @Override
+  public @NotNull ISpecialEnderChest createEnderChest(@NotNull Player player) {
+    return new OpenEnderChest(player);
+  }
+
+  @Override
+  public <T extends ISpecialInventory> @Nullable T get(@NotNull Inventory bukkitInventory, @NotNull Class<T> clazz) {
+    if (!(bukkitInventory instanceof CraftInventory craftInventory)) {
+      return null;
+    }
+    Container container = craftInventory.getInventory();
+    if (clazz.isInstance(container)) {
+      return clazz.cast(container);
+    }
+    return null;
+  }
+
+  @Override
+  public void reload(@NotNull ConfigurationSection config) {
+    ConfigurationSection placeholders = config.getConfigurationSection("placeholders");
+    if (placeholders != null) {
+      try {
+        Placeholders.load(placeholders);
+      } catch (Exception e) {
+        logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
+      }
+    }
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/AnySilentContainer.java

@@ -14,21 +14,19 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-package com.lishid.openinv.internal.v1_20_R1;
+package com.lishid.openinv.internal.v1_21_R2.container;
 
-import com.lishid.openinv.OpenInv;
-import com.lishid.openinv.internal.IAnySilentContainer;
+import com.lishid.openinv.internal.AnySilentContainerBase;
+import com.lishid.openinv.internal.v1_21_R2.container.menu.OpenChestMenu;
+import com.lishid.openinv.internal.v1_21_R2.player.PlayerManager;
 import com.lishid.openinv.util.ReflectionHelper;
-import java.lang.reflect.Field;
-import java.util.logging.Logger;
+import com.lishid.openinv.util.lang.LanguageManager;
 import net.minecraft.core.BlockPos;
 import net.minecraft.network.chat.Component;
-import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.server.level.ServerPlayerGameMode;
 import net.minecraft.world.MenuProvider;
 import net.minecraft.world.SimpleMenuProvider;
-import net.minecraft.world.entity.monster.Shulker;
 import net.minecraft.world.inventory.ChestMenu;
 import net.minecraft.world.inventory.MenuType;
 import net.minecraft.world.inventory.PlayerEnderChestContainer;
@@ -41,30 +39,31 @@ import net.minecraft.world.level.block.TrappedChestBlock;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.entity.EnderChestBlockEntity;
 import net.minecraft.world.level.block.entity.RandomizableContainerBlockEntity;
-import net.minecraft.world.level.block.entity.ShulkerBoxBlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
-import net.minecraft.world.phys.AABB;
-import org.bukkit.Bukkit;
 import org.bukkit.GameMode;
 import org.bukkit.Material;
 import org.bukkit.Statistic;
-import org.bukkit.block.ShulkerBox;
-import org.bukkit.craftbukkit.v1_20_R1.CraftWorld;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public class AnySilentContainer implements IAnySilentContainer {
+import java.lang.reflect.Field;
+import java.util.logging.Logger;
 
+public class AnySilentContainer extends AnySilentContainerBase {
+
+    private final @NotNull Logger logger;
+    private final @NotNull LanguageManager lang;
     private @Nullable Field serverPlayerGameModeGameType;
 
-    public AnySilentContainer() {
+    public AnySilentContainer(@NotNull Logger logger, @NotNull LanguageManager lang) {
+        this.logger = logger;
+        this.lang = lang;
         try {
             try {
                 this.serverPlayerGameModeGameType = ServerPlayerGameMode.class.getDeclaredField("b");
                 this.serverPlayerGameModeGameType.setAccessible(true);
             } catch (NoSuchFieldException e) {
-                Logger logger = OpenInv.getPlugin(OpenInv.class).getLogger();
                 logger.warning("ServerPlayerGameMode#gameModeForPlayer's obfuscated name has changed!");
                 logger.warning("Please report this at https://github.com/Jikoo/OpenInv/issues");
                 logger.warning("Attempting to fall through using reflection. Please verify that SilentContainer does not fail.");
@@ -72,43 +71,11 @@ public class AnySilentContainer implements IAnySilentContainer {
                 this.serverPlayerGameModeGameType = ReflectionHelper.grabFieldByType(ServerPlayerGameMode.class, GameType.class);
             }
         } catch (SecurityException e) {
-            Logger logger = OpenInv.getPlugin(OpenInv.class).getLogger();
             logger.warning("Unable to directly write player game mode! SilentContainer will fail.");
             logger.log(java.util.logging.Level.WARNING, "Error obtaining GameType field", e);
         }
     }
 
-    @Override
-    public boolean isShulkerBlocked(@NotNull ShulkerBox shulkerBox) {
-        org.bukkit.World bukkitWorld = shulkerBox.getWorld();
-        if (!(bukkitWorld instanceof CraftWorld)) {
-            bukkitWorld = Bukkit.getWorld(bukkitWorld.getUID());
-        }
-
-        if (!(bukkitWorld instanceof CraftWorld craftWorld)) {
-            Exception exception = new IllegalStateException("AnySilentContainer access attempted on an unknown world!");
-            OpenInv.getPlugin(OpenInv.class).getLogger().log(java.util.logging.Level.WARNING, exception.getMessage(), exception);
-            return false;
-        }
-
-        final ServerLevel world = craftWorld.getHandle();
-        final BlockPos blockPosition = new BlockPos(shulkerBox.getX(), shulkerBox.getY(), shulkerBox.getZ());
-        final BlockEntity tile = world.getBlockEntity(blockPosition);
-
-        if (!(tile instanceof ShulkerBoxBlockEntity shulkerBoxBlockEntity)
-                || shulkerBoxBlockEntity.getAnimationStatus() != ShulkerBoxBlockEntity.AnimationStatus.CLOSED) {
-            return false;
-        }
-
-        BlockState blockState = world.getBlockState(blockPosition);
-
-        // See net.minecraft.world.level.block.ShulkerBoxBlock#canOpen
-        AABB boundingBox = Shulker.getProgressDeltaAabb(blockState.getValue(ShulkerBoxBlock.FACING), 0.0F, 0.5F)
-                .move(blockPosition)
-                .deflate(1.0E-6D);
-        return !world.noCollision(boundingBox);
-    }
-
     @Override
     public boolean activateContainer(
             @NotNull final Player bukkitPlayer,
@@ -122,7 +89,7 @@ public class AnySilentContainer implements IAnySilentContainer {
             return true;
         }
 
-        ServerPlayer player = PlayerDataManager.getHandle(bukkitPlayer);
+        ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
 
         final net.minecraft.world.level.Level level = player.level();
         final BlockPos blockPos = new BlockPos(bukkitBlock.getX(), bukkitBlock.getY(), bukkitBlock.getZ());
@@ -137,10 +104,10 @@ public class AnySilentContainer implements IAnySilentContainer {
             PlayerEnderChestContainer enderChest = player.getEnderChestInventory();
             enderChest.setActiveChest(enderChestTile);
             player.openMenu(new SimpleMenuProvider((containerCounter, playerInventory, ignored) -> {
-                MenuType<?> containers = PlayerDataManager.getContainers(enderChest.getContainerSize());
+                MenuType<?> containers = OpenChestMenu.getChestMenuType(enderChest.getContainerSize());
                 int rows = enderChest.getContainerSize() / 9;
                 return new ChestMenu(containers, containerCounter, playerInventory, enderChest, rows);
-            }, Component.translatable(("container.enderchest"))));
+            }, Component.translatable("container.enderchest")));
             bukkitPlayer.incrementStatistic(Statistic.ENDERCHEST_OPENED);
             return true;
         }
@@ -158,7 +125,7 @@ public class AnySilentContainer implements IAnySilentContainer {
             menuProvider = chestBlock.getMenuProvider(blockState, level, blockPos, true);
 
             if (menuProvider == null) {
-                OpenInv.getPlugin(OpenInv.class).sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
+                lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
                 return false;
             }
 
@@ -190,7 +157,7 @@ public class AnySilentContainer implements IAnySilentContainer {
 
         if (blockEntity instanceof RandomizableContainerBlockEntity lootable) {
             if (lootable.lootTable != null) {
-                OpenInv.getPlugin(OpenInv.class).sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
+                lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
                 return false;
             }
         }
@@ -208,7 +175,7 @@ public class AnySilentContainer implements IAnySilentContainer {
             return;
         }
 
-        ServerPlayer player = PlayerDataManager.getHandle(bukkitPlayer);
+        ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
 
         // Force game mode change without informing plugins or players.
         // Regular game mode set calls GameModeChangeEvent and is cancellable.
@@ -236,7 +203,7 @@ public class AnySilentContainer implements IAnySilentContainer {
             this.serverPlayerGameModeGameType.setAccessible(true);
             this.serverPlayerGameModeGameType.set(player.gameMode, gameMode);
         } catch (IllegalArgumentException | IllegalAccessException e) {
-            e.printStackTrace();
+            logger.log(java.util.logging.Level.WARNING, "Error bypassing GameModeChangeEvent", e);
         }
     }
 

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/OpenEnderChest.java

@@ -0,0 +1,196 @@
+package com.lishid.openinv.internal.v1_21_R2.container;
+
+import com.lishid.openinv.internal.ISpecialEnderChest;
+import com.lishid.openinv.internal.InternalOwned;
+import com.lishid.openinv.internal.v1_21_R2.container.menu.OpenEnderChestMenu;
+import com.lishid.openinv.internal.v1_21_R2.player.PlayerManager;
+import net.minecraft.core.NonNullList;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.entity.player.StackedItemContents;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.StackedContentsCompatible;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.v1_21_R2.entity.CraftHumanEntity;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftInventory;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class OpenEnderChest implements Container, StackedContentsCompatible, InternalOwned<ServerPlayer>,
+    ISpecialEnderChest {
+
+  private CraftInventory inventory;
+  private @NotNull ServerPlayer owner;
+  private NonNullList<ItemStack> items;
+  private int maxStack = 64;
+  private final List<HumanEntity> transaction = new ArrayList<>();
+
+  public OpenEnderChest(@NotNull org.bukkit.entity.Player player) {
+    this.owner = PlayerManager.getHandle(player);
+    this.items = owner.getEnderChestInventory().items;
+  }
+
+  @Override
+  public @NotNull ServerPlayer getOwnerHandle() {
+    return owner;
+  }
+
+  @Override
+  public @NotNull org.bukkit.inventory.Inventory getBukkitInventory() {
+    if (inventory == null) {
+      inventory = new CraftInventory(this) {
+        @Override
+        public @NotNull InventoryType getType() {
+          return InventoryType.ENDER_CHEST;
+        }
+      };
+    }
+    return inventory;
+  }
+
+  @Override
+  public void setPlayerOnline(@NotNull org.bukkit.entity.Player player) {
+    owner = PlayerManager.getHandle(player);
+    NonNullList<ItemStack> activeItems = owner.getEnderChestInventory().items;
+
+    // Guard against size changing. Theoretically on Purpur all row variations still have 6 rows internally.
+    int max = Math.min(items.size(), activeItems.size());
+    for (int index = 0; index < max; ++index) {
+      activeItems.set(index, items.get(index));
+    }
+
+    items = activeItems;
+  }
+
+  @Override
+  public void setPlayerOffline() {}
+
+  @Override
+  public @NotNull org.bukkit.entity.Player getPlayer() {
+    return owner.getBukkitEntity();
+  }
+
+  @Override
+  public int getContainerSize() {
+    return items.size();
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return items.stream().allMatch(ItemStack::isEmpty);
+  }
+
+  @Override
+  public ItemStack getItem(int index) {
+    return index >= 0 && index < items.size() ? items.get(index) : ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack removeItem(int index, int amount) {
+    ItemStack itemstack = ContainerHelper.removeItem(items, index, amount);
+
+    if (!itemstack.isEmpty()) {
+      setChanged();
+    }
+
+    return itemstack;
+  }
+
+  @Override
+  public ItemStack removeItemNoUpdate(int index) {
+    return index >= 0 && index < items.size() ? items.set(index, ItemStack.EMPTY) : ItemStack.EMPTY;
+  }
+
+  @Override
+  public void setItem(int index, ItemStack itemStack) {
+    if (index >= 0 && index < items.size()) {
+      items.set(index, itemStack);
+    }
+  }
+
+  @Override
+  public int getMaxStackSize() {
+    return maxStack;
+  }
+
+  @Override
+  public void setChanged() {
+    this.owner.getEnderChestInventory().setChanged();
+  }
+
+  @Override
+  public boolean stillValid(Player player) {
+    return true;
+  }
+
+  @Override
+  public List<ItemStack> getContents() {
+    return items;
+  }
+
+  @Override
+  public void onOpen(CraftHumanEntity craftHumanEntity) {
+    transaction.add(craftHumanEntity);
+  }
+
+  @Override
+  public void onClose(CraftHumanEntity craftHumanEntity) {
+    transaction.remove(craftHumanEntity);
+  }
+
+  @Override
+  public List<HumanEntity> getViewers() {
+    return transaction;
+  }
+
+  @Override
+  public org.bukkit.entity.Player getOwner() {
+    return getPlayer();
+  }
+
+  @Override
+  public void setMaxStackSize(int size) {
+    maxStack = size;
+  }
+
+  @Override
+  public @Nullable Location getLocation() {
+    return null;
+  }
+
+  @Override
+  public void clearContent() {
+    items.clear();
+    setChanged();
+  }
+
+  @Override
+  public void fillStackedContents(StackedItemContents stackedContents) {
+    for (ItemStack itemstack : items) {
+      stackedContents.accountStack(itemstack);
+    }
+  }
+
+  public Component getTitle() {
+    return Component.translatableWithFallback("openinv.container.enderchest.prefix", "", owner.getName())
+        .append(Component.translatable("container.enderchest"))
+        .append(Component.translatableWithFallback("openinv.container.enderchest.suffix", " - %s", owner.getName()));
+  }
+
+  public @Nullable AbstractContainerMenu createMenu(Player player, int i, boolean viewOnly) {
+    if (player instanceof ServerPlayer serverPlayer) {
+      return new OpenEnderChestMenu(this, serverPlayer, i, viewOnly);
+    }
+    return null;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/OpenInventory.java

@@ -0,0 +1,364 @@
+package com.lishid.openinv.internal.v1_21_R2.container;
+
+import com.lishid.openinv.internal.ISpecialPlayerInventory;
+import com.lishid.openinv.internal.InternalOwned;
+import com.lishid.openinv.internal.v1_21_R2.container.bukkit.OpenPlayerInventory;
+import com.lishid.openinv.internal.v1_21_R2.container.menu.OpenInventoryMenu;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.Content;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentCrafting;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentCraftingResult;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentCursor;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentDrop;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentEquipment;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentList;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentOffHand;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentViewOnly;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.SlotViewOnly;
+import com.lishid.openinv.internal.v1_21_R2.player.PlayerManager;
+import net.minecraft.ChatFormatting;
+import net.minecraft.core.NonNullList;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.chat.MutableComponent;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.v1_21_R2.entity.CraftHumanEntity;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftInventory;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class OpenInventory implements Container, InternalOwned<ServerPlayer>, ISpecialPlayerInventory {
+
+  private final List<Content> slots;
+  private final int size;
+  private ServerPlayer owner;
+  private int maxStackSize = 99;
+  private CraftInventory bukkitEntity;
+  public List<HumanEntity> transaction = new ArrayList<>();
+
+  public OpenInventory(@NotNull org.bukkit.entity.Player bukkitPlayer) {
+    owner = PlayerManager.getHandle(bukkitPlayer);
+
+    // Get total size, rounding up to nearest 9 for client compatibility.
+    int rawSize = owner.getInventory().getContainerSize() + owner.inventoryMenu.getCraftSlots().getContainerSize() + 1;
+    size = ((int) Math.ceil(rawSize / 9.0)) * 9;
+
+    slots = NonNullList.withSize(size, new ContentViewOnly(owner));
+    setupSlots();
+  }
+
+  private void setupSlots() {
+    // Top of inventory: Regular contents.
+    int nextIndex = addMainInventory();
+
+    // If inventory is expected size, we can arrange slots to be pretty.
+    Inventory ownerInv = owner.getInventory();
+    if (ownerInv.items.size() == 36
+        && ownerInv.armor.size() == 4
+        && ownerInv.offhand.size() == 1
+        && owner.inventoryMenu.getCraftSlots().getContainerSize() == 4) {
+      // Armor slots: Bottom left.
+      addArmor(36);
+      // Off-hand: Below chestplate.
+      addOffHand(46);
+      // Drop slot: Bottom right.
+      slots.set(53, new ContentDrop(owner));
+      // Cursor slot: Above drop.
+      slots.set(44, new ContentCursor(owner));
+
+      // Crafting is displayed in the bottom right corner.
+      // As we're using the pretty view, this is a 3x2.
+      addCrafting(41, true);
+      return;
+    }
+
+    // Otherwise we'll just add elements linearly.
+    nextIndex = addArmor(nextIndex);
+    nextIndex = addOffHand(nextIndex);
+    nextIndex = addCrafting(nextIndex, false);
+    slots.set(nextIndex, new ContentCursor(owner));
+    // Drop slot last.
+    slots.set(slots.size() - 1, new ContentDrop(owner));
+  }
+
+  private int addMainInventory() {
+    int listSize = owner.getInventory().items.size();
+    // Hotbar slots are 0-8. We want those to appear on the bottom of the inventory like a normal player inventory,
+    // so everything else needs to move up a row.
+    int hotbarDiff = listSize - 9;
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      InventoryType.SlotType type;
+      int invIndex;
+      if (localIndex < hotbarDiff) {
+        invIndex = localIndex + 9;
+        type = InventoryType.SlotType.CONTAINER;
+      } else {
+        type = InventoryType.SlotType.QUICKBAR;
+        invIndex = localIndex - hotbarDiff;
+      }
+
+      slots.set(localIndex, new ContentList(owner, invIndex, type) {
+        @Override
+        public void setHolder(@NotNull ServerPlayer holder) {
+          items = holder.getInventory().items;
+        }
+      });
+    }
+    return listSize;
+  }
+
+  private int addArmor(int startIndex) {
+    int listSize = owner.getInventory().armor.size();
+
+    for (int i = 0; i < listSize; ++i) {
+      // Armor slots go bottom to top; boots are slot 0, helmet is slot 3.
+      // Since we have to display horizontally due to space restrictions,
+      // making the left side the "top" is more user-friendly.
+      int armorIndex;
+      EquipmentSlot slot;
+      switch (i) {
+        case 3 -> {
+          armorIndex = 0;
+          slot = EquipmentSlot.FEET;
+        }
+        case 2 -> {
+          armorIndex = 1;
+          slot = EquipmentSlot.LEGS;
+        }
+        case 1 -> {
+          armorIndex = 2;
+          slot = EquipmentSlot.CHEST;
+        }
+        case 0 -> {
+          armorIndex = 3;
+          slot = EquipmentSlot.HEAD;
+        }
+        default -> {
+          // In the event that new armor slots are added, they can be placed at the end.
+          armorIndex = i;
+          slot = EquipmentSlot.MAINHAND;
+        }
+      }
+
+      slots.set(startIndex + i, new ContentEquipment(owner, armorIndex, slot));
+    }
+
+    return startIndex + listSize;
+  }
+
+  private int addOffHand(int startIndex) {
+    int listSize = owner.getInventory().offhand.size();
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      slots.set(startIndex + localIndex, new ContentOffHand(owner, localIndex));
+    }
+    return startIndex + listSize;
+  }
+
+  private int addCrafting(int startIndex, boolean pretty) {
+    int listSize = owner.inventoryMenu.getCraftSlots().getContents().size();
+    pretty &= listSize == 4;
+
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      // Pretty display is a 2x2 rather than linear.
+      // If index is in top row, grid is not 2x2, or pretty is disabled, just use current index.
+      // Otherwise, subtract 2 and add 9 to start in the same position on the next row.
+      int modIndex = startIndex + (localIndex < 2 || !pretty ? localIndex : localIndex + 7);
+
+      slots.set(modIndex, new ContentCrafting(owner, localIndex));
+    }
+
+    if (pretty) {
+      slots.set(startIndex + 2, new ContentViewOnly(owner) {
+        @Override
+        public Slot asSlot(Container container, int slot, int x, int y) {
+          return new SlotViewOnly(container, slot, x, y) {
+            @Override
+            public ItemStack getOrDefault() {
+              return Placeholders.craftingOutput;
+            }
+          };
+        }
+      });
+      slots.set(startIndex + 11, new ContentCraftingResult(owner));
+    }
+
+    return startIndex + listSize;
+  }
+
+  public Slot getMenuSlot(int index, int x, int y) {
+    return slots.get(index).asSlot(this, index, x, y);
+  }
+
+  public InventoryType.SlotType getSlotType(int index) {
+    return slots.get(index).getSlotType();
+  }
+
+  public @NotNull Component getTitle(@Nullable ServerPlayer viewer) {
+    MutableComponent component = Component.empty();
+    // Prefix for use with custom bitmap image fonts.
+    if (owner.equals(viewer)) {
+      component.append(
+          Component.translatableWithFallback("openinv.container.inventory.self", "")
+              .withStyle(style -> style
+                  .withFont(ResourceLocation.parse("openinv:font/inventory"))
+                  .withColor(ChatFormatting.WHITE)));
+    } else {
+      component.append(
+          Component.translatableWithFallback("openinv.container.inventory.other", "")
+              .withStyle(style -> style
+                  .withFont(ResourceLocation.parse("openinv:font/inventory"))
+                  .withColor(ChatFormatting.WHITE)));
+    }
+    // Normal title: "Inventory - OwnerName"
+    component.append(Component.translatableWithFallback("openinv.container.inventory.prefix", "", owner.getName()))
+        .append(Component.translatable("container.inventory"))
+        .append(Component.translatableWithFallback("openinv.container.inventory.suffix", " - %s", owner.getName()));
+    return component;
+  }
+
+  @Override
+  public ServerPlayer getOwnerHandle() {
+    return owner;
+  }
+
+  @Override
+  public @NotNull org.bukkit.inventory.Inventory getBukkitInventory() {
+    if (bukkitEntity == null) {
+      bukkitEntity = new OpenPlayerInventory(this);
+    }
+    return bukkitEntity;
+  }
+
+  @Override
+  public void setPlayerOnline(@NotNull org.bukkit.entity.Player player) {
+    ServerPlayer newOwner = PlayerManager.getHandle(player);
+    // Only transfer regular inventory - crafting and cursor slots are transient.
+    newOwner.getInventory().replaceWith(owner.getInventory());
+    owner = newOwner;
+    // Update slots to point to new inventory.
+    slots.forEach(slot -> slot.setHolder(newOwner));
+  }
+
+  @Override
+  public void setPlayerOffline() {}
+
+  @Override
+  public boolean isInUse() {
+    return !transaction.isEmpty();
+  }
+
+  @Override
+  public @NotNull org.bukkit.entity.Player getPlayer() {
+    return getOwner();
+  }
+
+  @Override
+  public int getContainerSize() {
+    return size;
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return slots.stream().map(Content::get).allMatch(ItemStack::isEmpty);
+  }
+
+  @Override
+  public ItemStack getItem(int index) {
+    return slots.get(index).get();
+  }
+
+  @Override
+  public ItemStack removeItem(int index, int amount) {
+    return slots.get(index).removePartial(amount);
+  }
+
+  @Override
+  public ItemStack removeItemNoUpdate(int index) {
+    return slots.get(index).remove();
+  }
+
+  @Override
+  public void setItem(int index, ItemStack itemStack) {
+    slots.get(index).set(itemStack);
+  }
+
+  @Override
+  public int getMaxStackSize() {
+    return maxStackSize;
+  }
+
+  @Override
+  public void setMaxStackSize(int maxStackSize) {
+    this.maxStackSize = maxStackSize;
+  }
+
+  @Override
+  public void setChanged() {}
+
+  @Override
+  public boolean stillValid(Player player) {
+    return true;
+  }
+
+  @Override
+  public List<ItemStack> getContents() {
+    NonNullList<ItemStack> contents = NonNullList.withSize(getContainerSize(), ItemStack.EMPTY);
+    for (int i = 0; i < getContainerSize(); ++i) {
+      contents.set(i, getItem(i));
+    }
+    return contents;
+  }
+
+  @Override
+  public void onOpen(CraftHumanEntity viewer) {
+    transaction.add(viewer);
+  }
+
+  @Override
+  public void onClose(CraftHumanEntity viewer) {
+    transaction.remove(viewer);
+  }
+
+  @Override
+  public List<HumanEntity> getViewers() {
+    return transaction;
+  }
+
+  @Override
+  public org.bukkit.entity.Player getOwner() {
+    return owner.getBukkitEntity();
+  }
+
+  @Override
+  public Location getLocation() {
+    return owner.getBukkitEntity().getLocation();
+  }
+
+  @Override
+  public void clearContent() {
+    owner.getInventory().clearContent();
+    owner.inventoryMenu.getCraftSlots().clearContent();
+    owner.inventoryMenu.slotsChanged(owner.inventoryMenu.getCraftSlots());
+    owner.containerMenu.setCarried(ItemStack.EMPTY);
+  }
+
+  public @Nullable AbstractContainerMenu createMenu(Player player, int i, boolean viewOnly) {
+    if (player instanceof ServerPlayer serverPlayer) {
+      return new OpenInventoryMenu(this, serverPlayer, i, viewOnly);
+    }
+    return null;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/Placeholders.java

@@ -0,0 +1,183 @@
+package com.lishid.openinv.internal.v1_21_R2.container;
+
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.TagParser;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.util.Unit;
+import net.minecraft.world.item.DyeColor;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+import net.minecraft.world.item.component.CustomModelData;
+import net.minecraft.world.item.component.DyedItemColor;
+import net.minecraft.world.level.GameType;
+import net.minecraft.world.level.ItemLike;
+import net.minecraft.world.level.block.entity.BannerPattern;
+import net.minecraft.world.level.block.entity.BannerPatternLayers;
+import net.minecraft.world.level.block.entity.BannerPatterns;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.craftbukkit.v1_21_R2.CraftRegistry;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.EnumMap;
+import java.util.List;
+import java.util.Optional;
+
+public final class Placeholders {
+
+  private static final CustomModelData DEFAULT_CUSTOM_MODEL_DATA = new CustomModelData(9999);
+  public static final @NotNull EnumMap<GameType, ItemStack> BLOCKED_GAME_TYPE = new EnumMap<>(GameType.class);
+  public static @NotNull ItemStack craftingOutput = defaultCraftingOutput();
+  public static @NotNull ItemStack cursor = defaultCursor();
+  public static @NotNull ItemStack drop = defaultDrop();
+  public static @NotNull ItemStack emptyHelmet = getEmptyArmor(Items.LEATHER_HELMET);
+  public static @NotNull ItemStack emptyChestplate = getEmptyArmor(Items.LEATHER_CHESTPLATE);
+  public static @NotNull ItemStack emptyLeggings = getEmptyArmor(Items.LEATHER_LEGGINGS);
+  public static @NotNull ItemStack emptyBoots = getEmptyArmor(Items.LEATHER_BOOTS);
+  public static @NotNull ItemStack emptyOffHand = getEmptyShield();
+  public static @NotNull ItemStack notSlot = defaultNotSlot();
+  public static @NotNull ItemStack blockedOffline = defaultBlockedOffline();
+
+  static {
+    for (GameType type : GameType.values()) {
+      // Barrier: "Not available - Creative" etc.
+      ItemStack typeItem = new ItemStack(Items.BARRIER);
+      typeItem.set(
+          DataComponents.ITEM_NAME,
+          Component.translatable("options.narrator.notavailable").append(" - ").append(type.getShortDisplayName()));
+      BLOCKED_GAME_TYPE.put(type, typeItem);
+    }
+  }
+
+  public static void load(@NotNull ConfigurationSection section) throws Exception {
+    craftingOutput = parse(section, "crafting-output", craftingOutput);
+    cursor = parse(section, "cursor", cursor);
+    drop = parse(section, "drop", drop);
+    emptyHelmet = parse(section, "empty-helmet", emptyHelmet);
+    emptyChestplate = parse(section, "empty-chestplate", emptyChestplate);
+    emptyLeggings = parse(section, "empty-leggings", emptyLeggings);
+    emptyBoots = parse(section, "empty-boots", emptyBoots);
+    emptyOffHand = parse(section, "empty-off-hand", emptyOffHand);
+    notSlot = parse(section, "not-a-slot", notSlot);
+    blockedOffline = parse(section, "blocked.offline", blockedOffline);
+    BLOCKED_GAME_TYPE.put(GameType.CREATIVE, parse(section, "blocked.creative", BLOCKED_GAME_TYPE.get(GameType.CREATIVE)));
+    BLOCKED_GAME_TYPE.put(GameType.SPECTATOR, parse(section, "blocked.spectator", BLOCKED_GAME_TYPE.get(GameType.SPECTATOR)));
+  }
+
+  private static @NotNull ItemStack parse(
+      @NotNull ConfigurationSection section,
+      @NotNull String path,
+      @NotNull ItemStack defaultStack) throws Exception {
+    String itemText = section.getString(path);
+
+    if (itemText == null) {
+      return defaultStack;
+    }
+
+    CompoundTag compoundTag = TagParser.parseTag(itemText);
+    Optional<ItemStack> parsed = ItemStack.parse(CraftRegistry.getMinecraftRegistry(), compoundTag);
+    return parsed.filter(itemStack -> !itemStack.isEmpty()).orElse(defaultStack);
+  }
+
+  public static ItemStack survivalOnly(@NotNull ServerPlayer serverPlayer) {
+    if (serverPlayer.connection == null || serverPlayer.connection.isDisconnected()) {
+      return blockedOffline;
+    }
+
+    return BLOCKED_GAME_TYPE.getOrDefault(serverPlayer.gameMode.getGameModeForPlayer(), ItemStack.EMPTY);
+  }
+
+  private static ItemStack defaultCraftingOutput() {
+    // Crafting table: "Crafting"
+    ItemStack itemStack = new ItemStack(Items.CRAFTING_TABLE);
+    itemStack.set(DataComponents.ITEM_NAME, Component.translatable("container.crafting"));
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack defaultCursor() {
+    // Cursor-like banner with no tooltip
+    ItemStack itemStack = new ItemStack(Items.WHITE_BANNER);
+    RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
+    Registry<BannerPattern> bannerPatterns = minecraftRegistry.lookupOrThrow(Registries.BANNER_PATTERN);
+    BannerPattern halfDiagBottomRight = bannerPatterns.getOrThrow(BannerPatterns.DIAGONAL_RIGHT).value();
+    BannerPattern downRight = bannerPatterns.getOrThrow(BannerPatterns.STRIPE_DOWNRIGHT).value();
+    BannerPattern border = bannerPatterns.getOrThrow(BannerPatterns.BORDER).value();
+    itemStack.set(DataComponents.BANNER_PATTERNS,
+        new BannerPatternLayers(List.of(
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfDiagBottomRight), DyeColor.GRAY),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(downRight), DyeColor.WHITE),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(border), DyeColor.GRAY))));
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    return itemStack;
+  }
+
+  private static ItemStack defaultDrop() {
+    // Dropper: "Drop Selected Item"
+    ItemStack itemStack = new ItemStack(Items.DROPPER);
+    // Note: translatable component, not keybind component! We want the text identifying the keybind, not the key.
+    itemStack.set(DataComponents.ITEM_NAME, Component.translatable("key.drop"));
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack getEmptyArmor(ItemLike item) {
+    // Inventory-background-grey-ish leather armor with no tooltip
+    ItemStack itemStack = new ItemStack(item);
+    DyedItemColor color = new DyedItemColor(0xC8C8C8, false);
+    itemStack.set(DataComponents.DYED_COLOR, color);
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack getEmptyShield() {
+    ItemStack itemStack = new ItemStack(Items.SHIELD);
+    itemStack.set(DataComponents.BASE_COLOR, DyeColor.MAGENTA);
+    RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
+    Registry<BannerPattern> bannerPatterns = minecraftRegistry.lookupOrThrow(Registries.BANNER_PATTERN);
+    BannerPattern halfLeft = bannerPatterns.getOrThrow(BannerPatterns.HALF_VERTICAL).value();
+    BannerPattern topLeft = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_TOP_LEFT).value();
+    BannerPattern topRight = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_TOP_RIGHT).value();
+    BannerPattern bottomLeft = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_BOTTOM_LEFT).value();
+    BannerPattern bottomRight = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_BOTTOM_RIGHT).value();
+    itemStack.set(DataComponents.BANNER_PATTERNS,
+        new BannerPatternLayers(List.of(
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfLeft), DyeColor.BLACK),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topLeft), DyeColor.MAGENTA),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomLeft), DyeColor.MAGENTA),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topRight), DyeColor.BLACK),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomRight), DyeColor.BLACK))));
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack defaultNotSlot() {
+    // White pane with no tooltip
+    ItemStack itemStack = new ItemStack(Items.WHITE_STAINED_GLASS_PANE);
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack defaultBlockedOffline() {
+    // Barrier: "Not available - Offline"
+    ItemStack itemStack = new ItemStack(Items.BARRIER);
+    itemStack.set(DataComponents.ITEM_NAME,
+        Component.translatable("options.narrator.notavailable")
+            .append(Component.literal(" - "))
+            .append(Component.translatable("gui.socialInteractions.status_offline")));
+    return itemStack;
+  }
+
+  private Placeholders() {
+    throw new IllegalStateException("Cannot create instance of utility class.");
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/bukkit/OpenDummyInventory.java

@@ -0,0 +1,172 @@
+package com.lishid.openinv.internal.v1_21_R2.container.bukkit;
+
+import com.lishid.openinv.internal.ViewOnly;
+import net.minecraft.world.Container;
+import org.bukkit.Material;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftInventory;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.ListIterator;
+
+/**
+ * A locked down "empty" inventory that rejects plugin interaction.
+ */
+public class OpenDummyInventory extends CraftInventory implements ViewOnly {
+
+  private final InventoryType type;
+
+  public OpenDummyInventory(Container inventory, InventoryType type) {
+    super(inventory);
+    this.type = type;
+  }
+
+  @Override
+  public @NotNull InventoryType getType() {
+    return type;
+  }
+
+  @Override
+  public @Nullable ItemStack getItem(int index) {
+    return null;
+  }
+
+  @Override
+  public void setItem(int index, @Nullable ItemStack item) {
+
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> addItem(@NotNull ItemStack... items) throws IllegalArgumentException {
+    return arrayToHashMap(items);
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> removeItem(@NotNull ItemStack... items) throws IllegalArgumentException {
+    return arrayToHashMap(items);
+  }
+
+  @SuppressWarnings("NonApiType")
+  private static @NotNull HashMap<Integer, ItemStack> arrayToHashMap(@NotNull ItemStack[] items) {
+    HashMap<Integer, ItemStack> ignored = new HashMap<>();
+    for (int index = 0; index < items.length; ++index) {
+      ignored.put(index, items[index]);
+    }
+    return ignored;
+  }
+
+  @Override
+  public ItemStack[] getContents() {
+    return new ItemStack[getSize()];
+  }
+
+  @Override
+  public void setContents(@NotNull ItemStack[] items) throws IllegalArgumentException {
+
+  }
+
+  @Override
+  public @NotNull ItemStack[] getStorageContents() {
+    return new ItemStack[getSize()];
+  }
+
+  @Override
+  public void setStorageContents(@NotNull ItemStack[] items) throws IllegalArgumentException {
+
+  }
+
+  @Override
+  public boolean contains(@NotNull Material material) throws IllegalArgumentException {
+    return false;
+  }
+
+  @Override
+  public boolean contains(@Nullable ItemStack item) {
+    return false;
+  }
+
+  @Override
+  public boolean contains(@NotNull Material material, int amount) throws IllegalArgumentException {
+    return false;
+  }
+
+  @Override
+  public boolean contains(@Nullable ItemStack item, int amount) {
+    return false;
+  }
+
+  @Override
+  public boolean containsAtLeast(@Nullable ItemStack item, int amount) {
+    return false;
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> all(
+      @NotNull Material material) throws IllegalArgumentException {
+    return new HashMap<>();
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> all(@Nullable ItemStack item) {
+    return new HashMap<>();
+  }
+
+  @Override
+  public int first(@NotNull Material material) throws IllegalArgumentException {
+    return -1;
+  }
+
+  @Override
+  public int first(@NotNull ItemStack item) {
+    return -1;
+  }
+
+  @Override
+  public int firstEmpty() {
+    return -1;
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return true;
+  }
+
+  @Override
+  public void remove(@NotNull Material material) throws IllegalArgumentException {
+
+  }
+
+  @Override
+  public void remove(@NotNull ItemStack item) {
+
+  }
+
+  @Override
+  public void clear(int index) {
+
+  }
+
+  @Override
+  public void clear() {
+
+  }
+
+  @Override
+  public @NotNull ListIterator<ItemStack> iterator() {
+    return Collections.emptyListIterator();
+  }
+
+  @Override
+  public @NotNull ListIterator<ItemStack> iterator(int index) {
+    return Collections.emptyListIterator();
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/bukkit/OpenDummyPlayerInventory.java

@@ -0,0 +1,134 @@
+package com.lishid.openinv.internal.v1_21_R2.container.bukkit;
+
+import net.minecraft.world.Container;
+import org.bukkit.Material;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.EquipmentSlot;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenDummyPlayerInventory extends OpenDummyInventory implements PlayerInventory {
+
+  public OpenDummyPlayerInventory(Container inventory) {
+    super(inventory, InventoryType.PLAYER);
+  }
+
+  @Override
+  public HumanEntity getHolder() {
+    return (HumanEntity) super.getHolder();
+  }
+
+  @Override
+  public @NotNull ItemStack[] getArmorContents() {
+    return new ItemStack[4];
+  }
+
+  @Override
+  public @NotNull ItemStack[] getExtraContents() {
+    return new ItemStack[4];
+  }
+
+  @Override
+  public @Nullable ItemStack getHelmet() {
+    return null;
+  }
+
+  @Override
+  public @Nullable ItemStack getChestplate() {
+    return null;
+  }
+
+  @Override
+  public @Nullable ItemStack getLeggings() {
+    return null;
+  }
+
+  @Override
+  public @Nullable ItemStack getBoots() {
+    return null;
+  }
+
+  @Override
+  public void setItem(@NotNull EquipmentSlot slot, @Nullable ItemStack item) {
+
+  }
+
+  @Override
+  public @Nullable ItemStack getItem(@NotNull EquipmentSlot slot) {
+    return null;
+  }
+
+  @Override
+  public void setArmorContents(@Nullable ItemStack[] items) {
+
+  }
+
+  @Override
+  public void setExtraContents(@Nullable ItemStack[] items) {
+
+  }
+
+  @Override
+  public void setHelmet(@Nullable ItemStack helmet) {
+
+  }
+
+  @Override
+  public void setChestplate(@Nullable ItemStack chestplate) {
+
+  }
+
+  @Override
+  public void setLeggings(@Nullable ItemStack leggings) {
+
+  }
+
+  @Override
+  public void setBoots(@Nullable ItemStack boots) {
+
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInMainHand() {
+    return new ItemStack(Material.AIR);
+  }
+
+  @Override
+  public void setItemInMainHand(@Nullable ItemStack item) {
+
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInOffHand() {
+    return new ItemStack(Material.AIR);
+  }
+
+  @Override
+  public void setItemInOffHand(@Nullable ItemStack item) {
+
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInHand() {
+    return new ItemStack(Material.AIR);
+  }
+
+  @Override
+  public void setItemInHand(@Nullable ItemStack stack) {
+
+  }
+
+  @Override
+  public int getHeldItemSlot() {
+    return 0;
+  }
+
+  @Override
+  public void setHeldItemSlot(int slot) {
+
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/bukkit/OpenPlayerInventory.java

@@ -0,0 +1,221 @@
+package com.lishid.openinv.internal.v1_21_R2.container.bukkit;
+
+import com.google.common.base.Preconditions;
+import com.lishid.openinv.internal.v1_21_R2.container.OpenInventory;
+import net.minecraft.core.NonNullList;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Inventory;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftInventory;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftItemStack;
+import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenPlayerInventory extends CraftInventory implements PlayerInventory {
+
+  public OpenPlayerInventory(@NotNull OpenInventory inventory) {
+    super(inventory);
+  }
+
+  @Override
+  public @NotNull OpenInventory getInventory() {
+    return (OpenInventory) super.getInventory();
+  }
+
+  @Override
+  public ItemStack[] getContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().getContents());
+  }
+
+  @Override
+  public void setContents(ItemStack[] items) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    int size = internal.getContainerSize();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+
+    for (int index = 0; index < size; ++index) {
+      if (index < items.length) {
+        internal.setItem(index, CraftItemStack.asNMSCopy(items[index]));
+      } else {
+        internal.setItem(index, net.minecraft.world.item.ItemStack.EMPTY);
+      }
+    }
+  }
+
+  @Override
+  public ItemStack[] getStorageContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().items);
+  }
+
+  @Override
+  public void setStorageContents(ItemStack[] items) throws IllegalArgumentException {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().items;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull InventoryType getType() {
+    return InventoryType.PLAYER;
+  }
+
+  @Override
+  public @NotNull Player getHolder() {
+    return getInventory().getOwner();
+  }
+
+  @Override
+  public @NotNull ItemStack[] getArmorContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().armor);
+  }
+
+  @Override
+  public void setArmorContents(@Nullable ItemStack[] items) {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().armor;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull ItemStack[] getExtraContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand);
+  }
+
+  @Override
+  public void setExtraContents(@Nullable ItemStack[] items) {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().offhand;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @Nullable ItemStack getHelmet() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.HEAD.getIndex()));
+  }
+
+  @Override
+  public void setHelmet(@Nullable ItemStack helmet) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.HEAD.getIndex(), CraftItemStack.asNMSCopy(helmet));
+  }
+
+  @Override
+  public @Nullable ItemStack getChestplate() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.HEAD.getIndex()));
+  }
+
+  @Override
+  public void setChestplate(@Nullable ItemStack chestplate) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.CHEST.getIndex(), CraftItemStack.asNMSCopy(chestplate));
+  }
+
+  @Override
+  public @Nullable ItemStack getLeggings() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.LEGS.getIndex()));
+  }
+
+  @Override
+  public void setLeggings(@Nullable ItemStack leggings) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.LEGS.getIndex(), CraftItemStack.asNMSCopy(leggings));
+  }
+
+  @Override
+  public @Nullable ItemStack getBoots() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.FEET.getIndex()));
+  }
+
+  @Override
+  public void setBoots(@Nullable ItemStack boots) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.FEET.getIndex(), CraftItemStack.asNMSCopy(boots));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInMainHand() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return CraftItemStack.asCraftMirror(internal.getItem(internal.selected));
+  }
+
+  @Override
+  public void setItemInMainHand(@Nullable ItemStack item) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    internal.setItem(internal.selected, CraftItemStack.asNMSCopy(item));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInOffHand() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand.getFirst());
+  }
+
+  @Override
+  public void setItemInOffHand(@Nullable ItemStack item) {
+    getInventory().getOwnerHandle().getInventory().offhand.set(0, CraftItemStack.asNMSCopy(item));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInHand() {
+    return getItemInMainHand();
+  }
+
+  @Override
+  public void setItemInHand(@Nullable ItemStack stack) {
+    setItemInMainHand(stack);
+  }
+
+  @Override
+  public int getHeldItemSlot() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return internal.items.size() - 9 + internal.selected;
+  }
+
+  @Override
+  public void setHeldItemSlot(int slot) {
+    slot %= 9;
+    getInventory().getOwnerHandle().getInventory().selected = slot;
+  }
+
+  @Override
+  public @Nullable ItemStack getItem(@NotNull org.bukkit.inventory.EquipmentSlot slot) {
+    return switch (slot) {
+      case HAND -> getItemInMainHand();
+      case OFF_HAND -> getItemInOffHand();
+      case FEET -> getBoots();
+      case LEGS -> getLeggings();
+      case CHEST -> getChestplate();
+      case HEAD -> getHelmet();
+      default -> throw new IllegalArgumentException("Unsupported EquipmentSlot " + slot);
+    };
+  }
+
+  @Override
+  public void setItem(@NotNull org.bukkit.inventory.EquipmentSlot slot, @Nullable ItemStack item) {
+    switch (slot) {
+      case HAND -> setItemInMainHand(item);
+      case OFF_HAND -> setItemInOffHand(item);
+      case FEET -> setBoots(item);
+      case LEGS -> setLeggings(item);
+      case CHEST -> setChestplate(item);
+      case HEAD -> setHelmet(item);
+      default -> throw new IllegalArgumentException("Unsupported EquipmentSlot " + slot);
+    }
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/bukkit/OpenPlayerInventorySelf.java

@@ -0,0 +1,26 @@
+package com.lishid.openinv.internal.v1_21_R2.container.bukkit;
+
+import com.lishid.openinv.internal.v1_21_R2.container.OpenInventory;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+public class OpenPlayerInventorySelf extends OpenPlayerInventory {
+
+  private final int offset;
+
+  public OpenPlayerInventorySelf(@NotNull OpenInventory inventory, int offset) {
+    super(inventory);
+    this.offset = offset;
+  }
+
+  @Override
+  public ItemStack getItem(int index) {
+    return super.getItem(offset + index);
+  }
+
+  @Override
+  public void setItem(int index, ItemStack item) {
+    super.setItem(offset + index, item);
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/menu/OpenChestMenu.java

@@ -0,0 +1,478 @@
+package com.lishid.openinv.internal.v1_21_R2.container.menu;
+
+import com.google.common.base.Suppliers;
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.InternalOwned;
+import com.lishid.openinv.internal.v1_21_R2.container.bukkit.OpenDummyInventory;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.SlotPlaceholder;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.SlotViewOnly;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.ChestMenu;
+import net.minecraft.world.inventory.ClickType;
+import net.minecraft.world.inventory.ContainerData;
+import net.minecraft.world.inventory.ContainerListener;
+import net.minecraft.world.inventory.ContainerSynchronizer;
+import net.minecraft.world.inventory.DataSlot;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftInventoryView;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * An extension of {@link AbstractContainerMenu} that supports {@link SlotPlaceholder placeholders}.
+ */
+public abstract class OpenChestMenu<T extends Container & ISpecialInventory & InternalOwned<ServerPlayer>>
+    extends AbstractContainerMenu {
+
+  protected static final int BOTTOM_INVENTORY_SIZE = 36;
+
+  protected final T container;
+  protected final ServerPlayer viewer;
+  protected final boolean viewOnly;
+  protected final boolean ownContainer;
+  protected final int topSize;
+  private CraftInventoryView<OpenChestMenu<T>, Inventory> bukkitEntity;
+  // Syncher fields
+  private @Nullable ContainerSynchronizer synchronizer;
+  private final List<DataSlot> dataSlots = new ArrayList<>();
+  private final IntList remoteDataSlots = new IntArrayList();
+  private final List<ContainerListener> containerListeners = new ArrayList<>();
+  private ItemStack remoteCarried = ItemStack.EMPTY;
+  private boolean suppressRemoteUpdates;
+
+  protected OpenChestMenu(
+      @NotNull MenuType<ChestMenu> type,
+      int containerCounter,
+      @NotNull T container,
+      @NotNull ServerPlayer viewer,
+      boolean viewOnly) {
+    super(type, containerCounter);
+    this.container = container;
+    this.viewer = viewer;
+    this.viewOnly = viewOnly;
+    ownContainer = container.getOwnerHandle().equals(viewer);
+    topSize = getTopSize(viewer);
+
+    preSlotSetup();
+
+    int upperRows = topSize / 9;
+    // View's upper inventory - our container
+    for (int row = 0; row < upperRows; ++row) {
+      for (int col = 0; col < 9; ++col) {
+        // x and y for client purposes, but hey, we're thorough here.
+        // Adapted from net.minecraft.world.inventory.ChestMenu
+        int x = 8 + col * 18;
+        int y = 18 + row * 18;
+        int index = row * 9 + col;
+
+        // Guard against weird inventory sizes.
+        if (index >= container.getContainerSize()) {
+          addSlot(new SlotViewOnly(container, index, x, y));
+          continue;
+        }
+
+        Slot slot = getUpperSlot(index, x, y);
+
+        addSlot(slot);
+      }
+    }
+
+    // View's lower inventory - viewer inventory
+    int playerInvPad = (upperRows - 4) * 18;
+    for (int row = 0; row < 3; ++row) {
+      for (int col = 0; col < 9; ++col) {
+        int x = 8 + col * 18;
+        int y = playerInvPad + row * 18 + 103;
+        addSlot(new Slot(viewer.getInventory(), row * 9 + col + 9, x, y));
+      }
+    }
+    // Hotbar
+    for (int col = 0; col < 9; ++col) {
+      int x = 8 + col * 18;
+      int y = playerInvPad + 161;
+      addSlot(new Slot(viewer.getInventory(), col, x, y));
+    }
+  }
+
+  public static @NotNull MenuType<ChestMenu> getChestMenuType(int inventorySize) {
+    inventorySize = ((int) Math.ceil(inventorySize / 9.0)) * 9;
+    return switch (inventorySize) {
+      case 9 -> MenuType.GENERIC_9x1;
+      case 18 -> MenuType.GENERIC_9x2;
+      case 27 -> MenuType.GENERIC_9x3;
+      case 36 -> MenuType.GENERIC_9x4;
+      case 45 -> MenuType.GENERIC_9x5;
+      case 54 -> MenuType.GENERIC_9x6;
+      default -> throw new IllegalArgumentException("Inventory size unsupported: " + inventorySize);
+    };
+  }
+
+  protected void preSlotSetup() {}
+
+  protected @NotNull Slot getUpperSlot(int index, int x, int y) {
+    if (viewOnly) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+    return new Slot(container, index, x, y);
+  }
+
+
+  @Override
+  public final @NotNull CraftInventoryView<OpenChestMenu<T>, Inventory> getBukkitView() {
+    if (bukkitEntity == null) {
+      bukkitEntity = createBukkitEntity();
+    }
+
+    return bukkitEntity;
+  }
+
+  protected @NotNull CraftInventoryView<OpenChestMenu<T>, Inventory> createBukkitEntity() {
+    Inventory top;
+    if (viewOnly) {
+      top = new OpenDummyInventory(container, container.getBukkitType());
+    } else {
+      top = container.getBukkitInventory();
+    }
+    return new CraftInventoryView<>(viewer.getBukkitEntity(), top, this) {
+      @Override
+      public @Nullable Inventory getInventory(int rawSlot) {
+        if (viewOnly) {
+          return null;
+        }
+        return super.getInventory(rawSlot);
+      }
+
+      @Override
+      public int convertSlot(int rawSlot) {
+        if (viewOnly) {
+          return InventoryView.OUTSIDE;
+        }
+        return super.convertSlot(rawSlot);
+      }
+
+      @Override
+      public @NotNull InventoryType.SlotType getSlotType(int slot) {
+        if (viewOnly) {
+          return InventoryType.SlotType.OUTSIDE;
+        }
+        return super.getSlotType(slot);
+      }
+    };
+  }
+
+  private int getTopSize(ServerPlayer viewer) {
+    MenuType<?> menuType = getType();
+    if (menuType == null) {
+      throw new IllegalStateException("MenuType cannot be null!");
+    } else if (menuType == MenuType.GENERIC_9x1) {
+      return 9;
+    } else if (menuType == MenuType.GENERIC_9x2) {
+      return 18;
+    } else if (menuType == MenuType.GENERIC_9x3) {
+      return 27;
+    } else if (menuType == MenuType.GENERIC_9x4) {
+      return 36;
+    } else if (menuType == MenuType.GENERIC_9x5) {
+      return 45;
+    } else if (menuType == MenuType.GENERIC_9x6) {
+      return 54;
+    }
+    // This is a bit gross, but allows us a safe fallthrough.
+    return menuType.create(-1, viewer.getInventory()).slots.size() - BOTTOM_INVENTORY_SIZE;
+  }
+
+  /**
+   * Reimplementation of {@link AbstractContainerMenu#moveItemStackTo(ItemStack, int, int, boolean)} that ignores fake
+   * slots and respects {@link Slot#hasItem()}.
+   *
+   * @param itemStack the stack to quick-move
+   * @param rangeLow the start of the range of slots that can be moved to, inclusive
+   * @param rangeHigh the end of the range of slots that can be moved to, exclusive
+   * @param topDown whether to start at the top of the range or bottom
+   * @return whether the stack was modified as a result of being quick-moved
+   */
+  @Override
+  protected boolean moveItemStackTo(ItemStack itemStack, int rangeLow, int rangeHigh, boolean topDown) {
+    boolean modified = false;
+    boolean stackable = itemStack.isStackable();
+    Slot firstEmpty = null;
+
+    for (int index = topDown ? rangeHigh - 1 : rangeLow;
+         !itemStack.isEmpty() && (topDown ? index >= rangeLow : index < rangeHigh);
+         index += topDown ? -1 : 1
+    ) {
+      Slot slot = slots.get(index);
+      // If the slot cannot be added to, check the next slot.
+      if (slot.isFake() || !slot.mayPlace(itemStack)) {
+        continue;
+      }
+
+      if (slot.hasItem()) {
+        // If the item isn't stackable, check the next slot.
+        if (!stackable) {
+          continue;
+        }
+        // Otherwise, add as many as we can from our stack to the slot.
+        modified |= addToExistingStack(itemStack, slot);
+      } else {
+        // If this is the first empty slot, keep track of it for later use.
+        if (firstEmpty == null) {
+          firstEmpty = slot;
+        }
+        // If the item isn't stackable, we've located the slot we're adding it to, so we're done.
+        if (!stackable) {
+          break;
+        }
+      }
+    }
+
+    // If the item hasn't been fully added yet, add as many as we can to the first open slot.
+    if (!itemStack.isEmpty() && firstEmpty != null) {
+      firstEmpty.setByPlayer(itemStack.split(Math.min(itemStack.getCount(), firstEmpty.getMaxStackSize(itemStack))));
+      firstEmpty.setChanged();
+      modified = true;
+    }
+
+    return modified;
+  }
+
+  private static boolean addToExistingStack(ItemStack itemStack, Slot slot) {
+    ItemStack existing = slot.getItem();
+
+    // If the items aren't the same, we can't add our item.
+    if (!ItemStack.isSameItemSameComponents(itemStack, existing)) {
+      return false;
+    }
+
+    int max = slot.getMaxStackSize(existing);
+    int existingCount = existing.getCount();
+
+    // If the stack is already full, we can't add more.
+    if (existingCount >= max) {
+      return false;
+    }
+
+    int total = existingCount + itemStack.getCount();
+
+    // If the existing item can accept the entirety of our item, we're done!
+    if (total <= max) {
+      itemStack.setCount(0);
+      existing.setCount(total);
+      slot.setChanged();
+      return true;
+    }
+
+    // Otherwise, add as many as we can.
+    itemStack.shrink(max - existingCount);
+    existing.setCount(max);
+    slot.setChanged();
+    return true;
+  }
+
+  @Override
+  public void clicked(int i, int j, ClickType clickType, Player player) {
+    if (viewOnly) {
+      if (clickType == ClickType.QUICK_CRAFT) {
+        sendAllDataToRemote();
+      }
+      return;
+    }
+    super.clicked(i, j, clickType, player);
+  }
+
+  @Override
+  public boolean stillValid(Player player) {
+    return true;
+  }
+
+  // Overrides from here on are purely to modify the sync process to send placeholder items.
+  @Override
+  protected Slot addSlot(Slot slot) {
+    slot.index = this.slots.size();
+    this.slots.add(slot);
+    this.lastSlots.add(ItemStack.EMPTY);
+    this.remoteSlots.add(ItemStack.EMPTY);
+    return slot;
+  }
+
+  @Override
+  protected DataSlot addDataSlot(DataSlot dataSlot) {
+    this.dataSlots.add(dataSlot);
+    this.remoteDataSlots.add(0);
+    return dataSlot;
+  }
+
+  @Override
+  protected void addDataSlots(ContainerData containerData) {
+    for (int i = 0; i < containerData.getCount(); i++) {
+      this.addDataSlot(DataSlot.forContainer(containerData, i));
+    }
+  }
+
+  @Override
+  public void addSlotListener(ContainerListener containerListener) {
+    if (!this.containerListeners.contains(containerListener)) {
+      this.containerListeners.add(containerListener);
+      this.broadcastChanges();
+    }
+  }
+
+  @Override
+  public void setSynchronizer(ContainerSynchronizer containerSynchronizer) {
+    this.synchronizer = containerSynchronizer;
+    this.sendAllDataToRemote();
+  }
+
+  @Override
+  public void sendAllDataToRemote() {
+    for (int index = 0; index < slots.size(); ++index) {
+      Slot slot = slots.get(index);
+      this.remoteSlots.set(index, (slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem()).copy());
+    }
+
+    remoteCarried = getCarried().copy();
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      this.remoteDataSlots.set(index, this.dataSlots.get(index).get());
+    }
+
+    if (this.synchronizer != null) {
+      this.synchronizer.sendInitialData(this, this.remoteSlots, this.remoteCarried, this.remoteDataSlots.toIntArray());
+    }
+  }
+
+  @Override
+  public void broadcastCarriedItem() {
+    this.remoteCarried = this.getCarried().copy();
+    if (this.synchronizer != null) {
+      this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+    }
+  }
+
+  @Override
+  public void removeSlotListener(ContainerListener containerListener) {
+    this.containerListeners.remove(containerListener);
+  }
+
+  @Override
+  public void broadcastChanges() {
+    for (int index = 0; index < this.slots.size(); ++index) {
+      Slot slot = this.slots.get(index);
+      ItemStack itemstack = slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem();
+      Supplier<ItemStack> supplier = Suppliers.memoize(itemstack::copy);
+      this.triggerSlotListeners(index, itemstack, supplier);
+      this.synchronizeSlotToRemote(index, itemstack, supplier);
+    }
+
+    this.synchronizeCarriedToRemote();
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      DataSlot dataSlot = this.dataSlots.get(index);
+      int j = dataSlot.get();
+      if (dataSlot.checkAndClearUpdateFlag()) {
+        this.updateDataSlotListeners(index, j);
+      }
+
+      this.synchronizeDataSlotToRemote(index, j);
+    }
+  }
+
+  @Override
+  public void broadcastFullState() {
+    for (int index = 0; index < this.slots.size(); ++index) {
+      ItemStack itemstack = this.slots.get(index).getItem();
+      this.triggerSlotListeners(index, itemstack, itemstack::copy);
+    }
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      DataSlot containerproperty = this.dataSlots.get(index);
+      if (containerproperty.checkAndClearUpdateFlag()) {
+        this.updateDataSlotListeners(index, containerproperty.get());
+      }
+    }
+
+    this.sendAllDataToRemote();
+  }
+
+  private void updateDataSlotListeners(int i, int j) {
+    for (ContainerListener containerListener : this.containerListeners) {
+      containerListener.dataChanged(this, i, j);
+    }
+  }
+
+  private void triggerSlotListeners(int index, ItemStack itemStack, Supplier<ItemStack> supplier) {
+    ItemStack itemStack1 = this.lastSlots.get(index);
+    if (!ItemStack.matches(itemStack1, itemStack)) {
+      ItemStack itemStack2 = supplier.get();
+      this.lastSlots.set(index, itemStack2);
+
+      for (ContainerListener containerListener : this.containerListeners) {
+        containerListener.slotChanged(this, index, itemStack2);
+      }
+    }
+  }
+
+  private void synchronizeSlotToRemote(int i, ItemStack itemStack, Supplier<ItemStack> supplier) {
+    if (!this.suppressRemoteUpdates) {
+      ItemStack itemStack1 = this.remoteSlots.get(i);
+      if (!ItemStack.matches(itemStack1, itemStack)) {
+        ItemStack itemstack2 = supplier.get();
+        this.remoteSlots.set(i, itemstack2);
+        if (this.synchronizer != null) {
+          this.synchronizer.sendSlotChange(this, i, itemstack2);
+        }
+      }
+    }
+  }
+
+  private void synchronizeDataSlotToRemote(int index, int value) {
+    if (!this.suppressRemoteUpdates) {
+      int existing = this.remoteDataSlots.getInt(index);
+      if (existing != value) {
+        this.remoteDataSlots.set(index, value);
+        if (this.synchronizer != null) {
+          this.synchronizer.sendDataChange(this, index, value);
+        }
+      }
+    }
+  }
+
+  private void synchronizeCarriedToRemote() {
+    if (!this.suppressRemoteUpdates && !ItemStack.matches(this.getCarried(), this.remoteCarried)) {
+      this.remoteCarried = this.getCarried().copy();
+      if (this.synchronizer != null) {
+        this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+      }
+    }
+  }
+
+  @Override
+  public void setRemoteCarried(ItemStack itemstack) {
+    this.remoteCarried = itemstack.copy();
+  }
+
+  @Override
+  public void suppressRemoteUpdates() {
+    this.suppressRemoteUpdates = true;
+  }
+
+  @Override
+  public void resumeRemoteUpdates() {
+    this.suppressRemoteUpdates = false;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/menu/OpenEnderChestMenu.java

@@ -0,0 +1,53 @@
+package com.lishid.openinv.internal.v1_21_R2.container.menu;
+
+import com.lishid.openinv.internal.v1_21_R2.container.OpenEnderChest;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+public class OpenEnderChestMenu extends OpenChestMenu<OpenEnderChest> {
+
+  public OpenEnderChestMenu(
+      @NotNull OpenEnderChest enderChest,
+      @NotNull ServerPlayer viewer,
+      int containerId,
+      boolean viewOnly) {
+    super(getChestMenuType(enderChest.getContainerSize()), containerId, enderChest, viewer, viewOnly);
+  }
+
+  @Override
+  public ItemStack quickMoveStack(Player player, int index) {
+    if (viewOnly) {
+      return ItemStack.EMPTY;
+    }
+
+    // See ChestMenu
+    Slot slot = this.slots.get(index);
+
+    if (slot.isFake() || !slot.hasItem()) {
+      return ItemStack.EMPTY;
+    }
+
+    ItemStack itemStack = slot.getItem();
+    ItemStack original = itemStack.copy();
+
+    if (index < topSize) {
+      if (!this.moveItemStackTo(itemStack, topSize, this.slots.size(), true)) {
+        return ItemStack.EMPTY;
+      }
+    } else if (!this.moveItemStackTo(itemStack, 0, topSize, false)) {
+      return ItemStack.EMPTY;
+    }
+
+    if (itemStack.isEmpty()) {
+      slot.setByPlayer(ItemStack.EMPTY);
+    } else {
+      slot.setChanged();
+    }
+
+    return original;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/menu/OpenInventoryMenu.java

@@ -0,0 +1,262 @@
+package com.lishid.openinv.internal.v1_21_R2.container.menu;
+
+import com.google.common.base.Preconditions;
+import com.lishid.openinv.internal.v1_21_R2.container.OpenInventory;
+import com.lishid.openinv.internal.v1_21_R2.container.bukkit.OpenDummyPlayerInventory;
+import com.lishid.openinv.internal.v1_21_R2.container.bukkit.OpenPlayerInventorySelf;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentDrop;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.ContentEquipment;
+import com.lishid.openinv.internal.v1_21_R2.container.slot.SlotViewOnly;
+import com.lishid.openinv.util.Permissions;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.ChestMenu;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftInventoryView;
+import org.bukkit.craftbukkit.v1_21_R2.inventory.CraftItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
+
+  private int offset;
+
+  public OpenInventoryMenu(OpenInventory inventory, ServerPlayer viewer, int i, boolean viewOnly) {
+    super(getMenuType(inventory, viewer), i, inventory, viewer, viewOnly);
+  }
+
+  private static MenuType<ChestMenu> getMenuType(OpenInventory inventory, ServerPlayer viewer) {
+    int size = inventory.getContainerSize();
+    // Disallow duplicate access to own main inventory contents.
+    if (inventory.getOwnerHandle().equals(viewer)) {
+      size -= viewer.getInventory().items.size();
+      size = ((int) Math.ceil(size / 9.0)) * 9;
+    }
+
+    return getChestMenuType(size);
+  }
+
+  @Override
+  protected void preSlotSetup() {
+    offset = ownContainer ? viewer.getInventory().items.size() : 0;
+  }
+
+  @Override
+  protected @NotNull Slot getUpperSlot(int index, int x, int y) {
+    index += offset;
+    Slot slot = container.getMenuSlot(index, x, y);
+
+    // If the slot cannot be interacted with there's nothing to configure.
+    if (slot.getClass().equals(SlotViewOnly.class)) {
+      return slot;
+    }
+
+    // Remove drop slot if viewer is not allowed to use it.
+    if (slot instanceof ContentDrop.SlotDrop
+        && (viewOnly || !Permissions.INVENTORY_SLOT_DROP.hasPermission(viewer.getBukkitEntity()))) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+
+    if (slot instanceof ContentEquipment.SlotEquipment equipment) {
+      if (viewOnly) {
+        return SlotViewOnly.wrap(slot);
+      }
+
+      Permissions perm = switch (equipment.getEquipmentSlot()) {
+        case HEAD -> Permissions.INVENTORY_SLOT_HEAD_ANY;
+        case CHEST -> Permissions.INVENTORY_SLOT_CHEST_ANY;
+        case LEGS -> Permissions.INVENTORY_SLOT_LEGS_ANY;
+        case FEET -> Permissions.INVENTORY_SLOT_FEET_ANY;
+        // Off-hand can hold anything, not just equipment.
+        default -> null;
+      };
+
+      // If the viewer doesn't have permission, only allow equipment the viewee can equip in the slot.
+      if (perm != null && !perm.hasPermission(viewer.getBukkitEntity())) {
+        equipment.onlyEquipmentFor(container.getOwnerHandle());
+      }
+
+      // Equipment slots are a core part of the inventory, so they will always be shown.
+      return slot;
+    }
+
+    // When viewing own inventory, only allow access to equipment and drop slots (equipment allowed above).
+    if (ownContainer && !(slot instanceof ContentDrop.SlotDrop)) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+
+    if (viewOnly) {
+      return SlotViewOnly.wrap(slot);
+    }
+
+    return slot;
+  }
+
+  @Override
+  protected @NotNull CraftInventoryView<OpenChestMenu<OpenInventory>, Inventory> createBukkitEntity() {
+    org.bukkit.inventory.Inventory bukkitInventory;
+    if (viewOnly) {
+      bukkitInventory = new OpenDummyPlayerInventory(container);
+    } else if (ownContainer) {
+      bukkitInventory = new OpenPlayerInventorySelf(container, offset);
+    } else {
+      bukkitInventory = container.getBukkitInventory();
+    }
+
+    return new CraftInventoryView<>(viewer.getBukkitEntity(), bukkitInventory, this) {
+      @Override
+      public org.bukkit.inventory.ItemStack getItem(int index) {
+        if (viewOnly || index < 0) {
+          return null;
+        }
+
+        Slot slot = slots.get(index);
+        return CraftItemStack.asCraftMirror(slot.hasItem() ? slot.getItem() : ItemStack.EMPTY);
+      }
+
+      @Override
+      public boolean isInTop(int rawSlot) {
+        return rawSlot < topSize;
+      }
+
+      @Override
+      public @Nullable Inventory getInventory(int rawSlot) {
+        if (viewOnly) {
+          return null;
+        }
+        if (rawSlot == InventoryView.OUTSIDE || rawSlot == -1) {
+          return null;
+        }
+        Preconditions.checkArgument(rawSlot >= 0 && rawSlot < topSize + offset + BOTTOM_INVENTORY_SIZE,
+            "Slot %s outside of inventory", rawSlot);
+        if (rawSlot > topSize) {
+          return getBottomInventory();
+        }
+        Slot slot = slots.get(rawSlot);
+        if (slot.isFake()) {
+          return null;
+        }
+        return getTopInventory();
+      }
+
+      @Override
+      public int convertSlot(int rawSlot) {
+        if (viewOnly) {
+          return InventoryView.OUTSIDE;
+        }
+        if (rawSlot < 0) {
+          return rawSlot;
+        }
+        if (rawSlot < topSize) {
+          Slot slot = slots.get(rawSlot);
+          if (slot.isFake()) {
+            return InventoryView.OUTSIDE;
+          }
+          return rawSlot;
+        }
+
+        int slot = rawSlot - topSize;
+
+        if (slot >= 27) {
+          slot -= 27;
+        } else {
+          slot += 9;
+        }
+
+        return slot;
+      }
+
+      @Override
+      public @NotNull InventoryType.SlotType getSlotType(int slot) {
+        if (viewOnly || slot < 0) {
+          return InventoryType.SlotType.OUTSIDE;
+        }
+        if (slot >= topSize) {
+          slot -= topSize;
+          if (slot >= 27) {
+            return InventoryType.SlotType.QUICKBAR;
+          }
+          return InventoryType.SlotType.CONTAINER;
+        }
+        return OpenInventoryMenu.this.container.getSlotType(offset + slot);
+      }
+
+      @Override
+      public int countSlots() {
+        return topSize + BOTTOM_INVENTORY_SIZE;
+      }
+    };
+  }
+
+  @Override
+  public ItemStack quickMoveStack(Player player, int index) {
+    if (viewOnly) {
+      return ItemStack.EMPTY;
+    }
+
+    // See ChestMenu and InventoryMenu
+    Slot slot = this.slots.get(index);
+
+    if (!slot.hasItem() || slot.isFake()) {
+      return ItemStack.EMPTY;
+    }
+
+    ItemStack itemStack = slot.getItem();
+    ItemStack originalStack = itemStack.copy();
+
+    if (index < topSize) {
+      // If we're moving top to bottom, do a normal transfer.
+      if (!this.moveItemStackTo(itemStack, topSize, this.slots.size(), true)) {
+        return ItemStack.EMPTY;
+      }
+    } else {
+      EquipmentSlot equipmentSlot = player.getEquipmentSlotForItem(itemStack);
+      boolean movedGear = switch (equipmentSlot) {
+        // If this is gear, try to move it to the correct slot first.
+        case OFFHAND, FEET, LEGS, CHEST, HEAD -> {
+          // Locate the correct slot in the contents following the main inventory.
+          for (int extra = container.getOwnerHandle().getInventory().items.size() - offset; extra < topSize; ++extra) {
+            Slot extraSlot = getSlot(extra);
+            if (extraSlot instanceof ContentEquipment.SlotEquipment equipSlot
+                && equipSlot.getEquipmentSlot() == equipmentSlot) {
+              // If we've found a matching slot, try to move to it.
+              // If this succeeds, even partially, we will not attempt to move to other slots.
+              // Otherwise, armor is already occupied, so we'll fall through to main inventory.
+              yield this.moveItemStackTo(itemStack, extra, extra + 1, false);
+            }
+          }
+          yield false;
+        }
+        // Non-gear gets no special treatment.
+        default -> false;
+      };
+
+      // If main inventory is not available, there's nowhere else to move.
+      if (offset != 0) {
+        if (!movedGear) {
+          return ItemStack.EMPTY;
+        }
+      } else {
+        // If we didn't move to a gear slot, try to move to a main inventory slot.
+        if (!movedGear && !this.moveItemStackTo(itemStack, 0, container.getOwnerHandle().getInventory().items.size(), true)) {
+          return ItemStack.EMPTY;
+        }
+      }
+    }
+
+    if (itemStack.isEmpty()) {
+      slot.setByPlayer(ItemStack.EMPTY);
+    } else {
+      slot.setChanged();
+    }
+
+    return originalStack;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/Content.java

@@ -0,0 +1,69 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * An interface defining behaviors for entries in a {@link Container}. Used to reduce duplicate content reordering.
+ */
+public interface Content {
+
+  /**
+   * Update internal holder.
+   *
+   * @param holder the new holder
+   */
+  void setHolder(@NotNull ServerPlayer holder);
+
+  /**
+   * Get the current item.
+   *
+   * @return the current item
+   */
+  ItemStack get();
+
+  /**
+   * Remove the current item.
+   *
+   * @return the current item
+   */
+  ItemStack remove();
+
+  /**
+   * Remove some of the current item.
+   *
+   * @return the current item
+   */
+  ItemStack removePartial(int amount);
+
+  /**
+   * Set the current item. If slot is currently not usable, will drop item instead.
+   *
+   * @param itemStack the item to set
+   */
+  void set(ItemStack itemStack);
+
+  /**
+   * Get a {@link Slot} for use in a {@link net.minecraft.world.inventory.AbstractContainerMenu ContainerMenu}. Will
+   * impose any specific restrictions to insertion or removal.
+   *
+   * @param container the backing container
+   * @param slot the slot of the backing container represented
+   * @param x clientside x dimension from top left of inventory, not used
+   * @param y clientside y dimension from top left of inventory, not used
+   * @return a menu slot
+   */
+  Slot asSlot(Container container, int slot, int x, int y);
+
+  /**
+   * Get a loose Bukkit translation of what this slot stores. For example, any slot that drops items at the owner rather
+   * than insert them will report itself as being {@link org.bukkit.event.inventory.InventoryType.SlotType#OUTSIDE}.
+   *
+   * @return the closes Bukkit slot type
+   */
+  org.bukkit.event.inventory.InventoryType.SlotType getSlotType();
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentCrafting.java

@@ -0,0 +1,131 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R2.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * A slot in a survival crafting inventory. Unavailable when not online in a survival mode.
+ */
+public class ContentCrafting implements Content {
+
+  private final int index;
+  private ServerPlayer holder;
+  private List<ItemStack> items;
+
+  public ContentCrafting(@NotNull ServerPlayer holder, int index) {
+    setHolder(holder);
+    this.index = index;
+  }
+
+  private boolean isAvailable() {
+    return isAvailable(holder);
+  }
+
+  static boolean isAvailable(@NotNull ServerPlayer holder) {
+    // Player must be online and not in creative - since the creative client is (semi-)authoritative,
+    // it ignores changes without extra help, and will delete the item as a result.
+    // Spectator mode is technically possible but may cause the item to be dropped if the client opens an inventory.
+    return holder.connection != null && !holder.connection.isDisconnected() && holder.gameMode.isSurvival();
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+    // Note: CraftingContainer#getItems is immutable! Be careful with updates.
+    this.items = holder.inventoryMenu.getCraftSlots().getContents();
+  }
+
+  @Override
+  public ItemStack get() {
+    return isAvailable() ? items.get(index) : ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    if (!this.isAvailable()) {
+      return ItemStack.EMPTY;
+    }
+    ItemStack removed = items.remove(index);
+    if (removed.isEmpty()) {
+      return ItemStack.EMPTY;
+    }
+    holder.inventoryMenu.slotsChanged(holder.inventoryMenu.getCraftSlots());
+    return removed;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    if (!this.isAvailable()) {
+      return ItemStack.EMPTY;
+    }
+    ItemStack removed = ContainerHelper.removeItem(items, index, amount);
+    if (removed.isEmpty()) {
+      return ItemStack.EMPTY;
+    }
+    holder.inventoryMenu.slotsChanged(holder.inventoryMenu.getCraftSlots());
+    return removed;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    if (isAvailable()) {
+      items.set(index, itemStack);
+      holder.inventoryMenu.slotsChanged(holder.inventoryMenu.getCraftSlots());
+    } else {
+      holder.drop(itemStack, false);
+    }
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotCrafting(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return isAvailable() ? InventoryType.SlotType.CRAFTING : InventoryType.SlotType.OUTSIDE;
+  }
+
+  public class SlotCrafting extends SlotPlaceholder {
+
+    private SlotCrafting(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      return isAvailable() ? items.get(ContentCrafting.this.index) : Placeholders.survivalOnly(holder);
+    }
+
+    @Override
+    public boolean mayPickup(Player player) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack itemStack) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean hasItem() {
+      return isAvailable() && super.hasItem();
+    }
+
+    @Override
+    public boolean isFake() {
+      return !isAvailable();
+    }
+
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentCraftingResult.java

@@ -0,0 +1,48 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R2.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.InventoryMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot allowing viewing of the crafting result.
+ *
+ * <p>Unmodifiable because I said so. Use your own crafting grid.</p>
+ */
+public class ContentCraftingResult extends ContentViewOnly {
+
+  public ContentCraftingResult(@NotNull ServerPlayer holder) {
+    super(holder);
+  }
+
+  @Override
+  public ItemStack get() {
+    InventoryMenu inventoryMenu = holder.inventoryMenu;
+    return inventoryMenu.getResultSlot().getItem();
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotViewOnly(container, slot, x, y) {
+      @Override
+      public ItemStack getOrDefault() {
+        if (!ContentCrafting.isAvailable(holder)) {
+          return Placeholders.survivalOnly(holder);
+        }
+        InventoryMenu inventoryMenu = holder.inventoryMenu;
+        return inventoryMenu.getResultSlot().getItem();
+      }
+    };
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.RESULT;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentCursor.java

@@ -0,0 +1,117 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R2.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot wrapping the active menu's cursor. Unavailable when not online in a survival mode.
+ */
+public class ContentCursor implements Content {
+
+  private @NotNull ServerPlayer holder;
+
+  public ContentCursor(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public ItemStack get() {
+    return isAvailable() ? holder.containerMenu.getCarried() : ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    ItemStack carried = holder.containerMenu.getCarried();
+    holder.containerMenu.setCarried(ItemStack.EMPTY);
+    return carried;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    ItemStack carried = holder.containerMenu.getCarried();
+    if (!carried.isEmpty() && carried.getCount() >= amount) {
+      ItemStack value = carried.split(amount);
+      if (carried.isEmpty()) {
+        holder.containerMenu.setCarried(ItemStack.EMPTY);
+      }
+      return value;
+    }
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    if (isAvailable()) {
+      holder.containerMenu.setCarried(itemStack);
+    } else {
+      holder.drop(itemStack, false);
+    }
+  }
+
+  private boolean isAvailable() {
+    // Player must be online and not in creative - since the creative client is (semi-)authoritative,
+    // it ignores changes without extra help, and will delete the item as a result.
+    // Spectator mode is technically possible but may cause the item to be dropped if the client opens an inventory.
+    return holder.connection != null && !holder.connection.isDisconnected() && holder.gameMode.isSurvival();
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotCursor(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    // As close as possible to "not real"
+    return InventoryType.SlotType.OUTSIDE;
+  }
+
+  public class SlotCursor extends SlotPlaceholder {
+
+    private SlotCursor(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      if (!isAvailable()) {
+        return Placeholders.survivalOnly(holder);
+      }
+      ItemStack carried = holder.containerMenu.getCarried();
+      return carried.isEmpty() ? Placeholders.cursor : carried;
+    }
+
+    @Override
+    public boolean mayPickup(Player player) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack itemStack) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean hasItem() {
+      return isAvailable() && super.hasItem();
+    }
+
+    @Override
+    public boolean isFake() {
+      return true;
+    }
+
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentDrop.java

@@ -0,0 +1,88 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R2.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A fake slot used to drop items. Unavailable offline.
+ */
+public class ContentDrop implements Content {
+
+  private ServerPlayer holder;
+
+  public ContentDrop(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public ItemStack get() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    holder.drop(itemStack, true);
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotDrop(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    // Behaves like dropping an item outside the screen, just by the target player.
+    return InventoryType.SlotType.OUTSIDE;
+  }
+
+  public class SlotDrop extends SlotPlaceholder {
+
+    private SlotDrop(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      return holder.connection != null && !holder.connection.isDisconnected()
+          ? Placeholders.drop
+          : Placeholders.blockedOffline;
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack itemStack) {
+      return holder.connection != null && !holder.connection.isDisconnected();
+    }
+
+    @Override
+    public boolean hasItem() {
+      return false;
+    }
+
+    @Override
+    public boolean isFake() {
+      return true;
+    }
+
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentEquipment.java

@@ -0,0 +1,78 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R2.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot for equipment that displays placeholders if empty.
+ */
+public class ContentEquipment extends ContentList {
+
+  private final ItemStack placeholder;
+  private final EquipmentSlot equipmentSlot;
+
+  public ContentEquipment(ServerPlayer holder, int index, EquipmentSlot equipmentSlot) {
+    super(holder, index, InventoryType.SlotType.ARMOR);
+    placeholder = switch (equipmentSlot) {
+      case HEAD -> Placeholders.emptyHelmet;
+      case CHEST -> Placeholders.emptyChestplate;
+      case LEGS -> Placeholders.emptyLeggings;
+      case FEET -> Placeholders.emptyBoots;
+      default -> Placeholders.emptyOffHand;
+    };
+    this.equipmentSlot = equipmentSlot;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.items = holder.getInventory().armor;
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y);
+  }
+
+  public class SlotEquipment extends SlotPlaceholder {
+
+    private ServerPlayer viewer;
+
+    SlotEquipment(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      ItemStack itemStack = getItem();
+      if (!itemStack.isEmpty()) {
+        return itemStack;
+      }
+      return placeholder;
+    }
+
+    public EquipmentSlot getEquipmentSlot() {
+      return equipmentSlot;
+    }
+
+    public void onlyEquipmentFor(ServerPlayer viewer) {
+      this.viewer = viewer;
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack var0) {
+      if (viewer == null) {
+        return true;
+      }
+
+      return equipmentSlot == EquipmentSlot.OFFHAND || viewer.getEquipmentSlotForItem(var0) == equipmentSlot;
+    }
+
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentList.java

@@ -0,0 +1,58 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+
+import java.util.List;
+
+/**
+ * A normal slot backed by an item list.
+ */
+public abstract class ContentList implements Content {
+
+  private final int index;
+  private final InventoryType.SlotType slotType;
+  protected List<ItemStack> items;
+
+  public ContentList(ServerPlayer holder, int index, InventoryType.SlotType slotType) {
+    this.index = index;
+    this.slotType = slotType;
+    setHolder(holder);
+  }
+
+  @Override
+  public ItemStack get() {
+    return items.get(index);
+  }
+
+  @Override
+  public ItemStack remove() {
+    ItemStack removed = items.remove(index);
+    return removed == null || removed.isEmpty() ? ItemStack.EMPTY : removed;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    return ContainerHelper.removeItem(items, index, amount);
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    items.set(index, itemStack);
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new Slot(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return slotType;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentOffHand.java

@@ -0,0 +1,46 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.Slot;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot for equipment that updates held items if necessary.
+ */
+public class ContentOffHand extends ContentEquipment {
+
+  private ServerPlayer holder;
+
+  public ContentOffHand(ServerPlayer holder, int localIndex) {
+    super(holder, localIndex, EquipmentSlot.OFFHAND);
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.items = holder.getInventory().offhand;
+    this.holder = holder;
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.QUICKBAR;
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y) {
+      @Override
+      public void setChanged() {
+        if (holder.connection != null
+            && !holder.connection.isDisconnected()
+            && holder.containerMenu != holder.inventoryMenu) {
+          holder.resendItemInHands();
+        }
+      }
+    };
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/ContentViewOnly.java

@@ -0,0 +1,56 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A view-only slot that can't be interacted with.
+ */
+public class ContentViewOnly implements Content {
+
+  @NotNull ServerPlayer holder;
+
+  public ContentViewOnly(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public ItemStack get() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    this.holder.drop(itemStack, false);
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotViewOnly(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.OUTSIDE;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/SlotPlaceholder.java

@@ -0,0 +1,20 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+
+/**
+ * An implementation of a slot as used by a menu that may have fake placeholder items.
+ *
+ * <p>Used to prevent plugins (particularly sorting plugins) from adding placeholders to inventories.</p>
+ */
+public abstract class SlotPlaceholder extends Slot {
+
+  public SlotPlaceholder(Container container, int index, int x, int y) {
+    super(container, index, x, y);
+  }
+
+  public abstract ItemStack getOrDefault();
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/container/slot/SlotViewOnly.java

@@ -0,0 +1,151 @@
+package com.lishid.openinv.internal.v1_21_R2.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R2.container.Placeholders;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Optional;
+
+/**
+ * A view-only {@link Slot}. "Blank" by default, but can wrap another slot to display its content.
+ */
+public class SlotViewOnly extends SlotPlaceholder {
+
+  public static @NotNull SlotViewOnly wrap(@NotNull Slot wrapped) {
+    SlotViewOnly wrapper;
+    if (wrapped instanceof SlotPlaceholder placeholder) {
+      wrapper = new SlotViewOnly(wrapped.container, wrapped.slot, wrapped.x, wrapped.y) {
+        @Override
+        public ItemStack getOrDefault() {
+          return placeholder.getOrDefault();
+        }
+      };
+    } else {
+      wrapper = new SlotViewOnly(wrapped.container, wrapped.slot, wrapped.x, wrapped.y) {
+        @Override
+        public ItemStack getOrDefault() {
+          return wrapped.getItem();
+        }
+      };
+    }
+    wrapper.index = wrapped.index;
+    return wrapper;
+  }
+
+  public SlotViewOnly(Container container, int index, int x, int y) {
+    super(container, index, x, y);
+  }
+
+  @Override
+  public ItemStack getOrDefault() {
+    return Placeholders.notSlot;
+  }
+
+  @Override
+  public void onQuickCraft(ItemStack var0, ItemStack var1) {
+  }
+
+  @Override
+  public void onTake(Player var0, ItemStack var1) {
+  }
+
+  @Override
+  public boolean mayPlace(ItemStack var0) {
+    return false;
+  }
+
+  @Override
+  public ItemStack getItem() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public boolean hasItem() {
+    return false;
+  }
+
+  @Override
+  public void setByPlayer(ItemStack newStack) {
+  }
+
+  @Override
+  public void setByPlayer(ItemStack newStack, ItemStack oldStack) {
+  }
+
+  @Override
+  public void set(ItemStack var0) {
+  }
+
+  @Override
+  public void setChanged() {
+  }
+
+  @Override
+  public int getMaxStackSize() {
+    return 0;
+  }
+
+  @Override
+  public int getMaxStackSize(ItemStack itemStack) {
+    return 0;
+  }
+
+  @Override
+  public ItemStack remove(int amount) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public boolean mayPickup(Player var0) {
+    return false;
+  }
+
+  @Override
+  public boolean isActive() {
+    return false;
+  }
+
+  @Override
+  public Optional<ItemStack> tryRemove(int var0, int var1, Player var2) {
+    return Optional.empty();
+  }
+
+  @Override
+  public ItemStack safeTake(int var0, int var1, Player var2) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack safeInsert(ItemStack itemStack) {
+    return itemStack;
+  }
+
+  @Override
+  public ItemStack safeInsert(ItemStack itemStack, int amount) {
+    return itemStack;
+  }
+
+  @Override
+  public boolean allowModification(Player var0) {
+    return false;
+  }
+
+  @Override
+  public int getContainerSlot() {
+    return this.slot;
+  }
+
+  @Override
+  public boolean isHighlightable() {
+    return false;
+  }
+
+  @Override
+  public boolean isFake() {
+    return true;
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/player/OpenPlayer.java

@@ -0,0 +1,178 @@
+package com.lishid.openinv.internal.v1_21_R2.player;
+
+import com.lishid.openinv.event.OpenEvents;
+import com.mojang.logging.LogUtils;
+import net.minecraft.Util;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.nbt.NumericTag;
+import net.minecraft.nbt.Tag;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.level.storage.PlayerDataStorage;
+import org.bukkit.craftbukkit.v1_21_R2.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R2.entity.CraftPlayer;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Set;
+
+public class OpenPlayer extends CraftPlayer {
+
+  /**
+   * List of tags to always reset when saving.
+   *
+   * @see net.minecraft.world.entity.Entity#saveWithoutId(CompoundTag)
+   * @see net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
+   * @see net.minecraft.world.entity.player.Player#addAdditionalSaveData(CompoundTag)
+   * @see net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(CompoundTag)
+   */
+  private static final Set<String> RESET_TAGS = Set.of(
+      // Entity#saveWithoutId(CompoundTag)
+      "CustomName",
+      "CustomNameVisible",
+      "Silent",
+      "NoGravity",
+      "Glowing",
+      "TicksFrozen",
+      "HasVisualFire",
+      "Tags",
+      "Passengers",
+      // ServerPlayer#addAdditionalSaveData(CompoundTag)
+      // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
+      "warden_spawn_tracker",
+      "enteredNetherPosition",
+      "SpawnX",
+      "SpawnY",
+      "SpawnZ",
+      "SpawnForced",
+      "SpawnAngle",
+      "SpawnDimension",
+      "raid_omen_position",
+      "ender_pearls",
+      // Player#addAdditionalSaveData(CompoundTag)
+      "ShoulderEntityLeft",
+      "ShoulderEntityRight",
+      "LastDeathLocation",
+      "current_explosion_impact_pos",
+      // LivingEntity#addAdditionalSaveData(CompoundTag)
+      "active_effects",
+      "SleepingX",
+      "SleepingY",
+      "SleepingZ",
+      "Brain"
+  );
+
+  private final PlayerManager manager;
+
+  OpenPlayer(CraftServer server, ServerPlayer entity, PlayerManager manager) {
+    super(server, entity);
+    this.manager = manager;
+  }
+
+  @Override
+  public void loadData() {
+    manager.loadData(getHandle());
+  }
+
+  @Override
+  public void saveData() {
+    if (OpenEvents.saveCancelled(this)) {
+      return;
+    }
+
+    ServerPlayer player = this.getHandle();
+    // See net.minecraft.world.level.storage.PlayerDataStorage#save(EntityHuman)
+    try {
+      PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
+
+      CompoundTag oldData = isOnline() ? null : worldNBTStorage.load(player.getName().getString(), player.getStringUUID()).orElse(null);
+      CompoundTag playerData = getWritableTag(oldData);
+      playerData = player.saveWithoutId(playerData);
+      setExtraData(playerData);
+
+      if (oldData != null) {
+        // Revert certain special data values when offline.
+        revertSpecialValues(playerData, oldData);
+      }
+
+      Path playerDataDir = worldNBTStorage.getPlayerDir().toPath();
+      Path tempFile = Files.createTempFile(playerDataDir, player.getStringUUID() + "-", ".dat");
+      NbtIo.writeCompressed(playerData, tempFile);
+      Path dataFile = playerDataDir.resolve(player.getStringUUID() + ".dat");
+      Path backupFile = playerDataDir.resolve(player.getStringUUID() + ".dat_old");
+      Util.safeReplaceFile(dataFile, tempFile, backupFile);
+    } catch (Exception e) {
+      LogUtils.getLogger().warn("Failed to save player data for {}: {}", player.getScoreboardName(), e);
+    }
+  }
+
+  @Contract("null -> new")
+  private @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
+    if (oldData == null) {
+      return new CompoundTag();
+    }
+
+    // Copy old data. This is a deep clone, so operating on it should be safe.
+    oldData = oldData.copy();
+
+    // Remove vanilla/server data that is not written every time.
+    oldData.getAllKeys()
+        .removeIf(key -> RESET_TAGS.contains(key) || key.startsWith("Bukkit"));
+
+    return oldData;
+  }
+
+  private void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
+    // Revert automatic updates to play timestamps.
+    copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastLogin", NumericTag.class);
+  }
+
+  private <T extends Tag> void copyValue(
+      @NotNull CompoundTag source,
+      @NotNull CompoundTag target,
+      @NotNull String container,
+      @NotNull String key,
+      @SuppressWarnings("SameParameterValue") @NotNull Class<T> tagType) {
+    CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
+    CompoundTag newContainer = getTag(target, container, CompoundTag.class);
+
+    // New container being null means the server implementation doesn't store this data.
+    if (newContainer == null) {
+      return;
+    }
+
+    // If old tag exists, copy it to new location, removing otherwise.
+    setTag(newContainer, key, getTag(oldContainer, key, tagType));
+  }
+
+  private <T extends Tag> @Nullable T getTag(
+      @Nullable CompoundTag container,
+      @NotNull String key,
+      @NotNull Class<T> dataType) {
+    if (container == null) {
+      return null;
+    }
+    Tag value = container.get(key);
+    if (value == null || !dataType.isAssignableFrom(value.getClass())) {
+      return null;
+    }
+    return dataType.cast(value);
+  }
+
+  private <T extends Tag> void setTag(
+      @NotNull CompoundTag container,
+      @NotNull String key,
+      @Nullable T data) {
+    if (data == null) {
+      container.remove(key);
+    } else {
+      container.put(key, data);
+    }
+  }
+
+}

internal/v1_21_R2/src/main/java/com/lishid/openinv/internal/v1_21_R2/player/PlayerManager.java

@@ -0,0 +1,267 @@
+package com.lishid.openinv.internal.v1_21_R2.player;
+
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.v1_21_R2.container.OpenEnderChest;
+import com.lishid.openinv.internal.v1_21_R2.container.OpenInventory;
+import com.mojang.authlib.GameProfile;
+import com.mojang.serialization.Dynamic;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtOps;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.protocol.game.ClientboundOpenScreenPacket;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ClientInformation;
+import net.minecraft.server.level.ParticleStatus;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.player.ChatVisiblity;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.dimension.DimensionType;
+import org.bukkit.Bukkit;
+import org.bukkit.OfflinePlayer;
+import org.bukkit.Server;
+import org.bukkit.World;
+import org.bukkit.craftbukkit.v1_21_R2.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R2.CraftWorld;
+import org.bukkit.craftbukkit.v1_21_R2.entity.CraftPlayer;
+import org.bukkit.craftbukkit.v1_21_R2.event.CraftEventFactory;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.Field;
+import java.util.UUID;
+import java.util.logging.Logger;
+
+public class PlayerManager implements com.lishid.openinv.internal.PlayerManager {
+
+  private static boolean paper;
+
+  static {
+    try {
+      Class.forName("io.papermc.paper.configuration.Configuration");
+      paper = true;
+    } catch (ClassNotFoundException ignored) {
+      paper = false;
+    }
+  }
+
+  private final @NotNull Logger logger;
+  private @Nullable Field bukkitEntity;
+
+  public PlayerManager(@NotNull Logger logger) {
+    this.logger = logger;
+    try {
+      bukkitEntity = Entity.class.getDeclaredField("bukkitEntity");
+    } catch (NoSuchFieldException e) {
+      logger.warning("Unable to obtain field to inject custom save process - certain player data may be lost when saving!");
+      logger.log(java.util.logging.Level.WARNING, e.getMessage(), e);
+      bukkitEntity = null;
+    }
+  }
+
+  public static @NotNull ServerPlayer getHandle(final Player player) {
+    if (player instanceof CraftPlayer) {
+      return ((CraftPlayer) player).getHandle();
+    }
+
+    Server server = player.getServer();
+    ServerPlayer nmsPlayer = null;
+
+    if (server instanceof CraftServer) {
+      nmsPlayer = ((CraftServer) server).getHandle().getPlayer(player.getUniqueId());
+    }
+
+    if (nmsPlayer == null) {
+      // Could use reflection to examine fields, but it's honestly not worth the bother.
+      throw new RuntimeException("Unable to fetch EntityPlayer from Player implementation " + player.getClass().getName());
+    }
+
+    return nmsPlayer;
+  }
+
+  @Override
+  public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
+    MinecraftServer server = ((CraftServer) Bukkit.getServer()).getServer();
+    ServerLevel worldServer = server.getLevel(Level.OVERWORLD);
+
+    if (worldServer == null) {
+      return null;
+    }
+
+    // Create a new ServerPlayer.
+    ServerPlayer entity = createNewPlayer(server, worldServer, offline);
+
+    // Stop listening for advancement progression - if this is not cleaned up, loading causes a memory leak.
+    entity.getAdvancements().stopListening();
+
+    // Try to load the player's data.
+    if (loadData(entity)) {
+      // If data is loaded successfully, return the Bukkit entity.
+      return entity.getBukkitEntity();
+    }
+
+    return null;
+  }
+
+  private @NotNull ServerPlayer createNewPlayer(
+      @NotNull MinecraftServer server,
+      @NotNull ServerLevel worldServer,
+      @NotNull final OfflinePlayer offline) {
+    // See net.minecraft.server.players.PlayerList#canPlayerLogin(ServerLoginPacketListenerImpl, GameProfile)
+    // See net.minecraft.server.network.ServerLoginPacketListenerImpl#handleHello(ServerboundHelloPacket)
+    GameProfile profile = new GameProfile(offline.getUniqueId(),
+        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString());
+
+    ClientInformation dummyInfo = new ClientInformation(
+        "en_us",
+        1, // Reduce distance just in case.
+        ChatVisiblity.HIDDEN, // Don't accept chat.
+        false,
+        ServerPlayer.DEFAULT_MODEL_CUSTOMIZATION,
+        ServerPlayer.DEFAULT_MAIN_HAND,
+        true,
+        false, // Don't list in player list (not that this player is in the list anyway).
+        ParticleStatus.MINIMAL
+    );
+
+    ServerPlayer entity = new ServerPlayer(server, worldServer, profile, dummyInfo);
+
+    try {
+      injectPlayer(entity);
+    } catch (IllegalAccessException e) {
+      logger.log(
+          java.util.logging.Level.WARNING,
+          e,
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+    }
+
+    return entity;
+  }
+
+  boolean loadData(@NotNull ServerPlayer player) {
+    // See CraftPlayer#loadData
+    CompoundTag loadedData = player.server.getPlayerList().playerIo.load(player).orElse(null);
+
+    if (loadedData == null) {
+      // Exceptions with loading are logged by Mojang.
+      return false;
+    }
+
+    // Read basic data into the player.
+    player.load(loadedData);
+    // Also read "extra" data.
+    player.readAdditionalSaveData(loadedData);
+    // Game type settings are also loaded separately.
+    player.loadGameTypes(loadedData);
+
+    if (paper) {
+      // Paper: world is not loaded by ServerPlayer#load(CompoundTag).
+      parseWorld(player, loadedData);
+    }
+
+    return true;
+  }
+
+  private void parseWorld(@NotNull ServerPlayer player, @NotNull CompoundTag loadedData) {
+    // See PlayerList#placeNewPlayer
+    World bukkitWorld;
+    if (loadedData.contains("WorldUUIDMost") && loadedData.contains("WorldUUIDLeast")) {
+      // Modern Bukkit world.
+      bukkitWorld = Bukkit.getServer().getWorld(new UUID(loadedData.getLong("WorldUUIDMost"), loadedData.getLong("WorldUUIDLeast")));
+    } else if (loadedData.contains("world", net.minecraft.nbt.Tag.TAG_STRING)) {
+      // Legacy Bukkit world.
+      bukkitWorld = Bukkit.getServer().getWorld(loadedData.getString("world"));
+    } else {
+      // Vanilla player data.
+      DimensionType.parseLegacy(new Dynamic<>(NbtOps.INSTANCE, loadedData.get("Dimension")))
+          .resultOrPartial(logger::warning)
+          .map(player.server::getLevel)
+          // If ServerLevel exists, set, otherwise move to spawn.
+          .ifPresentOrElse(player::setServerLevel, () -> player.spawnIn(null));
+      return;
+    }
+    if (bukkitWorld == null) {
+      player.spawnIn(null);
+      return;
+    }
+    player.setServerLevel(((CraftWorld) bukkitWorld).getHandle());
+  }
+
+  private void injectPlayer(ServerPlayer player) throws IllegalAccessException {
+    if (bukkitEntity == null) {
+      return;
+    }
+
+    bukkitEntity.setAccessible(true);
+
+    bukkitEntity.set(player, new OpenPlayer(player.server.server, player, this));
+  }
+
+  @Override
+  public @NotNull Player inject(@NotNull Player player) {
+    try {
+      ServerPlayer nmsPlayer = getHandle(player);
+      if (nmsPlayer.getBukkitEntity() instanceof OpenPlayer openPlayer) {
+        return openPlayer;
+      }
+      injectPlayer(nmsPlayer);
+      return nmsPlayer.getBukkitEntity();
+    } catch (IllegalAccessException e) {
+      logger.log(
+          java.util.logging.Level.WARNING,
+          e,
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+      return player;
+    }
+  }
+
+  @Override
+  public @Nullable InventoryView openInventory(@NotNull Player bukkitPlayer, @NotNull ISpecialInventory inventory, boolean viewOnly) {
+    ServerPlayer player = getHandle(bukkitPlayer);
+
+    if (player.connection == null) {
+      return null;
+    }
+
+    // See net.minecraft.server.level.ServerPlayer#openMenu(MenuProvider)
+    AbstractContainerMenu menu;
+    Component title;
+    if (inventory instanceof OpenInventory playerInv) {
+      menu = playerInv.createMenu(player, player.nextContainerCounter(), viewOnly);
+      title = playerInv.getTitle(player);
+    } else if (inventory instanceof OpenEnderChest enderChest) {
+      menu = enderChest.createMenu(player, player.nextContainerCounter(), viewOnly);
+      title = enderChest.getTitle();
+    } else {
+      return null;
+    }
+
+    // Should never happen, player is a ServerPlayer with an active connection.
+    if (menu == null) {
+      return null;
+    }
+
+    // Set up title. Title can only be set once for a menu, and is set during the open process.
+    // Further title changes are a hack where the client is sent a "new" inventory with the same ID,
+    // resulting in a title change but no other state modifications (like cursor position).
+    menu.setTitle(title);
+
+    menu = CraftEventFactory.callInventoryOpenEvent(player, menu, false);
+
+    // Menu is null if event is cancelled.
+    if (menu == null) {
+      return null;
+    }
+
+    player.containerMenu = menu;
+    player.connection.send(new ClientboundOpenScreenPacket(menu.containerId, menu.getType(), menu.getTitle()));
+    player.initMenu(menu);
+
+    return menu.getBukkitView();
+  }
+
+}

internal/v1_21_R3/pom.xml

@@ -23,16 +23,16 @@
     <artifactId>openinvparent</artifactId>
     <groupId>com.lishid</groupId>
     <relativePath>../../pom.xml</relativePath>
-    <version>4.3.1</version>
+    <version>5.1.5</version>
   </parent>
 
-  <artifactId>openinvadapter1_19_R3</artifactId>
-  <name>OpenInvAdapter1_19_R3</name>
+  <artifactId>openinvadapter1_21_R3</artifactId>
+  <name>OpenInvAdapter1_21_R3</name>
 
   <properties>
-    <maven.compiler.source>17</maven.compiler.source>
-    <maven.compiler.target>17</maven.compiler.target>
-    <spigot.version>1.19.4-R0.1-SNAPSHOT</spigot.version>
+    <maven.compiler.system>21</maven.compiler.system>
+    <maven.compiler.release>21</maven.compiler.release>
+    <spigot.version>1.21.4-R0.1-SNAPSHOT</spigot.version>
   </properties>
 
   <dependencies>
@@ -51,10 +51,9 @@
     <dependency>
       <artifactId>openinvapi</artifactId>
       <groupId>com.lishid</groupId>
-      <scope>provided</scope>
     </dependency>
     <dependency>
-      <artifactId>openinvplugincore</artifactId>
+      <artifactId>openinvcommon</artifactId>
       <groupId>com.lishid</groupId>
     </dependency>
     <dependency>
@@ -65,9 +64,6 @@
 
   <build>
     <plugins>
-      <plugin>
-        <artifactId>maven-shade-plugin</artifactId>
-      </plugin>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
       </plugin>

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/InternalAccessor.java

@@ -0,0 +1,81 @@
+package com.lishid.openinv.internal.v1_21_R3;
+
+import com.lishid.openinv.internal.Accessor;
+import com.lishid.openinv.internal.IAnySilentContainer;
+import com.lishid.openinv.internal.ISpecialEnderChest;
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.ISpecialPlayerInventory;
+import com.lishid.openinv.internal.v1_21_R3.container.AnySilentContainer;
+import com.lishid.openinv.internal.v1_21_R3.container.OpenEnderChest;
+import com.lishid.openinv.internal.v1_21_R3.container.OpenInventory;
+import com.lishid.openinv.internal.v1_21_R3.container.Placeholders;
+import com.lishid.openinv.internal.v1_21_R3.player.PlayerManager;
+import com.lishid.openinv.util.lang.LanguageManager;
+import net.minecraft.world.Container;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftInventory;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.Inventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class InternalAccessor implements Accessor {
+
+  private final @NotNull Logger logger;
+  private final @NotNull PlayerManager manager;
+  private final @NotNull AnySilentContainer anySilentContainer;
+
+  public InternalAccessor(@NotNull Logger logger, @NotNull LanguageManager lang) {
+    this.logger = logger;
+    manager = new PlayerManager(logger);
+    anySilentContainer = new AnySilentContainer(logger, lang);
+  }
+
+  @Override
+  public @NotNull PlayerManager getPlayerManager() {
+    return manager;
+  }
+
+  @Override
+  public @NotNull IAnySilentContainer getAnySilentContainer() {
+    return anySilentContainer;
+  }
+
+  @Override
+  public @NotNull ISpecialPlayerInventory createPlayerInventory(@NotNull Player player) {
+    return new OpenInventory(player);
+  }
+
+  @Override
+  public @NotNull ISpecialEnderChest createEnderChest(@NotNull Player player) {
+    return new OpenEnderChest(player);
+  }
+
+  @Override
+  public <T extends ISpecialInventory> @Nullable T get(@NotNull Inventory bukkitInventory, @NotNull Class<T> clazz) {
+    if (!(bukkitInventory instanceof CraftInventory craftInventory)) {
+      return null;
+    }
+    Container container = craftInventory.getInventory();
+    if (clazz.isInstance(container)) {
+      return clazz.cast(container);
+    }
+    return null;
+  }
+
+  @Override
+  public void reload(@NotNull ConfigurationSection config) {
+    ConfigurationSection placeholders = config.getConfigurationSection("placeholders");
+    if (placeholders != null) {
+      try {
+        Placeholders.load(placeholders);
+      } catch (Exception e) {
+        logger.log(Level.WARNING, "Caught exception loading placeholder overrides!", e);
+      }
+    }
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/AnySilentContainer.java

@@ -14,22 +14,19 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-package com.lishid.openinv.internal.v1_19_R3;
+package com.lishid.openinv.internal.v1_21_R3.container;
 
-import com.lishid.openinv.OpenInv;
-import com.lishid.openinv.internal.IAnySilentContainer;
+import com.lishid.openinv.internal.AnySilentContainerBase;
+import com.lishid.openinv.internal.v1_21_R3.container.menu.OpenChestMenu;
+import com.lishid.openinv.internal.v1_21_R3.player.PlayerManager;
 import com.lishid.openinv.util.ReflectionHelper;
-import java.lang.reflect.Field;
-import java.util.logging.Level;
-import java.util.logging.Logger;
+import com.lishid.openinv.util.lang.LanguageManager;
 import net.minecraft.core.BlockPos;
 import net.minecraft.network.chat.Component;
-import net.minecraft.server.level.ServerLevel;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.server.level.ServerPlayerGameMode;
 import net.minecraft.world.MenuProvider;
 import net.minecraft.world.SimpleMenuProvider;
-import net.minecraft.world.entity.monster.Shulker;
 import net.minecraft.world.inventory.ChestMenu;
 import net.minecraft.world.inventory.MenuType;
 import net.minecraft.world.inventory.PlayerEnderChestContainer;
@@ -42,30 +39,31 @@ import net.minecraft.world.level.block.TrappedChestBlock;
 import net.minecraft.world.level.block.entity.BlockEntity;
 import net.minecraft.world.level.block.entity.EnderChestBlockEntity;
 import net.minecraft.world.level.block.entity.RandomizableContainerBlockEntity;
-import net.minecraft.world.level.block.entity.ShulkerBoxBlockEntity;
 import net.minecraft.world.level.block.state.BlockState;
-import net.minecraft.world.phys.AABB;
-import org.bukkit.Bukkit;
 import org.bukkit.GameMode;
 import org.bukkit.Material;
 import org.bukkit.Statistic;
-import org.bukkit.block.ShulkerBox;
-import org.bukkit.craftbukkit.v1_19_R3.CraftWorld;
 import org.bukkit.entity.Player;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public class AnySilentContainer implements IAnySilentContainer {
+import java.lang.reflect.Field;
+import java.util.logging.Logger;
 
+public class AnySilentContainer extends AnySilentContainerBase {
+
+    private final @NotNull Logger logger;
+    private final @NotNull LanguageManager lang;
     private @Nullable Field serverPlayerGameModeGameType;
 
-    public AnySilentContainer() {
+    public AnySilentContainer(@NotNull Logger logger, @NotNull LanguageManager lang) {
+        this.logger = logger;
+        this.lang = lang;
         try {
             try {
                 this.serverPlayerGameModeGameType = ServerPlayerGameMode.class.getDeclaredField("b");
                 this.serverPlayerGameModeGameType.setAccessible(true);
             } catch (NoSuchFieldException e) {
-                Logger logger = OpenInv.getPlugin(OpenInv.class).getLogger();
                 logger.warning("ServerPlayerGameMode#gameModeForPlayer's obfuscated name has changed!");
                 logger.warning("Please report this at https://github.com/Jikoo/OpenInv/issues");
                 logger.warning("Attempting to fall through using reflection. Please verify that SilentContainer does not fail.");
@@ -73,43 +71,11 @@ public class AnySilentContainer implements IAnySilentContainer {
                 this.serverPlayerGameModeGameType = ReflectionHelper.grabFieldByType(ServerPlayerGameMode.class, GameType.class);
             }
         } catch (SecurityException e) {
-            Logger logger = OpenInv.getPlugin(OpenInv.class).getLogger();
             logger.warning("Unable to directly write player game mode! SilentContainer will fail.");
-            logger.log(Level.WARNING, "Error obtaining GameType field", e);
+            logger.log(java.util.logging.Level.WARNING, "Error obtaining GameType field", e);
         }
     }
 
-    @Override
-    public boolean isShulkerBlocked(@NotNull ShulkerBox shulkerBox) {
-        org.bukkit.World bukkitWorld = shulkerBox.getWorld();
-        if (!(bukkitWorld instanceof CraftWorld)) {
-            bukkitWorld = Bukkit.getWorld(bukkitWorld.getUID());
-        }
-
-        if (!(bukkitWorld instanceof CraftWorld craftWorld)) {
-            Exception exception = new IllegalStateException("AnySilentContainer access attempted on an unknown world!");
-            OpenInv.getPlugin(OpenInv.class).getLogger().log(Level.WARNING, exception.getMessage(), exception);
-            return false;
-        }
-
-        final ServerLevel world = craftWorld.getHandle();
-        final BlockPos blockPosition = new BlockPos(shulkerBox.getX(), shulkerBox.getY(), shulkerBox.getZ());
-        final BlockEntity tile = world.getBlockEntity(blockPosition);
-
-        if (!(tile instanceof ShulkerBoxBlockEntity shulkerBoxBlockEntity)
-                || shulkerBoxBlockEntity.getAnimationStatus() != ShulkerBoxBlockEntity.AnimationStatus.CLOSED) {
-            return false;
-        }
-
-        BlockState blockState = world.getBlockState(blockPosition);
-
-        // See net.minecraft.world.level.block.ShulkerBoxBlock#canOpen
-        AABB boundingBox = Shulker.getProgressDeltaAabb(blockState.getValue(ShulkerBoxBlock.FACING), 0.0F, 0.5F)
-                .move(blockPosition)
-                .deflate(1.0E-6D);
-        return !world.noCollision(boundingBox);
-    }
-
     @Override
     public boolean activateContainer(
             @NotNull final Player bukkitPlayer,
@@ -123,9 +89,9 @@ public class AnySilentContainer implements IAnySilentContainer {
             return true;
         }
 
-        ServerPlayer player = PlayerDataManager.getHandle(bukkitPlayer);
+        ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
 
-        final ServerLevel level = player.getLevel();
+        final net.minecraft.world.level.Level level = player.level();
         final BlockPos blockPos = new BlockPos(bukkitBlock.getX(), bukkitBlock.getY(), bukkitBlock.getZ());
         final BlockEntity blockEntity = level.getBlockEntity(blockPos);
 
@@ -138,10 +104,10 @@ public class AnySilentContainer implements IAnySilentContainer {
             PlayerEnderChestContainer enderChest = player.getEnderChestInventory();
             enderChest.setActiveChest(enderChestTile);
             player.openMenu(new SimpleMenuProvider((containerCounter, playerInventory, ignored) -> {
-                MenuType<?> containers = PlayerDataManager.getContainers(enderChest.getContainerSize());
+                MenuType<?> containers = OpenChestMenu.getChestMenuType(enderChest.getContainerSize());
                 int rows = enderChest.getContainerSize() / 9;
                 return new ChestMenu(containers, containerCounter, playerInventory, enderChest, rows);
-            }, Component.translatable(("container.enderchest"))));
+            }, Component.translatable("container.enderchest")));
             bukkitPlayer.incrementStatistic(Statistic.ENDERCHEST_OPENED);
             return true;
         }
@@ -159,7 +125,7 @@ public class AnySilentContainer implements IAnySilentContainer {
             menuProvider = chestBlock.getMenuProvider(blockState, level, blockPos, true);
 
             if (menuProvider == null) {
-                OpenInv.getPlugin(OpenInv.class).sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
+                lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
                 return false;
             }
 
@@ -191,7 +157,7 @@ public class AnySilentContainer implements IAnySilentContainer {
 
         if (blockEntity instanceof RandomizableContainerBlockEntity lootable) {
             if (lootable.lootTable != null) {
-                OpenInv.getPlugin(OpenInv.class).sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
+                lang.sendSystemMessage(bukkitPlayer, "messages.error.lootNotGenerated");
                 return false;
             }
         }
@@ -209,7 +175,7 @@ public class AnySilentContainer implements IAnySilentContainer {
             return;
         }
 
-        ServerPlayer player = PlayerDataManager.getHandle(bukkitPlayer);
+        ServerPlayer player = PlayerManager.getHandle(bukkitPlayer);
 
         // Force game mode change without informing plugins or players.
         // Regular game mode set calls GameModeChangeEvent and is cancellable.
@@ -237,7 +203,7 @@ public class AnySilentContainer implements IAnySilentContainer {
             this.serverPlayerGameModeGameType.setAccessible(true);
             this.serverPlayerGameModeGameType.set(player.gameMode, gameMode);
         } catch (IllegalArgumentException | IllegalAccessException e) {
-            e.printStackTrace();
+            logger.log(java.util.logging.Level.WARNING, "Error bypassing GameModeChangeEvent", e);
         }
     }
 

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/OpenEnderChest.java

@@ -0,0 +1,196 @@
+package com.lishid.openinv.internal.v1_21_R3.container;
+
+import com.lishid.openinv.internal.ISpecialEnderChest;
+import com.lishid.openinv.internal.InternalOwned;
+import com.lishid.openinv.internal.v1_21_R3.container.menu.OpenEnderChestMenu;
+import com.lishid.openinv.internal.v1_21_R3.player.PlayerManager;
+import net.minecraft.core.NonNullList;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.entity.player.StackedItemContents;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.StackedContentsCompatible;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.v1_21_R3.entity.CraftHumanEntity;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftInventory;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class OpenEnderChest implements Container, StackedContentsCompatible, InternalOwned<ServerPlayer>,
+    ISpecialEnderChest {
+
+  private CraftInventory inventory;
+  private @NotNull ServerPlayer owner;
+  private NonNullList<ItemStack> items;
+  private int maxStack = 64;
+  private final List<HumanEntity> transaction = new ArrayList<>();
+
+  public OpenEnderChest(@NotNull org.bukkit.entity.Player player) {
+    this.owner = PlayerManager.getHandle(player);
+    this.items = owner.getEnderChestInventory().items;
+  }
+
+  @Override
+  public @NotNull ServerPlayer getOwnerHandle() {
+    return owner;
+  }
+
+  @Override
+  public @NotNull org.bukkit.inventory.Inventory getBukkitInventory() {
+    if (inventory == null) {
+      inventory = new CraftInventory(this) {
+        @Override
+        public @NotNull InventoryType getType() {
+          return InventoryType.ENDER_CHEST;
+        }
+      };
+    }
+    return inventory;
+  }
+
+  @Override
+  public void setPlayerOnline(@NotNull org.bukkit.entity.Player player) {
+    owner = PlayerManager.getHandle(player);
+    NonNullList<ItemStack> activeItems = owner.getEnderChestInventory().items;
+
+    // Guard against size changing. Theoretically on Purpur all row variations still have 6 rows internally.
+    int max = Math.min(items.size(), activeItems.size());
+    for (int index = 0; index < max; ++index) {
+      activeItems.set(index, items.get(index));
+    }
+
+    items = activeItems;
+  }
+
+  @Override
+  public void setPlayerOffline() {}
+
+  @Override
+  public @NotNull org.bukkit.entity.Player getPlayer() {
+    return owner.getBukkitEntity();
+  }
+
+  @Override
+  public int getContainerSize() {
+    return items.size();
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return items.stream().allMatch(ItemStack::isEmpty);
+  }
+
+  @Override
+  public ItemStack getItem(int index) {
+    return index >= 0 && index < items.size() ? items.get(index) : ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack removeItem(int index, int amount) {
+    ItemStack itemstack = ContainerHelper.removeItem(items, index, amount);
+
+    if (!itemstack.isEmpty()) {
+      setChanged();
+    }
+
+    return itemstack;
+  }
+
+  @Override
+  public ItemStack removeItemNoUpdate(int index) {
+    return index >= 0 && index < items.size() ? items.set(index, ItemStack.EMPTY) : ItemStack.EMPTY;
+  }
+
+  @Override
+  public void setItem(int index, ItemStack itemStack) {
+    if (index >= 0 && index < items.size()) {
+      items.set(index, itemStack);
+    }
+  }
+
+  @Override
+  public int getMaxStackSize() {
+    return maxStack;
+  }
+
+  @Override
+  public void setChanged() {
+    this.owner.getEnderChestInventory().setChanged();
+  }
+
+  @Override
+  public boolean stillValid(Player player) {
+    return true;
+  }
+
+  @Override
+  public List<ItemStack> getContents() {
+    return items;
+  }
+
+  @Override
+  public void onOpen(CraftHumanEntity craftHumanEntity) {
+    transaction.add(craftHumanEntity);
+  }
+
+  @Override
+  public void onClose(CraftHumanEntity craftHumanEntity) {
+    transaction.remove(craftHumanEntity);
+  }
+
+  @Override
+  public List<HumanEntity> getViewers() {
+    return transaction;
+  }
+
+  @Override
+  public org.bukkit.entity.Player getOwner() {
+    return getPlayer();
+  }
+
+  @Override
+  public void setMaxStackSize(int size) {
+    maxStack = size;
+  }
+
+  @Override
+  public @Nullable Location getLocation() {
+    return null;
+  }
+
+  @Override
+  public void clearContent() {
+    items.clear();
+    setChanged();
+  }
+
+  @Override
+  public void fillStackedContents(StackedItemContents stackedContents) {
+    for (ItemStack itemstack : items) {
+      stackedContents.accountStack(itemstack);
+    }
+  }
+
+  public Component getTitle() {
+    return Component.translatableWithFallback("openinv.container.enderchest.prefix", "", owner.getName())
+        .append(Component.translatable("container.enderchest"))
+        .append(Component.translatableWithFallback("openinv.container.enderchest.suffix", " - %s", owner.getName()));
+  }
+
+  public @Nullable AbstractContainerMenu createMenu(Player player, int i, boolean viewOnly) {
+    if (player instanceof ServerPlayer serverPlayer) {
+      return new OpenEnderChestMenu(this, serverPlayer, i, viewOnly);
+    }
+    return null;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/OpenInventory.java

@@ -0,0 +1,364 @@
+package com.lishid.openinv.internal.v1_21_R3.container;
+
+import com.lishid.openinv.internal.ISpecialPlayerInventory;
+import com.lishid.openinv.internal.InternalOwned;
+import com.lishid.openinv.internal.v1_21_R3.container.bukkit.OpenPlayerInventory;
+import com.lishid.openinv.internal.v1_21_R3.container.menu.OpenInventoryMenu;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.Content;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentCrafting;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentCraftingResult;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentCursor;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentDrop;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentEquipment;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentList;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentOffHand;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentViewOnly;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.SlotViewOnly;
+import com.lishid.openinv.internal.v1_21_R3.player.PlayerManager;
+import net.minecraft.ChatFormatting;
+import net.minecraft.core.NonNullList;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.chat.MutableComponent;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Inventory;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.Location;
+import org.bukkit.craftbukkit.v1_21_R3.entity.CraftHumanEntity;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftInventory;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class OpenInventory implements Container, InternalOwned<ServerPlayer>, ISpecialPlayerInventory {
+
+  private final List<Content> slots;
+  private final int size;
+  private ServerPlayer owner;
+  private int maxStackSize = 99;
+  private CraftInventory bukkitEntity;
+  public List<HumanEntity> transaction = new ArrayList<>();
+
+  public OpenInventory(@NotNull org.bukkit.entity.Player bukkitPlayer) {
+    owner = PlayerManager.getHandle(bukkitPlayer);
+
+    // Get total size, rounding up to nearest 9 for client compatibility.
+    int rawSize = owner.getInventory().getContainerSize() + owner.inventoryMenu.getCraftSlots().getContainerSize() + 1;
+    size = ((int) Math.ceil(rawSize / 9.0)) * 9;
+
+    slots = NonNullList.withSize(size, new ContentViewOnly(owner));
+    setupSlots();
+  }
+
+  private void setupSlots() {
+    // Top of inventory: Regular contents.
+    int nextIndex = addMainInventory();
+
+    // If inventory is expected size, we can arrange slots to be pretty.
+    Inventory ownerInv = owner.getInventory();
+    if (ownerInv.items.size() == 36
+        && ownerInv.armor.size() == 4
+        && ownerInv.offhand.size() == 1
+        && owner.inventoryMenu.getCraftSlots().getContainerSize() == 4) {
+      // Armor slots: Bottom left.
+      addArmor(36);
+      // Off-hand: Below chestplate.
+      addOffHand(46);
+      // Drop slot: Bottom right.
+      slots.set(53, new ContentDrop(owner));
+      // Cursor slot: Above drop.
+      slots.set(44, new ContentCursor(owner));
+
+      // Crafting is displayed in the bottom right corner.
+      // As we're using the pretty view, this is a 3x2.
+      addCrafting(41, true);
+      return;
+    }
+
+    // Otherwise we'll just add elements linearly.
+    nextIndex = addArmor(nextIndex);
+    nextIndex = addOffHand(nextIndex);
+    nextIndex = addCrafting(nextIndex, false);
+    slots.set(nextIndex, new ContentCursor(owner));
+    // Drop slot last.
+    slots.set(slots.size() - 1, new ContentDrop(owner));
+  }
+
+  private int addMainInventory() {
+    int listSize = owner.getInventory().items.size();
+    // Hotbar slots are 0-8. We want those to appear on the bottom of the inventory like a normal player inventory,
+    // so everything else needs to move up a row.
+    int hotbarDiff = listSize - 9;
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      InventoryType.SlotType type;
+      int invIndex;
+      if (localIndex < hotbarDiff) {
+        invIndex = localIndex + 9;
+        type = InventoryType.SlotType.CONTAINER;
+      } else {
+        type = InventoryType.SlotType.QUICKBAR;
+        invIndex = localIndex - hotbarDiff;
+      }
+
+      slots.set(localIndex, new ContentList(owner, invIndex, type) {
+        @Override
+        public void setHolder(@NotNull ServerPlayer holder) {
+          items = holder.getInventory().items;
+        }
+      });
+    }
+    return listSize;
+  }
+
+  private int addArmor(int startIndex) {
+    int listSize = owner.getInventory().armor.size();
+
+    for (int i = 0; i < listSize; ++i) {
+      // Armor slots go bottom to top; boots are slot 0, helmet is slot 3.
+      // Since we have to display horizontally due to space restrictions,
+      // making the left side the "top" is more user-friendly.
+      int armorIndex;
+      EquipmentSlot slot;
+      switch (i) {
+        case 3 -> {
+          armorIndex = 0;
+          slot = EquipmentSlot.FEET;
+        }
+        case 2 -> {
+          armorIndex = 1;
+          slot = EquipmentSlot.LEGS;
+        }
+        case 1 -> {
+          armorIndex = 2;
+          slot = EquipmentSlot.CHEST;
+        }
+        case 0 -> {
+          armorIndex = 3;
+          slot = EquipmentSlot.HEAD;
+        }
+        default -> {
+          // In the event that new armor slots are added, they can be placed at the end.
+          armorIndex = i;
+          slot = EquipmentSlot.MAINHAND;
+        }
+      }
+
+      slots.set(startIndex + i, new ContentEquipment(owner, armorIndex, slot));
+    }
+
+    return startIndex + listSize;
+  }
+
+  private int addOffHand(int startIndex) {
+    int listSize = owner.getInventory().offhand.size();
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      slots.set(startIndex + localIndex, new ContentOffHand(owner, localIndex));
+    }
+    return startIndex + listSize;
+  }
+
+  private int addCrafting(int startIndex, boolean pretty) {
+    int listSize = owner.inventoryMenu.getCraftSlots().getContents().size();
+    pretty &= listSize == 4;
+
+    for (int localIndex = 0; localIndex < listSize; ++localIndex) {
+      // Pretty display is a 2x2 rather than linear.
+      // If index is in top row, grid is not 2x2, or pretty is disabled, just use current index.
+      // Otherwise, subtract 2 and add 9 to start in the same position on the next row.
+      int modIndex = startIndex + (localIndex < 2 || !pretty ? localIndex : localIndex + 7);
+
+      slots.set(modIndex, new ContentCrafting(owner, localIndex));
+    }
+
+    if (pretty) {
+      slots.set(startIndex + 2, new ContentViewOnly(owner) {
+        @Override
+        public Slot asSlot(Container container, int slot, int x, int y) {
+          return new SlotViewOnly(container, slot, x, y) {
+            @Override
+            public ItemStack getOrDefault() {
+              return Placeholders.craftingOutput;
+            }
+          };
+        }
+      });
+      slots.set(startIndex + 11, new ContentCraftingResult(owner));
+    }
+
+    return startIndex + listSize;
+  }
+
+  public Slot getMenuSlot(int index, int x, int y) {
+    return slots.get(index).asSlot(this, index, x, y);
+  }
+
+  public InventoryType.SlotType getSlotType(int index) {
+    return slots.get(index).getSlotType();
+  }
+
+  public @NotNull Component getTitle(@Nullable ServerPlayer viewer) {
+    MutableComponent component = Component.empty();
+    // Prefix for use with custom bitmap image fonts.
+    if (owner.equals(viewer)) {
+      component.append(
+          Component.translatableWithFallback("openinv.container.inventory.self", "")
+              .withStyle(style -> style
+                  .withFont(ResourceLocation.parse("openinv:font/inventory"))
+                  .withColor(ChatFormatting.WHITE)));
+    } else {
+      component.append(
+          Component.translatableWithFallback("openinv.container.inventory.other", "")
+              .withStyle(style -> style
+                  .withFont(ResourceLocation.parse("openinv:font/inventory"))
+                  .withColor(ChatFormatting.WHITE)));
+    }
+    // Normal title: "Inventory - OwnerName"
+    component.append(Component.translatableWithFallback("openinv.container.inventory.prefix", "", owner.getName()))
+        .append(Component.translatable("container.inventory"))
+        .append(Component.translatableWithFallback("openinv.container.inventory.suffix", " - %s", owner.getName()));
+    return component;
+  }
+
+  @Override
+  public ServerPlayer getOwnerHandle() {
+    return owner;
+  }
+
+  @Override
+  public @NotNull org.bukkit.inventory.Inventory getBukkitInventory() {
+    if (bukkitEntity == null) {
+      bukkitEntity = new OpenPlayerInventory(this);
+    }
+    return bukkitEntity;
+  }
+
+  @Override
+  public void setPlayerOnline(@NotNull org.bukkit.entity.Player player) {
+    ServerPlayer newOwner = PlayerManager.getHandle(player);
+    // Only transfer regular inventory - crafting and cursor slots are transient.
+    newOwner.getInventory().replaceWith(owner.getInventory());
+    owner = newOwner;
+    // Update slots to point to new inventory.
+    slots.forEach(slot -> slot.setHolder(newOwner));
+  }
+
+  @Override
+  public void setPlayerOffline() {}
+
+  @Override
+  public boolean isInUse() {
+    return !transaction.isEmpty();
+  }
+
+  @Override
+  public @NotNull org.bukkit.entity.Player getPlayer() {
+    return getOwner();
+  }
+
+  @Override
+  public int getContainerSize() {
+    return size;
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return slots.stream().map(Content::get).allMatch(ItemStack::isEmpty);
+  }
+
+  @Override
+  public ItemStack getItem(int index) {
+    return slots.get(index).get();
+  }
+
+  @Override
+  public ItemStack removeItem(int index, int amount) {
+    return slots.get(index).removePartial(amount);
+  }
+
+  @Override
+  public ItemStack removeItemNoUpdate(int index) {
+    return slots.get(index).remove();
+  }
+
+  @Override
+  public void setItem(int index, ItemStack itemStack) {
+    slots.get(index).set(itemStack);
+  }
+
+  @Override
+  public int getMaxStackSize() {
+    return maxStackSize;
+  }
+
+  @Override
+  public void setMaxStackSize(int maxStackSize) {
+    this.maxStackSize = maxStackSize;
+  }
+
+  @Override
+  public void setChanged() {}
+
+  @Override
+  public boolean stillValid(Player player) {
+    return true;
+  }
+
+  @Override
+  public List<ItemStack> getContents() {
+    NonNullList<ItemStack> contents = NonNullList.withSize(getContainerSize(), ItemStack.EMPTY);
+    for (int i = 0; i < getContainerSize(); ++i) {
+      contents.set(i, getItem(i));
+    }
+    return contents;
+  }
+
+  @Override
+  public void onOpen(CraftHumanEntity viewer) {
+    transaction.add(viewer);
+  }
+
+  @Override
+  public void onClose(CraftHumanEntity viewer) {
+    transaction.remove(viewer);
+  }
+
+  @Override
+  public List<HumanEntity> getViewers() {
+    return transaction;
+  }
+
+  @Override
+  public org.bukkit.entity.Player getOwner() {
+    return owner.getBukkitEntity();
+  }
+
+  @Override
+  public Location getLocation() {
+    return owner.getBukkitEntity().getLocation();
+  }
+
+  @Override
+  public void clearContent() {
+    owner.getInventory().clearContent();
+    owner.inventoryMenu.getCraftSlots().clearContent();
+    owner.inventoryMenu.slotsChanged(owner.inventoryMenu.getCraftSlots());
+    owner.containerMenu.setCarried(ItemStack.EMPTY);
+  }
+
+  public @Nullable AbstractContainerMenu createMenu(Player player, int i, boolean viewOnly) {
+    if (player instanceof ServerPlayer serverPlayer) {
+      return new OpenInventoryMenu(this, serverPlayer, i, viewOnly);
+    }
+    return null;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/Placeholders.java

@@ -0,0 +1,183 @@
+package com.lishid.openinv.internal.v1_21_R3.container;
+
+import net.minecraft.core.Registry;
+import net.minecraft.core.RegistryAccess;
+import net.minecraft.core.component.DataComponents;
+import net.minecraft.core.registries.Registries;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.TagParser;
+import net.minecraft.network.chat.Component;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.util.Unit;
+import net.minecraft.world.item.DyeColor;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+import net.minecraft.world.item.component.CustomModelData;
+import net.minecraft.world.item.component.DyedItemColor;
+import net.minecraft.world.level.GameType;
+import net.minecraft.world.level.ItemLike;
+import net.minecraft.world.level.block.entity.BannerPattern;
+import net.minecraft.world.level.block.entity.BannerPatternLayers;
+import net.minecraft.world.level.block.entity.BannerPatterns;
+import org.bukkit.configuration.ConfigurationSection;
+import org.bukkit.craftbukkit.v1_21_R3.CraftRegistry;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.EnumMap;
+import java.util.List;
+import java.util.Optional;
+
+public final class Placeholders {
+
+  private static final CustomModelData DEFAULT_CUSTOM_MODEL_DATA = new CustomModelData(List.of(), List.of(), List.of("openinv:custom"), List.of());
+  public static final @NotNull EnumMap<GameType, ItemStack> BLOCKED_GAME_TYPE = new EnumMap<>(GameType.class);
+  public static @NotNull ItemStack craftingOutput = defaultCraftingOutput();
+  public static @NotNull ItemStack cursor = defaultCursor();
+  public static @NotNull ItemStack drop = defaultDrop();
+  public static @NotNull ItemStack emptyHelmet = getEmptyArmor(Items.LEATHER_HELMET);
+  public static @NotNull ItemStack emptyChestplate = getEmptyArmor(Items.LEATHER_CHESTPLATE);
+  public static @NotNull ItemStack emptyLeggings = getEmptyArmor(Items.LEATHER_LEGGINGS);
+  public static @NotNull ItemStack emptyBoots = getEmptyArmor(Items.LEATHER_BOOTS);
+  public static @NotNull ItemStack emptyOffHand = getEmptyShield();
+  public static @NotNull ItemStack notSlot = defaultNotSlot();
+  public static @NotNull ItemStack blockedOffline = defaultBlockedOffline();
+
+  static {
+    for (GameType type : GameType.values()) {
+      // Barrier: "Not available - Creative" etc.
+      ItemStack typeItem = new ItemStack(Items.BARRIER);
+      typeItem.set(
+          DataComponents.ITEM_NAME,
+          Component.translatable("options.narrator.notavailable").append(" - ").append(type.getShortDisplayName()));
+      BLOCKED_GAME_TYPE.put(type, typeItem);
+    }
+  }
+
+  public static void load(@NotNull ConfigurationSection section) throws Exception {
+    craftingOutput = parse(section, "crafting-output", craftingOutput);
+    cursor = parse(section, "cursor", cursor);
+    drop = parse(section, "drop", drop);
+    emptyHelmet = parse(section, "empty-helmet", emptyHelmet);
+    emptyChestplate = parse(section, "empty-chestplate", emptyChestplate);
+    emptyLeggings = parse(section, "empty-leggings", emptyLeggings);
+    emptyBoots = parse(section, "empty-boots", emptyBoots);
+    emptyOffHand = parse(section, "empty-off-hand", emptyOffHand);
+    notSlot = parse(section, "not-a-slot", notSlot);
+    blockedOffline = parse(section, "blocked.offline", blockedOffline);
+    BLOCKED_GAME_TYPE.put(GameType.CREATIVE, parse(section, "blocked.creative", BLOCKED_GAME_TYPE.get(GameType.CREATIVE)));
+    BLOCKED_GAME_TYPE.put(GameType.SPECTATOR, parse(section, "blocked.spectator", BLOCKED_GAME_TYPE.get(GameType.SPECTATOR)));
+  }
+
+  private static @NotNull ItemStack parse(
+      @NotNull ConfigurationSection section,
+      @NotNull String path,
+      @NotNull ItemStack defaultStack) throws Exception {
+    String itemText = section.getString(path);
+
+    if (itemText == null) {
+      return defaultStack;
+    }
+
+    CompoundTag compoundTag = TagParser.parseTag(itemText);
+    Optional<ItemStack> parsed = ItemStack.parse(CraftRegistry.getMinecraftRegistry(), compoundTag);
+    return parsed.filter(itemStack -> !itemStack.isEmpty()).orElse(defaultStack);
+  }
+
+  public static ItemStack survivalOnly(@NotNull ServerPlayer serverPlayer) {
+    if (serverPlayer.connection == null || serverPlayer.connection.isDisconnected()) {
+      return blockedOffline;
+    }
+
+    return BLOCKED_GAME_TYPE.getOrDefault(serverPlayer.gameMode.getGameModeForPlayer(), ItemStack.EMPTY);
+  }
+
+  private static ItemStack defaultCraftingOutput() {
+    // Crafting table: "Crafting"
+    ItemStack itemStack = new ItemStack(Items.CRAFTING_TABLE);
+    itemStack.set(DataComponents.ITEM_NAME, Component.translatable("container.crafting"));
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack defaultCursor() {
+    // Cursor-like banner with no tooltip
+    ItemStack itemStack = new ItemStack(Items.WHITE_BANNER);
+    RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
+    Registry<BannerPattern> bannerPatterns = minecraftRegistry.lookupOrThrow(Registries.BANNER_PATTERN);
+    BannerPattern halfDiagBottomRight = bannerPatterns.getOrThrow(BannerPatterns.DIAGONAL_RIGHT).value();
+    BannerPattern downRight = bannerPatterns.getOrThrow(BannerPatterns.STRIPE_DOWNRIGHT).value();
+    BannerPattern border = bannerPatterns.getOrThrow(BannerPatterns.BORDER).value();
+    itemStack.set(DataComponents.BANNER_PATTERNS,
+        new BannerPatternLayers(List.of(
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfDiagBottomRight), DyeColor.GRAY),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(downRight), DyeColor.WHITE),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(border), DyeColor.GRAY))));
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    return itemStack;
+  }
+
+  private static ItemStack defaultDrop() {
+    // Dropper: "Drop Selected Item"
+    ItemStack itemStack = new ItemStack(Items.DROPPER);
+    // Note: translatable component, not keybind component! We want the text identifying the keybind, not the key.
+    itemStack.set(DataComponents.ITEM_NAME, Component.translatable("key.drop"));
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack getEmptyArmor(ItemLike item) {
+    // Inventory-background-grey-ish leather armor with no tooltip
+    ItemStack itemStack = new ItemStack(item);
+    DyedItemColor color = new DyedItemColor(0xC8C8C8, false);
+    itemStack.set(DataComponents.DYED_COLOR, color);
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack getEmptyShield() {
+    ItemStack itemStack = new ItemStack(Items.SHIELD);
+    itemStack.set(DataComponents.BASE_COLOR, DyeColor.MAGENTA);
+    RegistryAccess minecraftRegistry = CraftRegistry.getMinecraftRegistry();
+    Registry<BannerPattern> bannerPatterns = minecraftRegistry.lookupOrThrow(Registries.BANNER_PATTERN);
+    BannerPattern halfLeft = bannerPatterns.getOrThrow(BannerPatterns.HALF_VERTICAL).value();
+    BannerPattern topLeft = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_TOP_LEFT).value();
+    BannerPattern topRight = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_TOP_RIGHT).value();
+    BannerPattern bottomLeft = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_BOTTOM_LEFT).value();
+    BannerPattern bottomRight = bannerPatterns.getOrThrow(BannerPatterns.SQUARE_BOTTOM_RIGHT).value();
+    itemStack.set(DataComponents.BANNER_PATTERNS,
+        new BannerPatternLayers(List.of(
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(halfLeft), DyeColor.BLACK),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topLeft), DyeColor.MAGENTA),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomLeft), DyeColor.MAGENTA),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(topRight), DyeColor.BLACK),
+            new BannerPatternLayers.Layer(bannerPatterns.wrapAsHolder(bottomRight), DyeColor.BLACK))));
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack defaultNotSlot() {
+    // White pane with no tooltip
+    ItemStack itemStack = new ItemStack(Items.WHITE_STAINED_GLASS_PANE);
+    itemStack.set(DataComponents.HIDE_TOOLTIP, Unit.INSTANCE);
+    itemStack.set(DataComponents.CUSTOM_MODEL_DATA, DEFAULT_CUSTOM_MODEL_DATA);
+    return itemStack;
+  }
+
+  private static ItemStack defaultBlockedOffline() {
+    // Barrier: "Not available - Offline"
+    ItemStack itemStack = new ItemStack(Items.BARRIER);
+    itemStack.set(DataComponents.ITEM_NAME,
+        Component.translatable("options.narrator.notavailable")
+            .append(Component.literal(" - "))
+            .append(Component.translatable("gui.socialInteractions.status_offline")));
+    return itemStack;
+  }
+
+  private Placeholders() {
+    throw new IllegalStateException("Cannot create instance of utility class.");
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/bukkit/OpenDummyInventory.java

@@ -0,0 +1,172 @@
+package com.lishid.openinv.internal.v1_21_R3.container.bukkit;
+
+import com.lishid.openinv.internal.ViewOnly;
+import net.minecraft.world.Container;
+import org.bukkit.Material;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftInventory;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.ListIterator;
+
+/**
+ * A locked down "empty" inventory that rejects plugin interaction.
+ */
+public class OpenDummyInventory extends CraftInventory implements ViewOnly {
+
+  private final InventoryType type;
+
+  public OpenDummyInventory(Container inventory, InventoryType type) {
+    super(inventory);
+    this.type = type;
+  }
+
+  @Override
+  public @NotNull InventoryType getType() {
+    return type;
+  }
+
+  @Override
+  public @Nullable ItemStack getItem(int index) {
+    return null;
+  }
+
+  @Override
+  public void setItem(int index, @Nullable ItemStack item) {
+
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> addItem(@NotNull ItemStack... items) throws IllegalArgumentException {
+    return arrayToHashMap(items);
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> removeItem(@NotNull ItemStack... items) throws IllegalArgumentException {
+    return arrayToHashMap(items);
+  }
+
+  @SuppressWarnings("NonApiType")
+  private static @NotNull HashMap<Integer, ItemStack> arrayToHashMap(@NotNull ItemStack[] items) {
+    HashMap<Integer, ItemStack> ignored = new HashMap<>();
+    for (int index = 0; index < items.length; ++index) {
+      ignored.put(index, items[index]);
+    }
+    return ignored;
+  }
+
+  @Override
+  public ItemStack[] getContents() {
+    return new ItemStack[getSize()];
+  }
+
+  @Override
+  public void setContents(@NotNull ItemStack[] items) throws IllegalArgumentException {
+
+  }
+
+  @Override
+  public @NotNull ItemStack[] getStorageContents() {
+    return new ItemStack[getSize()];
+  }
+
+  @Override
+  public void setStorageContents(@NotNull ItemStack[] items) throws IllegalArgumentException {
+
+  }
+
+  @Override
+  public boolean contains(@NotNull Material material) throws IllegalArgumentException {
+    return false;
+  }
+
+  @Override
+  public boolean contains(@Nullable ItemStack item) {
+    return false;
+  }
+
+  @Override
+  public boolean contains(@NotNull Material material, int amount) throws IllegalArgumentException {
+    return false;
+  }
+
+  @Override
+  public boolean contains(@Nullable ItemStack item, int amount) {
+    return false;
+  }
+
+  @Override
+  public boolean containsAtLeast(@Nullable ItemStack item, int amount) {
+    return false;
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> all(
+      @NotNull Material material) throws IllegalArgumentException {
+    return new HashMap<>();
+  }
+
+  @SuppressWarnings("NonApiType")
+  @Override
+  public @NotNull HashMap<Integer, ItemStack> all(@Nullable ItemStack item) {
+    return new HashMap<>();
+  }
+
+  @Override
+  public int first(@NotNull Material material) throws IllegalArgumentException {
+    return -1;
+  }
+
+  @Override
+  public int first(@NotNull ItemStack item) {
+    return -1;
+  }
+
+  @Override
+  public int firstEmpty() {
+    return -1;
+  }
+
+  @Override
+  public boolean isEmpty() {
+    return true;
+  }
+
+  @Override
+  public void remove(@NotNull Material material) throws IllegalArgumentException {
+
+  }
+
+  @Override
+  public void remove(@NotNull ItemStack item) {
+
+  }
+
+  @Override
+  public void clear(int index) {
+
+  }
+
+  @Override
+  public void clear() {
+
+  }
+
+  @Override
+  public @NotNull ListIterator<ItemStack> iterator() {
+    return Collections.emptyListIterator();
+  }
+
+  @Override
+  public @NotNull ListIterator<ItemStack> iterator(int index) {
+    return Collections.emptyListIterator();
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/bukkit/OpenDummyPlayerInventory.java

@@ -0,0 +1,134 @@
+package com.lishid.openinv.internal.v1_21_R3.container.bukkit;
+
+import net.minecraft.world.Container;
+import org.bukkit.Material;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.EquipmentSlot;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenDummyPlayerInventory extends OpenDummyInventory implements PlayerInventory {
+
+  public OpenDummyPlayerInventory(Container inventory) {
+    super(inventory, InventoryType.PLAYER);
+  }
+
+  @Override
+  public HumanEntity getHolder() {
+    return (HumanEntity) super.getHolder();
+  }
+
+  @Override
+  public @NotNull ItemStack[] getArmorContents() {
+    return new ItemStack[4];
+  }
+
+  @Override
+  public @NotNull ItemStack[] getExtraContents() {
+    return new ItemStack[4];
+  }
+
+  @Override
+  public @Nullable ItemStack getHelmet() {
+    return null;
+  }
+
+  @Override
+  public @Nullable ItemStack getChestplate() {
+    return null;
+  }
+
+  @Override
+  public @Nullable ItemStack getLeggings() {
+    return null;
+  }
+
+  @Override
+  public @Nullable ItemStack getBoots() {
+    return null;
+  }
+
+  @Override
+  public void setItem(@NotNull EquipmentSlot slot, @Nullable ItemStack item) {
+
+  }
+
+  @Override
+  public @Nullable ItemStack getItem(@NotNull EquipmentSlot slot) {
+    return null;
+  }
+
+  @Override
+  public void setArmorContents(@Nullable ItemStack[] items) {
+
+  }
+
+  @Override
+  public void setExtraContents(@Nullable ItemStack[] items) {
+
+  }
+
+  @Override
+  public void setHelmet(@Nullable ItemStack helmet) {
+
+  }
+
+  @Override
+  public void setChestplate(@Nullable ItemStack chestplate) {
+
+  }
+
+  @Override
+  public void setLeggings(@Nullable ItemStack leggings) {
+
+  }
+
+  @Override
+  public void setBoots(@Nullable ItemStack boots) {
+
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInMainHand() {
+    return new ItemStack(Material.AIR);
+  }
+
+  @Override
+  public void setItemInMainHand(@Nullable ItemStack item) {
+
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInOffHand() {
+    return new ItemStack(Material.AIR);
+  }
+
+  @Override
+  public void setItemInOffHand(@Nullable ItemStack item) {
+
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInHand() {
+    return new ItemStack(Material.AIR);
+  }
+
+  @Override
+  public void setItemInHand(@Nullable ItemStack stack) {
+
+  }
+
+  @Override
+  public int getHeldItemSlot() {
+    return 0;
+  }
+
+  @Override
+  public void setHeldItemSlot(int slot) {
+
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/bukkit/OpenPlayerInventory.java

@@ -0,0 +1,221 @@
+package com.lishid.openinv.internal.v1_21_R3.container.bukkit;
+
+import com.google.common.base.Preconditions;
+import com.lishid.openinv.internal.v1_21_R3.container.OpenInventory;
+import net.minecraft.core.NonNullList;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Inventory;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftInventory;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftItemStack;
+import org.bukkit.entity.Player;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.PlayerInventory;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenPlayerInventory extends CraftInventory implements PlayerInventory {
+
+  public OpenPlayerInventory(@NotNull OpenInventory inventory) {
+    super(inventory);
+  }
+
+  @Override
+  public @NotNull OpenInventory getInventory() {
+    return (OpenInventory) super.getInventory();
+  }
+
+  @Override
+  public ItemStack[] getContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().getContents());
+  }
+
+  @Override
+  public void setContents(ItemStack[] items) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    int size = internal.getContainerSize();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+
+    for (int index = 0; index < size; ++index) {
+      if (index < items.length) {
+        internal.setItem(index, CraftItemStack.asNMSCopy(items[index]));
+      } else {
+        internal.setItem(index, net.minecraft.world.item.ItemStack.EMPTY);
+      }
+    }
+  }
+
+  @Override
+  public ItemStack[] getStorageContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().items);
+  }
+
+  @Override
+  public void setStorageContents(ItemStack[] items) throws IllegalArgumentException {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().items;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull InventoryType getType() {
+    return InventoryType.PLAYER;
+  }
+
+  @Override
+  public @NotNull Player getHolder() {
+    return getInventory().getOwner();
+  }
+
+  @Override
+  public @NotNull ItemStack[] getArmorContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().armor);
+  }
+
+  @Override
+  public void setArmorContents(@Nullable ItemStack[] items) {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().armor;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @NotNull ItemStack[] getExtraContents() {
+    return asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand);
+  }
+
+  @Override
+  public void setExtraContents(@Nullable ItemStack[] items) {
+    NonNullList<net.minecraft.world.item.ItemStack> list = getInventory().getOwnerHandle().getInventory().offhand;
+    int size = list.size();
+    Preconditions.checkArgument(items.length <= size, "items.length must be <= %s", size);
+    for (int index = 0; index < items.length; ++index) {
+      list.set(index, CraftItemStack.asNMSCopy(items[index]));
+    }
+  }
+
+  @Override
+  public @Nullable ItemStack getHelmet() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.HEAD.getIndex()));
+  }
+
+  @Override
+  public void setHelmet(@Nullable ItemStack helmet) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.HEAD.getIndex(), CraftItemStack.asNMSCopy(helmet));
+  }
+
+  @Override
+  public @Nullable ItemStack getChestplate() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.HEAD.getIndex()));
+  }
+
+  @Override
+  public void setChestplate(@Nullable ItemStack chestplate) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.CHEST.getIndex(), CraftItemStack.asNMSCopy(chestplate));
+  }
+
+  @Override
+  public @Nullable ItemStack getLeggings() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.LEGS.getIndex()));
+  }
+
+  @Override
+  public void setLeggings(@Nullable ItemStack leggings) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.LEGS.getIndex(), CraftItemStack.asNMSCopy(leggings));
+  }
+
+  @Override
+  public @Nullable ItemStack getBoots() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory()
+        .getArmor(EquipmentSlot.FEET.getIndex()));
+  }
+
+  @Override
+  public void setBoots(@Nullable ItemStack boots) {
+    getInventory().getOwnerHandle().getInventory().armor
+        .set(EquipmentSlot.FEET.getIndex(), CraftItemStack.asNMSCopy(boots));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInMainHand() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return CraftItemStack.asCraftMirror(internal.getItem(internal.selected));
+  }
+
+  @Override
+  public void setItemInMainHand(@Nullable ItemStack item) {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    internal.setItem(internal.selected, CraftItemStack.asNMSCopy(item));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInOffHand() {
+    return CraftItemStack.asCraftMirror(getInventory().getOwnerHandle().getInventory().offhand.getFirst());
+  }
+
+  @Override
+  public void setItemInOffHand(@Nullable ItemStack item) {
+    getInventory().getOwnerHandle().getInventory().offhand.set(0, CraftItemStack.asNMSCopy(item));
+  }
+
+  @Override
+  public @NotNull ItemStack getItemInHand() {
+    return getItemInMainHand();
+  }
+
+  @Override
+  public void setItemInHand(@Nullable ItemStack stack) {
+    setItemInMainHand(stack);
+  }
+
+  @Override
+  public int getHeldItemSlot() {
+    Inventory internal = getInventory().getOwnerHandle().getInventory();
+    return internal.items.size() - 9 + internal.selected;
+  }
+
+  @Override
+  public void setHeldItemSlot(int slot) {
+    slot %= 9;
+    getInventory().getOwnerHandle().getInventory().selected = slot;
+  }
+
+  @Override
+  public @Nullable ItemStack getItem(@NotNull org.bukkit.inventory.EquipmentSlot slot) {
+    return switch (slot) {
+      case HAND -> getItemInMainHand();
+      case OFF_HAND -> getItemInOffHand();
+      case FEET -> getBoots();
+      case LEGS -> getLeggings();
+      case CHEST -> getChestplate();
+      case HEAD -> getHelmet();
+      default -> throw new IllegalArgumentException("Unsupported EquipmentSlot " + slot);
+    };
+  }
+
+  @Override
+  public void setItem(@NotNull org.bukkit.inventory.EquipmentSlot slot, @Nullable ItemStack item) {
+    switch (slot) {
+      case HAND -> setItemInMainHand(item);
+      case OFF_HAND -> setItemInOffHand(item);
+      case FEET -> setBoots(item);
+      case LEGS -> setLeggings(item);
+      case CHEST -> setChestplate(item);
+      case HEAD -> setHelmet(item);
+      default -> throw new IllegalArgumentException("Unsupported EquipmentSlot " + slot);
+    }
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/bukkit/OpenPlayerInventorySelf.java

@@ -0,0 +1,26 @@
+package com.lishid.openinv.internal.v1_21_R3.container.bukkit;
+
+import com.lishid.openinv.internal.v1_21_R3.container.OpenInventory;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+public class OpenPlayerInventorySelf extends OpenPlayerInventory {
+
+  private final int offset;
+
+  public OpenPlayerInventorySelf(@NotNull OpenInventory inventory, int offset) {
+    super(inventory);
+    this.offset = offset;
+  }
+
+  @Override
+  public ItemStack getItem(int index) {
+    return super.getItem(offset + index);
+  }
+
+  @Override
+  public void setItem(int index, ItemStack item) {
+    super.setItem(offset + index, item);
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/menu/OpenChestMenu.java

@@ -0,0 +1,478 @@
+package com.lishid.openinv.internal.v1_21_R3.container.menu;
+
+import com.google.common.base.Suppliers;
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.InternalOwned;
+import com.lishid.openinv.internal.v1_21_R3.container.bukkit.OpenDummyInventory;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.SlotPlaceholder;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.SlotViewOnly;
+import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.inventory.ChestMenu;
+import net.minecraft.world.inventory.ClickType;
+import net.minecraft.world.inventory.ContainerData;
+import net.minecraft.world.inventory.ContainerListener;
+import net.minecraft.world.inventory.ContainerSynchronizer;
+import net.minecraft.world.inventory.DataSlot;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftInventoryView;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.Supplier;
+
+/**
+ * An extension of {@link AbstractContainerMenu} that supports {@link SlotPlaceholder placeholders}.
+ */
+public abstract class OpenChestMenu<T extends Container & ISpecialInventory & InternalOwned<ServerPlayer>>
+    extends AbstractContainerMenu {
+
+  protected static final int BOTTOM_INVENTORY_SIZE = 36;
+
+  protected final T container;
+  protected final ServerPlayer viewer;
+  protected final boolean viewOnly;
+  protected final boolean ownContainer;
+  protected final int topSize;
+  private CraftInventoryView<OpenChestMenu<T>, Inventory> bukkitEntity;
+  // Syncher fields
+  private @Nullable ContainerSynchronizer synchronizer;
+  private final List<DataSlot> dataSlots = new ArrayList<>();
+  private final IntList remoteDataSlots = new IntArrayList();
+  private final List<ContainerListener> containerListeners = new ArrayList<>();
+  private ItemStack remoteCarried = ItemStack.EMPTY;
+  private boolean suppressRemoteUpdates;
+
+  protected OpenChestMenu(
+      @NotNull MenuType<ChestMenu> type,
+      int containerCounter,
+      @NotNull T container,
+      @NotNull ServerPlayer viewer,
+      boolean viewOnly) {
+    super(type, containerCounter);
+    this.container = container;
+    this.viewer = viewer;
+    this.viewOnly = viewOnly;
+    ownContainer = container.getOwnerHandle().equals(viewer);
+    topSize = getTopSize(viewer);
+
+    preSlotSetup();
+
+    int upperRows = topSize / 9;
+    // View's upper inventory - our container
+    for (int row = 0; row < upperRows; ++row) {
+      for (int col = 0; col < 9; ++col) {
+        // x and y for client purposes, but hey, we're thorough here.
+        // Adapted from net.minecraft.world.inventory.ChestMenu
+        int x = 8 + col * 18;
+        int y = 18 + row * 18;
+        int index = row * 9 + col;
+
+        // Guard against weird inventory sizes.
+        if (index >= container.getContainerSize()) {
+          addSlot(new SlotViewOnly(container, index, x, y));
+          continue;
+        }
+
+        Slot slot = getUpperSlot(index, x, y);
+
+        addSlot(slot);
+      }
+    }
+
+    // View's lower inventory - viewer inventory
+    int playerInvPad = (upperRows - 4) * 18;
+    for (int row = 0; row < 3; ++row) {
+      for (int col = 0; col < 9; ++col) {
+        int x = 8 + col * 18;
+        int y = playerInvPad + row * 18 + 103;
+        addSlot(new Slot(viewer.getInventory(), row * 9 + col + 9, x, y));
+      }
+    }
+    // Hotbar
+    for (int col = 0; col < 9; ++col) {
+      int x = 8 + col * 18;
+      int y = playerInvPad + 161;
+      addSlot(new Slot(viewer.getInventory(), col, x, y));
+    }
+  }
+
+  public static @NotNull MenuType<ChestMenu> getChestMenuType(int inventorySize) {
+    inventorySize = ((int) Math.ceil(inventorySize / 9.0)) * 9;
+    return switch (inventorySize) {
+      case 9 -> MenuType.GENERIC_9x1;
+      case 18 -> MenuType.GENERIC_9x2;
+      case 27 -> MenuType.GENERIC_9x3;
+      case 36 -> MenuType.GENERIC_9x4;
+      case 45 -> MenuType.GENERIC_9x5;
+      case 54 -> MenuType.GENERIC_9x6;
+      default -> throw new IllegalArgumentException("Inventory size unsupported: " + inventorySize);
+    };
+  }
+
+  protected void preSlotSetup() {}
+
+  protected @NotNull Slot getUpperSlot(int index, int x, int y) {
+    if (viewOnly) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+    return new Slot(container, index, x, y);
+  }
+
+
+  @Override
+  public final @NotNull CraftInventoryView<OpenChestMenu<T>, Inventory> getBukkitView() {
+    if (bukkitEntity == null) {
+      bukkitEntity = createBukkitEntity();
+    }
+
+    return bukkitEntity;
+  }
+
+  protected @NotNull CraftInventoryView<OpenChestMenu<T>, Inventory> createBukkitEntity() {
+    Inventory top;
+    if (viewOnly) {
+      top = new OpenDummyInventory(container, container.getBukkitType());
+    } else {
+      top = container.getBukkitInventory();
+    }
+    return new CraftInventoryView<>(viewer.getBukkitEntity(), top, this) {
+      @Override
+      public @Nullable Inventory getInventory(int rawSlot) {
+        if (viewOnly) {
+          return null;
+        }
+        return super.getInventory(rawSlot);
+      }
+
+      @Override
+      public int convertSlot(int rawSlot) {
+        if (viewOnly) {
+          return InventoryView.OUTSIDE;
+        }
+        return super.convertSlot(rawSlot);
+      }
+
+      @Override
+      public @NotNull InventoryType.SlotType getSlotType(int slot) {
+        if (viewOnly) {
+          return InventoryType.SlotType.OUTSIDE;
+        }
+        return super.getSlotType(slot);
+      }
+    };
+  }
+
+  private int getTopSize(ServerPlayer viewer) {
+    MenuType<?> menuType = getType();
+    if (menuType == null) {
+      throw new IllegalStateException("MenuType cannot be null!");
+    } else if (menuType == MenuType.GENERIC_9x1) {
+      return 9;
+    } else if (menuType == MenuType.GENERIC_9x2) {
+      return 18;
+    } else if (menuType == MenuType.GENERIC_9x3) {
+      return 27;
+    } else if (menuType == MenuType.GENERIC_9x4) {
+      return 36;
+    } else if (menuType == MenuType.GENERIC_9x5) {
+      return 45;
+    } else if (menuType == MenuType.GENERIC_9x6) {
+      return 54;
+    }
+    // This is a bit gross, but allows us a safe fallthrough.
+    return menuType.create(-1, viewer.getInventory()).slots.size() - BOTTOM_INVENTORY_SIZE;
+  }
+
+  /**
+   * Reimplementation of {@link AbstractContainerMenu#moveItemStackTo(ItemStack, int, int, boolean)} that ignores fake
+   * slots and respects {@link Slot#hasItem()}.
+   *
+   * @param itemStack the stack to quick-move
+   * @param rangeLow the start of the range of slots that can be moved to, inclusive
+   * @param rangeHigh the end of the range of slots that can be moved to, exclusive
+   * @param topDown whether to start at the top of the range or bottom
+   * @return whether the stack was modified as a result of being quick-moved
+   */
+  @Override
+  protected boolean moveItemStackTo(ItemStack itemStack, int rangeLow, int rangeHigh, boolean topDown) {
+    boolean modified = false;
+    boolean stackable = itemStack.isStackable();
+    Slot firstEmpty = null;
+
+    for (int index = topDown ? rangeHigh - 1 : rangeLow;
+         !itemStack.isEmpty() && (topDown ? index >= rangeLow : index < rangeHigh);
+         index += topDown ? -1 : 1
+    ) {
+      Slot slot = slots.get(index);
+      // If the slot cannot be added to, check the next slot.
+      if (slot.isFake() || !slot.mayPlace(itemStack)) {
+        continue;
+      }
+
+      if (slot.hasItem()) {
+        // If the item isn't stackable, check the next slot.
+        if (!stackable) {
+          continue;
+        }
+        // Otherwise, add as many as we can from our stack to the slot.
+        modified |= addToExistingStack(itemStack, slot);
+      } else {
+        // If this is the first empty slot, keep track of it for later use.
+        if (firstEmpty == null) {
+          firstEmpty = slot;
+        }
+        // If the item isn't stackable, we've located the slot we're adding it to, so we're done.
+        if (!stackable) {
+          break;
+        }
+      }
+    }
+
+    // If the item hasn't been fully added yet, add as many as we can to the first open slot.
+    if (!itemStack.isEmpty() && firstEmpty != null) {
+      firstEmpty.setByPlayer(itemStack.split(Math.min(itemStack.getCount(), firstEmpty.getMaxStackSize(itemStack))));
+      firstEmpty.setChanged();
+      modified = true;
+    }
+
+    return modified;
+  }
+
+  private static boolean addToExistingStack(ItemStack itemStack, Slot slot) {
+    ItemStack existing = slot.getItem();
+
+    // If the items aren't the same, we can't add our item.
+    if (!ItemStack.isSameItemSameComponents(itemStack, existing)) {
+      return false;
+    }
+
+    int max = slot.getMaxStackSize(existing);
+    int existingCount = existing.getCount();
+
+    // If the stack is already full, we can't add more.
+    if (existingCount >= max) {
+      return false;
+    }
+
+    int total = existingCount + itemStack.getCount();
+
+    // If the existing item can accept the entirety of our item, we're done!
+    if (total <= max) {
+      itemStack.setCount(0);
+      existing.setCount(total);
+      slot.setChanged();
+      return true;
+    }
+
+    // Otherwise, add as many as we can.
+    itemStack.shrink(max - existingCount);
+    existing.setCount(max);
+    slot.setChanged();
+    return true;
+  }
+
+  @Override
+  public void clicked(int i, int j, ClickType clickType, Player player) {
+    if (viewOnly) {
+      if (clickType == ClickType.QUICK_CRAFT) {
+        sendAllDataToRemote();
+      }
+      return;
+    }
+    super.clicked(i, j, clickType, player);
+  }
+
+  @Override
+  public boolean stillValid(Player player) {
+    return true;
+  }
+
+  // Overrides from here on are purely to modify the sync process to send placeholder items.
+  @Override
+  protected Slot addSlot(Slot slot) {
+    slot.index = this.slots.size();
+    this.slots.add(slot);
+    this.lastSlots.add(ItemStack.EMPTY);
+    this.remoteSlots.add(ItemStack.EMPTY);
+    return slot;
+  }
+
+  @Override
+  protected DataSlot addDataSlot(DataSlot dataSlot) {
+    this.dataSlots.add(dataSlot);
+    this.remoteDataSlots.add(0);
+    return dataSlot;
+  }
+
+  @Override
+  protected void addDataSlots(ContainerData containerData) {
+    for (int i = 0; i < containerData.getCount(); i++) {
+      this.addDataSlot(DataSlot.forContainer(containerData, i));
+    }
+  }
+
+  @Override
+  public void addSlotListener(ContainerListener containerListener) {
+    if (!this.containerListeners.contains(containerListener)) {
+      this.containerListeners.add(containerListener);
+      this.broadcastChanges();
+    }
+  }
+
+  @Override
+  public void setSynchronizer(ContainerSynchronizer containerSynchronizer) {
+    this.synchronizer = containerSynchronizer;
+    this.sendAllDataToRemote();
+  }
+
+  @Override
+  public void sendAllDataToRemote() {
+    for (int index = 0; index < slots.size(); ++index) {
+      Slot slot = slots.get(index);
+      this.remoteSlots.set(index, (slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem()).copy());
+    }
+
+    remoteCarried = getCarried().copy();
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      this.remoteDataSlots.set(index, this.dataSlots.get(index).get());
+    }
+
+    if (this.synchronizer != null) {
+      this.synchronizer.sendInitialData(this, this.remoteSlots, this.remoteCarried, this.remoteDataSlots.toIntArray());
+    }
+  }
+
+  @Override
+  public void broadcastCarriedItem() {
+    this.remoteCarried = this.getCarried().copy();
+    if (this.synchronizer != null) {
+      this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+    }
+  }
+
+  @Override
+  public void removeSlotListener(ContainerListener containerListener) {
+    this.containerListeners.remove(containerListener);
+  }
+
+  @Override
+  public void broadcastChanges() {
+    for (int index = 0; index < this.slots.size(); ++index) {
+      Slot slot = this.slots.get(index);
+      ItemStack itemstack = slot instanceof SlotPlaceholder placeholder ? placeholder.getOrDefault() : slot.getItem();
+      Supplier<ItemStack> supplier = Suppliers.memoize(itemstack::copy);
+      this.triggerSlotListeners(index, itemstack, supplier);
+      this.synchronizeSlotToRemote(index, itemstack, supplier);
+    }
+
+    this.synchronizeCarriedToRemote();
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      DataSlot dataSlot = this.dataSlots.get(index);
+      int j = dataSlot.get();
+      if (dataSlot.checkAndClearUpdateFlag()) {
+        this.updateDataSlotListeners(index, j);
+      }
+
+      this.synchronizeDataSlotToRemote(index, j);
+    }
+  }
+
+  @Override
+  public void broadcastFullState() {
+    for (int index = 0; index < this.slots.size(); ++index) {
+      ItemStack itemstack = this.slots.get(index).getItem();
+      this.triggerSlotListeners(index, itemstack, itemstack::copy);
+    }
+
+    for (int index = 0; index < this.dataSlots.size(); ++index) {
+      DataSlot containerproperty = this.dataSlots.get(index);
+      if (containerproperty.checkAndClearUpdateFlag()) {
+        this.updateDataSlotListeners(index, containerproperty.get());
+      }
+    }
+
+    this.sendAllDataToRemote();
+  }
+
+  private void updateDataSlotListeners(int i, int j) {
+    for (ContainerListener containerListener : this.containerListeners) {
+      containerListener.dataChanged(this, i, j);
+    }
+  }
+
+  private void triggerSlotListeners(int index, ItemStack itemStack, Supplier<ItemStack> supplier) {
+    ItemStack itemStack1 = this.lastSlots.get(index);
+    if (!ItemStack.matches(itemStack1, itemStack)) {
+      ItemStack itemStack2 = supplier.get();
+      this.lastSlots.set(index, itemStack2);
+
+      for (ContainerListener containerListener : this.containerListeners) {
+        containerListener.slotChanged(this, index, itemStack2);
+      }
+    }
+  }
+
+  private void synchronizeSlotToRemote(int i, ItemStack itemStack, Supplier<ItemStack> supplier) {
+    if (!this.suppressRemoteUpdates) {
+      ItemStack itemStack1 = this.remoteSlots.get(i);
+      if (!ItemStack.matches(itemStack1, itemStack)) {
+        ItemStack itemstack2 = supplier.get();
+        this.remoteSlots.set(i, itemstack2);
+        if (this.synchronizer != null) {
+          this.synchronizer.sendSlotChange(this, i, itemstack2);
+        }
+      }
+    }
+  }
+
+  private void synchronizeDataSlotToRemote(int index, int value) {
+    if (!this.suppressRemoteUpdates) {
+      int existing = this.remoteDataSlots.getInt(index);
+      if (existing != value) {
+        this.remoteDataSlots.set(index, value);
+        if (this.synchronizer != null) {
+          this.synchronizer.sendDataChange(this, index, value);
+        }
+      }
+    }
+  }
+
+  private void synchronizeCarriedToRemote() {
+    if (!this.suppressRemoteUpdates && !ItemStack.matches(this.getCarried(), this.remoteCarried)) {
+      this.remoteCarried = this.getCarried().copy();
+      if (this.synchronizer != null) {
+        this.synchronizer.sendCarriedChange(this, this.remoteCarried);
+      }
+    }
+  }
+
+  @Override
+  public void setRemoteCarried(ItemStack itemstack) {
+    this.remoteCarried = itemstack.copy();
+  }
+
+  @Override
+  public void suppressRemoteUpdates() {
+    this.suppressRemoteUpdates = true;
+  }
+
+  @Override
+  public void resumeRemoteUpdates() {
+    this.suppressRemoteUpdates = false;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/menu/OpenEnderChestMenu.java

@@ -0,0 +1,53 @@
+package com.lishid.openinv.internal.v1_21_R3.container.menu;
+
+import com.lishid.openinv.internal.v1_21_R3.container.OpenEnderChest;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+public class OpenEnderChestMenu extends OpenChestMenu<OpenEnderChest> {
+
+  public OpenEnderChestMenu(
+      @NotNull OpenEnderChest enderChest,
+      @NotNull ServerPlayer viewer,
+      int containerId,
+      boolean viewOnly) {
+    super(getChestMenuType(enderChest.getContainerSize()), containerId, enderChest, viewer, viewOnly);
+  }
+
+  @Override
+  public ItemStack quickMoveStack(Player player, int index) {
+    if (viewOnly) {
+      return ItemStack.EMPTY;
+    }
+
+    // See ChestMenu
+    Slot slot = this.slots.get(index);
+
+    if (slot.isFake() || !slot.hasItem()) {
+      return ItemStack.EMPTY;
+    }
+
+    ItemStack itemStack = slot.getItem();
+    ItemStack original = itemStack.copy();
+
+    if (index < topSize) {
+      if (!this.moveItemStackTo(itemStack, topSize, this.slots.size(), true)) {
+        return ItemStack.EMPTY;
+      }
+    } else if (!this.moveItemStackTo(itemStack, 0, topSize, false)) {
+      return ItemStack.EMPTY;
+    }
+
+    if (itemStack.isEmpty()) {
+      slot.setByPlayer(ItemStack.EMPTY);
+    } else {
+      slot.setChanged();
+    }
+
+    return original;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/menu/OpenInventoryMenu.java

@@ -0,0 +1,262 @@
+package com.lishid.openinv.internal.v1_21_R3.container.menu;
+
+import com.google.common.base.Preconditions;
+import com.lishid.openinv.internal.v1_21_R3.container.OpenInventory;
+import com.lishid.openinv.internal.v1_21_R3.container.bukkit.OpenDummyPlayerInventory;
+import com.lishid.openinv.internal.v1_21_R3.container.bukkit.OpenPlayerInventorySelf;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentDrop;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.ContentEquipment;
+import com.lishid.openinv.internal.v1_21_R3.container.slot.SlotViewOnly;
+import com.lishid.openinv.util.Permissions;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.ChestMenu;
+import net.minecraft.world.inventory.MenuType;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftInventoryView;
+import org.bukkit.craftbukkit.v1_21_R3.inventory.CraftItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class OpenInventoryMenu extends OpenChestMenu<OpenInventory> {
+
+  private int offset;
+
+  public OpenInventoryMenu(OpenInventory inventory, ServerPlayer viewer, int i, boolean viewOnly) {
+    super(getMenuType(inventory, viewer), i, inventory, viewer, viewOnly);
+  }
+
+  private static MenuType<ChestMenu> getMenuType(OpenInventory inventory, ServerPlayer viewer) {
+    int size = inventory.getContainerSize();
+    // Disallow duplicate access to own main inventory contents.
+    if (inventory.getOwnerHandle().equals(viewer)) {
+      size -= viewer.getInventory().items.size();
+      size = ((int) Math.ceil(size / 9.0)) * 9;
+    }
+
+    return getChestMenuType(size);
+  }
+
+  @Override
+  protected void preSlotSetup() {
+    offset = ownContainer ? viewer.getInventory().items.size() : 0;
+  }
+
+  @Override
+  protected @NotNull Slot getUpperSlot(int index, int x, int y) {
+    index += offset;
+    Slot slot = container.getMenuSlot(index, x, y);
+
+    // If the slot cannot be interacted with there's nothing to configure.
+    if (slot.getClass().equals(SlotViewOnly.class)) {
+      return slot;
+    }
+
+    // Remove drop slot if viewer is not allowed to use it.
+    if (slot instanceof ContentDrop.SlotDrop
+        && (viewOnly || !Permissions.INVENTORY_SLOT_DROP.hasPermission(viewer.getBukkitEntity()))) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+
+    if (slot instanceof ContentEquipment.SlotEquipment equipment) {
+      if (viewOnly) {
+        return SlotViewOnly.wrap(slot);
+      }
+
+      Permissions perm = switch (equipment.getEquipmentSlot()) {
+        case HEAD -> Permissions.INVENTORY_SLOT_HEAD_ANY;
+        case CHEST -> Permissions.INVENTORY_SLOT_CHEST_ANY;
+        case LEGS -> Permissions.INVENTORY_SLOT_LEGS_ANY;
+        case FEET -> Permissions.INVENTORY_SLOT_FEET_ANY;
+        // Off-hand can hold anything, not just equipment.
+        default -> null;
+      };
+
+      // If the viewer doesn't have permission, only allow equipment the viewee can equip in the slot.
+      if (perm != null && !perm.hasPermission(viewer.getBukkitEntity())) {
+        equipment.onlyEquipmentFor(container.getOwnerHandle());
+      }
+
+      // Equipment slots are a core part of the inventory, so they will always be shown.
+      return slot;
+    }
+
+    // When viewing own inventory, only allow access to equipment and drop slots (equipment allowed above).
+    if (ownContainer && !(slot instanceof ContentDrop.SlotDrop)) {
+      return new SlotViewOnly(container, index, x, y);
+    }
+
+    if (viewOnly) {
+      return SlotViewOnly.wrap(slot);
+    }
+
+    return slot;
+  }
+
+  @Override
+  protected @NotNull CraftInventoryView<OpenChestMenu<OpenInventory>, Inventory> createBukkitEntity() {
+    org.bukkit.inventory.Inventory bukkitInventory;
+    if (viewOnly) {
+      bukkitInventory = new OpenDummyPlayerInventory(container);
+    } else if (ownContainer) {
+      bukkitInventory = new OpenPlayerInventorySelf(container, offset);
+    } else {
+      bukkitInventory = container.getBukkitInventory();
+    }
+
+    return new CraftInventoryView<>(viewer.getBukkitEntity(), bukkitInventory, this) {
+      @Override
+      public org.bukkit.inventory.ItemStack getItem(int index) {
+        if (viewOnly || index < 0) {
+          return null;
+        }
+
+        Slot slot = slots.get(index);
+        return CraftItemStack.asCraftMirror(slot.hasItem() ? slot.getItem() : ItemStack.EMPTY);
+      }
+
+      @Override
+      public boolean isInTop(int rawSlot) {
+        return rawSlot < topSize;
+      }
+
+      @Override
+      public @Nullable Inventory getInventory(int rawSlot) {
+        if (viewOnly) {
+          return null;
+        }
+        if (rawSlot == InventoryView.OUTSIDE || rawSlot == -1) {
+          return null;
+        }
+        Preconditions.checkArgument(rawSlot >= 0 && rawSlot < topSize + offset + BOTTOM_INVENTORY_SIZE,
+            "Slot %s outside of inventory", rawSlot);
+        if (rawSlot > topSize) {
+          return getBottomInventory();
+        }
+        Slot slot = slots.get(rawSlot);
+        if (slot.isFake()) {
+          return null;
+        }
+        return getTopInventory();
+      }
+
+      @Override
+      public int convertSlot(int rawSlot) {
+        if (viewOnly) {
+          return InventoryView.OUTSIDE;
+        }
+        if (rawSlot < 0) {
+          return rawSlot;
+        }
+        if (rawSlot < topSize) {
+          Slot slot = slots.get(rawSlot);
+          if (slot.isFake()) {
+            return InventoryView.OUTSIDE;
+          }
+          return rawSlot;
+        }
+
+        int slot = rawSlot - topSize;
+
+        if (slot >= 27) {
+          slot -= 27;
+        } else {
+          slot += 9;
+        }
+
+        return slot;
+      }
+
+      @Override
+      public @NotNull InventoryType.SlotType getSlotType(int slot) {
+        if (viewOnly || slot < 0) {
+          return InventoryType.SlotType.OUTSIDE;
+        }
+        if (slot >= topSize) {
+          slot -= topSize;
+          if (slot >= 27) {
+            return InventoryType.SlotType.QUICKBAR;
+          }
+          return InventoryType.SlotType.CONTAINER;
+        }
+        return OpenInventoryMenu.this.container.getSlotType(offset + slot);
+      }
+
+      @Override
+      public int countSlots() {
+        return topSize + BOTTOM_INVENTORY_SIZE;
+      }
+    };
+  }
+
+  @Override
+  public ItemStack quickMoveStack(Player player, int index) {
+    if (viewOnly) {
+      return ItemStack.EMPTY;
+    }
+
+    // See ChestMenu and InventoryMenu
+    Slot slot = this.slots.get(index);
+
+    if (!slot.hasItem() || slot.isFake()) {
+      return ItemStack.EMPTY;
+    }
+
+    ItemStack itemStack = slot.getItem();
+    ItemStack originalStack = itemStack.copy();
+
+    if (index < topSize) {
+      // If we're moving top to bottom, do a normal transfer.
+      if (!this.moveItemStackTo(itemStack, topSize, this.slots.size(), true)) {
+        return ItemStack.EMPTY;
+      }
+    } else {
+      EquipmentSlot equipmentSlot = player.getEquipmentSlotForItem(itemStack);
+      boolean movedGear = switch (equipmentSlot) {
+        // If this is gear, try to move it to the correct slot first.
+        case OFFHAND, FEET, LEGS, CHEST, HEAD -> {
+          // Locate the correct slot in the contents following the main inventory.
+          for (int extra = container.getOwnerHandle().getInventory().items.size() - offset; extra < topSize; ++extra) {
+            Slot extraSlot = getSlot(extra);
+            if (extraSlot instanceof ContentEquipment.SlotEquipment equipSlot
+                && equipSlot.getEquipmentSlot() == equipmentSlot) {
+              // If we've found a matching slot, try to move to it.
+              // If this succeeds, even partially, we will not attempt to move to other slots.
+              // Otherwise, armor is already occupied, so we'll fall through to main inventory.
+              yield this.moveItemStackTo(itemStack, extra, extra + 1, false);
+            }
+          }
+          yield false;
+        }
+        // Non-gear gets no special treatment.
+        default -> false;
+      };
+
+      // If main inventory is not available, there's nowhere else to move.
+      if (offset != 0) {
+        if (!movedGear) {
+          return ItemStack.EMPTY;
+        }
+      } else {
+        // If we didn't move to a gear slot, try to move to a main inventory slot.
+        if (!movedGear && !this.moveItemStackTo(itemStack, 0, container.getOwnerHandle().getInventory().items.size(), true)) {
+          return ItemStack.EMPTY;
+        }
+      }
+    }
+
+    if (itemStack.isEmpty()) {
+      slot.setByPlayer(ItemStack.EMPTY);
+    } else {
+      slot.setChanged();
+    }
+
+    return originalStack;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/Content.java

@@ -0,0 +1,69 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * An interface defining behaviors for entries in a {@link Container}. Used to reduce duplicate content reordering.
+ */
+public interface Content {
+
+  /**
+   * Update internal holder.
+   *
+   * @param holder the new holder
+   */
+  void setHolder(@NotNull ServerPlayer holder);
+
+  /**
+   * Get the current item.
+   *
+   * @return the current item
+   */
+  ItemStack get();
+
+  /**
+   * Remove the current item.
+   *
+   * @return the current item
+   */
+  ItemStack remove();
+
+  /**
+   * Remove some of the current item.
+   *
+   * @return the current item
+   */
+  ItemStack removePartial(int amount);
+
+  /**
+   * Set the current item. If slot is currently not usable, will drop item instead.
+   *
+   * @param itemStack the item to set
+   */
+  void set(ItemStack itemStack);
+
+  /**
+   * Get a {@link Slot} for use in a {@link net.minecraft.world.inventory.AbstractContainerMenu ContainerMenu}. Will
+   * impose any specific restrictions to insertion or removal.
+   *
+   * @param container the backing container
+   * @param slot the slot of the backing container represented
+   * @param x clientside x dimension from top left of inventory, not used
+   * @param y clientside y dimension from top left of inventory, not used
+   * @return a menu slot
+   */
+  Slot asSlot(Container container, int slot, int x, int y);
+
+  /**
+   * Get a loose Bukkit translation of what this slot stores. For example, any slot that drops items at the owner rather
+   * than insert them will report itself as being {@link org.bukkit.event.inventory.InventoryType.SlotType#OUTSIDE}.
+   *
+   * @return the closes Bukkit slot type
+   */
+  org.bukkit.event.inventory.InventoryType.SlotType getSlotType();
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentCrafting.java

@@ -0,0 +1,131 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R3.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+
+/**
+ * A slot in a survival crafting inventory. Unavailable when not online in a survival mode.
+ */
+public class ContentCrafting implements Content {
+
+  private final int index;
+  private ServerPlayer holder;
+  private List<ItemStack> items;
+
+  public ContentCrafting(@NotNull ServerPlayer holder, int index) {
+    setHolder(holder);
+    this.index = index;
+  }
+
+  private boolean isAvailable() {
+    return isAvailable(holder);
+  }
+
+  static boolean isAvailable(@NotNull ServerPlayer holder) {
+    // Player must be online and not in creative - since the creative client is (semi-)authoritative,
+    // it ignores changes without extra help, and will delete the item as a result.
+    // Spectator mode is technically possible but may cause the item to be dropped if the client opens an inventory.
+    return holder.connection != null && !holder.connection.isDisconnected() && holder.gameMode.isSurvival();
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+    // Note: CraftingContainer#getItems is immutable! Be careful with updates.
+    this.items = holder.inventoryMenu.getCraftSlots().getContents();
+  }
+
+  @Override
+  public ItemStack get() {
+    return isAvailable() ? items.get(index) : ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    if (!this.isAvailable()) {
+      return ItemStack.EMPTY;
+    }
+    ItemStack removed = items.remove(index);
+    if (removed.isEmpty()) {
+      return ItemStack.EMPTY;
+    }
+    holder.inventoryMenu.slotsChanged(holder.inventoryMenu.getCraftSlots());
+    return removed;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    if (!this.isAvailable()) {
+      return ItemStack.EMPTY;
+    }
+    ItemStack removed = ContainerHelper.removeItem(items, index, amount);
+    if (removed.isEmpty()) {
+      return ItemStack.EMPTY;
+    }
+    holder.inventoryMenu.slotsChanged(holder.inventoryMenu.getCraftSlots());
+    return removed;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    if (isAvailable()) {
+      items.set(index, itemStack);
+      holder.inventoryMenu.slotsChanged(holder.inventoryMenu.getCraftSlots());
+    } else {
+      holder.drop(itemStack, false);
+    }
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotCrafting(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return isAvailable() ? InventoryType.SlotType.CRAFTING : InventoryType.SlotType.OUTSIDE;
+  }
+
+  public class SlotCrafting extends SlotPlaceholder {
+
+    private SlotCrafting(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      return isAvailable() ? items.get(ContentCrafting.this.index) : Placeholders.survivalOnly(holder);
+    }
+
+    @Override
+    public boolean mayPickup(Player player) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack itemStack) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean hasItem() {
+      return isAvailable() && super.hasItem();
+    }
+
+    @Override
+    public boolean isFake() {
+      return !isAvailable();
+    }
+
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentCraftingResult.java

@@ -0,0 +1,48 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R3.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.InventoryMenu;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot allowing viewing of the crafting result.
+ *
+ * <p>Unmodifiable because I said so. Use your own crafting grid.</p>
+ */
+public class ContentCraftingResult extends ContentViewOnly {
+
+  public ContentCraftingResult(@NotNull ServerPlayer holder) {
+    super(holder);
+  }
+
+  @Override
+  public ItemStack get() {
+    InventoryMenu inventoryMenu = holder.inventoryMenu;
+    return inventoryMenu.getResultSlot().getItem();
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotViewOnly(container, slot, x, y) {
+      @Override
+      public ItemStack getOrDefault() {
+        if (!ContentCrafting.isAvailable(holder)) {
+          return Placeholders.survivalOnly(holder);
+        }
+        InventoryMenu inventoryMenu = holder.inventoryMenu;
+        return inventoryMenu.getResultSlot().getItem();
+      }
+    };
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.RESULT;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentCursor.java

@@ -0,0 +1,117 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R3.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot wrapping the active menu's cursor. Unavailable when not online in a survival mode.
+ */
+public class ContentCursor implements Content {
+
+  private @NotNull ServerPlayer holder;
+
+  public ContentCursor(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public ItemStack get() {
+    return isAvailable() ? holder.containerMenu.getCarried() : ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    ItemStack carried = holder.containerMenu.getCarried();
+    holder.containerMenu.setCarried(ItemStack.EMPTY);
+    return carried;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    ItemStack carried = holder.containerMenu.getCarried();
+    if (!carried.isEmpty() && carried.getCount() >= amount) {
+      ItemStack value = carried.split(amount);
+      if (carried.isEmpty()) {
+        holder.containerMenu.setCarried(ItemStack.EMPTY);
+      }
+      return value;
+    }
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    if (isAvailable()) {
+      holder.containerMenu.setCarried(itemStack);
+    } else {
+      holder.drop(itemStack, false);
+    }
+  }
+
+  private boolean isAvailable() {
+    // Player must be online and not in creative - since the creative client is (semi-)authoritative,
+    // it ignores changes without extra help, and will delete the item as a result.
+    // Spectator mode is technically possible but may cause the item to be dropped if the client opens an inventory.
+    return holder.connection != null && !holder.connection.isDisconnected() && holder.gameMode.isSurvival();
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotCursor(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    // As close as possible to "not real"
+    return InventoryType.SlotType.OUTSIDE;
+  }
+
+  public class SlotCursor extends SlotPlaceholder {
+
+    private SlotCursor(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      if (!isAvailable()) {
+        return Placeholders.survivalOnly(holder);
+      }
+      ItemStack carried = holder.containerMenu.getCarried();
+      return carried.isEmpty() ? Placeholders.cursor : carried;
+    }
+
+    @Override
+    public boolean mayPickup(Player player) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack itemStack) {
+      return isAvailable();
+    }
+
+    @Override
+    public boolean hasItem() {
+      return isAvailable() && super.hasItem();
+    }
+
+    @Override
+    public boolean isFake() {
+      return true;
+    }
+
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentDrop.java

@@ -0,0 +1,88 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R3.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A fake slot used to drop items. Unavailable offline.
+ */
+public class ContentDrop implements Content {
+
+  private ServerPlayer holder;
+
+  public ContentDrop(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public ItemStack get() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    holder.drop(itemStack, true);
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotDrop(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    // Behaves like dropping an item outside the screen, just by the target player.
+    return InventoryType.SlotType.OUTSIDE;
+  }
+
+  public class SlotDrop extends SlotPlaceholder {
+
+    private SlotDrop(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      return holder.connection != null && !holder.connection.isDisconnected()
+          ? Placeholders.drop
+          : Placeholders.blockedOffline;
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack itemStack) {
+      return holder.connection != null && !holder.connection.isDisconnected();
+    }
+
+    @Override
+    public boolean hasItem() {
+      return false;
+    }
+
+    @Override
+    public boolean isFake() {
+      return true;
+    }
+
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentEquipment.java

@@ -0,0 +1,78 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R3.container.Placeholders;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot for equipment that displays placeholders if empty.
+ */
+public class ContentEquipment extends ContentList {
+
+  private final ItemStack placeholder;
+  private final EquipmentSlot equipmentSlot;
+
+  public ContentEquipment(ServerPlayer holder, int index, EquipmentSlot equipmentSlot) {
+    super(holder, index, InventoryType.SlotType.ARMOR);
+    placeholder = switch (equipmentSlot) {
+      case HEAD -> Placeholders.emptyHelmet;
+      case CHEST -> Placeholders.emptyChestplate;
+      case LEGS -> Placeholders.emptyLeggings;
+      case FEET -> Placeholders.emptyBoots;
+      default -> Placeholders.emptyOffHand;
+    };
+    this.equipmentSlot = equipmentSlot;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.items = holder.getInventory().armor;
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y);
+  }
+
+  public class SlotEquipment extends SlotPlaceholder {
+
+    private ServerPlayer viewer;
+
+    SlotEquipment(Container container, int index, int x, int y) {
+      super(container, index, x, y);
+    }
+
+    @Override
+    public ItemStack getOrDefault() {
+      ItemStack itemStack = getItem();
+      if (!itemStack.isEmpty()) {
+        return itemStack;
+      }
+      return placeholder;
+    }
+
+    public EquipmentSlot getEquipmentSlot() {
+      return equipmentSlot;
+    }
+
+    public void onlyEquipmentFor(ServerPlayer viewer) {
+      this.viewer = viewer;
+    }
+
+    @Override
+    public boolean mayPlace(ItemStack var0) {
+      if (viewer == null) {
+        return true;
+      }
+
+      return equipmentSlot == EquipmentSlot.OFFHAND || viewer.getEquipmentSlotForItem(var0) == equipmentSlot;
+    }
+
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentList.java

@@ -0,0 +1,58 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.ContainerHelper;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+
+import java.util.List;
+
+/**
+ * A normal slot backed by an item list.
+ */
+public abstract class ContentList implements Content {
+
+  private final int index;
+  private final InventoryType.SlotType slotType;
+  protected List<ItemStack> items;
+
+  public ContentList(ServerPlayer holder, int index, InventoryType.SlotType slotType) {
+    this.index = index;
+    this.slotType = slotType;
+    setHolder(holder);
+  }
+
+  @Override
+  public ItemStack get() {
+    return items.get(index);
+  }
+
+  @Override
+  public ItemStack remove() {
+    ItemStack removed = items.remove(index);
+    return removed == null || removed.isEmpty() ? ItemStack.EMPTY : removed;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    return ContainerHelper.removeItem(items, index, amount);
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    items.set(index, itemStack);
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new Slot(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return slotType;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentOffHand.java

@@ -0,0 +1,46 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.EquipmentSlot;
+import net.minecraft.world.inventory.Slot;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A slot for equipment that updates held items if necessary.
+ */
+public class ContentOffHand extends ContentEquipment {
+
+  private ServerPlayer holder;
+
+  public ContentOffHand(ServerPlayer holder, int localIndex) {
+    super(holder, localIndex, EquipmentSlot.OFFHAND);
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.items = holder.getInventory().offhand;
+    this.holder = holder;
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.QUICKBAR;
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotEquipment(container, slot, x, y) {
+      @Override
+      public void setChanged() {
+        if (holder.connection != null
+            && !holder.connection.isDisconnected()
+            && holder.containerMenu != holder.inventoryMenu) {
+          holder.resendItemInHands();
+        }
+      }
+    };
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/ContentViewOnly.java

@@ -0,0 +1,56 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.bukkit.event.inventory.InventoryType;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A view-only slot that can't be interacted with.
+ */
+public class ContentViewOnly implements Content {
+
+  @NotNull ServerPlayer holder;
+
+  public ContentViewOnly(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public void setHolder(@NotNull ServerPlayer holder) {
+    this.holder = holder;
+  }
+
+  @Override
+  public ItemStack get() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack remove() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack removePartial(int amount) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public void set(ItemStack itemStack) {
+    this.holder.drop(itemStack, false);
+  }
+
+  @Override
+  public Slot asSlot(Container container, int slot, int x, int y) {
+    return new SlotViewOnly(container, slot, x, y);
+  }
+
+  @Override
+  public InventoryType.SlotType getSlotType() {
+    return InventoryType.SlotType.OUTSIDE;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/SlotPlaceholder.java

@@ -0,0 +1,20 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import net.minecraft.world.Container;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+
+/**
+ * An implementation of a slot as used by a menu that may have fake placeholder items.
+ *
+ * <p>Used to prevent plugins (particularly sorting plugins) from adding placeholders to inventories.</p>
+ */
+public abstract class SlotPlaceholder extends Slot {
+
+  public SlotPlaceholder(Container container, int index, int x, int y) {
+    super(container, index, x, y);
+  }
+
+  public abstract ItemStack getOrDefault();
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/container/slot/SlotViewOnly.java

@@ -0,0 +1,151 @@
+package com.lishid.openinv.internal.v1_21_R3.container.slot;
+
+import com.lishid.openinv.internal.v1_21_R3.container.Placeholders;
+import net.minecraft.world.Container;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.inventory.Slot;
+import net.minecraft.world.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Optional;
+
+/**
+ * A view-only {@link Slot}. "Blank" by default, but can wrap another slot to display its content.
+ */
+public class SlotViewOnly extends SlotPlaceholder {
+
+  public static @NotNull SlotViewOnly wrap(@NotNull Slot wrapped) {
+    SlotViewOnly wrapper;
+    if (wrapped instanceof SlotPlaceholder placeholder) {
+      wrapper = new SlotViewOnly(wrapped.container, wrapped.slot, wrapped.x, wrapped.y) {
+        @Override
+        public ItemStack getOrDefault() {
+          return placeholder.getOrDefault();
+        }
+      };
+    } else {
+      wrapper = new SlotViewOnly(wrapped.container, wrapped.slot, wrapped.x, wrapped.y) {
+        @Override
+        public ItemStack getOrDefault() {
+          return wrapped.getItem();
+        }
+      };
+    }
+    wrapper.index = wrapped.index;
+    return wrapper;
+  }
+
+  public SlotViewOnly(Container container, int index, int x, int y) {
+    super(container, index, x, y);
+  }
+
+  @Override
+  public ItemStack getOrDefault() {
+    return Placeholders.notSlot;
+  }
+
+  @Override
+  public void onQuickCraft(ItemStack var0, ItemStack var1) {
+  }
+
+  @Override
+  public void onTake(Player var0, ItemStack var1) {
+  }
+
+  @Override
+  public boolean mayPlace(ItemStack var0) {
+    return false;
+  }
+
+  @Override
+  public ItemStack getItem() {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public boolean hasItem() {
+    return false;
+  }
+
+  @Override
+  public void setByPlayer(ItemStack newStack) {
+  }
+
+  @Override
+  public void setByPlayer(ItemStack newStack, ItemStack oldStack) {
+  }
+
+  @Override
+  public void set(ItemStack var0) {
+  }
+
+  @Override
+  public void setChanged() {
+  }
+
+  @Override
+  public int getMaxStackSize() {
+    return 0;
+  }
+
+  @Override
+  public int getMaxStackSize(ItemStack itemStack) {
+    return 0;
+  }
+
+  @Override
+  public ItemStack remove(int amount) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public boolean mayPickup(Player var0) {
+    return false;
+  }
+
+  @Override
+  public boolean isActive() {
+    return false;
+  }
+
+  @Override
+  public Optional<ItemStack> tryRemove(int var0, int var1, Player var2) {
+    return Optional.empty();
+  }
+
+  @Override
+  public ItemStack safeTake(int var0, int var1, Player var2) {
+    return ItemStack.EMPTY;
+  }
+
+  @Override
+  public ItemStack safeInsert(ItemStack itemStack) {
+    return itemStack;
+  }
+
+  @Override
+  public ItemStack safeInsert(ItemStack itemStack, int amount) {
+    return itemStack;
+  }
+
+  @Override
+  public boolean allowModification(Player var0) {
+    return false;
+  }
+
+  @Override
+  public int getContainerSlot() {
+    return this.slot;
+  }
+
+  @Override
+  public boolean isHighlightable() {
+    return false;
+  }
+
+  @Override
+  public boolean isFake() {
+    return true;
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/player/OpenPlayer.java

@@ -0,0 +1,178 @@
+package com.lishid.openinv.internal.v1_21_R3.player;
+
+import com.lishid.openinv.event.OpenEvents;
+import com.mojang.logging.LogUtils;
+import net.minecraft.Util;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtIo;
+import net.minecraft.nbt.NumericTag;
+import net.minecraft.nbt.Tag;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.level.storage.PlayerDataStorage;
+import org.bukkit.craftbukkit.v1_21_R3.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R3.entity.CraftPlayer;
+import org.jetbrains.annotations.Contract;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Set;
+
+public class OpenPlayer extends CraftPlayer {
+
+  /**
+   * List of tags to always reset when saving.
+   *
+   * @see net.minecraft.world.entity.Entity#saveWithoutId(CompoundTag)
+   * @see net.minecraft.server.level.ServerPlayer#addAdditionalSaveData(CompoundTag)
+   * @see net.minecraft.world.entity.player.Player#addAdditionalSaveData(CompoundTag)
+   * @see net.minecraft.world.entity.LivingEntity#addAdditionalSaveData(CompoundTag)
+   */
+  private static final Set<String> RESET_TAGS = Set.of(
+      // Entity#saveWithoutId(CompoundTag)
+      "CustomName",
+      "CustomNameVisible",
+      "Silent",
+      "NoGravity",
+      "Glowing",
+      "TicksFrozen",
+      "HasVisualFire",
+      "Tags",
+      "Passengers",
+      // ServerPlayer#addAdditionalSaveData(CompoundTag)
+      // Intentional omissions to prevent mount loss: Attach, Entity, and RootVehicle
+      "warden_spawn_tracker",
+      "enteredNetherPosition",
+      "SpawnX",
+      "SpawnY",
+      "SpawnZ",
+      "SpawnForced",
+      "SpawnAngle",
+      "SpawnDimension",
+      "raid_omen_position",
+      "ender_pearls",
+      // Player#addAdditionalSaveData(CompoundTag)
+      "ShoulderEntityLeft",
+      "ShoulderEntityRight",
+      "LastDeathLocation",
+      "current_explosion_impact_pos",
+      // LivingEntity#addAdditionalSaveData(CompoundTag)
+      "active_effects",
+      "SleepingX",
+      "SleepingY",
+      "SleepingZ",
+      "Brain"
+  );
+
+  private final PlayerManager manager;
+
+  OpenPlayer(CraftServer server, ServerPlayer entity, PlayerManager manager) {
+    super(server, entity);
+    this.manager = manager;
+  }
+
+  @Override
+  public void loadData() {
+    manager.loadData(getHandle());
+  }
+
+  @Override
+  public void saveData() {
+    if (OpenEvents.saveCancelled(this)) {
+      return;
+    }
+
+    ServerPlayer player = this.getHandle();
+    // See net.minecraft.world.level.storage.PlayerDataStorage#save(EntityHuman)
+    try {
+      PlayerDataStorage worldNBTStorage = player.server.getPlayerList().playerIo;
+
+      CompoundTag oldData = isOnline() ? null : worldNBTStorage.load(player.getName().getString(), player.getStringUUID()).orElse(null);
+      CompoundTag playerData = getWritableTag(oldData);
+      playerData = player.saveWithoutId(playerData);
+      setExtraData(playerData);
+
+      if (oldData != null) {
+        // Revert certain special data values when offline.
+        revertSpecialValues(playerData, oldData);
+      }
+
+      Path playerDataDir = worldNBTStorage.getPlayerDir().toPath();
+      Path tempFile = Files.createTempFile(playerDataDir, player.getStringUUID() + "-", ".dat");
+      NbtIo.writeCompressed(playerData, tempFile);
+      Path dataFile = playerDataDir.resolve(player.getStringUUID() + ".dat");
+      Path backupFile = playerDataDir.resolve(player.getStringUUID() + ".dat_old");
+      Util.safeReplaceFile(dataFile, tempFile, backupFile);
+    } catch (Exception e) {
+      LogUtils.getLogger().warn("Failed to save player data for {}: {}", player.getScoreboardName(), e);
+    }
+  }
+
+  @Contract("null -> new")
+  private @NotNull CompoundTag getWritableTag(@Nullable CompoundTag oldData) {
+    if (oldData == null) {
+      return new CompoundTag();
+    }
+
+    // Copy old data. This is a deep clone, so operating on it should be safe.
+    oldData = oldData.copy();
+
+    // Remove vanilla/server data that is not written every time.
+    oldData.getAllKeys()
+        .removeIf(key -> RESET_TAGS.contains(key) || key.startsWith("Bukkit"));
+
+    return oldData;
+  }
+
+  private void revertSpecialValues(@NotNull CompoundTag newData, @NotNull CompoundTag oldData) {
+    // Revert automatic updates to play timestamps.
+    copyValue(oldData, newData, "bukkit", "lastPlayed", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastSeen", NumericTag.class);
+    copyValue(oldData, newData, "Paper", "LastLogin", NumericTag.class);
+  }
+
+  private <T extends Tag> void copyValue(
+      @NotNull CompoundTag source,
+      @NotNull CompoundTag target,
+      @NotNull String container,
+      @NotNull String key,
+      @SuppressWarnings("SameParameterValue") @NotNull Class<T> tagType) {
+    CompoundTag oldContainer = getTag(source, container, CompoundTag.class);
+    CompoundTag newContainer = getTag(target, container, CompoundTag.class);
+
+    // New container being null means the server implementation doesn't store this data.
+    if (newContainer == null) {
+      return;
+    }
+
+    // If old tag exists, copy it to new location, removing otherwise.
+    setTag(newContainer, key, getTag(oldContainer, key, tagType));
+  }
+
+  private <T extends Tag> @Nullable T getTag(
+      @Nullable CompoundTag container,
+      @NotNull String key,
+      @NotNull Class<T> dataType) {
+    if (container == null) {
+      return null;
+    }
+    Tag value = container.get(key);
+    if (value == null || !dataType.isAssignableFrom(value.getClass())) {
+      return null;
+    }
+    return dataType.cast(value);
+  }
+
+  private <T extends Tag> void setTag(
+      @NotNull CompoundTag container,
+      @NotNull String key,
+      @Nullable T data) {
+    if (data == null) {
+      container.remove(key);
+    } else {
+      container.put(key, data);
+    }
+  }
+
+}

internal/v1_21_R3/src/main/java/com/lishid/openinv/internal/v1_21_R3/player/PlayerManager.java

@@ -0,0 +1,267 @@
+package com.lishid.openinv.internal.v1_21_R3.player;
+
+import com.lishid.openinv.internal.ISpecialInventory;
+import com.lishid.openinv.internal.v1_21_R3.container.OpenEnderChest;
+import com.lishid.openinv.internal.v1_21_R3.container.OpenInventory;
+import com.mojang.authlib.GameProfile;
+import com.mojang.serialization.Dynamic;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.nbt.NbtOps;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.protocol.game.ClientboundOpenScreenPacket;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ClientInformation;
+import net.minecraft.server.level.ParticleStatus;
+import net.minecraft.server.level.ServerLevel;
+import net.minecraft.server.level.ServerPlayer;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.player.ChatVisiblity;
+import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.level.Level;
+import net.minecraft.world.level.dimension.DimensionType;
+import org.bukkit.Bukkit;
+import org.bukkit.OfflinePlayer;
+import org.bukkit.Server;
+import org.bukkit.World;
+import org.bukkit.craftbukkit.v1_21_R3.CraftServer;
+import org.bukkit.craftbukkit.v1_21_R3.CraftWorld;
+import org.bukkit.craftbukkit.v1_21_R3.entity.CraftPlayer;
+import org.bukkit.craftbukkit.v1_21_R3.event.CraftEventFactory;
+import org.bukkit.entity.Player;
+import org.bukkit.inventory.InventoryView;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.lang.reflect.Field;
+import java.util.UUID;
+import java.util.logging.Logger;
+
+public class PlayerManager implements com.lishid.openinv.internal.PlayerManager {
+
+  private static boolean paper;
+
+  static {
+    try {
+      Class.forName("io.papermc.paper.configuration.Configuration");
+      paper = true;
+    } catch (ClassNotFoundException ignored) {
+      paper = false;
+    }
+  }
+
+  private final @NotNull Logger logger;
+  private @Nullable Field bukkitEntity;
+
+  public PlayerManager(@NotNull Logger logger) {
+    this.logger = logger;
+    try {
+      bukkitEntity = Entity.class.getDeclaredField("bukkitEntity");
+    } catch (NoSuchFieldException e) {
+      logger.warning("Unable to obtain field to inject custom save process - certain player data may be lost when saving!");
+      logger.log(java.util.logging.Level.WARNING, e.getMessage(), e);
+      bukkitEntity = null;
+    }
+  }
+
+  public static @NotNull ServerPlayer getHandle(final Player player) {
+    if (player instanceof CraftPlayer) {
+      return ((CraftPlayer) player).getHandle();
+    }
+
+    Server server = player.getServer();
+    ServerPlayer nmsPlayer = null;
+
+    if (server instanceof CraftServer) {
+      nmsPlayer = ((CraftServer) server).getHandle().getPlayer(player.getUniqueId());
+    }
+
+    if (nmsPlayer == null) {
+      // Could use reflection to examine fields, but it's honestly not worth the bother.
+      throw new RuntimeException("Unable to fetch EntityPlayer from Player implementation " + player.getClass().getName());
+    }
+
+    return nmsPlayer;
+  }
+
+  @Override
+  public @Nullable Player loadPlayer(@NotNull final OfflinePlayer offline) {
+    MinecraftServer server = ((CraftServer) Bukkit.getServer()).getServer();
+    ServerLevel worldServer = server.getLevel(Level.OVERWORLD);
+
+    if (worldServer == null) {
+      return null;
+    }
+
+    // Create a new ServerPlayer.
+    ServerPlayer entity = createNewPlayer(server, worldServer, offline);
+
+    // Stop listening for advancement progression - if this is not cleaned up, loading causes a memory leak.
+    entity.getAdvancements().stopListening();
+
+    // Try to load the player's data.
+    if (loadData(entity)) {
+      // If data is loaded successfully, return the Bukkit entity.
+      return entity.getBukkitEntity();
+    }
+
+    return null;
+  }
+
+  private @NotNull ServerPlayer createNewPlayer(
+      @NotNull MinecraftServer server,
+      @NotNull ServerLevel worldServer,
+      @NotNull final OfflinePlayer offline) {
+    // See net.minecraft.server.players.PlayerList#canPlayerLogin(ServerLoginPacketListenerImpl, GameProfile)
+    // See net.minecraft.server.network.ServerLoginPacketListenerImpl#handleHello(ServerboundHelloPacket)
+    GameProfile profile = new GameProfile(offline.getUniqueId(),
+        offline.getName() != null ? offline.getName() : offline.getUniqueId().toString());
+
+    ClientInformation dummyInfo = new ClientInformation(
+        "en_us",
+        1, // Reduce distance just in case.
+        ChatVisiblity.HIDDEN, // Don't accept chat.
+        false,
+        ServerPlayer.DEFAULT_MODEL_CUSTOMIZATION,
+        ServerPlayer.DEFAULT_MAIN_HAND,
+        true,
+        false, // Don't list in player list (not that this player is in the list anyway).
+        ParticleStatus.MINIMAL
+    );
+
+    ServerPlayer entity = new ServerPlayer(server, worldServer, profile, dummyInfo);
+
+    try {
+      injectPlayer(entity);
+    } catch (IllegalAccessException e) {
+      logger.log(
+          java.util.logging.Level.WARNING,
+          e,
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+    }
+
+    return entity;
+  }
+
+  boolean loadData(@NotNull ServerPlayer player) {
+    // See CraftPlayer#loadData
+    CompoundTag loadedData = player.server.getPlayerList().playerIo.load(player).orElse(null);
+
+    if (loadedData == null) {
+      // Exceptions with loading are logged by Mojang.
+      return false;
+    }
+
+    // Read basic data into the player.
+    player.load(loadedData);
+    // Also read "extra" data.
+    player.readAdditionalSaveData(loadedData);
+    // Game type settings are also loaded separately.
+    player.loadGameTypes(loadedData);
+
+    if (paper) {
+      // Paper: world is not loaded by ServerPlayer#load(CompoundTag).
+      parseWorld(player, loadedData);
+    }
+
+    return true;
+  }
+
+  private void parseWorld(@NotNull ServerPlayer player, @NotNull CompoundTag loadedData) {
+    // See PlayerList#placeNewPlayer
+    World bukkitWorld;
+    if (loadedData.contains("WorldUUIDMost") && loadedData.contains("WorldUUIDLeast")) {
+      // Modern Bukkit world.
+      bukkitWorld = Bukkit.getServer().getWorld(new UUID(loadedData.getLong("WorldUUIDMost"), loadedData.getLong("WorldUUIDLeast")));
+    } else if (loadedData.contains("world", net.minecraft.nbt.Tag.TAG_STRING)) {
+      // Legacy Bukkit world.
+      bukkitWorld = Bukkit.getServer().getWorld(loadedData.getString("world"));
+    } else {
+      // Vanilla player data.
+      DimensionType.parseLegacy(new Dynamic<>(NbtOps.INSTANCE, loadedData.get("Dimension")))
+          .resultOrPartial(logger::warning)
+          .map(player.server::getLevel)
+          // If ServerLevel exists, set, otherwise move to spawn.
+          .ifPresentOrElse(player::setServerLevel, () -> player.spawnIn(null));
+      return;
+    }
+    if (bukkitWorld == null) {
+      player.spawnIn(null);
+      return;
+    }
+    player.setServerLevel(((CraftWorld) bukkitWorld).getHandle());
+  }
+
+  private void injectPlayer(ServerPlayer player) throws IllegalAccessException {
+    if (bukkitEntity == null) {
+      return;
+    }
+
+    bukkitEntity.setAccessible(true);
+
+    bukkitEntity.set(player, new OpenPlayer(player.server.server, player, this));
+  }
+
+  @Override
+  public @NotNull Player inject(@NotNull Player player) {
+    try {
+      ServerPlayer nmsPlayer = getHandle(player);
+      if (nmsPlayer.getBukkitEntity() instanceof OpenPlayer openPlayer) {
+        return openPlayer;
+      }
+      injectPlayer(nmsPlayer);
+      return nmsPlayer.getBukkitEntity();
+    } catch (IllegalAccessException e) {
+      logger.log(
+          java.util.logging.Level.WARNING,
+          e,
+          () -> "Unable to inject ServerPlayer, certain player data may be lost when saving!");
+      return player;
+    }
+  }
+
+  @Override
+  public @Nullable InventoryView openInventory(@NotNull Player bukkitPlayer, @NotNull ISpecialInventory inventory, boolean viewOnly) {
+    ServerPlayer player = getHandle(bukkitPlayer);
+
+    if (player.connection == null) {
+      return null;
+    }
+
+    // See net.minecraft.server.level.ServerPlayer#openMenu(MenuProvider)
+    AbstractContainerMenu menu;
+    Component title;
+    if (inventory instanceof OpenInventory playerInv) {
+      menu = playerInv.createMenu(player, player.nextContainerCounter(), viewOnly);
+      title = playerInv.getTitle(player);
+    } else if (inventory instanceof OpenEnderChest enderChest) {
+      menu = enderChest.createMenu(player, player.nextContainerCounter(), viewOnly);
+      title = enderChest.getTitle();
+    } else {
+      return null;
+    }
+
+    // Should never happen, player is a ServerPlayer with an active connection.
+    if (menu == null) {
+      return null;
+    }
+
+    // Set up title. Title can only be set once for a menu, and is set during the open process.
+    // Further title changes are a hack where the client is sent a "new" inventory with the same ID,
+    // resulting in a title change but no other state modifications (like cursor position).
+    menu.setTitle(title);
+
+    menu = CraftEventFactory.callInventoryOpenEvent(player, menu, false);
+
+    // Menu is null if event is cancelled.
+    if (menu == null) {
+      return null;
+    }
+
+    player.containerMenu = menu;
+    player.connection.send(new ClientboundOpenScreenPacket(menu.containerId, menu.getType(), menu.getTitle()));
+    player.initMenu(menu);
+
+    return menu.getBukkitView();
+  }
+
+}

jitpack.yml

@@ -0,0 +1,4 @@
+before_install:
+  - sdk install java 21.0.4-tem
+  - sdk use java 21.0.4-tem
+  - mvn wrapper:wrapper -Dmaven=3.9.8

plugin/pom.xml

@@ -21,28 +21,49 @@
   <parent>
     <artifactId>openinvparent</artifactId>
     <groupId>com.lishid</groupId>
-    <version>4.3.1</version>
+    <version>5.1.5</version>
   </parent>
 
-  <artifactId>openinvplugincore</artifactId>
+  <artifactId>openinvplugin</artifactId>
   <name>OpenInvPlugin</name>
 
   <dependencies>
+    <dependency>
+      <artifactId>spigot-api</artifactId>
+      <groupId>org.spigotmc</groupId>
+    </dependency>
+    <dependency>
+      <artifactId>planarwrappers</artifactId>
+      <groupId>com.github.jikoo</groupId>
+    </dependency>
     <dependency>
       <artifactId>openinvapi</artifactId>
       <groupId>com.lishid</groupId>
     </dependency>
     <dependency>
-      <artifactId>annotations</artifactId>
-      <groupId>org.jetbrains</groupId>
+      <artifactId>openinvcommon</artifactId>
+      <groupId>com.lishid</groupId>
     </dependency>
     <dependency>
-      <artifactId>spigot-api</artifactId>
-      <groupId>org.spigotmc</groupId>
+      <groupId>com.lishid</groupId>
+      <artifactId>openinvadapter1_21_R3</artifactId>
+      <version>5.1.5</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <groupId>com.lishid</groupId>
+      <artifactId>openinvadapter1_21_R2</artifactId>
+      <version>5.1.5</version>
+      <scope>compile</scope>
+    </dependency>
+    <dependency>
+      <artifactId>annotations</artifactId>
+      <groupId>org.jetbrains</groupId>
     </dependency>
   </dependencies>
 
   <build>
+    <finalName>OpenInv</finalName>
     <resources>
       <resource>
         <directory>src/main/resources</directory>
@@ -53,10 +74,66 @@
     <plugins>
       <plugin>
         <artifactId>maven-shade-plugin</artifactId>
+        <executions>
+          <execution>
+            <phase>package</phase>
+            <goals>
+              <goal>shade</goal>
+            </goals>
+          </execution>
+        </executions>
+        <configuration>
+          <filters>
+            <filter>
+              <!-- Always shade entirety of required modules. -->
+              <artifact>com.lishid:openinv*</artifact>
+              <includes>
+                <include>**</include>
+              </includes>
+            </filter>
+            <filter>
+              <artifact>*:*</artifact>
+              <!-- Don't warn about file conflicts that'll be clobbered anyway. -->
+              <excludes>
+                <exclude>META-INF/MANIFEST.MF</exclude>
+              </excludes>
+            </filter>
+          </filters>
+          <relocations>
+            <relocation>
+              <pattern>com.github.jikoo.planarwrappers</pattern>
+              <shadedPattern>com.github.jikoo.openinv.planarwrappers</shadedPattern>
+            </relocation>
+          </relocations>
+          <minimizeJar>true</minimizeJar>
+        </configuration>
       </plugin>
       <plugin>
         <artifactId>maven-compiler-plugin</artifactId>
       </plugin>
+      <plugin>
+        <artifactId>maven-resources-plugin</artifactId>
+        <executions>
+          <execution>
+            <id>copy-final-jar</id>
+            <phase>package</phase>
+            <goals>
+              <goal>copy-resources</goal>
+            </goals>
+            <configuration>
+              <outputDirectory>${project.parent.build.directory}</outputDirectory>
+              <resources>
+                <resource>
+                  <directory>${project.build.directory}</directory>
+                  <includes>
+                    <include>${project.build.finalName}.jar</include>
+                  </includes>
+                </resource>
+              </resources>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
     </plugins>
   </build>
 

plugin/src/main/java/com/lishid/openinv/InternalAccessor.java

@@ -1,199 +0,0 @@
-/*
- * Copyright (C) 2011-2023 lishid. All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program. If not, see <http://www.gnu.org/licenses/>.
- */
-
-package com.lishid.openinv;
-
-import com.lishid.openinv.internal.IAnySilentContainer;
-import com.lishid.openinv.internal.IPlayerDataManager;
-import com.lishid.openinv.internal.ISpecialEnderChest;
-import com.lishid.openinv.internal.ISpecialInventory;
-import com.lishid.openinv.internal.ISpecialPlayerInventory;
-import com.lishid.openinv.util.InventoryAccess;
-import java.lang.reflect.Constructor;
-import org.bukkit.entity.Player;
-import org.bukkit.plugin.Plugin;
-import org.jetbrains.annotations.NotNull;
-
-class InternalAccessor {
-
-    private final @NotNull Plugin plugin;
-    private final String version;
-    private boolean supported = false;
-    private IPlayerDataManager playerDataManager;
-    private IAnySilentContainer anySilentContainer;
-
-    InternalAccessor(@NotNull Plugin plugin) {
-        this.plugin = plugin;
-
-        String packageName = plugin.getServer().getClass().getPackage().getName();
-        this.version = packageName.substring(packageName.lastIndexOf('.') + 1);
-
-        try {
-            Class.forName("com.lishid.openinv.internal." + this.version + ".SpecialPlayerInventory");
-            Class.forName("com.lishid.openinv.internal." + this.version + ".SpecialEnderChest");
-            this.playerDataManager = this.createObject(IPlayerDataManager.class, "PlayerDataManager");
-            this.anySilentContainer = this.createObject(IAnySilentContainer.class, "AnySilentContainer");
-            this.supported = InventoryAccess.isUsable();
-        } catch (Exception ignored) {}
-    }
-
-    public String getReleasesLink() {
-
-        return switch (version) {
-            case "1_4_5", "1_4_6", "v1_4_R1", "v1_5_R2", "v1_5_R3", "v1_6_R1", "v1_6_R2", "v1_6_R3",
-                    "v1_7_R1", "v1_7_R2", "v1_7_R3", "v1_7_R4", "v1_8_R1", "v1_8_R2",
-                    "v1_9_R1", "v1_9_R2", "v1_10_R1", "v1_11_R1", "v1_12_R1"
-                    -> "https://github.com/lishid/OpenInv/releases/tag/4.0.0 (OpenInv-legacy)";
-            case "v1_13_R1" -> "https://github.com/lishid/OpenInv/releases/tag/4.0.0";
-            case "v1_13_R2" -> "https://github.com/lishid/OpenInv/releases/tag/4.0.7";
-            case "v1_14_R1" -> "https://github.com/lishid/OpenInv/releases/tag/4.1.1";
-            case "v1_16_R1" -> "https://github.com/lishid/OpenInv/releases/tag/4.1.4";
-            case "v1_8_R3", "v1_15_R1", "v1_16_R2" -> "https://github.com/lishid/OpenInv/releases/tag/4.1.5";
-            case "v1_16_R3" -> "https://github.com/Jikoo/OpenInv/releases/tag/4.1.8";
-            case "v1_17_R1", "v1_18_R1" -> "https://github.com/Jikoo/OpenInv/releases/tag/4.1.10";
-            case "v1_19_R1" -> "https://github.com/Jikoo/OpenInv/releases/tag/4.2.2";
-            case "v1_18_R2", "v1_19_R2" -> "https://github.com/Jikoo/OpenInv/releases/tag/4.3.0";
-            default -> "https://github.com/Jikoo/OpenInv/releases";
-        };
-    }
-
-    private @NotNull <T> T createObject(
-            @NotNull Class<? extends T> assignableClass,
-            @NotNull String className,
-            @NotNull Object @NotNull ... params)
-            throws ClassCastException, ReflectiveOperationException {
-        // Fetch internal class if it exists.
-        Class<?> internalClass = Class.forName("com.lishid.openinv.internal." + this.version + "." + className);
-
-        // Quick return: no parameters, no need to fiddle about finding the correct constructor.
-        if (params.length == 0) {
-            return assignableClass.cast(internalClass.getConstructor().newInstance());
-        }
-
-        // Search constructors for one matching the given parameters
-        nextConstructor: for (Constructor<?> constructor : internalClass.getConstructors()) {
-            Class<?>[] requiredClasses = constructor.getParameterTypes();
-            if (requiredClasses.length != params.length) {
-                continue;
-            }
-            for (int i = 0; i < params.length; ++i) {
-                if (!requiredClasses[i].isAssignableFrom(params[i].getClass())) {
-                    continue nextConstructor;
-                }
-            }
-            return assignableClass.cast(constructor.newInstance(params));
-        }
-
-        StringBuilder builder = new StringBuilder("Found class ").append(internalClass.getName())
-                .append(" but cannot find any matching constructors for [");
-        for (Object object : params) {
-            builder.append(object.getClass().getName()).append(", ");
-        }
-        builder.delete(builder.length() - 2, builder.length());
-
-        String message = builder.append(']').toString();
-        this.plugin.getLogger().warning(message);
-
-        throw new NoSuchMethodException(message);
-    }
-
-    private @NotNull <T extends ISpecialInventory> T createSpecialInventory(
-            @NotNull Class<? extends T> assignableClass,
-            @NotNull String className,
-            @NotNull Player player,
-            boolean online) throws InstantiationException {
-        if (!this.supported) {
-            throw new IllegalStateException(String.format("Unsupported server version %s!", this.version));
-        }
-        try {
-            return this.createObject(assignableClass, className, player, online);
-        } catch (Exception original) {
-            InstantiationException exception = new InstantiationException(String.format("Unable to create a new %s", className));
-            exception.initCause(original.fillInStackTrace());
-            throw exception;
-        }
-    }
-
-    /**
-     * Creates an instance of the IAnySilentContainer implementation for the current server version.
-     *
-     * @return the IAnySilentContainer
-     * @throws IllegalStateException if server version is unsupported
-     */
-    public @NotNull IAnySilentContainer getAnySilentContainer() {
-        if (!this.supported) {
-            throw new IllegalStateException(String.format("Unsupported server version %s!", this.version));
-        }
-        return this.anySilentContainer;
-    }
-
-    /**
-     * Creates an instance of the IPlayerDataManager implementation for the current server version.
-     *
-     * @return the IPlayerDataManager
-     * @throws IllegalStateException if server version is unsupported
-     */
-    public @NotNull IPlayerDataManager getPlayerDataManager() {
-        if (!this.supported) {
-            throw new IllegalStateException(String.format("Unsupported server version %s!", this.version));
-        }
-        return this.playerDataManager;
-    }
-
-    /**
-     * Gets the server implementation version.
-     *
-     * @return the version
-     */
-    public @NotNull String getVersion() {
-        return this.version;
-    }
-
-    /**
-     * Checks if the server implementation is supported.
-     *
-     * @return true if initialized for a supported server version
-     */
-    public boolean isSupported() {
-        return this.supported;
-    }
-
-    /**
-     * Creates an instance of the ISpecialEnderChest implementation for the given Player, or
-     * null if the current version is unsupported.
-     *
-     * @param player the Player
-     * @param online true if the Player is online
-     * @return the ISpecialEnderChest created
-     * @throws InstantiationException if the ISpecialEnderChest could not be instantiated
-     */
-    public ISpecialEnderChest newSpecialEnderChest(final Player player, final boolean online) throws InstantiationException {
-        return this.createSpecialInventory(ISpecialEnderChest.class, "SpecialEnderChest", player, online);
-    }
-
-    /**
-     * Creates an instance of the ISpecialPlayerInventory implementation for the given Player..
-     *
-     * @param player the Player
-     * @param online true if the Player is online
-     * @return the ISpecialPlayerInventory created
-     * @throws InstantiationException if the ISpecialPlayerInventory could not be instantiated
-     */
-    public ISpecialPlayerInventory newSpecialPlayerInventory(final Player player, final boolean online) throws InstantiationException {
-        return this.createSpecialInventory(ISpecialPlayerInventory.class, "SpecialPlayerInventory", player, online);
-    }
-
-}