From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sat, 19 Feb 2022 20:15:41 -0800
Subject: [PATCH] Option to have default CustomSpawners in custom worlds

By default, only LevelStem's that specifically match the ResourceKey for
OVERWORLD will have the 5 (currently) impls of CustomSpawner (for
phantoms, wandering traders, etc.). This adds an option to instead of
just looking at the LevelStem key, look at the DimensionType key which
is one level below that. Defaults to off to keep vanilla behavior.

diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
index 153f07bac06093b43a1f5b0f8e1a46ffbe6407e5..a7ebf6d9f79ce50a90c3c903563e00a10607f9f2 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -679,4 +679,9 @@ public class PaperConfig {
         }
         globalMaxConcurrentChunkLoads = getDouble("settings.chunk-loading.global-max-concurrent-loads", 500.0);
     }
+
+    public static boolean useDimensionTypeForCustomSpawners;
+    private static void useDimensionTypeForCustomSpawners() {
+        useDimensionTypeForCustomSpawners = getBoolean("settings.use-dimension-type-for-custom-spawners", false);
+    }
 }
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index d19d816ee511bf5d44151c3e159adb288b60bc03..115e06e0c6865f1c04f58a74509332f7c5043d91 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -619,7 +619,15 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
                 this.commandStorage = new CommandStorage(worldpersistentdata);
             } else {
                 ChunkProgressListener worldloadlistener = this.progressListenerFactory.create(11);
-                world = new ServerLevel(this, this.executor, worldSession, iworlddataserver, worldKey, holder, worldloadlistener, chunkgenerator, flag, j, ImmutableList.of(), true, org.bukkit.World.Environment.getEnvironment(dimension), gen, biomeProvider);
+                // Paper start - option to use the dimension_type to check if spawners should be added. I imagine mojang will add some datapack-y way of managing this in the future.
+                final List<CustomSpawner> spawners;
+                if (com.destroystokyo.paper.PaperConfig.useDimensionTypeForCustomSpawners && this.registryHolder.registryOrThrow(Registry.DIMENSION_TYPE_REGISTRY).getResourceKey(holder.value()).orElseThrow() == DimensionType.OVERWORLD_LOCATION) {
+                    spawners = list;
+                } else {
+                    spawners = Collections.emptyList();
+                }
+                world = new ServerLevel(this, this.executor, worldSession, iworlddataserver, worldKey, holder, worldloadlistener, chunkgenerator, flag, j, spawners, true, org.bukkit.World.Environment.getEnvironment(dimension), gen, biomeProvider);
+                // Paper end
             }
 
             worlddata.setModdedInfo(this.getServerModName(), this.getModdedStatus().shouldReportAsModified());