From ed91e2aa7bdb73ddd1d88385aa28b7b58af386d6 Mon Sep 17 00:00:00 2001
From: krzys-h <krzys_h@interia.pl>
Date: Mon, 24 Aug 2020 22:19:28 +0200
Subject: [PATCH] Fix "#entity follow <name>" under Forge

One of the Forge patches removes EntityList.REGISTRY and provides
the getClass method as a replacement.

The fix is based on a similar one I found in WorldDownloader

Closes #1376 (and duplicates: #1777 and #1815)
---
 .../api/command/datatypes/EntityClassById.java     | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/api/java/baritone/api/command/datatypes/EntityClassById.java b/src/api/java/baritone/api/command/datatypes/EntityClassById.java
index aed7cdf41..becc649c1 100644
--- a/src/api/java/baritone/api/command/datatypes/EntityClassById.java
+++ b/src/api/java/baritone/api/command/datatypes/EntityClassById.java
@@ -32,7 +32,19 @@ public enum EntityClassById implements IDatatypeFor<Class<? extends Entity>> {
     public Class<? extends Entity> get(IDatatypeContext ctx) throws CommandException {
         ResourceLocation id = new ResourceLocation(ctx.getConsumer().getString());
         Class<? extends Entity> entity;
-        if ((entity = EntityList.REGISTRY.getObject(id)) == null) {
+        try {
+            entity = EntityList.REGISTRY.getObject(id);
+        } catch(NoSuchFieldError e) {
+            // Forge removes EntityList.REGISTRY field and provides the getClass method as a replacement
+            // See https://github.com/MinecraftForge/MinecraftForge/blob/1.12.x/patches/minecraft/net/minecraft/entity/EntityList.java.patch
+            try {
+                entity = (Class<? extends Entity>) EntityList.class.getMethod("getClass", ResourceLocation.class).invoke(null, id);
+            } catch (Exception ex) {
+                throw new RuntimeException("EntityList.REGISTRY does not exist and failed to call the Forge-replacement method", ex);
+            }
+        }
+
+        if (entity == null) {
             throw new IllegalArgumentException("no entity found by that id");
         }
         return entity;