Merge pull request #5 from Salandora/StackableShulkerboxes

Empty stackable shulker boxes

src/main/java/carpet/mixins/ItemEntityMixin.java

@@ -0,0 +1,108 @@
+package carpet.mixins;
+
+import carpet.CarpetSettings;
+import carpet.helpers.InventoryHelper;
+import carpet.utils.IItemEntity;
+import net.minecraft.block.ShulkerBoxBlock;
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.EntityType;
+import net.minecraft.entity.ItemEntity;
+import net.minecraft.item.BlockItem;
+import net.minecraft.item.ItemStack;
+import net.minecraft.world.World;
+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;
+
+@Mixin(ItemEntity.class)
+public abstract class ItemEntityMixin extends Entity implements IItemEntity {
+    private static final int SHULKERBOX_MAX_STACK_AMOUNT = 64;
+
+    @Shadow private int age;
+    @Shadow private int pickupDelay;
+
+    public ItemEntityMixin(EntityType<?> entityType_1, World world_1) {
+        super(entityType_1, world_1);
+    }
+
+    @Override
+    public int getAge() {
+        return this.age;
+    }
+
+    @Override
+    public int getPickupDelay() {
+        return this.pickupDelay;
+    }
+
+    @Inject(method="<init>(Lnet/minecraft/world/World;DDDLnet/minecraft/item/ItemStack;)V", at = @At("RETURN"))
+    private void removeEmptyShulkerBoxTags(World worldIn, double x, double y, double z, ItemStack stack, CallbackInfo ci)
+    {
+        if (CarpetSettings.b_stackableShulkerBoxes
+                && stack.getItem() instanceof BlockItem
+                && ((BlockItem)stack.getItem()).getBlock() instanceof ShulkerBoxBlock)
+        {
+            if (InventoryHelper.cleanUpShulkerBoxTag(stack)) {
+                ((ItemEntity) (Object) this).setStack(stack);
+            }
+        }
+    }
+
+    @Redirect(
+            method = "method_20397",
+            at = @At(
+                    value = "INVOKE",
+                    target = "Lnet/minecraft/item/ItemStack;getMaxAmount()I"
+            )
+    )
+    private int getItemStackMaxAmount(ItemStack stack) {
+        if (CarpetSettings.b_stackableShulkerBoxes && stack.getItem() instanceof BlockItem && ((BlockItem)stack.getItem()).getBlock() instanceof ShulkerBoxBlock)
+            return SHULKERBOX_MAX_STACK_AMOUNT;
+
+        return stack.getMaxAmount();
+    }
+
+    @Inject(
+            method = "tryMerge(Lnet/minecraft/entity/ItemEntity;)V",
+            at = @At("HEAD"),
+            cancellable = true
+    )
+    private void tryStackShulkerBoxes(ItemEntity other, CallbackInfo ci)
+    {
+        ItemEntity self = (ItemEntity)(Object)this;
+        ItemStack selfStack = self.getStack();
+        if (!CarpetSettings.b_stackableShulkerBoxes || !(selfStack.getItem() instanceof BlockItem) || !(((BlockItem)selfStack.getItem()).getBlock() instanceof ShulkerBoxBlock)) {
+            return;
+        }
+
+        ItemStack otherStack = other.getStack();
+        if (selfStack.getItem() == otherStack.getItem()
+                && !InventoryHelper.shulkerBoxHasItems(selfStack)
+                && selfStack.hasTag() == otherStack.hasTag()
+                && selfStack.getAmount() + otherStack.getAmount() <= SHULKERBOX_MAX_STACK_AMOUNT)
+        {
+            int amount = Math.min(otherStack.getAmount(), SHULKERBOX_MAX_STACK_AMOUNT - selfStack.getAmount());
+
+            selfStack.addAmount(amount);
+            self.setStack(selfStack);
+
+            this.pickupDelay = Math.max(((IItemEntity)other).getPickupDelay(), this.pickupDelay);
+            this.age = Math.min(other.getAge(), this.age);
+
+            otherStack.subtractAmount(amount);
+            if (otherStack.isEmpty())
+            {
+                other.remove();
+            }
+            else
+            {
+                other.setStack(otherStack);
+            }
+            ci.cancel();
+        }
+    }
+
+}