Make getOnlinePlayers unmodifiable and getPlayerWorld return option

Author: benwoo1110

src/main/java/org/mvplugins/multiverse/core/listeners/MVChatListener.java

@@ -96,11 +96,9 @@ void asyncPlayerChat(AsyncPlayerChatEvent event) {
     }
 
     private String getWorldName(Player player) {
-        String world = playerWorldTracker.getPlayerWorld(player.getName());
-        if (world == null) {
-            world = player.getWorld().getName();
-        }
-        return this.worldManager.getLoadedWorld(world)
+        String worldName = playerWorldTracker.getPlayerWorld(player.getName())
+                .getOrElse(() -> player.getWorld().getName());
+        return this.worldManager.getLoadedWorld(worldName)
                 .map(mvworld -> mvworld.isHidden() ? "" : mvworld.getAliasOrName())
                 .getOrElse("");
     }

src/main/java/org/mvplugins/multiverse/core/world/helpers/ConcurrentPlayerWorldTracker.java

@@ -1,5 +1,6 @@
 package org.mvplugins.multiverse.core.world.helpers;
 
+import io.vavr.control.Option;
 import jakarta.inject.Inject;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
@@ -10,14 +11,19 @@
 import org.bukkit.event.player.PlayerQuitEvent;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.UnmodifiableView;
 import org.jvnet.hk2.annotations.Service;
 import org.mvplugins.multiverse.core.MultiverseCore;
 
-import java.util.List;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 
+/**
+ * Tracks which players are in which worlds, using a thread-safe map.
+ * This allows async access to online players list and the world they are in.
+ */
 @ApiStatus.AvailableSince("5.4")
 @Service
 public final class ConcurrentPlayerWorldTracker implements Listener {
@@ -30,16 +36,28 @@ public final class ConcurrentPlayerWorldTracker implements Listener {
         plugin.getServer().getPluginManager().registerEvents(this, plugin);
     }
 
+    /**
+     * Get an unmodifiable collection of all online player names on the server.
+     *
+     * @return Unmodifiable collection of online player names.
+     */
     @ApiStatus.AvailableSince("5.4")
     @NotNull
-    public List<String> getOnlinePlayers() {
-        return List.copyOf(playerWorldMap.keySet());
+    @UnmodifiableView
+    public Collection<String> getOnlinePlayers() {
+        return Collections.unmodifiableCollection(playerWorldMap.keySet());
     }
 
+    /**
+     * Get the world name a player is currently in.
+     *
+     * @param playerName Name of the player.
+     * @return World name the player is in, or null if the player is not online.
+     */
     @ApiStatus.AvailableSince("5.4")
-    @Nullable
-    public String getPlayerWorld(String playerName) {
-        return playerWorldMap.get(playerName);
+    @NotNull
+    public Option<String> getPlayerWorld(String playerName) {
+        return Option.of(playerWorldMap.get(playerName));
     }
 
     @EventHandler(priority = EventPriority.LOWEST)