Expand world key API

paper-api/src/main/java/org/bukkit/Bukkit.java

@@ -865,6 +865,29 @@ public final class Bukkit {
     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);
+    }
+
+    /**
+     * Gets the world from the given Key
+     *
+     * @param worldKey the Key of the world to retrieve
+     * @return a world with the given Key, or null if none exists
+     */
+    @Nullable
+    public static World getWorld(@NotNull net.kyori.adventure.key.Key worldKey) {
+        return server.getWorld(worldKey);
+    }
+    // Paper end
 
     /**
      * Create a new virtual {@link WorldBorder}.

paper-api/src/main/java/org/bukkit/RegionAccessor.java

@@ -18,7 +18,7 @@ import org.jetbrains.annotations.Nullable;
  * 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}.
@@ -452,5 +452,14 @@ public interface RegionAccessor {
      */
     @NotNull
     io.papermc.paper.world.MoonPhase getMoonPhase();
+
+    /**
+     * Get the world's key
+     *
+     * @return the world's key
+     */
+    @NotNull
+    @Override
+    NamespacedKey getKey();
     // Paper end
 }

paper-api/src/main/java/org/bukkit/Server.java

@@ -726,6 +726,28 @@ public interface Server extends PluginMessageRecipient, net.kyori.adventure.audi
     @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
+    default World getWorld(@NotNull NamespacedKey worldKey) {
+        return getWorld((net.kyori.adventure.key.Key) worldKey);
+    }
+
+    /**
+     * Gets the world from the given Key
+     *
+     * @param worldKey the Key of the world to retrieve
+     * @return a world with the given Key, or null if none exists
+     */
+    @Nullable
+    World getWorld(@NotNull net.kyori.adventure.key.Key worldKey);
+    // Paper end
+
     /**
      * Create a new virtual {@link WorldBorder}.
      * <p>

paper-api/src/main/java/org/bukkit/UnsafeValues.java

@@ -175,5 +175,10 @@ public interface UnsafeValues {
      * Use this when sending custom packets, so that there are no collisions on the client or server.
      */
     public int nextEntityId();
+
+    /**
+     * Just don't use it.
+     */
+    @org.jetbrains.annotations.NotNull String getMainLevelName();
     // Paper end
 }

paper-api/src/main/java/org/bukkit/WorldCreator.java

@@ -13,6 +13,7 @@ import org.jetbrains.annotations.Nullable;
  * 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;
@@ -30,12 +31,81 @@ public class WorldCreator {
      * @param name Name of the world that will be created
      */
     public WorldCreator(@NotNull String name) {
-        Preconditions.checkArgument(name != null, "World name cannot be null");
+        // Paper start
-
+        this(name, getWorldKey(name));
-        this.name = name;
-        this.seed = (new Random()).nextLong();
     }
 
+    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(" ", "_"));
+        }
+    }
+
+    /**
+     * 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
      *