Add Mixin to update banner patterns

build.gradle

@@ -4,6 +4,7 @@ plugins {
     id 'idea'
     id 'maven-publish'
     id 'net.neoforged.gradle.userdev' version '7.0.151'
+    id 'net.neoforged.gradle.mixin' version '7.0.151'
 }
 
 tasks.named('wrapper', Wrapper).configure {
@@ -103,6 +104,14 @@ repositories {
     }
 }
 
+mixin {
+    // add sourceSets.main, "${mod_id}.refmap.json"
+    // Sets up the mixin config; this gets added to run configurations and the manifest in the final jar
+    config "${mod_id}.mixins.json"
+
+    // Enables exporting mixin-changed classes to .mixin.out in the run folder
+    // debug.export = true
+}
 
 dependencies {
     // Specify the version of Minecraft to use.

src/main/java/com/legobmw99/allomancy/modules/consumables/item/VialItem.java

@@ -99,6 +99,7 @@ public static void fillVial(ItemStack stack, FlakeStorage storage) {
     /**
      * TEMPORARY: Used to port pre-1.20.5 worlds to post.
      * Loads custom NBT data and convets it to the data component.
+     * TODO: Remove in future version once worlds have updated
      */
     @Override
     public void verifyComponentsAfterLoad(ItemStack pStack) {

src/main/java/com/legobmw99/allomancy/modules/extras/mixin/BannerDFUMixin.java

@@ -0,0 +1,46 @@
+package com.legobmw99.allomancy.modules.extras.mixin;
+
+import com.legobmw99.allomancy.Allomancy;
+import com.legobmw99.allomancy.api.enums.Metal;
+import net.minecraft.resources.ResourceLocation;
+import net.minecraft.util.datafix.fixes.BannerPatternFormatFix;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Mutable;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+
+
+/**
+ * TEMPORARY: Used to port 1.20 banners to 1.21
+ * TODO: Remove in future version once worlds have updated
+ */
+@Mixin(BannerPatternFormatFix.class)
+public class BannerDFUMixin {
+    @Mutable
+    @Final
+    @Shadow
+    private static Map<String, String> PATTERN_ID_MAP;
+
+    @Inject(at = @At("RETURN"), method = "<clinit>")
+    private static void onConstruct(CallbackInfo info) {
+
+        Allomancy.LOGGER.info("Injecting to banner DFU");
+        var patternMap = new HashMap<>(PATTERN_ID_MAP);
+
+        for (Metal mt : Metal.values()) {
+            String name = mt.getName();
+            Allomancy.LOGGER.info("Redirecting banner pattern for {}", name);
+            patternMap.put("ALLOMANCY" + name.toUpperCase(Locale.ROOT),
+                           ResourceLocation.fromNamespaceAndPath(Allomancy.MODID, name).toString());
+        }
+
+        PATTERN_ID_MAP = patternMap;
+    }
+}

src/main/java/com/legobmw99/allomancy/modules/powers/CommonEventHandler.java

@@ -51,6 +51,7 @@ private CommonEventHandler() {}
     /**
      * TEMPORARY: Used to port Forge worlds to Neoforged.
      * Loads the player's data file and sees if they have an old forge Capability stored.
+     * TODO: Remove in future version once worlds have updated
      */
     @SubscribeEvent
     public static void onPlayerLoad(final PlayerEvent.LoadFromFile event) {

src/main/resources/META-INF/neoforge.mods.toml

@@ -40,6 +40,11 @@ authors = "${mod_authors}" #optional
 
 # The description text for the mod (multi line!) (#mandatory)
 description = '''${mod_description}'''
+
+# The [[mixins]] block allows you to declare your mixin config to FML so that it gets loaded.
+[[mixins]]
+config="${mod_id}.mixins.json"
+
 # A dependency - use the . to indicate dependency for a specific modid. Dependencies are optional.
 [[dependencies.${ mod_id }]] #optional
 # the modid of the dependency

src/main/resources/allomancy.mixins.json

@@ -0,0 +1,12 @@
+{
+  "required": true,
+  "minVersion": "0.8",
+  "package": "com.legobmw99.allomancy.modules.extras.mixin",
+  "compatibilityLevel": "JAVA_21",
+  "mixins": ["BannerDFUMixin"],
+  "client": [],
+  "server": [],
+  "injectors": {
+    "defaultRequire": 1
+  }
+}