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 9bff729df7156b071b08913549838024bb17c3c9..88a4dda44e59fbe6215d7ac2e5af0c54527a2fc7 100644
--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
@@ -681,4 +681,9 @@ 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 c2c1242bcf26c73b3520c797e77c3c2d430dfac7..443fb9cdce8bf542ca6216aa65c3e48c66dde654 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -617,7 +617,15 @@ 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());