feat: add some more placeholders and comments

src/main/java/at/helpch/placeholderapi/expansion/server/ServerExpansion.java

@@ -3,6 +3,8 @@ package at.helpch.placeholderapi.expansion.server;
 import at.helpch.placeholderapi.expansion.server.util.ServerUtil;
 import com.google.common.cache.Cache;
 import com.google.common.cache.CacheBuilder;
+import com.google.common.collect.ImmutableMap;
+import me.clip.placeholderapi.PlaceholderAPIPlugin;
 import me.clip.placeholderapi.expansion.Cacheable;
 import me.clip.placeholderapi.expansion.Configurable;
 import me.clip.placeholderapi.expansion.PlaceholderExpansion;
@@ -12,19 +14,32 @@ import org.bukkit.World;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.function.ToIntFunction;
+import java.util.logging.Level;
 
-public class ServerExpansion extends PlaceholderExpansion implements Cacheable, Configurable {
+public final class ServerExpansion extends PlaceholderExpansion implements Cacheable, Configurable {
 
     private final Cache<String, Integer> cache = CacheBuilder.newBuilder()
             .expireAfterWrite(1, TimeUnit.MINUTES)
             .build();
 
+    private final Map<String, SimpleDateFormat> dateFormats = new HashMap<>();
+
     private final Runtime runtime = Runtime.getRuntime();
+    /**
+     * Constant that represents how many bytes are in a megabyte
+     */
+    private final int MB = 1_048_576;
+
+    // ----- Values from config
+    private String serverName;
 
     @Override
     public @NotNull String getIdentifier() {
@@ -41,6 +56,12 @@ public class ServerExpansion extends PlaceholderExpansion implements Cacheable,
         return "3.0.0";
     }
 
+    @Override
+    public boolean canRegister() {
+        this.serverName = getString("server_name", "A Minecraft Server");
+        return true;
+    }
+
     @Override
     public void clear() {
 
@@ -48,36 +69,139 @@ public class ServerExpansion extends PlaceholderExpansion implements Cacheable,
 
     @Override
     public Map<String, Object> getDefaults() {
-        return null;
+        return ImmutableMap.<String, Object>builder()
+                .put("server_name", "A Minecraft Server")
+                .build();
     }
 
-    private int sumAllWorlds(@NotNull final ToIntFunction<? super World> function) {
+    /**
+     * Get some data from all worlds
+     *
+     * @param function data to get (e.g. total entities)
+     * @return sum
+     */
+    private int getFromAllWorlds(@NotNull final ToIntFunction<? super World> function) {
         return Bukkit.getWorlds()
                 .stream()
                 .mapToInt(function)
                 .sum();
     }
 
-    private String getFromCache(@NotNull final String key, @NotNull final Callable<Integer> callable) {
+    /**
+     * Get a value from the {@link #cache}
+     *
+     * @param key      key
+     * @param callable cache method
+     * @return value if found otherwise empty
+     */
+    private @NotNull String getFromCache(@NotNull final String key, @NotNull final Callable<Integer> callable) {
         try {
             return String.valueOf(cache.get(key, callable));
         } catch (ExecutionException e) {
-            e.printStackTrace();
+            PlaceholderAPIPlugin.getInstance()
+                    .getLogger()
+                    .log(Level.WARNING, "[server] Could not get '" + key + "' from cache", e);
             return "";
         }
     }
 
+    /**
+     * Format a boolean {@code boolean} as {@link PlaceholderAPIPlugin#booleanTrue()} or {@link PlaceholderAPIPlugin#booleanFalse()}
+     *
+     * @param bool boolean
+     * @return {@link PlaceholderAPIPlugin#booleanTrue()} if the boolean is true, otherwise {@link PlaceholderAPIPlugin#booleanFalse()}
+     */
+    private @NotNull String bool(final boolean bool) {
+        return bool ? PlaceholderAPIPlugin.booleanTrue() : PlaceholderAPIPlugin.booleanFalse();
+    }
+
+    /**
+     * Get the number of online players from a world
+     *
+     * @param worldName the name of the world
+     * @return {@code -1} if {@code worldName} is empty or the world doesn't exist, otherwise {@link World#getPlayers()}.size()
+     */
+    private int getOnlinePlayers(@NotNull final String worldName) {
+        if (worldName.trim().isEmpty()) {
+            return -1;
+        }
+
+        final World world = Bukkit.getWorld(worldName);
+        return world == null ? -1 : world.getPlayers().size();
+    }
+
+    /**
+     * Format the current time with the given format
+     *
+     * @param format format
+     * @return {@code null} if the format is empty or invalid, otherwise the current {@link Date} formatted
+     */
+    private @Nullable String formatTime(@NotNull final String format) {
+        if (format.trim().isEmpty()) {
+            return null;
+        }
+
+        final SimpleDateFormat simpleDateFormat = dateFormats.computeIfAbsent(format, __ -> {
+            try {
+                return new SimpleDateFormat(format);
+            } catch (IllegalArgumentException ignored) {
+                return null;
+            }
+        });
+        return simpleDateFormat == null ? null : simpleDateFormat.format(new Date());
+    }
+
     @Override
     public @Nullable String onRequest(OfflinePlayer player, @NotNull String params) {
         switch (params) {
+            // ----- Players placeholders
+            case "online":
+                return String.valueOf(Bukkit.getOnlinePlayers().size());
+            case "max_players":
+                return String.valueOf(Bukkit.getMaxPlayers());
+            case "unique_joins":
+                return String.valueOf(Bukkit.getOfflinePlayers().length);
+            // -----
+
+            // ----- Server software placeholders
+            case "name":
+                return this.serverName;
             case "variant":
                 return ServerUtil.getVariant();
+            case "version":
+                return ServerUtil.getServerVersion();
+            // TODO add version_build and version_full (same placeholder)
+            // -----
+
+            // ----- RAM placeholders
+            case "ram":
+                return String.valueOf((runtime.totalMemory() - runtime.freeMemory()) / MB);
+            case "ram_free":
+                return String.valueOf(runtime.freeMemory() / MB);
+            case "ram_total":
+                return String.valueOf(runtime.totalMemory() / MB);
+            case "ram_max":
+                return String.valueOf(runtime.maxMemory() / MB);
+            // -----
+
             case "total_chunks":
-                return getFromCache("chunks", () -> sumAllWorlds(world -> world.getLoadedChunks().length));
+                return getFromCache("chunks", () -> getFromAllWorlds(world -> world.getLoadedChunks().length));
             case "total_living_entities":
-                return getFromCache("livingEntities", () -> sumAllWorlds(world -> world.getLivingEntities().size()));
+                return getFromCache("livingEntities", () -> getFromAllWorlds(world -> world.getLivingEntities().size()));
             case "total_entities":
-                return getFromCache("totalEntities", () -> sumAllWorlds(world -> world.getEntities().size()));
+                return getFromCache("totalEntities", () -> getFromAllWorlds(world -> world.getEntities().size()));
+            case "has_whitelist":
+                return bool(Bukkit.hasWhitelist());
+        }
+
+        // online_<world name>
+        if (params.startsWith("online_")) {
+            return String.valueOf(getOnlinePlayers(params.replace("online_", "")));
+        }
+
+        // time_<simple date format>
+        if (params.startsWith("time_")) {
+            return formatTime(params.replace("time_", ""));
         }
 
         return null;

src/main/java/at/helpch/placeholderapi/expansion/server/util/ServerUtil.java

@@ -13,6 +13,7 @@ public final class ServerUtil {
 
     private static final Map<String, String> variants = new TreeMap<>();
     private static final String variant;
+    private static final String serverVersion;
 
     // TPS stuff
     private static final Object craftServer;
@@ -28,6 +29,7 @@ public final class ServerUtil {
         variants.put("org.spigotmc.SpigotConfig", "Spigot");
 
         variant = findVariant();
+        serverVersion = Bukkit.getBukkitVersion().split("-")[0]; // The version is formatted as 1.20.1-R0.1-SNAPSHOT
         craftServer = getCraftServer();
         tpsField = getTpsHandler();
     }
@@ -50,7 +52,7 @@ public final class ServerUtil {
         try {
             Class<?> clas;
 
-            if (VersionHelper.OVER_1_17) {
+            if (VersionHelper.IS_1_17_OR_HIGHER) {
                 clas = Class.forName("net.minecraft.server.MinecraftServer");
             } else {
                 clas = Class.forName(String.format("net.minecraft.server.%s.MinecraftServer", VersionHelper.NMS_VERSION));
@@ -70,17 +72,22 @@ public final class ServerUtil {
         try {
             Bukkit.class.getMethod("getTPS");
             hasTpsMethod = true;
+            return null;
         } catch (NoSuchMethodException ignored) { }
 
         if (craftServer == null) {
-            PlaceholderAPIPlugin.getInstance().getLogger().log(Level.WARNING, "Could not get field 'recentTps' from class MinecraftServer because variable 'craftServer' is null");
+            PlaceholderAPIPlugin.getInstance()
+                    .getLogger()
+                    .log(Level.WARNING, "[server] Could not get field 'recentTps' from class MinecraftServer because variable 'craftServer' is null");
             return null;
         }
 
         try {
             return craftServer.getClass().getField("recentTps");
         } catch (NoSuchFieldException e) {
-            PlaceholderAPIPlugin.getInstance().getLogger().log(Level.WARNING, "Could not find field 'recentTps' in class " + craftServer.getClass().getName(), e);
+            PlaceholderAPIPlugin.getInstance()
+                    .getLogger()
+                    .log(Level.WARNING, "[server] Could not find field 'recentTps' in class " + craftServer.getClass().getName(), e);
             return null;
         }
     }
@@ -89,6 +96,10 @@ public final class ServerUtil {
         return variant;
     }
 
+    public static String getServerVersion() {
+        return serverVersion;
+    }
+
     public static double[] getTps() {
         if (hasTpsMethod) {
             return Bukkit.getTPS();

src/main/java/at/helpch/placeholderapi/expansion/server/util/VersionHelper.java

@@ -38,55 +38,13 @@ public final class VersionHelper {
 
     public static final String NMS_VERSION = getNmsVersion();
 
-    // Unbreakable change
-    private static final int V1_11 = 1110;
-    // Material and components on items change
-    private static final int V1_13 = 1130;
-    // PDC and customModelData
-    private static final int V1_14 = 1140;
-    // Paper adventure changes
-    private static final int V1_16_5 = 1165;
-    // SkullMeta#setOwningPlayer was added
-    private static final int V1_12_1 = 1121;
     private static final int V1_17 = 1_17_0;
 
     private static final int CURRENT_VERSION = getCurrentVersion();
 
     private static final boolean IS_PAPER = checkPaper();
 
-    /**
-     * Checks if the version supports Components or not
-     * Spigot always false
-     */
-    public static final boolean IS_COMPONENT_LEGACY = CURRENT_VERSION < V1_16_5;
-
-    /**
-     * Checks if the version is lower than 1.13 due to the item changes
-     */
-    public static final boolean IS_ITEM_LEGACY = CURRENT_VERSION < V1_13;
-
-    /**
-     * Checks if the version supports the {@link org.bukkit.inventory.meta.ItemMeta#setUnbreakable(boolean)} method
-     */
-    public static final boolean IS_UNBREAKABLE_LEGACY = CURRENT_VERSION < V1_11;
-
-    /**
-     * Checks if the version supports {@link org.bukkit.persistence.PersistentDataContainer}
-     */
-    public static final boolean IS_PDC_VERSION = CURRENT_VERSION >= V1_14;
-
-    /**
-     * Checks if the version doesn't have {@link org.bukkit.inventory.meta.SkullMeta#setOwningPlayer(OfflinePlayer)} and
-     * {@link org.bukkit.inventory.meta.SkullMeta#setOwner(String)} should be used instead
-     */
-    public static final boolean IS_SKULL_OWNER_LEGACY = CURRENT_VERSION < V1_12_1;
-
-    /**
-     * Checks if the version has {@link org.bukkit.inventory.meta.ItemMeta#setCustomModelData(Integer)}
-     */
-    public static final boolean IS_CUSTOM_MODEL_DATA = CURRENT_VERSION >= V1_14;
-
-    public static final boolean OVER_1_17 = CURRENT_VERSION >= V1_17;
+    public static final boolean IS_1_17_OR_HIGHER = CURRENT_VERSION >= V1_17;
 
     /**
      * Check if the server has access to the Paper API