From 69eb9407649ddfdcc53a44b81695a06c58ee5a22 Mon Sep 17 00:00:00 2001
From: LexManos <LexManos@gmail.com>
Date: Fri, 9 Dec 2022 12:29:23 -0800
Subject: [PATCH] Fix merged mod resource pack not returning all resources with
 the same name when asked. Closes #9194

---
 .../FallbackResourceManager.java.patch        | 24 +++++++++++++++++++
 .../extensions/IForgePackResources.java       | 15 ++++++++++++
 .../resource/DelegatingPackResources.java     |  7 ++++++
 3 files changed, 46 insertions(+)
 create mode 100644 patches/minecraft/net/minecraft/server/packs/resources/FallbackResourceManager.java.patch

diff --git a/patches/minecraft/net/minecraft/server/packs/resources/FallbackResourceManager.java.patch b/patches/minecraft/net/minecraft/server/packs/resources/FallbackResourceManager.java.patch
new file mode 100644
index 0000000000..b79d0bffd4
--- /dev/null
+++ b/patches/minecraft/net/minecraft/server/packs/resources/FallbackResourceManager.java.patch
@@ -0,0 +1,24 @@
+--- a/net/minecraft/server/packs/resources/FallbackResourceManager.java
++++ b/net/minecraft/server/packs/resources/FallbackResourceManager.java
+@@ -98,8 +_,11 @@
+ 
+       for(int i = this.f_10599_.size() - 1; i >= 0; --i) {
+          FallbackResourceManager.PackEntry fallbackresourcemanager$packentry = this.f_10599_.get(i);
+-         PackResources packresources = fallbackresourcemanager$packentry.f_215433_;
+-         if (packresources != null) {
++         PackResources pack = fallbackresourcemanager$packentry.f_215433_;
++         if (pack != null) {
++            var children = pack.getChildren();
++            var packs = children == null ? List.of(pack) : children;
++            for (final PackResources packresources : packs) {
+             IoSupplier<InputStream> iosupplier = packresources.m_214146_(this.f_10601_, p_215367_);
+             if (iosupplier != null) {
+                IoSupplier<ResourceMetadata> iosupplier1;
+@@ -113,6 +_,7 @@
+                }
+ 
+                list.add(new Resource(packresources, iosupplier, iosupplier1));
++            }
+             }
+          }
+ 
diff --git a/src/main/java/net/minecraftforge/common/extensions/IForgePackResources.java b/src/main/java/net/minecraftforge/common/extensions/IForgePackResources.java
index a42e324125..eccf3465f5 100644
--- a/src/main/java/net/minecraftforge/common/extensions/IForgePackResources.java
+++ b/src/main/java/net/minecraftforge/common/extensions/IForgePackResources.java
@@ -5,7 +5,12 @@
 
 package net.minecraftforge.common.extensions;
 
+import java.util.Collection;
+import org.jetbrains.annotations.Nullable;
+import net.minecraft.server.packs.PackResources;
 import net.minecraft.server.packs.PackType;
+import net.minecraft.server.packs.resources.ResourceManager;
+import net.minecraftforge.resource.DelegatingPackResources;
 
 public interface IForgePackResources
 {
@@ -20,4 +25,14 @@ public interface IForgePackResources
     default void initForNamespace(final String nameSpace) {}
 
     default void init(final PackType packType) {}
+
+    /**
+     * Gets a collection of {@code PackResource} instances nested inside this pack.
+     * Used to merge several packs into one entry in the resource pack selection UI without
+     * losing the ability for each pack to return a resource in
+     * {@link ResourceManager#getResourceStack(ResourceLocation)}
+     * @return Collection of nested {@code PackResource}, or null if this pack has no children
+     * @see DelegatingPackResources
+     */
+    @Nullable default Collection<PackResources> getChildren() { return null; }
 }
diff --git a/src/main/java/net/minecraftforge/resource/DelegatingPackResources.java b/src/main/java/net/minecraftforge/resource/DelegatingPackResources.java
index 57d8e1e2c9..07436ed80a 100644
--- a/src/main/java/net/minecraftforge/resource/DelegatingPackResources.java
+++ b/src/main/java/net/minecraftforge/resource/DelegatingPackResources.java
@@ -10,6 +10,7 @@ import com.google.common.collect.ImmutableMap;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -123,6 +124,12 @@ public class DelegatingPackResources extends AbstractPackResources
         return null;
     }
 
+    @Nullable
+    public Collection<PackResources> getChildren()
+    {
+        return delegates;
+    }
+
     private List<PackResources> getCandidatePacks(PackType type, ResourceLocation location)
     {
         Map<String, List<PackResources>> map = type == PackType.CLIENT_RESOURCES ? namespacesAssets : namespacesData;