GuiHandler

public class GuiHandler implements IGuiHandler
{
    private Minecraft mc;

    @Override
    public Object getServerGuiElement(int ID, EntityPlayer player, World world, int x, int y, int z)
    {
        TileEntity tileEntity = world.getTileEntity(x, y, z);
        mc = Minecraft.getMinecraft();

        switch(ID)
        {
        case 0: return ID == 0 ? new ContainerAltar(player.inventory, (TileEntityAltar) tileEntity) : null;
        case 2: return ID == 2 ? new ContainerCobaltFurnace(player.inventory, (TileEntityCobaltFurnace) tileEntity) : null;
        case 3: return ID == 3 ? new ContainerRitualStone(player.inventory, (TileEntityRitualStone) tileEntity) : null;
        case 4: return ID == 4 && world.getBlock(x, y, z) == CMStuff.cobexworkbench ? new ContainerBlueWoodWorkBench(player.inventory, world, x, y, z) : null;
        case 5:

            ItemStack[] armor = mc.thePlayer.inventory.armorInventory;

            if (player != null) {
                System.out.println("player");
                if (player.getHeldItem() != null) {
                    System.out.println("hold in hands");
                    if (player.getHeldItem().getItem() == CMStuff.cobaltbackpack) {
                        System.out.println("right item in Hands");
                        System.out.println("hands/Server");
                        return ID == 5 ? new ContainerBackpack(player, player.inventory, new InventoryBackpack(player.getHeldItem())) : null;
                    }
                }
                else if(armor[2] != null)
                {
                    System.out.println("not holding");
                    System.out.println("in armor slot");
                    Item item = armor[2].getItem();
                    if(item instanceof ItemArmor)
                    {
                        System.out.println("armoritem in slot");
                        ItemArmor itemA = (ItemArmor) item;
                        if(itemA.getArmorMaterial() == CMStuff.WoolArmor)
                        {
                            ItemStack backpack = armor[2];
                            System.out.println("right item");
                            System.out.println("armor slot/Server");
                            return ID == 5 ? new ContainerBackpack(player, player.inventory, new InventoryBackpack(backpack)) : null;
                        }
                    }
                }
            }
        }

        return null;
    }

    @Override
    public Object getClientGuiElement(int ID, EntityPlayer player, World world, int x, int y, int z)
    {
        TileEntity tileEntity = world.getTileEntity(x, y, z);

        switch(ID)
        {
        case 0: return ID == 0 ? new GuiAltar(player.inventory, (TileEntityAltar) tileEntity) : null;
        case 1: return ID == 1 ? new GuiRecipeBook(player) : null;
        case 2: return ID == 2 ? new GuiCobaltFurnace(player.inventory, (TileEntityCobaltFurnace) tileEntity) : null;
        case 3: return ID == 3 ? new GuiRitualStone(player.inventory, (TileEntityRitualStone) tileEntity) : null;
        case 4: return ID == 4 && world.getBlock(x, y, z) == CMStuff.cobexworkbench ? new GuiBlueWoodWorkBench(player.inventory, world, x, y, z) : null;
        case 5:

            ItemStack[] armor = mc.thePlayer.inventory.armorInventory;

            if (player != null) {
                System.out.println("player");
                if (player.getHeldItem() != null) {
                    System.out.println("hold in hands");
                    if (player.getHeldItem().getItem() == CMStuff.cobaltbackpack) {
                        System.out.println("right item in Hands");
                        System.out.println("hands/Client");
                        return ID == 5 ? new GuiBackpack((ContainerBackpack) new ContainerBackpack(player, player.inventory, new InventoryBackpack(player.getHeldItem()))) : null;
                    }
                }
                else if(armor[2] != null)
                {
                    System.out.println("not holding");
                    System.out.println("in armor slot");
                    Item item = armor[2].getItem();
                    if(item instanceof ItemArmor)
                    {
                        System.out.println("armoritem in slot");
                        ItemArmor itemA = (ItemArmor) item;
                        if(itemA.getArmorMaterial() == CMStuff.WoolArmor)
                        {
                            ItemStack backpack = armor[2];
                            System.out.println("right item");
                            System.out.println("armor slot/Client");
                            return ID == 5 ? new GuiBackpack((ContainerBackpack) new ContainerBackpack(player, player.inventory, new InventoryBackpack(backpack))) : null;
                        }
                    }
                }
            }
        }
        return null;
    }

}