Block replacement working, but only on reload, not initial generation.

src/main/java/com/colen/postea/API/BlockKey.java

@@ -0,0 +1,38 @@
+package com.colen.postea.API;
+
+import java.util.Objects;
+
+import net.minecraft.block.Block;
+import net.minecraft.item.Item;
+
+public class BlockKey {
+
+    private final Block block;
+    private final int meta;
+
+    public BlockKey(Block block, int meta) {
+        this.block = block;
+        this.meta = meta;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (o == null) return false;
+        if (o instanceof BlockKey that) {
+            return (this.meta == that.meta) && (this.block == that.block);
+        } else return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(block, meta);
+    }
+
+    public int getDamage() {
+        return meta;
+    }
+
+    public Block getBlock() {
+        return block;
+    }
+}

src/main/java/com/colen/postea/API/BlockReplacementManager.java

@@ -0,0 +1,21 @@
+package com.colen.postea.API;
+
+import net.minecraft.block.Block;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class BlockReplacementManager {
+
+    private static final Map<BlockKey, BlockKey> replacementMap = new HashMap<>();
+
+    @SuppressWarnings("unused")
+    public static void addBlockReplacement(Block blockIn, int metadataIn, Block blockOut, int metadataOut) {
+        replacementMap.put(new BlockKey(blockIn, metadataIn), new BlockKey(blockOut, metadataOut));
+    }
+
+    @SuppressWarnings("unused")
+    public static BlockKey getBlockReplacement(Block blockIn, int metadataIn) {
+        return replacementMap.getOrDefault(new BlockKey(blockIn, metadataIn), null);
+    }
+}

src/main/java/com/colen/postea/API/ItemStackReplacementManager.java

@@ -5,19 +5,19 @@ import java.util.Map;
 
 import net.minecraft.item.Item;
 
-public class ReplacementManager {
+public class ItemStackReplacementManager {
 
     private static final Map<ItemStackKey, ItemStackKey> replacementMap = new HashMap<>();
 
-    // Public API for adding replacements.
+    // Public API for adding replacement ItemStacks.
 
     @SuppressWarnings("unused")
-    public static void addReplacement(Item itemIn, int metaIn, Item itemOut, int metaOut) {
+    public static void addItemReplacement(Item itemIn, int metaIn, Item itemOut, int metaOut) {
         replacementMap.put(new ItemStackKey(itemIn, metaIn), new ItemStackKey(itemOut, metaOut));
     }
 
     @SuppressWarnings("unused")
-    public static ItemStackKey getReplacement(Item itemIn, int metaIn) {
+    public static ItemStackKey getItemReplacement(Item itemIn, int metaIn) {
         return replacementMap.getOrDefault(new ItemStackKey(itemIn, metaIn), null);
     }
 }

src/main/java/com/colen/postea/Postea.java

@@ -1,9 +1,19 @@
 package com.colen.postea;
 
+import com.colen.postea.API.BlockReplacementManager;
+import com.colen.postea.API.ItemStackReplacementManager;
 import cpw.mods.fml.common.Mod;
+import cpw.mods.fml.common.event.FMLPreInitializationEvent;
+import net.minecraft.init.Blocks;
+import net.minecraft.item.Item;
 
 @Mod(modid = Tags.MODID, version = Tags.VERSION, name = Tags.MODNAME, acceptedMinecraftVersions = "[1.7.10]")
 @SuppressWarnings("unused")
 public class Postea {
 
+    @Mod.EventHandler
+    public void preInit(FMLPreInitializationEvent event) {
+        ItemStackReplacementManager.addItemReplacement(Item.getItemFromBlock(Blocks.grass), 0, Item.getItemFromBlock(Blocks.coal_ore), 10);
+        BlockReplacementManager.addBlockReplacement(Blocks.bedrock, 0, Blocks.wool, 2);
+    }
 }

src/main/java/com/colen/postea/mixins/PosteaLoadingPlugin.java

@@ -44,6 +44,7 @@ public final class PosteaLoadingPlugin implements IEarlyMixinLoader, IFMLLoading
     public List<String> getMixins(Set<String> loadedCoreMods) {
         final List<String> mixins = new ArrayList<>();
         mixins.add("MixinItemStack");
+        mixins.add("MixinChunk");
 
         return mixins;
     }

src/main/java/com/colen/postea/mixins/early/MixinChunk.java

@@ -0,0 +1,57 @@
+package com.colen.postea.mixins.early;
+
+import com.colen.postea.API.BlockKey;
+import com.colen.postea.API.BlockReplacementManager;
+import net.minecraft.block.Block;
+import net.minecraft.init.Blocks;
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.world.World;
+import net.minecraft.world.chunk.Chunk;
+import net.minecraft.world.chunk.storage.AnvilChunkLoader;
+import net.minecraft.world.chunk.storage.ExtendedBlockStorage;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
+
+@Mixin(AnvilChunkLoader.class)
+public abstract class MixinChunk {
+
+    @Inject(
+        method = "readChunkFromNBT(Lnet/minecraft/world/World;Lnet/minecraft/nbt/NBTTagCompound;)Lnet/minecraft/world/chunk/Chunk;",
+        at = @At("RETURN"),
+        cancellable = true
+    )
+    private void modifyChunkData(World world, NBTTagCompound compound, CallbackInfoReturnable<Chunk> cir) {
+        Chunk chunk = cir.getReturnValue();
+
+        // Iterate over each ExtendedBlockStorage. Kinda ugly but does the job...
+        for (ExtendedBlockStorage storage : chunk.getBlockStorageArray()) {
+            if (storage != null) { // Always check if storage isn't null before using it
+                for (int x = 0; x < 16; x++) {
+                    for (int y = 0; y < 16; y++) { // This is not a mistake, we do this on purpose because of how minecraft stores stuff.
+                        for (int z = 0; z < 16; z++) {
+
+                            // Get the current block and metadata at the position
+                            Block currentBlock = storage.getBlockByExtId(x, y, z);
+                            int currentMeta = storage.getExtBlockMetadata(x, y, z);
+
+                            // Check if there's a replacement for this block+metadata combination
+                            BlockKey replacement = BlockReplacementManager.getBlockReplacement(currentBlock, currentMeta);
+
+                            // If there's a replacement, set the new block and metadata
+                            if (replacement != null) {
+                                storage.func_150818_a(x, y, z, replacement.getBlock());
+                                storage.setExtBlockMetadata(x, y, z, replacement.getDamage());
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        cir.setReturnValue(chunk);
+    }
+
+
+}

src/main/java/com/colen/postea/mixins/early/MixinItemStack.java

@@ -12,7 +12,7 @@ import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 import com.colen.postea.API.ItemStackKey;
-import com.colen.postea.API.ReplacementManager;
+import com.colen.postea.API.ItemStackReplacementManager;
 
 @Mixin(ItemStack.class)
 public abstract class MixinItemStack {
@@ -24,7 +24,7 @@ public abstract class MixinItemStack {
 
     @Inject(method = "<init>(Lnet/minecraft/item/Item;II)V", at = @At("RETURN"))
     private void onConstructorReturn(Item item, int size, int metadata, CallbackInfo ci) {
-        ItemStackKey replacement = ReplacementManager.getReplacement(item, metadata);
+        ItemStackKey replacement = ItemStackReplacementManager.getItemReplacement(item, metadata);
 
         if (replacement == null) return;
 
@@ -35,7 +35,7 @@ public abstract class MixinItemStack {
 
     @Inject(method = "readFromNBT(Lnet/minecraft/nbt/NBTTagCompound;)V", at = @At("RETURN"))
     private void onReadFromNBTReturn(NBTTagCompound p_77963_1_, CallbackInfo ci) {
-        ItemStackKey replacement = ReplacementManager.getReplacement(field_151002_e, itemDamage);
+        ItemStackKey replacement = ItemStackReplacementManager.getItemReplacement(field_151002_e, itemDamage);
 
         if (replacement == null) return;