Skip first datapack reload

Implementation from https://github.com/MinecraftForge/MinecraftForge/pull/8163

Fixes https://github.com/MinecraftForge/MinecraftForge/issues/8125

src/main/java/org/embeddedt/modernfix/duck/ILevelSave.java

@@ -0,0 +1,5 @@
+package org.embeddedt.modernfix.duck;
+
+public interface ILevelSave {
+    public void runWorldPersistenceHooks();
+}

src/main/java/org/embeddedt/modernfix/mixin/LevelSaveMixin.java

@@ -0,0 +1,32 @@
+package org.embeddedt.modernfix.mixin;
+
+import net.minecraft.nbt.CompoundNBT;
+import net.minecraft.nbt.CompressedStreamTools;
+import net.minecraft.world.storage.SaveFormat;
+import org.embeddedt.modernfix.ModernFix;
+import org.embeddedt.modernfix.duck.ILevelSave;
+import org.embeddedt.modernfix.util.DummyServerConfiguration;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+
+import java.nio.file.Path;
+
+@Mixin(SaveFormat.LevelSave.class)
+public class LevelSaveMixin implements ILevelSave {
+    @Shadow @Final private SaveFormat this$0;
+
+    @Shadow @Final private Path saveDir;
+
+    public void runWorldPersistenceHooks() {
+        ((SaveFormatAccessor)this.this$0).invokeReadFromLevelData(this.saveDir.toFile(), (file, dataFixer) -> {
+            try {
+                CompoundNBT compoundTag = CompressedStreamTools.readCompressed(file);
+                net.minecraftforge.fml.WorldPersistenceHooks.handleWorldDataLoad((SaveFormat.LevelSave)(Object)this, new DummyServerConfiguration(), compoundTag);
+            } catch (Exception e) {
+                ModernFix.LOGGER.error("Exception reading {}", file, e);
+            }
+            return null;
+        });
+    }
+}

src/main/java/org/embeddedt/modernfix/mixin/MinecraftMixin.java

@@ -9,17 +9,24 @@ import net.minecraft.world.storage.IServerConfiguration;
 import net.minecraft.world.storage.SaveFormat;
 import org.embeddedt.modernfix.ModernFix;
 import org.embeddedt.modernfix.ModernFixClient;
+import org.embeddedt.modernfix.duck.ILevelSave;
 import org.spongepowered.asm.mixin.Mixin;
+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.Redirect;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
+import java.util.concurrent.ExecutionException;
 import java.util.function.Function;
 
 @Mixin(Minecraft.class)
-public class MinecraftMixin {
+public abstract class MinecraftMixin {
+    @Shadow public abstract Minecraft.PackManager reloadDatapacks(DynamicRegistries.Impl dynamicRegistries, Function<SaveFormat.LevelSave, DatapackCodec> worldStorageToDatapackFunction, Function4<SaveFormat.LevelSave, DynamicRegistries.Impl, IResourceManager, DatapackCodec, IServerConfiguration> quadFunction, boolean vanillaOnly, SaveFormat.LevelSave worldStorage) throws InterruptedException, ExecutionException;
+
     private long datapackReloadStartTime;
+    private int registryHash;
     @Inject(method = "reloadDatapacks", at = @At(value = "HEAD"))
     private void recordReloadStart(DynamicRegistries.Impl p_238189_1_, Function<SaveFormat.LevelSave, DatapackCodec> p_238189_2_, Function4<SaveFormat.LevelSave, DynamicRegistries.Impl, IResourceManager, DatapackCodec, IServerConfiguration> p_238189_3_, boolean p_238189_4_, SaveFormat.LevelSave p_238189_5_, CallbackInfoReturnable<Minecraft.PackManager> cir) {
         datapackReloadStartTime = System.nanoTime();
@@ -35,4 +42,21 @@ public class MinecraftMixin {
     private void recordWorldLoadStart(String worldName, DynamicRegistries.Impl dynamicRegistries, Function<SaveFormat.LevelSave, DatapackCodec> levelSaveToDatapackFunction, Function4<SaveFormat.LevelSave, DynamicRegistries.Impl, IResourceManager, DatapackCodec, IServerConfiguration> quadFunction, boolean vanillaOnly, Minecraft.WorldSelectionType selectionType, boolean creating, CallbackInfo ci) {
         ModernFixClient.worldLoadStartTime = System.nanoTime();
     }
+
+    @Redirect(method = "loadWorld(Ljava/lang/String;)V", at = @At(value = "INVOKE", target = "Lnet/minecraft/util/registry/DynamicRegistries;func_239770_b_()Lnet/minecraft/util/registry/DynamicRegistries$Impl;"))
+    private DynamicRegistries.Impl useNullRegistry() {
+        return null;
+    }
+
+    @Redirect(method = "loadWorld(Ljava/lang/String;Lnet/minecraft/util/registry/DynamicRegistries$Impl;Ljava/util/function/Function;Lcom/mojang/datafixers/util/Function4;ZLnet/minecraft/client/Minecraft$WorldSelectionType;Z)V", at = @At(value = "INVOKE", target = "Lnet/minecraft/client/Minecraft;reloadDatapacks(Lnet/minecraft/util/registry/DynamicRegistries$Impl;Ljava/util/function/Function;Lcom/mojang/datafixers/util/Function4;ZLnet/minecraft/world/storage/SaveFormat$LevelSave;)Lnet/minecraft/client/Minecraft$PackManager;", ordinal = 0))
+    private Minecraft.PackManager skipFirstReload(Minecraft client, DynamicRegistries.Impl dynamicRegistries, Function<SaveFormat.LevelSave, DatapackCodec> worldStorageToDatapackFunction, Function4<SaveFormat.LevelSave, DynamicRegistries.Impl, IResourceManager, DatapackCodec, IServerConfiguration> quadFunction, boolean vanillaOnly, SaveFormat.LevelSave levelSave, String worldName, DynamicRegistries.Impl originalRegistries, Function<SaveFormat.LevelSave, DatapackCodec> levelSaveToDatapackFunction, Function4<SaveFormat.LevelSave, DynamicRegistries.Impl, IResourceManager, DatapackCodec, IServerConfiguration> quadFunction2, boolean vanillaOnly2, Minecraft.WorldSelectionType selectionType, boolean creating) throws InterruptedException, ExecutionException {
+        if(!creating) {
+            ModernFix.LOGGER.warn("Skipping first reload, this is still experimental");
+            ((ILevelSave)levelSave).runWorldPersistenceHooks();
+            return null;
+        } else {
+            /* allow reload */
+            return reloadDatapacks(dynamicRegistries, worldStorageToDatapackFunction, quadFunction, vanillaOnly, levelSave);
+        }
+    }
 }

src/main/java/org/embeddedt/modernfix/mixin/SaveFormatAccessor.java

@@ -0,0 +1,15 @@
+package org.embeddedt.modernfix.mixin;
+
+import com.mojang.datafixers.DataFixer;
+import net.minecraft.world.storage.SaveFormat;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.gen.Invoker;
+
+import java.io.File;
+import java.util.function.BiFunction;
+
+@Mixin(SaveFormat.class)
+public interface SaveFormatAccessor {
+    @Invoker
+    <T> T invokeReadFromLevelData(File saveDir, BiFunction<File, DataFixer, T> levelDatReader);
+}

src/main/java/org/embeddedt/modernfix/util/DummyServerConfiguration.java

@@ -0,0 +1,150 @@
+package org.embeddedt.modernfix.util;
+
+import com.google.common.collect.ImmutableSet;
+import com.mojang.serialization.Lifecycle;
+import net.minecraft.nbt.CompoundNBT;
+import net.minecraft.util.datafix.codec.DatapackCodec;
+import net.minecraft.util.registry.DynamicRegistries;
+import net.minecraft.world.Difficulty;
+import net.minecraft.world.GameRules;
+import net.minecraft.world.GameType;
+import net.minecraft.world.WorldSettings;
+import net.minecraft.world.gen.settings.DimensionGeneratorSettings;
+import net.minecraft.world.storage.IServerConfiguration;
+import net.minecraft.world.storage.IServerWorldInfo;
+
+import javax.annotation.Nullable;
+import java.util.Set;
+
+public class DummyServerConfiguration implements IServerConfiguration {
+    @Override
+    public DatapackCodec getDatapackCodec() {
+        return DatapackCodec.VANILLA_CODEC;
+    }
+
+    @Override
+    public void setDatapackCodec(DatapackCodec codec) {
+
+    }
+
+    @Override
+    public boolean isModded() {
+        return true;
+    }
+
+    @Override
+    public Set<String> getServerBranding() {
+        return ImmutableSet.of("forge");
+    }
+
+    @Override
+    public void addServerBranding(String name, boolean isModded) {
+
+    }
+
+    @Nullable
+    @Override
+    public CompoundNBT getCustomBossEventData() {
+        return null;
+    }
+
+    @Override
+    public void setCustomBossEventData(@Nullable CompoundNBT nbt) {
+
+    }
+
+    @Override
+    public IServerWorldInfo getServerWorldInfo() {
+        return null;
+    }
+
+    @Override
+    public WorldSettings getWorldSettings() {
+        return null;
+    }
+
+    @Override
+    public CompoundNBT serialize(DynamicRegistries registries, @Nullable CompoundNBT hostPlayerNBT) {
+        return null;
+    }
+
+    @Override
+    public boolean isHardcore() {
+        return false;
+    }
+
+    @Override
+    public int getStorageVersionId() {
+        return 0;
+    }
+
+    @Override
+    public String getWorldName() {
+        return null;
+    }
+
+    @Override
+    public GameType getGameType() {
+        return null;
+    }
+
+    @Override
+    public void setGameType(GameType type) {
+
+    }
+
+    @Override
+    public boolean areCommandsAllowed() {
+        return false;
+    }
+
+    @Override
+    public Difficulty getDifficulty() {
+        return null;
+    }
+
+    @Override
+    public void setDifficulty(Difficulty difficulty) {
+
+    }
+
+    @Override
+    public boolean isDifficultyLocked() {
+        return false;
+    }
+
+    @Override
+    public void setDifficultyLocked(boolean locked) {
+
+    }
+
+    @Override
+    public GameRules getGameRulesInstance() {
+        return null;
+    }
+
+    @Override
+    public CompoundNBT getHostPlayerNBT() {
+        return null;
+    }
+
+    @Override
+    public CompoundNBT getDragonFightData() {
+        return null;
+    }
+
+    @Override
+    public void setDragonFightData(CompoundNBT nbt) {
+
+    }
+
+    @Override
+    public DimensionGeneratorSettings getDimensionGeneratorSettings() {
+        return null;
+    }
+
+    @Override
+    public Lifecycle getLifecycle() {
+        return Lifecycle.stable();
+    }
+}

src/main/resources/modernfix.mixins.json

@@ -6,7 +6,9 @@
   "refmap": "modernfix.refmap.json",
   "mixins": [
     "ModFileResourcePackMixin",
-    "VanillaPackMixin"
+    "VanillaPackMixin",
+    "LevelSaveMixin",
+    "SaveFormatAccessor"
   ],
   "client": [
     "MinecraftMixin"