Container Carpenter Bench

package minefantasy.mf2.block.crafting;

import minefantasy.mf2.block.tileentity.TileEntityCarpenter;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.player.InventoryPlayer;
import net.minecraft.inventory.Container;
import net.minecraft.inventory.Slot;
import net.minecraft.item.ItemStack;


public class ContainerCarpenterBench extends Container {

	protected TileEntityCarpenter tec;
	protected int PLAYER_INVENTORY_ROWS = 3;
	protected int PLAYER_INVENTORY_COLUMNS = 9;

	public ContainerCarpenterBench(TileEntityCarpenter te,
			InventoryPlayer player_inventory) {

		this.tec = te;
		addSlots(player_inventory);

	}

	@Override
	public boolean canInteractWith(EntityPlayer player) {
		return tec.isUseableByPlayer(player);
	}

	protected void addSlots(InventoryPlayer player_inventory) {

		this.addSlotToContainer(new Slot(tec, 0, 10, 23));

		int x = 0;
		// Add the player's inventory slots to the container


		//Slots 9-35
		for (int inventoryRowIndex = 0; inventoryRowIndex < PLAYER_INVENTORY_ROWS; ++inventoryRowIndex) {
			for (int inventoryColumnIndex = 0; inventoryColumnIndex < PLAYER_INVENTORY_COLUMNS; ++inventoryColumnIndex) {
				x++;
				System.out.println(x + ": " + (int)(inventoryColumnIndex + inventoryRowIndex * 9 + 9));
				this.addSlotToContainer(new Slot(player_inventory,
						inventoryColumnIndex + inventoryRowIndex * 9 + 9,
						7 + inventoryColumnIndex * 18,
						83 + inventoryRowIndex * 18));
			}
		}

		//slots 0-8
		// Add the player's action bar slots to the container
		for (int actionBarSlotIndex = 0; actionBarSlotIndex < PLAYER_INVENTORY_COLUMNS; ++actionBarSlotIndex) {
			this.addSlotToContainer(new Slot(player_inventory,
					actionBarSlotIndex, 7 + actionBarSlotIndex * 18, 177));
		}
	}
	@Override
	public ItemStack transferStackInSlot(EntityPlayer player, int sn)
	{
		ItemStack itemstack = null;
        Slot slot = (Slot)this.inventorySlots.get(sn);

        if (slot != null && slot.getHasStack())
        {
            ItemStack itemstack1 = slot.getStack();
            itemstack = itemstack1.copy();

            if (sn < 9)
            {
                if (!this.mergeItemStack(itemstack1, 9, 36, true))
                {
                    return null;
                }
            }
            else if (!this.mergeItemStack(itemstack1, 0, 9, false))
            {
                return null;
            }

            if (itemstack1.stackSize == 0)
            {
                slot.putStack((ItemStack)null);
            }
            else
            {
                slot.onSlotChanged();
            }
        }

        return itemstack;
	}



}