Paper/nms-patches/TileEntityFurnace.patch

--- a/net/minecraft/server/TileEntityFurnace.java
+++ b/net/minecraft/server/TileEntityFurnace.java
@@ -7,6 +7,15 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import javax.annotation.Nullable;
+// CraftBukkit start
+import java.util.List;
+import org.bukkit.craftbukkit.block.CraftBlock;
+import org.bukkit.craftbukkit.entity.CraftHumanEntity;
+import org.bukkit.craftbukkit.inventory.CraftItemStack;
+import org.bukkit.entity.HumanEntity;
+import org.bukkit.event.inventory.FurnaceBurnEvent;
+import org.bukkit.event.inventory.FurnaceSmeltEvent;
+// CraftBukkit end
 
 public class TileEntityFurnace extends TileEntityContainer implements IWorldInventory, RecipeHolder, AutoRecipeOutput, ITickable {
 
@@ -91,6 +100,31 @@
         return map;
     }
 
+    // CraftBukkit start - add fields and methods
+    private int maxStack = MAX_STACK;
+    public List<HumanEntity> transaction = new java.util.ArrayList<HumanEntity>();
+
+    public List<ItemStack> getContents() {
+        return this.items;
+    }
+
+    public void onOpen(CraftHumanEntity who) {
+        transaction.add(who);
+    }
+
+    public void onClose(CraftHumanEntity who) {
+        transaction.remove(who);
+    }
+
+    public List<HumanEntity> getViewers() {
+        return transaction;
+    }
+
+    public void setMaxStackSize(int size) {
+        maxStack = size;
+    }
+    // CraftBukkit end
+
     public TileEntityFurnace() {
         super(TileEntityTypes.FURNACE);
         this.items = NonNullList.a(3, ItemStack.a);
@@ -236,9 +270,20 @@
                 IRecipe irecipe = this.world.getCraftingManager().b(this, this.world);
 
                 if (!this.isBurning() && this.canBurn(irecipe)) {
-                    this.burnTime = fuelTime(itemstack);
+                    // CraftBukkit start
+                    CraftItemStack fuel = CraftItemStack.asCraftMirror(itemstack);
+
+                    FurnaceBurnEvent furnaceBurnEvent = new FurnaceBurnEvent(CraftBlock.at(this.world, this.position), fuel, fuelTime(itemstack));
+                    this.world.getServer().getPluginManager().callEvent(furnaceBurnEvent);
+
+                    if (furnaceBurnEvent.isCancelled()) {
+                        return;
+                    }
+
+                    this.burnTime = furnaceBurnEvent.getBurnTime();
                     this.ticksForCurrentFuel = this.burnTime;
-                    if (this.isBurning()) {
+                    if (this.isBurning() && furnaceBurnEvent.isBurning()) {
+                        // CraftBukkit end
                         flag1 = true;
                         if (!itemstack.isEmpty()) {
                             Item item = itemstack.getItem();
@@ -279,7 +324,7 @@
     }
 
     private int s() {
-        FurnaceRecipe furnacerecipe = (FurnaceRecipe) this.world.getCraftingManager().b(this, this.world);
+        FurnaceRecipe furnacerecipe = (this.hasWorld()) ? (FurnaceRecipe) this.world.getCraftingManager().b(this, this.world) : null; // CraftBukkit - SPIGOT-4302
 
         return furnacerecipe != null ? furnacerecipe.h() : 200;
     }
@@ -306,11 +351,38 @@
             ItemStack itemstack1 = irecipe.d();
             ItemStack itemstack2 = (ItemStack) this.items.get(2);
 
+            // CraftBukkit start - fire FurnaceSmeltEvent
+            CraftItemStack source = CraftItemStack.asCraftMirror(itemstack);
+            org.bukkit.inventory.ItemStack result = CraftItemStack.asBukkitCopy(itemstack1);
+
+            FurnaceSmeltEvent furnaceSmeltEvent = new FurnaceSmeltEvent(this.world.getWorld().getBlockAt(position.getX(), position.getY(), position.getZ()), source, result);
+            this.world.getServer().getPluginManager().callEvent(furnaceSmeltEvent);
+
+            if (furnaceSmeltEvent.isCancelled()) {
+                return;
+            }
+
+            result = furnaceSmeltEvent.getResult();
+            itemstack1 = CraftItemStack.asNMSCopy(result);
+
+            if (!itemstack1.isEmpty()) {
+                if (itemstack2.isEmpty()) {
+                    this.items.set(2, itemstack1.cloneItemStack());
+                } else if (CraftItemStack.asCraftMirror(itemstack2).isSimilar(result)) {
+                    itemstack2.add(itemstack1.getCount());
+                } else {
+                    return;
+                }
+            }
+
+            /*
             if (itemstack2.isEmpty()) {
                 this.items.set(2, itemstack1.cloneItemStack());
             } else if (itemstack2.getItem() == itemstack1.getItem()) {
                 itemstack2.add(1);
             }
+            */
+            // CraftBukkit end
 
             if (!this.world.isClientSide) {
                 this.a(this.world, (EntityPlayer) null, irecipe);