Implement new queue command system.

src/main/java/com/onarandombox/MultiverseCore/MultiverseCore.java

@@ -68,6 +68,7 @@ import com.onarandombox.MultiverseCore.commands.TeleportCommand;
 import com.onarandombox.MultiverseCore.commands.UnloadCommand;
 import com.onarandombox.MultiverseCore.commands.VersionCommand;
 import com.onarandombox.MultiverseCore.commands.WhoCommand;
+import com.onarandombox.MultiverseCore.commandtools.queue.CommandQueueManager;
 import com.onarandombox.MultiverseCore.destination.AnchorDestination;
 import com.onarandombox.MultiverseCore.destination.BedDestination;
 import com.onarandombox.MultiverseCore.destination.CannonDestination;
@@ -204,6 +205,7 @@ public class MultiverseCore extends JavaPlugin implements MVPlugin, Core {
 
     // Setup our Map for our Commands using the CommandHandler.
     private CommandHandler commandHandler;
+    private CommandQueueManager commandQueueManager;
 
     private static final String LOG_TAG = "[Multiverse-Core]";
 
@@ -288,6 +290,7 @@ public class MultiverseCore extends JavaPlugin implements MVPlugin, Core {
 
         // Setup the command manager
         this.commandHandler = new CommandHandler(this, this.ph);
+        this.commandQueueManager = new CommandQueueManager(this);
         // Call the Function to assign all the Commands to their Class.
         this.registerCommands();
 
@@ -917,6 +920,15 @@ public class MultiverseCore extends JavaPlugin implements MVPlugin, Core {
         return this.commandHandler;
     }
 
+    /**
+     * {@inheritDoc}
+     */
+    @Override
+    @Deprecated
+    public CommandQueueManager getCommandQueueManager() {
+        return commandQueueManager;
+    }
+
     /**
      * Gets the log-tag.
      *

src/main/java/com/onarandombox/MultiverseCore/api/Core.java

@@ -8,6 +8,7 @@
 package com.onarandombox.MultiverseCore.api;
 
 import buscript.Buscript;
+import com.onarandombox.MultiverseCore.commandtools.queue.CommandQueueManager;
 import com.onarandombox.MultiverseCore.destination.DestinationFactory;
 import com.onarandombox.MultiverseCore.utils.AnchorManager;
 import com.onarandombox.MultiverseCore.utils.MVEconomist;
@@ -86,6 +87,15 @@ public interface Core {
      */
     CommandHandler getCommandHandler();
 
+    /**
+     * Manager for command that requires /mv confirm before execution.
+     *
+     * @return A non-null {@link CommandQueueManager}.
+     * @deprecated To be moved to new command manager in 5.0.0
+     */
+    @Deprecated
+    CommandQueueManager getCommandQueueManager();
+
     /**
      * Gets the factory class responsible for loading many different destinations
      * on demand.

src/main/java/com/onarandombox/MultiverseCore/commands/ConfirmCommand.java

@@ -33,7 +33,7 @@ public class ConfirmCommand extends MultiverseCommand {
 
     @Override
     public void runCommand(CommandSender sender, List<String> args) {
-        this.plugin.getCommandHandler().confirmQueuedCommand(sender);
+        this.plugin.getCommandQueueManager().runQueuedCommand(sender);
     }
 
 }

src/main/java/com/onarandombox/MultiverseCore/commands/DeleteCommand.java

@@ -8,9 +8,11 @@
 package com.onarandombox.MultiverseCore.commands;
 
 import com.onarandombox.MultiverseCore.MultiverseCore;
+import com.onarandombox.MultiverseCore.commandtools.queue.QueuedCommand;
 import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
 import org.bukkit.permissions.PermissionDefault;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -35,11 +37,24 @@ public class DeleteCommand extends MultiverseCommand {
     public void runCommand(CommandSender sender, List<String> args) {
         String worldName = args.get(0);
 
-        Class<?>[] paramTypes = {String.class};
-        List<Object> objectArgs = new ArrayList<Object>(args);
-        this.plugin.getCommandHandler()
-                   .queueCommand(sender, "mvdelete", "deleteWorld", objectArgs,
-                                 paramTypes, ChatColor.GREEN + "World '" + worldName + "' Deleted!",
-                                 ChatColor.RED + "World '" + worldName + "' could NOT be deleted!");
+        this.plugin.getCommandQueueManager().addToQueue(new QueuedCommand(
+                sender,
+                deleteRunnable(sender, worldName),
+                String.format("Are you sure you want to delete world '%s'? You cannot undo this action.", worldName)
+        ));
+    }
+
+    private Runnable deleteRunnable(@NotNull CommandSender sender,
+                                    @NotNull String worldName) {
+
+        return () -> {
+            sender.sendMessage(String.format("Deleting world '%s'...", worldName));
+            if (this.plugin.getMVWorldManager().deleteWorld(worldName)) {
+                sender.sendMessage(String.format("%sWorld %s was deleted!", ChatColor.GREEN, worldName));
+                return;
+            }
+            sender.sendMessage(String.format("%sThere was an issue deleting '%s'! Please check console for errors.",
+                    ChatColor.RED, worldName));
+        };
     }
 }

src/main/java/com/onarandombox/MultiverseCore/commands/GamerulesCommand.java

@@ -8,9 +8,6 @@
 package com.onarandombox.MultiverseCore.commands;
 
 import com.onarandombox.MultiverseCore.MultiverseCore;
-import com.onarandombox.MultiverseCore.display.ColorAlternator;
-import com.onarandombox.MultiverseCore.display.ContentDisplay;
-import com.onarandombox.MultiverseCore.display.settings.MapDisplaySettings;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
 import org.bukkit.GameRule;
@@ -19,9 +16,7 @@ import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 import org.bukkit.permissions.PermissionDefault;
 
-import java.util.HashMap;
 import java.util.List;
-import java.util.Map;
 
 /**
  * Allows management of Anchor Destinations.
@@ -73,23 +68,15 @@ public class GamerulesCommand extends MultiverseCommand {
             }
         }
 
-        ContentDisplay.forContent(getGameRuleMap(world))
-                .header("=== Gamerules for %s%s%s ===", ChatColor.AQUA, world.getName(), ChatColor.WHITE)
-                .colorTool(ColorAlternator.with(ChatColor.GREEN, ChatColor.GOLD))
-                .setting(MapDisplaySettings.OPERATOR, ": ")
-                .show(sender);
-    }
-
-    private Map<String, Object> getGameRuleMap(World world) {
-        Map<String, Object> gameRuleMap = new HashMap<>();
-        for (GameRule<?> rule : GameRule.values()) {
-            Object value = world.getGameRuleValue(rule);
-            if (value == null) {
-                gameRuleMap.put(rule.getName(), "null");
-                continue;
+        final StringBuilder gameRules = new StringBuilder();
+        for (final String gameRule : world.getGameRules()) {
+            if (gameRules.length() != 0) {
+                gameRules.append(ChatColor.WHITE).append(", ");
             }
-            gameRuleMap.put(rule.getName(), value);
+            gameRules.append(ChatColor.AQUA).append(gameRule).append(ChatColor.WHITE).append(": ");
+            gameRules.append(ChatColor.GREEN).append(world.getGameRuleValue(GameRule.getByName(gameRule)));
         }
-        return gameRuleMap;
+        sender.sendMessage("=== Gamerules for " + ChatColor.AQUA + world.getName() + ChatColor.WHITE + " ===");
+        sender.sendMessage(gameRules.toString());
     }
 }

src/main/java/com/onarandombox/MultiverseCore/commands/ListCommand.java

@@ -9,111 +9,122 @@ package com.onarandombox.MultiverseCore.commands;
 
 import com.onarandombox.MultiverseCore.MultiverseCore;
 import com.onarandombox.MultiverseCore.api.MultiverseWorld;
-import com.onarandombox.MultiverseCore.display.ColorAlternator;
-import com.onarandombox.MultiverseCore.display.ContentDisplay;
-import com.onarandombox.MultiverseCore.display.ContentFilter;
-import com.onarandombox.MultiverseCore.display.DisplayHandlers;
-import com.onarandombox.MultiverseCore.display.settings.PagedDisplaySettings;
 import org.bukkit.ChatColor;
-import org.bukkit.World;
+import org.bukkit.World.Environment;
 import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 import org.bukkit.permissions.PermissionDefault;
-import org.jetbrains.annotations.NotNull;
 
-import java.util.Collection;
+import java.util.ArrayList;
 import java.util.List;
-import java.util.stream.Collectors;
 
 /**
  * Displays a listing of all worlds that a player can enter.
  */
-public class ListCommand extends MultiverseCommand {
+public class ListCommand extends PaginatedCoreCommand<String> {
 
     public ListCommand(MultiverseCore plugin) {
         super(plugin);
         this.setName("World Listing");
-        this.setCommandUsage("/mv list [filter] [page]");
+        this.setCommandUsage("/mv list [page]");
         this.setArgRange(0, 2);
         this.addKey("mvlist");
         this.addKey("mvl");
         this.addKey("mv list");
         this.setPermission("multiverse.core.list.worlds", "Displays a listing of all worlds that you can enter.", PermissionDefault.OP);
+        this.setItemsPerPage(8); // SUPPRESS CHECKSTYLE: MagicNumberCheck
+    }
+
+    private List<String> getFancyWorldList(Player p) {
+        List<String> worldList = new ArrayList<String>();
+        for (MultiverseWorld world : this.plugin.getMVWorldManager().getMVWorlds()) {
+
+            if (p != null && (!this.plugin.getMVPerms().canEnterWorld(p, world))) {
+                continue;
+            }
+
+            ChatColor color = ChatColor.GOLD;
+            Environment env = world.getEnvironment();
+            if (env == Environment.NETHER) {
+                color = ChatColor.RED;
+            } else if (env == Environment.NORMAL) {
+                color = ChatColor.GREEN;
+            } else if (env == Environment.THE_END) {
+                color = ChatColor.AQUA;
+            }
+            StringBuilder builder = new StringBuilder();
+            builder.append(world.getColoredWorldString()).append(ChatColor.WHITE);
+            builder.append(" - ").append(color).append(world.getEnvironment());
+            if (world.isHidden()) {
+                if (p == null || this.plugin.getMVPerms().hasPermission(p, "multiverse.core.modify", true)) {
+                    // Prefix hidden worlds with an "[H]"
+                    worldList.add(ChatColor.GRAY + "[H]" + builder.toString());
+                }
+            } else {
+                worldList.add(builder.toString());
+            }
+        }
+        for (String name : this.plugin.getMVWorldManager().getUnloadedWorlds()) {
+            if (p == null || this.plugin.getMVPerms().hasPermission(p, "multiverse.access." + name, true)) {
+                worldList.add(ChatColor.GRAY + name + " - UNLOADED");
+            }
+        }
+        return worldList;
+    }
+
+    @Override
+    protected List<String> getFilteredItems(List<String> availableItems, String filter) {
+        List<String> filtered = new ArrayList<String>();
+
+        for (String s : availableItems) {
+            if (s.matches("(?i).*" + filter + ".*")) {
+                filtered.add(s);
+            }
+        }
+        return filtered;
+    }
+
+    @Override
+    protected String getItemText(String item) {
+        return item;
     }
 
     @Override
     public void runCommand(CommandSender sender, List<String> args) {
-        ContentFilter filter = ContentFilter.DEFAULT;
-        int page = 1;
+        sender.sendMessage(ChatColor.LIGHT_PURPLE + "====[ Multiverse World List ]====");
+        Player p = null;
+        if (sender instanceof Player) {
+            p = (Player) sender;
+        }
 
-        // Either page or filter.
-        if (args.size() == 1) {
-            try {
-                page = Integer.parseInt(args.get(0));
-            } catch (NumberFormatException ignore) {
-                filter = new ContentFilter(args.get(0));
+
+        FilterObject filterObject = this.getPageAndFilter(args);
+
+        List<String> availableWorlds = new ArrayList<String>(this.getFancyWorldList(p));
+        if (filterObject.getFilter().length() > 0) {
+            availableWorlds = this.getFilteredItems(availableWorlds, filterObject.getFilter());
+            if (availableWorlds.size() == 0) {
+                sender.sendMessage(ChatColor.RED + "Sorry... " + ChatColor.WHITE
+                        + "No worlds matched your filter: " + ChatColor.AQUA + filterObject.getFilter());
+                return;
             }
         }
 
-        // Filter then page.
-        if (args.size() == 2) {
-            filter = new ContentFilter(args.get(0));
-            try {
-                page = Integer.parseInt(args.get(1));
-            } catch (NumberFormatException ignore) {
-                sender.sendMessage(ChatColor.RED + args.get(1) + " is not valid number!");
+        if (!(sender instanceof Player)) {
+            for (String c : availableWorlds) {
+                sender.sendMessage(c);
             }
+            return;
         }
 
-        ContentDisplay.forContent(getListContents(sender))
-                .header("%s====[ Multiverse World List ]====", ChatColor.GOLD)
-                .displayHandler(DisplayHandlers.PAGE_LIST)
-                .colorTool(ColorAlternator.with(ChatColor.AQUA, ChatColor.GOLD))
-                .filter(filter)
-                .setting(PagedDisplaySettings.SHOW_PAGE, page)
-                .show(sender);
-    }
+        int totalPages = (int) Math.ceil(availableWorlds.size() / (this.itemsPerPage + 0.0));
 
-    private Collection<String> getListContents(@NotNull CommandSender sender) {
-        Player player = (sender instanceof Player) ? (Player) sender : null;
-
-        List<String> worldList = this.plugin.getMVWorldManager().getMVWorlds().stream()
-                .filter(world -> player == null || plugin.getMVPerms().canEnterWorld(player, world))
-                .filter(world -> canSeeWorld(player, world))
-                .map(world -> hiddenText(world) + world.getColoredWorldString() + " - " + parseColouredEnvironment(world.getEnvironment()))
-                .collect(Collectors.toList());
-
-        this.plugin.getMVWorldManager().getUnloadedWorlds().stream()
-                .filter(world -> plugin.getMVPerms().hasPermission(sender, "multiverse.access." + world, true))
-                .map(world -> ChatColor.GRAY + world + " - UNLOADED")
-                .forEach(worldList::add);
-        
-        return worldList;
-    }
-
-    private boolean canSeeWorld(Player player, MultiverseWorld world) {
-        return !world.isHidden()
-                || player == null
-                || this.plugin.getMVPerms().hasPermission(player, "multiverse.core.modify", true);
-    }
-
-    private String hiddenText(MultiverseWorld world) {
-        return (world.isHidden()) ? String.format("%s[H] ", ChatColor.GRAY) : "";
-    }
-
-    private String parseColouredEnvironment(World.Environment env) {
-        ChatColor color = ChatColor.GOLD;
-        switch (env) {
-            case NETHER:
-                color = ChatColor.RED;
-                break;
-            case NORMAL:
-                color = ChatColor.GREEN;
-                break;
-            case THE_END:
-                color = ChatColor.AQUA;
-                break;
+        if (filterObject.getPage() > totalPages) {
+            filterObject.setPage(totalPages);
         }
-        return color + env.toString();
+
+        sender.sendMessage(ChatColor.AQUA + " Page " + filterObject.getPage() + " of " + totalPages);
+
+        this.showPage(filterObject.getPage(), sender, availableWorlds);
     }
 }

src/main/java/com/onarandombox/MultiverseCore/commands/RegenCommand.java

@@ -8,9 +8,11 @@
 package com.onarandombox.MultiverseCore.commands;
 
 import com.onarandombox.MultiverseCore.MultiverseCore;
+import com.onarandombox.MultiverseCore.commandtools.queue.QueuedCommand;
 import org.bukkit.ChatColor;
 import org.bukkit.command.CommandSender;
 import org.bukkit.permissions.PermissionDefault;
+import org.jetbrains.annotations.NotNull;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -37,17 +39,30 @@ public class RegenCommand extends MultiverseCommand {
 
     @Override
     public void runCommand(CommandSender sender, List<String> args) {
-        Boolean useseed = (!(args.size() == 1));
-        Boolean randomseed = (args.size() == 2 && args.get(1).equalsIgnoreCase("-s"));
+        String worldName = args.get(0);
+        boolean useseed = (!(args.size() == 1));
+        boolean randomseed = (args.size() == 2 && args.get(1).equalsIgnoreCase("-s"));
         String seed = (args.size() == 3) ? args.get(2) : "";
 
-        Class<?>[] paramTypes = {String.class, Boolean.class, Boolean.class, String.class};
-        List<Object> objectArgs = new ArrayList<Object>();
-        objectArgs.add(args.get(0));
-        objectArgs.add(useseed);
-        objectArgs.add(randomseed);
-        objectArgs.add(seed);
-        this.plugin.getCommandHandler().queueCommand(sender, "mvregen", "regenWorld", objectArgs,
-                paramTypes, ChatColor.GREEN + "World Regenerated!", ChatColor.RED + "World could NOT be regenerated!");
+        this.plugin.getCommandQueueManager().addToQueue(new QueuedCommand(
+                sender,
+                doWorldRegen(sender, worldName, useseed, randomseed, seed),
+                String.format("Are you sure you want to regen '%s'? You cannot undo this action.", worldName)
+        ));
+    }
+
+    private Runnable doWorldRegen(@NotNull CommandSender sender,
+                                  @NotNull String worldName,
+                                  boolean useSeed,
+                                  boolean randomSeed,
+                                  @NotNull String seed) {
+
+        return () -> {
+            if (this.plugin.getMVWorldManager().regenWorld(worldName, useSeed, randomSeed, seed)) {
+                sender.sendMessage(ChatColor.GREEN + "World Regenerated!");
+                return;
+            }
+            sender.sendMessage(ChatColor.RED + "World could NOT be regenerated!");
+        };
     }
 }

src/main/java/com/onarandombox/MultiverseCore/commands/TeleportCommand.java

@@ -11,6 +11,7 @@ import com.dumptruckman.minecraft.util.Logging;
 import com.onarandombox.MultiverseCore.MultiverseCore;
 import com.onarandombox.MultiverseCore.api.Teleporter;
 import com.onarandombox.MultiverseCore.api.MVDestination;
+import com.onarandombox.MultiverseCore.commandtools.queue.QueuedCommand;
 import com.onarandombox.MultiverseCore.destination.CustomTeleporterDestination;
 import com.onarandombox.MultiverseCore.destination.DestinationFactory;
 import com.onarandombox.MultiverseCore.destination.InvalidDestination;
@@ -165,24 +166,27 @@ public class TeleportCommand extends MultiverseCommand {
         if (result == TeleportResult.FAIL_UNSAFE) {
             Logging.fine("Could not teleport " + teleportee.getName()
                     + " to " + plugin.getLocationManipulation().strCoordsRaw(d.getLocation(teleportee)));
-            Logging.fine("Queueing Command");
-            Class<?>[] paramTypes = { CommandSender.class, Player.class, Location.class };
-            List<Object> items = new ArrayList<Object>();
-            items.add(teleporter);
-            items.add(teleportee);
-            items.add(d.getLocation(teleportee));
+
             String player = "you";
             if (!teleportee.equals(teleporter)) {
                 player = teleportee.getName();
             }
-            String message = String.format("%sMultiverse %sdid not teleport %s%s %sto %s%s %sbecause it was unsafe.",
-                    ChatColor.GREEN, ChatColor.WHITE, ChatColor.AQUA, player, ChatColor.WHITE, ChatColor.DARK_AQUA, d.getName(), ChatColor.WHITE);
-            this.plugin.getCommandHandler().queueCommand(sender, "mvteleport", "teleportPlayer", items,
-                    paramTypes, message, "Would you like to try anyway?", "", "", UNSAFE_TELEPORT_EXPIRE_DELAY);
+
+            this.plugin.getCommandQueueManager().addToQueue(new QueuedCommand(
+                    sender,
+                    doUnsafeTeleport(teleporter, teleportee, d.getLocation(teleportee)),
+                    String.format("%sMultiverse %sdid not teleport %s%s %sto %s%s %sbecause it was unsafe. Would you like to try anyway?",
+                            ChatColor.GREEN, ChatColor.WHITE, ChatColor.AQUA, player, ChatColor.WHITE, ChatColor.DARK_AQUA, d.getName(), ChatColor.WHITE),
+                    UNSAFE_TELEPORT_EXPIRE_DELAY
+            ));
         }
         // else: Player was teleported successfully (or the tp event was fired I should say)
     }
 
+    private Runnable doUnsafeTeleport(CommandSender teleporter, Player player, Location location) {
+        return () -> this.plugin.getSafeTTeleporter().safelyTeleport(teleporter, player, location, false);
+    }
+
     private boolean checkSendPermissions(CommandSender teleporter, Player teleportee, MVDestination destination) {
         if (teleporter.equals(teleportee)) {
             if (!this.plugin.getMVPerms().hasPermission(teleporter, "multiverse.teleport.self." + destination.getIdentifier(), true)) {

src/main/java/com/onarandombox/MultiverseCore/commandtools/queue/CommandQueueManager.java

@@ -0,0 +1,158 @@
+/******************************************************************************
+ * Multiverse 2 Copyright (c) the Multiverse Team 2020.                       *
+ * Multiverse 2 is licensed under the BSD License.                            *
+ * For more information please check the README.md file included              *
+ * with this project.                                                         *
+ ******************************************************************************/
+
+package com.onarandombox.MultiverseCore.commandtools.queue;
+
+import com.dumptruckman.minecraft.util.Logging;
+import com.onarandombox.MultiverseCore.MultiverseCore;
+import org.bukkit.Bukkit;
+import org.bukkit.ChatColor;
+import org.bukkit.block.data.type.CommandBlock;
+import org.bukkit.command.BlockCommandSender;
+import org.bukkit.command.CommandSender;
+import org.bukkit.scheduler.BukkitTask;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.Map;
+import java.util.WeakHashMap;
+
+/**
+ * Managers the queuing of dangerous commands that needs to use '/mv confirm' before executing.
+ */
+public class CommandQueueManager {
+
+    private static final long TICKS_PER_SECOND = 20;
+    private static final DummyCommandBlockSender COMMAND_BLOCK = new DummyCommandBlockSender();
+
+    private final MultiverseCore plugin;
+    private final Map<CommandSender, QueuedCommand> queuedCommandMap;
+
+    public CommandQueueManager(@NotNull MultiverseCore plugin) {
+        this.plugin = plugin;
+        this.queuedCommandMap = new WeakHashMap<>();
+    }
+
+    /**
+     * Adds a queue command into queue.
+     *
+     * @param queuedCommand The queue command to add.
+     */
+    public void addToQueue(QueuedCommand queuedCommand) {
+        CommandSender targetSender = parseSender(queuedCommand.getSender());
+
+        // Since only one command is stored in queue per sender, we remove the old one.
+        this.removeFromQueue(targetSender);
+
+        Logging.finer("Add new command to queue for sender %s.", targetSender);
+        this.queuedCommandMap.put(targetSender, queuedCommand);
+        queuedCommand.setExpireTask(runExpireLater(queuedCommand));
+
+        queuedCommand.getSender().sendMessage(queuedCommand.getPrompt());
+        queuedCommand.getSender().sendMessage(String.format("Run %s/mv confirm %sto continue. This will expire in %s seconds.",
+                ChatColor.GREEN, ChatColor.WHITE, queuedCommand.getValidDuration()));
+    }
+
+    /**
+     * Expire task that remove {@link QueuedCommand} from queue after valid duration defined.
+     *
+     * @param queuedCommand Command to run the expire task on.
+     * @return The expire {@link BukkitTask}.
+     */
+    @NotNull
+    private BukkitTask runExpireLater(@NotNull QueuedCommand queuedCommand) {
+        return Bukkit.getScheduler().runTaskLater(
+                this.plugin,
+                expireRunnable(queuedCommand),
+                queuedCommand.getValidDuration() * TICKS_PER_SECOND
+        );
+    }
+
+    /**
+     * Runnable responsible for expiring the queued command.
+     *
+     * @param queuedCommand Command to create the expire task on.
+     * @return The expire runnable.
+     */
+    @NotNull
+    private Runnable expireRunnable(@NotNull QueuedCommand queuedCommand) {
+        return () -> {
+            CommandSender targetSender = parseSender(queuedCommand.getSender());
+            QueuedCommand matchingQueuedCommand = this.queuedCommandMap.get(targetSender);
+            if (!queuedCommand.equals(matchingQueuedCommand) || queuedCommand.getExpireTask().isCancelled()) {
+                // To be safe, but this shouldn't happen since we cancel old commands before add new once.
+                Logging.finer("This is an old queue command already.");
+                return;
+            }
+            queuedCommand.getSender().sendMessage("Your queued command has expired.");
+            this.queuedCommandMap.remove(queuedCommand.getSender());
+        };
+    }
+
+    /**
+     * Runs the command in queue for the given sender, if any.
+     *
+     * @param sender    {@link CommandSender} that confirmed the command.
+     * @return True if queued command ran successfully, else false.
+     */
+    public boolean runQueuedCommand(@NotNull CommandSender sender) {
+        CommandSender targetSender = parseSender(sender);
+        QueuedCommand queuedCommand = this.queuedCommandMap.get(targetSender);
+        if (queuedCommand == null) {
+            sender.sendMessage(ChatColor.RED + "You do not have any commands in queue.");
+            return false;
+        }
+        Logging.finer("Running queued command...");
+        queuedCommand.getAction().run();
+        return removeFromQueue(targetSender);
+    }
+
+    /**
+     * Since only one command is stored in queue per sender, we remove the old one.
+     *
+     * @param sender    The {@link CommandSender} that executed the command.
+     * @return True if queue command is removed from sender successfully, else false.
+     */
+    public boolean removeFromQueue(@NotNull CommandSender sender) {
+        CommandSender targetSender = parseSender(sender);
+        QueuedCommand previousCommand = this.queuedCommandMap.remove(targetSender);
+        if (previousCommand == null) {
+            Logging.finer("No queue command to remove for sender %s.", targetSender.getName());
+            return false;
+        }
+        previousCommand.getExpireTask().cancel();
+        Logging.finer("Removed queue command for sender %s.", targetSender.getName());
+        return true;
+    }
+
+    /**
+     * To allow all CommandBlocks to be a common sender with use of {@link DummyCommandBlockSender}.
+     * So confirm command can be used for a queue command on another command block.
+     *
+     * @param sender    The sender to parse.
+     * @return The sender, or if its a command block, a {@link DummyCommandBlockSender}.
+     */
+    @NotNull
+    private CommandSender parseSender(@NotNull CommandSender sender) {
+        Logging.fine(sender.getClass().getName());
+        if (isCommandBlock(sender)) {
+            Logging.finer("Is command block.");
+            return COMMAND_BLOCK;
+        }
+        return sender;
+    }
+
+    /**
+     * Check if sender is a command block.
+     *
+     * @param sender    The sender to check on.
+     * @return True if sender is a command block, else false.
+     */
+    private boolean isCommandBlock(@NotNull CommandSender sender) {
+        return sender instanceof BlockCommandSender
+                && ((BlockCommandSender) sender).getBlock().getBlockData() instanceof CommandBlock;
+    }
+}

src/main/java/com/onarandombox/MultiverseCore/commandtools/queue/DummyCommandBlockSender.java

@@ -0,0 +1,104 @@
+package com.onarandombox.MultiverseCore.commandtools.queue;
+
+import org.bukkit.Bukkit;
+import org.bukkit.Server;
+import org.bukkit.command.CommandSender;
+import org.bukkit.permissions.Permission;
+import org.bukkit.permissions.PermissionAttachment;
+import org.bukkit.permissions.PermissionAttachmentInfo;
+import org.bukkit.plugin.Plugin;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Set;
+
+/**
+ * Used by {@link CommandQueueManager}, so different commands block can be recognised as one.
+ */
+class DummyCommandBlockSender implements CommandSender {
+
+    @Override
+    public void sendMessage(@NotNull String message) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void sendMessage(@NotNull String[] messages) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @NotNull Server getServer() {
+        return Bukkit.getServer();
+    }
+
+    @Override
+    public @NotNull String getName() {
+        return "DummyCommandBlockSender";
+    }
+
+    @Override
+    public boolean isPermissionSet(@NotNull String name) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean isPermissionSet(@NotNull Permission perm) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean hasPermission(@NotNull String name) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean hasPermission(@NotNull Permission perm) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @NotNull PermissionAttachment addAttachment(@NotNull Plugin plugin, @NotNull String name, boolean value) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @NotNull PermissionAttachment addAttachment(@NotNull Plugin plugin) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @Nullable PermissionAttachment addAttachment(@NotNull Plugin plugin, @NotNull String name, boolean value, int ticks) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @Nullable PermissionAttachment addAttachment(@NotNull Plugin plugin, int ticks) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void removeAttachment(@NotNull PermissionAttachment attachment) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void recalculatePermissions() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public @NotNull Set<PermissionAttachmentInfo> getEffectivePermissions() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean isOp() {
+        return true;
+    }
+
+    @Override
+    public void setOp(boolean value) {
+        throw new UnsupportedOperationException();
+    }
+}

src/main/java/com/onarandombox/MultiverseCore/commandtools/queue/QueuedCommand.java

@@ -0,0 +1,86 @@
+/******************************************************************************
+ * Multiverse 2 Copyright (c) the Multiverse Team 2020.                       *
+ * Multiverse 2 is licensed under the BSD License.                            *
+ * For more information please check the README.md file included              *
+ * with this project.                                                         *
+ ******************************************************************************/
+
+package com.onarandombox.MultiverseCore.commandtools.queue;
+
+import org.bukkit.command.CommandSender;
+import org.bukkit.scheduler.BukkitTask;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Represents a single command used in {@link CommandQueueManager} for confirming before running potentially
+ * dangerous action.
+ */
+public class QueuedCommand {
+
+    private static final String DEFAULT_PROMPT_MESSAGE = "The command you are trying to run is deemed dangerous.";
+    private static final int DEFAULT_VALID_TIME = 10;
+
+    private final CommandSender sender;
+    private final Runnable action;
+    private final String prompt;
+    private final int validDuration;
+    private BukkitTask expireTask;
+
+    public QueuedCommand(CommandSender sender, Runnable action) {
+        this(sender, action, DEFAULT_PROMPT_MESSAGE, DEFAULT_VALID_TIME);
+    }
+
+    public QueuedCommand(CommandSender sender, Runnable action, String prompt) {
+        this(sender, action, prompt, DEFAULT_VALID_TIME);
+    }
+
+    public QueuedCommand(CommandSender sender, Runnable action, int validDuration) {
+        this(sender, action, DEFAULT_PROMPT_MESSAGE, validDuration);
+    }
+
+    /**
+     * Creates a new queue command, to be registered at {@link CommandQueueManager#addToQueue(QueuedCommand)}.
+     *
+     * @param sender        The sender that ran the command needed for confirmation.
+     * @param action        The logic to execute upon confirming.
+     * @param prompt        Question to ask sender to confirm.
+     * @param validDuration Duration in which the command is valid for confirm in seconds.
+     */
+    public QueuedCommand(CommandSender sender, Runnable action, String prompt, int validDuration) {
+        this.sender = sender;
+        this.action = action;
+        this.prompt = prompt;
+        this.validDuration = validDuration;
+    }
+
+    @NotNull
+    CommandSender getSender() {
+        return sender;
+    }
+
+    @NotNull
+    String getPrompt() {
+        return prompt;
+    }
+
+    int getValidDuration() {
+        return validDuration;
+    }
+
+    @NotNull
+    Runnable getAction() {
+        return action;
+    }
+
+    @NotNull
+    BukkitTask getExpireTask() {
+        return expireTask;
+    }
+
+    void setExpireTask(@NotNull BukkitTask expireTask) {
+        if (this.expireTask != null) {
+            throw new IllegalStateException("This queue command already has an expire task. You can't register twice!");
+        }
+        this.expireTask = expireTask;
+    }
+}

src/main/java/com/onarandombox/MultiverseCore/commandtools/queue/package-info.java

@@ -0,0 +1,4 @@
+/**
+ * Manager queuing of dangerous commands in need of confirmation.
+ */
+package com.onarandombox.MultiverseCore.commandtools.queue;

src/main/java/com/onarandombox/MultiverseCore/display/ColorAlternator.java

@@ -1,62 +0,0 @@
-package com.onarandombox.MultiverseCore.display;
-
-import org.bukkit.ChatColor;
-import org.jetbrains.annotations.NotNull;
-
-/**
- * Helper class to switch between 2 {@link ChatColor}.
- */
-public class ColorAlternator implements ColorTool {
-
-    /**
-     * Creates a new {@link ColorAlternator} with 2 {@link ChatColor}s.
-     *
-     * @param colorThis The first color.
-     * @param colorThat The second color.
-     * @return The {@link ColorAlternator} created for you.
-     */
-    public static ColorAlternator with(@NotNull ChatColor colorThis,
-                                       @NotNull ChatColor colorThat) {
-
-        return new ColorAlternator(colorThis, colorThat);
-    }
-
-    private boolean switcher;
-    private final ChatColor thisColor;
-    private final ChatColor thatColor;
-
-    /**
-     * @param colorThis The first color.
-     * @param colorThat The second color.
-     */
-    public ColorAlternator(@NotNull ChatColor colorThis,
-                           @NotNull ChatColor colorThat) {
-
-        this.thisColor = colorThis;
-        this.thatColor = colorThat;
-    }
-
-    /**
-     * Gets the color. Everytime this method is called, it swaps the color that it returns.
-     *
-     * @return The color.
-     */
-    @Override
-    public ChatColor get() {
-        return (this.switcher ^= true) ? this.thisColor : this.thatColor;
-    }
-
-    /**
-     * @return The first color.
-     */
-    public ChatColor getThisColor() {
-        return thisColor;
-    }
-
-    /**
-     * @return The second color.
-     */
-    public ChatColor getThatColor() {
-        return thatColor;
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/ColorTool.java

@@ -1,22 +0,0 @@
-package com.onarandombox.MultiverseCore.display;
-
-import org.bukkit.ChatColor;
-
-/**
- * Tools to allow customisation.
- */
-@FunctionalInterface
-public interface ColorTool {
-
-    /**
-     * Gets a chat color.
-     *
-     * @return The color.
-     */
-    ChatColor get();
-
-    /**
-     * Default implementation of this interface. Returns a default white color.
-     */
-    ColorTool DEFAULT = () -> ChatColor.WHITE;
-}

src/main/java/com/onarandombox/MultiverseCore/display/ContentDisplay.java

@@ -1,268 +0,0 @@
-package com.onarandombox.MultiverseCore.display;
-
-import com.onarandombox.MultiverseCore.display.settings.DisplaySetting;
-import org.bukkit.ChatColor;
-import org.bukkit.command.CommandSender;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Collection;
-import java.util.Map;
-import java.util.Objects;
-import java.util.WeakHashMap;
-
-/**
- * Helps to display contents such as list and maps in a nicely formatted fashion.
- *
- * @param <T>   Type of content to display.
- */
-public class ContentDisplay<T> {
-
-    public static final String LINE_BREAK = "%br%";
-
-    /**
-     * Creates a ContentDisplay.Builder for the given content.
-     *
-     * @param content The content to be displayed.
-     * @param <T> The type of the content which can be inferred.
-     * @return A new Builder.
-     */
-    public static <T> Builder<T> forContent(T content) {
-        return new Builder<>(content);
-    }
-
-    /**
-     * Creates a ContentDisplay.Builder for the given collection of content.
-     *
-     * @param content The content to be displayed.
-     * @return A new Builder.
-     */
-    public static Builder<Collection<String>> forContent(Collection<String> content) {
-        return new Builder<>(content).displayHandler(DisplayHandlers.LIST);
-    }
-
-    /**
-     * Creates a ContentDisplay.Builder for the given map of content.
-     *
-     * @param content The content to be displayed.
-     * @return A new Builder.
-     */
-    public static Builder<Map<String, Object>> forContent(Map<String, Object> content) {
-        return new Builder<>(content).displayHandler(DisplayHandlers.INLINE_MAP);
-    }
-
-    private final T contents;
-
-    private String header;
-    private String emptyMessage = "No matching content to display.";
-    private DisplayHandler<T> displayHandler;
-    private ColorTool colorTool = ColorTool.DEFAULT;
-    private ContentFilter filter = ContentFilter.DEFAULT;
-    private final Map<DisplaySetting<?>, Object> settingsMap = new WeakHashMap<>();
-
-    private ContentDisplay(T contents) {
-        this.contents = contents;
-    }
-
-    /**
-     * Do the actual displaying of contents to the sender.
-     *
-     * @param sender The CommandSender to show the display to.
-     */
-    public void show(@NotNull CommandSender sender) {
-        Collection<String> formattedContent;
-        try {
-            formattedContent = (this.contents == null) ? null : this.displayHandler.format(sender, this);
-        } catch (DisplayFormatException e) {
-            sender.sendMessage(String.format("%sError: %s", ChatColor.RED, e.getMessage()));
-            return;
-        }
-        this.displayHandler.sendHeader(sender, this);
-        this.displayHandler.sendSubHeader(sender, this);
-        this.displayHandler.sendBody(sender, this, formattedContent);
-    }
-
-    /**
-     * @return Gets the header to display.
-     */
-    public String getHeader() {
-        return header;
-    }
-
-    /**
-     * Sets the header text.
-     */
-    public void setHeader(@NotNull String header) {
-        this.header = header;
-    }
-
-    /**
-     * @return Gets the contents to display.
-     */
-    public T getContents() {
-        return contents;
-    }
-
-    /**
-     * @return Gets the message to display when no content is shown.
-     */
-    @NotNull
-    public String getEmptyMessage() {
-        return emptyMessage;
-    }
-
-    /**
-     * @return Gets the display handler that formats and sends content to sender.
-     */
-    @NotNull
-    public DisplayHandler<T> getDisplayHandler() {
-        return displayHandler;
-    }
-
-    /**
-     * @return Gets the color tool used.
-     */
-    @NotNull
-    public ColorTool getColorTool() {
-        return colorTool;
-    }
-
-    /**
-     * @return Gets the filter used.
-     */
-    @NotNull
-    public ContentFilter getFilter() {
-        return filter;
-    }
-
-    /**
-     * Gets the value for a given setting option.
-     *
-     * @param setting   The setting option.
-     * @param <S>       The setting type.
-     * @return Value set for the given setting.
-     */
-    public <S> S getSetting(@NotNull DisplaySetting<S> setting) {
-        return (S) settingsMap.getOrDefault(setting, setting.defaultValue());
-    }
-
-    /**
-     * Sets other specific settings that may be used by the {@link DisplayHandler}.
-     *
-     * @param setting   The settings option.
-     * @param value     The value to set.
-     * @param <S>       The type of setting.
-     */
-    public <S> void setSetting(@NotNull DisplaySetting<S> setting, S value) {
-        this.settingsMap.put(setting, value);
-    }
-
-    /**
-     * Builds a {@link ContentDisplay}.
-     *
-     * @param <T>   Type of content to display.
-     */
-    public static class Builder<T> {
-
-        private final ContentDisplay<T> display;
-
-        private Builder(T content) {
-            this.display = new ContentDisplay<>(content);
-        }
-
-        /**
-         * Sets header to be displayed.
-         *
-         * @param header        The header text.
-         * @param replacements  String formatting replacements.
-         * @return The builder.
-         */
-        @NotNull
-        public Builder<T> header(@NotNull String header, Object...replacements) {
-            this.display.header = String.format(header, replacements);
-            return this;
-        }
-
-        /**
-         * Sets the message to show when no content is available for display.
-         *
-         * @param emptyMessage  The message text.
-         * @param replacements  String formatting replacements.
-         * @return The builder.
-         */
-        @NotNull
-        public Builder<T> emptyMessage(@NotNull String emptyMessage, Object...replacements) {
-            this.display.emptyMessage = String.format(emptyMessage, replacements);
-            return this;
-        }
-
-        /**
-         * Sets the display handler that does the formatting and sending of content. <b>Required.</b>
-         *
-         * @param displayHandler    The display handler for the given content type.
-         * @return The builder.
-         */
-        @NotNull
-        public Builder<T> displayHandler(@NotNull DisplayHandler<T> displayHandler) {
-            this.display.displayHandler = displayHandler;
-            return this;
-        }
-
-        /**
-         * Sets the color tool used to make messages more colourful.
-         *
-         * @param colorTool The color tool to use.
-         * @return The builder.
-         */
-        @NotNull
-        public Builder<T> colorTool(@NotNull ColorTool colorTool) {
-            this.display.colorTool = colorTool;
-            return this;
-        }
-
-        /**
-         * Sets content filter used to match specific content to be displayed.
-         *
-         * @param filter    The filter to use.
-         * @return The builder.
-         */
-        @NotNull
-        public Builder<T> filter(@NotNull ContentFilter filter) {
-            this.display.filter = filter;
-            return this;
-        }
-
-        /**
-         * Sets other specific settings that may be used by the {@link DisplayHandler}.
-         *
-         * @param setting   The settings option.
-         * @param value     The value to set.
-         * @param <S>       The type of setting.
-         * @return The builder.
-         */
-        @NotNull
-        public <S> Builder<T> setting(@NotNull DisplaySetting<S> setting, S value) {
-            this.display.settingsMap.put(setting, value);
-            return this;
-        }
-
-        /**
-         * Validates and build the content display.
-         *
-         * @return The content display.
-         */
-        @NotNull
-        public ContentDisplay<T> build() {
-            Objects.requireNonNull(this.display.displayHandler);
-            return this.display;
-        }
-
-        /**
-         * Build and show the content to the sender.
-         *
-         * @param sender The CommandSender to show the display to.
-         */
-        public void show(CommandSender sender) {
-            this.build().show(sender);
-        }
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/ContentFilter.java

@@ -1,153 +0,0 @@
-package com.onarandombox.MultiverseCore.display;
-
-import com.dumptruckman.minecraft.util.Logging;
-import org.bukkit.ChatColor;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.regex.Pattern;
-import java.util.regex.PatternSyntaxException;
-
-/**
- * <p>Filter content and text based on regex matching.</p>
- *
- * <p>Compile regex pattern based on {@link ContentFilter#filterString}. When prefixed with 'r=',
- * use {@link ContentFilter#filterString} as the full regex pattern. Else, set to any match that
- * contains the {@link ContentFilter#filterString}.<p>
- */
-public class ContentFilter {
-
-    public static final ContentFilter DEFAULT = new ContentFilter();
-    private static final Pattern REGEX_SPECIAL_CHARS = Pattern.compile("[.+*?\\[^\\]$(){}=!<>|:-\\\\]");
-
-    private String filterString;
-    private Pattern filterPattern;
-    private boolean exactMatch;
-
-    private ContentFilter() {
-    }
-
-    /**
-     * @param filterString  The text to do matching, either plaintext or regex.
-     */
-    public ContentFilter(@NotNull String filterString) {
-        this(filterString, false);
-    }
-
-    /**
-     * @param filterString  The text to do matching, else plaintext or regex.
-     * @param exactMatch    Should check for exact match when doing regex matching.
-     */
-    public ContentFilter(@NotNull String filterString,
-                         boolean exactMatch) {
-
-        this.filterString = filterString;
-        this.exactMatch = exactMatch;
-        parseFilter();
-    }
-
-    private void parseFilter() {
-        if (filterString == null) {
-            return;
-        }
-        if (filterString.startsWith("r=")) {
-            convertToMatcher(filterString.substring(2));
-            return;
-        }
-        String cleanedFilter = REGEX_SPECIAL_CHARS.matcher(filterString.toLowerCase()).replaceAll("\\\\$0");
-        convertToMatcher("(?i).*" + cleanedFilter + ".*");
-    }
-
-    /**
-     * Compile and store the regex into a {@link Pattern}.
-     *
-     * @param regex The regex text.
-     */
-    private void convertToMatcher(@NotNull String regex) {
-        try {
-            this.filterPattern = Pattern.compile(regex);
-            Logging.finest("Parsed regex pattern: %s", this.filterPattern.toString());
-        }
-        catch (PatternSyntaxException ignored) {
-            Logging.warning("Error parsing regex: %s", filterString);
-        }
-    }
-
-    /**
-     * Do regex matching.
-     *
-     * @param text String to check regex on.
-     * @return True of matches regex pattern, false otherwise.
-     */
-    public boolean checkMatch(@Nullable Object text) {
-        if (!hasFilter()) {
-            return true;
-        }
-        if (text == null || !hasValidPattern()) {
-            return false;
-        }
-        text = ChatColor.stripColor(String.valueOf(text));
-        return (exactMatch)
-                ? filterPattern.matcher((CharSequence) text).matches()
-                : filterPattern.matcher((CharSequence) text).find();
-    }
-
-    /**
-     * Checks if a filter string is present.
-     *
-     * @return True if there is a filter string, else false.
-     */
-    public boolean hasFilter() {
-        return filterString != null;
-    }
-
-    /**
-     * Checks if regex pattern syntax is valid.
-     *
-     * @return True if valid, else false.
-     */
-    public boolean hasValidPattern() {
-        return filterPattern != null;
-    }
-
-    /**
-     * @return The filter string.
-     */
-    @Nullable
-    public String getString() {
-        return filterString;
-    }
-
-    /**
-     * @return The regex pattern.
-     */
-    @Nullable
-    public Pattern getPattern() {
-        return filterPattern;
-    }
-
-    /**
-     * @return True if filter is set to do exact matching, else false.
-     */
-    public boolean isExactMatch() {
-        return exactMatch;
-    }
-
-    /**
-     * Nicely format the filter string to be used for showing the sender.
-     *
-     * @return The formatted filter string.
-     */
-    public @NotNull String getFormattedString() {
-        return String.format("%sFilter: '%s'", ChatColor.ITALIC, filterString);
-    }
-
-    @Override
-    public String toString() {
-        return "ContentFilter{" +
-                "filterString='" + filterString + '\'' +
-                ", filterPattern=" + filterPattern +
-                ", exactMatch=" + exactMatch +
-                '}';
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/DisplayFormatException.java

@@ -1,25 +0,0 @@
-package com.onarandombox.MultiverseCore.display;
-
-/**
- * Thrown when an issue occur while formatting content.
- */
-public class DisplayFormatException extends Exception {
-    public DisplayFormatException() {
-    }
-
-    public DisplayFormatException(String message) {
-        super(message);
-    }
-
-    public DisplayFormatException(String message, Throwable cause) {
-        super(message, cause);
-    }
-
-    public DisplayFormatException(Throwable cause) {
-        super(cause);
-    }
-
-    public DisplayFormatException(String message, Throwable cause, boolean enableSuppression, boolean writableStackTrace) {
-        super(message, cause, enableSuppression, writableStackTrace);
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/DisplayHandler.java

@@ -1,68 +0,0 @@
-package com.onarandombox.MultiverseCore.display;
-
-import com.google.common.base.Strings;
-import org.bukkit.ChatColor;
-import org.bukkit.command.CommandSender;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Collection;
-
-/**
- * Handles the formatting and sending of all content by the {@link ContentDisplay}.
- *
- * @param <T>   Type of content to display.
- */
-@FunctionalInterface
-public interface DisplayHandler<T> {
-
-    /**
-     * Formats the raw content into a {@link Collection<String>} for displaying to the given sender.
-     *
-     * @param sender The {@link CommandSender} who will the content will be displayed to.
-     * @param display The responsible {@link ContentDisplay}.
-     * @return The formatted content.
-     * @throws DisplayFormatException Issue occurred while formatting content. E.g. invalid page.
-     */
-    Collection<String> format(@NotNull CommandSender sender, @NotNull ContentDisplay<T> display)
-            throws DisplayFormatException;
-
-    /**
-     * Sends the header.
-     *
-     * @param sender The {@link CommandSender} who will the header will be displayed to.
-     * @param display The responsible {@link ContentDisplay}.
-     */
-    default void sendHeader(@NotNull CommandSender sender, @NotNull ContentDisplay<T> display) {
-        if (!Strings.isNullOrEmpty(display.getHeader())) {
-            sender.sendMessage(display.getHeader());
-        }
-    }
-
-    /**
-     * Sends info such as filter and page.
-     *
-     * @param sender The {@link CommandSender} who will the sub header will be displayed to.
-     * @param display The responsible {@link ContentDisplay}.
-     */
-    default void sendSubHeader(@NotNull CommandSender sender, @NotNull ContentDisplay<T> display) {
-        if (display.getFilter().hasFilter()) {
-            sender.sendMessage(String.format("%s[ %s ]", ChatColor.GRAY, display.getFilter().getFormattedString()));
-        }
-    }
-
-    /**
-     * Sends the content.
-     *
-     * @param sender The {@link CommandSender} who will the body will be displayed to.
-     * @param display The responsible {@link ContentDisplay}.
-     * @param formattedContent The content after being formatted by {@link #format(CommandSender, ContentDisplay)}
-     */
-    default void sendBody(@NotNull CommandSender sender, @NotNull ContentDisplay<T> display,
-                          Collection<String> formattedContent) {
-        if (formattedContent == null || formattedContent.size() == 0) {
-            sender.sendMessage(display.getEmptyMessage());
-            return;
-        }
-        sender.sendMessage(formattedContent.toArray(new String[0]));
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/DisplayHandlers.java

@@ -1,47 +0,0 @@
-package com.onarandombox.MultiverseCore.display;
-
-import com.onarandombox.MultiverseCore.display.handlers.InlineListDisplayHandler;
-import com.onarandombox.MultiverseCore.display.handlers.InlineMapDisplayHandler;
-import com.onarandombox.MultiverseCore.display.handlers.ListDisplayHandler;
-import com.onarandombox.MultiverseCore.display.handlers.PagedListDisplayHandler;
-import com.onarandombox.MultiverseCore.display.settings.InlineDisplaySettings;
-import com.onarandombox.MultiverseCore.display.settings.PagedDisplaySettings;
-import com.onarandombox.MultiverseCore.display.settings.MapDisplaySettings;
-
-import java.util.Collection;
-import java.util.Map;
-
-/**
- * Various implementations of {@link DisplayHandler}.
- */
-public class DisplayHandlers {
-
-    /**
-     * Standard list display.
-     *
-     * Supported settings: none.
-     */
-    public static final DisplayHandler<Collection<String>> LIST = new ListDisplayHandler();
-
-    /**
-     * List display with paging.
-     *
-     * Supported settings: {@link PagedDisplaySettings#SHOW_PAGE}, {@link PagedDisplaySettings#LINES_PER_PAGE},
-     * {@link PagedDisplaySettings#PAGE_IN_CONSOLE}, {@link PagedDisplaySettings#DO_END_PADDING}.
-     */
-    public static final DisplayHandler<Collection<String>> PAGE_LIST = new PagedListDisplayHandler();
-
-    /**
-     * Display a list inline.
-     *
-     * Supported settings: {@link InlineDisplaySettings#SEPARATOR}.
-     */
-    public static final DisplayHandler<Collection<String>> INLINE_LIST = new InlineListDisplayHandler();
-
-    /**
-     * Display key value pair inline.
-     *
-     * Supported settings: {@link InlineDisplaySettings#SEPARATOR}, {@link MapDisplaySettings#OPERATOR}.
-     */
-    public static final DisplayHandler<Map<String, Object>> INLINE_MAP = new InlineMapDisplayHandler();
-}

src/main/java/com/onarandombox/MultiverseCore/display/handlers/InlineListDisplayHandler.java

@@ -1,36 +0,0 @@
-package com.onarandombox.MultiverseCore.display.handlers;
-
-import com.onarandombox.MultiverseCore.display.ContentDisplay;
-import com.onarandombox.MultiverseCore.display.DisplayFormatException;
-import com.onarandombox.MultiverseCore.display.DisplayHandler;
-import com.onarandombox.MultiverseCore.display.settings.InlineDisplaySettings;
-import org.bukkit.command.CommandSender;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Iterator;
-
-public class InlineListDisplayHandler implements DisplayHandler<Collection<String>> {
-
-    @Override
-    public Collection<String> format(@NotNull CommandSender sender, @NotNull ContentDisplay<Collection<String>> display)
-            throws DisplayFormatException {
-        StringBuilder builder = new StringBuilder();
-        String separator = display.getSetting(InlineDisplaySettings.SEPARATOR);
-
-        for (Iterator<String> iterator = display.getContents().iterator(); iterator.hasNext(); ) {
-            String content = iterator.next();
-            if (!display.getFilter().checkMatch(content)) {
-                continue;
-            }
-            builder.append(display.getColorTool().get()).append(content);
-            if (iterator.hasNext()) {
-                builder.append(separator);
-            }
-        }
-        return (builder.length() == 0)
-                ? Collections.singletonList(display.getEmptyMessage())
-                : Collections.singleton(builder.toString());
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/handlers/InlineMapDisplayHandler.java

@@ -1,44 +0,0 @@
-package com.onarandombox.MultiverseCore.display.handlers;
-
-import com.onarandombox.MultiverseCore.display.ContentDisplay;
-import com.onarandombox.MultiverseCore.display.DisplayFormatException;
-import com.onarandombox.MultiverseCore.display.DisplayHandler;
-import com.onarandombox.MultiverseCore.display.settings.InlineDisplaySettings;
-import com.onarandombox.MultiverseCore.display.settings.MapDisplaySettings;
-import org.bukkit.command.CommandSender;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Collection;
-import java.util.Collections;
-import java.util.Iterator;
-import java.util.Map;
-
-public class InlineMapDisplayHandler implements DisplayHandler<Map<String, Object>> {
-
-    @Override
-    public Collection<String> format(@NotNull CommandSender sender,
-                                     @NotNull ContentDisplay<Map<String, Object>> display)
-            throws DisplayFormatException {
-        StringBuilder builder = new StringBuilder();
-        String separator = display.getSetting(InlineDisplaySettings.SEPARATOR);
-        String operator = display.getSetting(MapDisplaySettings.OPERATOR);
-
-        for (Iterator<Map.Entry<String, Object>> iterator = display.getContents().entrySet().iterator(); iterator.hasNext(); ) {
-            Map.Entry<String, Object> entry = iterator.next();
-            if (!display.getFilter().checkMatch(entry.getKey()) && !display.getFilter().checkMatch(entry.getValue())) {
-                continue;
-            }
-            builder.append(display.getColorTool().get())
-                    .append(entry.getKey())
-                    .append(operator)
-                    .append(display.getColorTool().get())
-                    .append(entry.getValue());
-            if (iterator.hasNext()) {
-                builder.append(separator);
-            }
-        }
-        return (builder.length() == 0)
-                ? Collections.singletonList(display.getEmptyMessage())
-                : Collections.singleton(builder.toString());
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/handlers/ListDisplayHandler.java

@@ -1,22 +0,0 @@
-package com.onarandombox.MultiverseCore.display.handlers;
-
-import com.onarandombox.MultiverseCore.display.ContentDisplay;
-import com.onarandombox.MultiverseCore.display.DisplayFormatException;
-import com.onarandombox.MultiverseCore.display.DisplayHandler;
-import org.bukkit.command.CommandSender;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.Collection;
-import java.util.stream.Collectors;
-
-public class ListDisplayHandler implements DisplayHandler<Collection<String>> {
-
-    @Override
-    public Collection<String> format(@NotNull CommandSender sender, @NotNull ContentDisplay<Collection<String>> display)
-            throws DisplayFormatException {
-        return display.getContents().stream()
-                .filter(display.getFilter()::checkMatch)
-                .map(s -> (ContentDisplay.LINE_BREAK.equals(s)) ? "" : display.getColorTool().get() + s)
-                .collect(Collectors.toList());
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/handlers/PagedListDisplayHandler.java

@@ -1,105 +0,0 @@
-package com.onarandombox.MultiverseCore.display.handlers;
-
-import com.onarandombox.MultiverseCore.display.ContentDisplay;
-import com.onarandombox.MultiverseCore.display.DisplayFormatException;
-import com.onarandombox.MultiverseCore.display.settings.PagedDisplaySettings;
-import org.bukkit.ChatColor;
-import org.bukkit.command.CommandSender;
-import org.bukkit.command.ConsoleCommandSender;
-import org.jetbrains.annotations.NotNull;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.List;
-import java.util.stream.IntStream;
-
-public class PagedListDisplayHandler extends ListDisplayHandler {
-
-    @Override
-    public Collection<String> format(@NotNull CommandSender sender, @NotNull ContentDisplay<Collection<String>> display)
-            throws DisplayFormatException {
-        if (dontNeedPaging(sender, display)) {
-            return super.format(sender, display);
-        }
-
-        int pages = 1;
-        int currentLength = 0;
-        int targetPage = display.getSetting(PagedDisplaySettings.SHOW_PAGE);
-        int linesPerPage = display.getSetting(PagedDisplaySettings.LINES_PER_PAGE);
-        List<String> content = new ArrayList<>(linesPerPage);
-
-        // Calculate the paging.
-        for (String line : display.getContents()) {
-            if (!display.getFilter().checkMatch(line)) {
-                continue;
-            }
-            // When it's the next page.
-            boolean isLineBreak = ContentDisplay.LINE_BREAK.equals(line);
-            if (isLineBreak || ++currentLength > linesPerPage) {
-                pages++;
-                currentLength = 0;
-                if (isLineBreak) {
-                    continue;
-                }
-            }
-            if (pages == targetPage) {
-                // Let first line be the header when no header is defined.
-                if (display.getHeader() == null) {
-                    display.setHeader(line);
-                    currentLength--;
-                    continue;
-                }
-                content.add(display.getColorTool().get() + line);
-            }
-        }
-
-        // Page out of range.
-        if (targetPage < 1 || targetPage > pages) {
-            if (pages == 1) {
-                throw new DisplayFormatException("There is only 1 page!");
-            }
-            throw new DisplayFormatException("Please enter a page from 1 to " + pages + ".");
-        }
-
-        // No content
-        if (content.size() == 0) {
-            content.add(display.getEmptyMessage());
-        }
-
-        // Add empty lines to make output length consistent.
-        if (display.getSetting(PagedDisplaySettings.DO_END_PADDING)) {
-            IntStream.range(0, linesPerPage - content.size()).forEach(i -> content.add(""));
-        }
-        display.setSetting(PagedDisplaySettings.TOTAL_PAGE, pages);
-
-        return content;
-    }
-
-    @Override
-    public void sendSubHeader(@NotNull CommandSender sender, @NotNull ContentDisplay<Collection<String>> display) {
-        if (dontNeedPaging(sender, display)) {
-            super.sendSubHeader(sender, display);
-            return;
-        }
-
-        if (display.getFilter().hasFilter()) {
-            sender.sendMessage(String.format("%s[ Page %s of %s, %s ]",
-                    ChatColor.GRAY,
-                    display.getSetting(PagedDisplaySettings.SHOW_PAGE),
-                    display.getSetting(PagedDisplaySettings.TOTAL_PAGE),
-                    display.getFilter().getFormattedString())
-            );
-            return;
-        }
-        sender.sendMessage(String.format("%s[ Page %s of %s ]",
-                ChatColor.GRAY,
-                display.getSetting(PagedDisplaySettings.SHOW_PAGE),
-                display.getSetting(PagedDisplaySettings.TOTAL_PAGE))
-        );
-    }
-
-    private boolean dontNeedPaging(CommandSender sender, ContentDisplay<Collection<String>> display) {
-        return sender instanceof ConsoleCommandSender
-                && !display.getSetting(PagedDisplaySettings.PAGE_IN_CONSOLE);
-    }
-}

src/main/java/com/onarandombox/MultiverseCore/display/settings/DisplaySetting.java

@@ -1,19 +0,0 @@
-package com.onarandombox.MultiverseCore.display.settings;
-
-import com.onarandombox.MultiverseCore.display.DisplayHandler;
-
-/**
- * Represents a setting option that can be used by {@link DisplayHandler}.
- *
- * @param <T>
- */
-@FunctionalInterface
-public interface DisplaySetting<T> {
-
-     /**
-      * Gets the default value of this Display Setting.
-      *
-      * @return The default value.
-      */
-     T defaultValue();
-}

src/main/java/com/onarandombox/MultiverseCore/display/settings/InlineDisplaySettings.java

@@ -1,15 +0,0 @@
-package com.onarandombox.MultiverseCore.display.settings;
-
-import com.onarandombox.MultiverseCore.display.DisplayHandler;
-import org.bukkit.ChatColor;
-
-/**
- * Collection of {@link DisplaySetting} that are used by various {@link DisplayHandler}.
- */
-public class InlineDisplaySettings {
-
-    /**
-     * Inline separator. E.g. '1, 2, 3'
-     */
-    public static final DisplaySetting<String> SEPARATOR = () -> ChatColor.WHITE + ", ";
-}

src/main/java/com/onarandombox/MultiverseCore/display/settings/MapDisplaySettings.java

@@ -1,15 +0,0 @@
-package com.onarandombox.MultiverseCore.display.settings;
-
-import com.onarandombox.MultiverseCore.display.DisplayHandler;
-import org.bukkit.ChatColor;
-
-/**
- * Collection of {@link DisplaySetting} that are used by various {@link DisplayHandler}.
- */
-public class MapDisplaySettings {
-
-    /**
-     * The thing between a key value pair. E.g. 'Me = Smart'
-     */
-    public static final DisplaySetting<String> OPERATOR = () -> ChatColor.WHITE + " = ";
-}

src/main/java/com/onarandombox/MultiverseCore/display/settings/PagedDisplaySettings.java

@@ -1,30 +0,0 @@
-package com.onarandombox.MultiverseCore.display.settings;
-
-public class PagedDisplaySettings {
-
-    /**
-     * Page to display.
-     */
-    public static final DisplaySetting<Integer> SHOW_PAGE = () -> 1;
-
-    /**
-     * Total pages available to display.
-     */
-    public static final DisplaySetting<Integer> TOTAL_PAGE = () -> 1;
-
-    /**
-     * The max number of lines per page. This excludes header.
-     */
-    public static final DisplaySetting<Integer> LINES_PER_PAGE = () -> 8;
-
-    /**
-     * Should add empty lines if content lines shown is less that {@link #LINES_PER_PAGE}.
-     */
-    public static final DisplaySetting<Boolean> DO_END_PADDING = () -> true;
-
-    /**
-     * Should display with paging when it's sent to console.
-     */
-    public static final DisplaySetting<Boolean> PAGE_IN_CONSOLE = () -> false;
-
-}