New LootTable interaction system and event.

Modders can now modify and reference internal elements of a loot table by name.
Editing can ONLY be done in the event and any external editing will cause a exception to be thrown.
See this gist for more information: https://gist.github.com/LexManos/77c983d67b9ad27010428478b66d50fd

src/main/java/net/minecraftforge/common/ForgeHooks.java

@@ -3,12 +3,21 @@ package net.minecraftforge.common;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.util.ArrayList;
+import java.util.Deque;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Random;
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import com.google.common.base.Throwables;
+import com.google.common.collect.Queues;
+import com.google.common.collect.Sets;
+import com.google.gson.Gson;
+import com.google.gson.JsonObject;
+import com.google.gson.JsonParseException;
+
 import net.minecraft.block.Block;
 import net.minecraft.block.BlockLiquid;
 import net.minecraft.block.material.Material;
@@ -47,6 +56,8 @@ import net.minecraft.util.DamageSource;
 import net.minecraft.util.EnumActionResult;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.EnumHand;
+import net.minecraft.util.JsonUtils;
+import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.WeightedRandom;
 import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
@@ -61,6 +72,10 @@ import net.minecraft.world.IBlockAccess;
 import net.minecraft.world.World;
 import net.minecraft.world.WorldSettings;
 import net.minecraft.world.WorldSettings.GameType;
+import net.minecraft.world.storage.loot.LootEntry;
+import net.minecraft.world.storage.loot.LootTable;
+import net.minecraft.world.storage.loot.LootTableManager;
+import net.minecraft.world.storage.loot.conditions.LootCondition;
 import net.minecraftforge.common.util.BlockSnapshot;
 import net.minecraftforge.event.AnvilUpdateEvent;
 import net.minecraftforge.event.ForgeEventFactory;
@@ -970,4 +985,132 @@ public class ForgeHooks
     {
         MinecraftForge.EVENT_BUS.post(new PlayerInteractEvent.RightClickEmpty(player, hand));
     }
+
+    private static ThreadLocal<Deque<LootTableContext>> lootContext = new ThreadLocal<Deque<LootTableContext>>();
+    private static LootTableContext getLootTableContext()
+    {
+        LootTableContext ctx = lootContext.get().peek();
+
+        if (ctx == null)
+            throw new JsonParseException("Invalid call stack, could to grab json context!"); // Show I throw this? Do we care about custom deserializers outside the manager?
+
+        return ctx;
+    }
+    public static LootTable loadLootTable(Gson gson, ResourceLocation name, String data, boolean custom)
+    {
+        Deque<LootTableContext> que = lootContext.get();
+        if (que == null)
+        {
+            que = Queues.newArrayDeque();
+            lootContext.set(que);
+        }
+
+        LootTable ret = null;
+        try
+        {
+            que.push(new LootTableContext(name, custom));
+            ret = gson.fromJson(data, LootTable.class);
+            que.pop();
+        }
+        catch (JsonParseException e)
+        {
+            que.pop();
+            throw e;
+        }
+
+        if (!custom)
+            ret = ForgeEventFactory.loadLootTable(name, ret);
+
+        return ret;
+    }
+
+    private static class LootTableContext
+    {
+        public final ResourceLocation name;
+        private final boolean vanilla;
+        public final boolean custom;
+        public int poolCount = 0;
+        public int entryCount = 0;
+        private HashSet<String> entryNames = Sets.newHashSet();
+
+        private LootTableContext(ResourceLocation name, boolean custom)
+        {
+            this.name = name;
+            this.custom = custom;
+            this.vanilla = "minecraft".equals(this.name.getResourceDomain());
+        }
+
+        private void resetPoolCtx()
+        {
+            this.entryCount = 0;
+            this.entryNames.clear();
+        }
+
+        public String validateEntryName(String name)
+        {
+            if (!this.entryNames.contains(name))
+            {
+                this.entryNames.add(name);
+                return name;
+            }
+
+            if (!this.vanilla)
+                throw new JsonParseException("Loot Table \"" + this.name.toString() + "\" Duplicate entry name \"" + name + "\" for pool #" + (this.poolCount - 1) + " entry #" + (this.entryCount-1));
+
+            int x = 0;
+            while (this.entryNames.contains(name + "#" + x))
+                x++;
+
+            name = name + "#" + x;
+            this.entryNames.add(name);
+
+            return name;
+        }
+    }
+
+    public static String readPoolName(JsonObject json)
+    {
+        LootTableContext ctx = ForgeHooks.getLootTableContext();
+        ctx.resetPoolCtx();
+
+        if (json.has("name"))
+            return JsonUtils.getString(json, "name");
+
+        if (ctx.custom)
+            return "custom#" + json.hashCode(); //We don't care about custom ones modders shouldn't be editing them!
+
+        ctx.poolCount++;
+
+        if (!ctx.vanilla)
+            throw new JsonParseException("Loot Table \"" + ctx.name.toString() + "\" Missing `name` entry for pool #" + (ctx.poolCount - 1));
+
+        return ctx.poolCount == 1 ? "main" : "pool" + (ctx.poolCount - 1);
+    }
+
+    public static String readLootEntryName(JsonObject json, String type)
+    {
+        LootTableContext ctx = ForgeHooks.getLootTableContext();
+        ctx.entryCount++;
+
+        if (json.has("entryName"))
+            return ctx.validateEntryName(JsonUtils.getString(json, "EntryName"));
+
+        if (ctx.custom)
+            return "custom#" + json.hashCode(); //We don't care about custom ones modders shouldn't be editing them!
+
+        String name = null;
+        if ("item".equals(type))
+            name = JsonUtils.getString(json, "name");
+        else if ("loot_table".equals(type))
+            name = JsonUtils.getString(json, "name");
+        else if ("empty".equals(type))
+            name = "empty";
+
+        return ctx.validateEntryName(name);
+    }
+
+
+    //TODO: Some registry to support custom LootEntry types?
+    public static LootEntry deserializeJsonLootEntry(String type, JsonObject json, int weight, int quality, LootCondition[] conditions){ return null; }
+    public static String getLootEntryType(LootEntry entry){ return null; } //Companion to above function
 }

src/main/java/net/minecraftforge/event/ForgeEventFactory.java

@@ -24,6 +24,7 @@ import net.minecraft.util.DamageSource;
 import net.minecraft.util.EnumActionResult;
 import net.minecraft.util.EnumFacing;
 import net.minecraft.util.EnumHand;
+import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.SoundCategory;
 import net.minecraft.util.SoundEvent;
 import net.minecraft.util.math.BlockPos;
@@ -39,6 +40,7 @@ import net.minecraft.world.chunk.ChunkPrimer;
 import net.minecraft.world.chunk.IChunkGenerator;
 import net.minecraft.world.storage.IPlayerFileData;
 import net.minecraft.world.storage.SaveHandler;
+import net.minecraft.world.storage.loot.LootTable;
 import net.minecraftforge.client.event.ClientChatReceivedEvent;
 import net.minecraftforge.client.event.RenderBlockOverlayEvent;
 import net.minecraftforge.client.event.RenderBlockOverlayEvent.OverlayType;
@@ -541,4 +543,12 @@ public class ForgeEventFactory
         MinecraftForge.EVENT_BUS.post(pre ? new PopulateChunkEvent.Pre(gen, world, rand, x, z, hasVillageGenerated) : new PopulateChunkEvent.Post(gen, world, rand, x, z, hasVillageGenerated));
     }
 
+    public static LootTable loadLootTable(ResourceLocation name, LootTable table)
+    {
+        LootTableLoadEvent event = new LootTableLoadEvent(name, table);
+        if (MinecraftForge.EVENT_BUS.post(event))
+            return LootTable.EMPTY_LOOT_TABLE;
+        return event.getTable();
+    }
+
 }

src/main/java/net/minecraftforge/event/LootTableLoadEvent.java

@@ -0,0 +1,43 @@
+package net.minecraftforge.event;
+
+import net.minecraft.util.ResourceLocation;
+import net.minecraft.world.storage.loot.LootTable;
+import net.minecraftforge.fml.common.eventhandler.Cancelable;
+import net.minecraftforge.fml.common.eventhandler.Event;
+
+/**
+ * Event fired when a LootTable json is loaded from json.
+ * This event is fired whenever resources are loaded, or when the server starts.
+ * This event will NOT be fired for LootTables loaded from the world folder, these are
+ * considered configurations files and should not be modified by mods.
+ *
+ * Canceling the event will make it load a empty loot table.
+ *
+ */
+@Cancelable
+public class LootTableLoadEvent extends Event
+{
+    private final ResourceLocation name;
+    private LootTable table;
+
+    public LootTableLoadEvent(ResourceLocation name, LootTable table)
+    {
+        this.name = name;
+        this.table = table;
+    }
+
+    public ResourceLocation getName()
+    {
+        return this.name;
+    }
+
+    public LootTable getTable()
+    {
+        return this.table;
+    }
+
+    public void setTable(LootTable table)
+    {
+        this.table = table;
+    }
+}