Make Furnace Support More Than One Count of Output

[Phoupraw]

Description

In vanilla code, AbstractCookingRecipe natively supports more than one item count of output. However, AbstractFurnaceBlockEntity outputs correct count of items only if there is no item in the result slot. If there is existing item in the result slot, AbstractFurnaceBlockEntity just increases its count by one but not the actual count of the recipe output.

if (itemStack3.isEmpty()) {
    slots.set(2, itemStack2.copy());
} else if (itemStack3.isOf(itemStack2.getItem())) {
    itemStack3.increment(1);
}

I wrote a little mixin to fix it. A modder suggested me to commit my fix to Fabric API to get it fixed for everyone.

@Mixin(AbstractFurnaceBlockEntity.class)
abstract class MAbstractFurnaceBlockEntity {

    @Unique
    private static final ThreadLocal<ItemStack> LOCAL_recipe_output = new ThreadLocal<>();

    @Redirect(method = "craftRecipe", at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;increment(I)V"))
    private static void correctIncrement(ItemStack instance, int amount) {
        instance.increment(LOCAL_recipe_output.get().getCount());
    }

    /**
     @param itemStack recipe output
     @param itemStack2 result slot
     */
    @Inject(method = "canAcceptRecipeOutput", at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;areItemsEqual(Lnet/minecraft/item/ItemStack;Lnet/minecraft/item/ItemStack;)Z"), cancellable = true, locals = LocalCapture.CAPTURE_FAILHARD)
    private static void correctPredicate(DynamicRegistryManager registryManager, @Nullable Recipe<?> recipe, DefaultedList<ItemStack> slots, int count, CallbackInfoReturnable<Boolean> cir, ItemStack itemStack, ItemStack itemStack2) {
        LOCAL_recipe_output.set(itemStack);
        cir.setReturnValue(itemStack2.isEmpty() || ItemStack.canCombine(itemStack, itemStack2) && itemStack.getCount() + itemStack2.getCount() <= itemStack2.getMaxCount());
    }

}