Port "Expand world key API" patch

src/main/java/org/bukkit/Bukkit.java

@@ -758,6 +758,18 @@ public static World getWorld(@NotNull String name) {
     public static World getWorld(@NotNull UUID uid) {
         return server.getWorld(uid);
     }
+    // Paper start
+    /**
+     * Gets the world from the given NamespacedKey
+     *
+     * @param worldKey the NamespacedKey of the world to retrieve
+     * @return a world with the given NamespacedKey, or null if none exists
+     */
+    @Nullable
+    public static World getWorld(@NotNull NamespacedKey worldKey) {
+        return server.getWorld(worldKey);
+    }
+    // Paper end
 
     /**
      * Create a new virtual {@link WorldBorder}.

src/main/java/org/bukkit/RegionAccessor.java

@@ -19,7 +19,7 @@
  * A RegionAccessor gives access to getting, modifying and spawning {@link Biome}, {@link BlockState} and {@link Entity},
  * as well as generating some basic structures.
  */
-public interface RegionAccessor {
+public interface RegionAccessor extends Keyed { // Paper
 
     /**
      * Gets the {@link Biome} at the given {@link Location}.
@@ -397,4 +397,15 @@ public interface RegionAccessor {
      * {@link HeightMap}
      */
     public int getHighestBlockYAt(@NotNull Location location, @NotNull HeightMap heightMap);
+
+    // Paper start
+    /**
+     * Get the world's key
+     *
+     * @return the world's key
+     */
+    @NotNull
+    @Override
+    NamespacedKey getKey();
+    // Paper end
 }

src/main/java/org/bukkit/Server.java

@@ -657,6 +657,17 @@ public interface Server extends PluginMessageRecipient {
     @Nullable
     public World getWorld(@NotNull UUID uid);
 
+    // Paper start
+    /**
+     * Gets the world from the given NamespacedKey
+     *
+     * @param worldKey the NamespacedKey of the world to retrieve
+     * @return a world with the given NamespacedKey, or null if none exists
+     */
+    @Nullable
+    public World getWorld(@NotNull NamespacedKey worldKey);
+    // Paper end
+
     /**
      * Create a new virtual {@link WorldBorder}.
      * <p>

src/main/java/org/bukkit/WorldCreator.java

@@ -13,6 +13,7 @@
  * Represents various types of options that may be used to create a world.
  */
 public class WorldCreator {
+    private final NamespacedKey key; // Paper
     private final String name;
     private long seed;
     private World.Environment environment = World.Environment.NORMAL;
@@ -30,13 +31,80 @@ public class WorldCreator {
      * @param name Name of the world that will be created
      */
     public WorldCreator(@NotNull String name) {
-        if (name == null) {
-            throw new IllegalArgumentException("World name cannot be null");
+        // Paper start
+        this(name, getWorldKey(name));
+    }
+
+    private static NamespacedKey getWorldKey(String name) {
+        final String mainLevelName = Bukkit.getUnsafe().getMainLevelName();
+        if (name.equals(mainLevelName)) {
+            return NamespacedKey.minecraft("overworld");
+        } else if (name.equals(mainLevelName + "_nether")) {
+            return NamespacedKey.minecraft("the_nether");
+        } else if (name.equals(mainLevelName + "_the_end")) {
+            return NamespacedKey.minecraft("the_end");
+        } else {
+            return NamespacedKey.minecraft(name.toLowerCase(java.util.Locale.ENGLISH).replace(" ", "_"));
         }
+    }
 
-        this.name = name;
+    /**
+     * Creates an empty WorldCreator for the given world name and key
+     *
+     * @param levelName LevelName of the world that will be created
+     * @param worldKey NamespacedKey of the world that will be created
+     */
+    public WorldCreator(@NotNull String levelName, @NotNull NamespacedKey worldKey) {
+        if (levelName == null || worldKey == null) {
+            throw new IllegalArgumentException("World name and key cannot be null");
+        }
+        this.name = levelName;
         this.seed = (new Random()).nextLong();
+        this.key = worldKey;
+    }
+
+    /**
+     * Creates an empty WorldCreator for the given key.
+     * LevelName will be the Key part of the NamespacedKey.
+     *
+     * @param worldKey NamespacedKey of the world that will be created
+     */
+    public WorldCreator(@NotNull NamespacedKey worldKey) {
+        this(worldKey.getKey(), worldKey);
+    }
+
+    /**
+     * Gets the key for this WorldCreator
+     *
+     * @return the key
+     */
+    @NotNull
+    public NamespacedKey key() {
+        return key;
+    }
+
+    /**
+     * Creates an empty WorldCreator for the given world name and key
+     *
+     * @param levelName LevelName of the world that will be created
+     * @param worldKey NamespacedKey of the world that will be created
+     */
+    @NotNull
+    public static WorldCreator ofNameAndKey(@NotNull String levelName, @NotNull NamespacedKey worldKey) {
+        return new WorldCreator(levelName, worldKey);
+    }
+
+    /**
+     * Creates an empty WorldCreator for the given key.
+     * LevelName will be the Key part of the NamespacedKey.
+     *
+     * @param worldKey NamespacedKey of the world that will be created
+     */
+    @NotNull
+    public static WorldCreator ofKey(@NotNull NamespacedKey worldKey) {
+        return new WorldCreator(worldKey);
     }
+    // Paper end
 
     /**
      * Copies the options from the specified world

src/main/java/org/bukkit/craftbukkit/v1_20_R1/CraftServer.java

@@ -1038,6 +1038,16 @@ public World createWorld(WorldCreator creator) {
             return world;
         }
 
+        // Paper start
+        World worldByKey = this.getWorld(creator.key());
+        if (world != null || worldByKey != null) {
+            if (world == worldByKey) {
+                return world;
+            }
+            throw new IllegalArgumentException("Cannot create a world with key " + creator.key() + " and name " + name + " one (or both) already match a world that exists");
+        }
+        // Paper end
+
         if ((folder.exists()) && (!folder.isDirectory())) {
             throw new IllegalArgumentException("File exists with the name '" + name + "' and isn't a folder");
         }
@@ -1112,7 +1122,7 @@ public World createWorld(WorldCreator creator) {
         } else if (name.equals(levelName + "_the_end")) {
             worldKey = net.minecraft.world.level.Level.END;
         } else {
-            worldKey = ResourceKey.create(Registries.DIMENSION, new ResourceLocation(name.toLowerCase(java.util.Locale.ENGLISH)));
+            worldKey = ResourceKey.create(Registries.DIMENSION, new net.minecraft.resources.ResourceLocation(creator.key().getNamespace().toLowerCase(java.util.Locale.ENGLISH), creator.key().getKey().toLowerCase(java.util.Locale.ENGLISH))); // Paper
         }
 
         net.minecraft.world.level.Level.craftWorldData(generator, creator.environment(), biomeProvider);
@@ -1223,6 +1233,15 @@ public World getWorld(UUID uid) {
         return null;
     }
 
+    // Paper start
+    @Override
+    public World getWorld(NamespacedKey worldKey) {
+        ServerLevel worldServer = console.getLevel(ResourceKey.create(net.minecraft.core.registries.Registries.DIMENSION, CraftNamespacedKey.toMinecraft(worldKey)));
+        if (worldServer == null) return null;
+        return worldServer.getWorld();
+    }
+    // Paper end
+
     public void addWorld(World world) {
         // Check if a World already exists with the UID.
         if (getWorld(world.getUID()) != null) {