Container

public class RubyBarrelContainer extends Container {
    public final RubyBarrelTileEntity tileEntity;
    private final IWorldPosCallable canInteractWithCallable;

    public RubyBarrelContainer(final int windowId,
                               @NotNull final PlayerInventory playerInventory,
                               final RubyBarrelTileEntity tileEntity) {
        super(ContainersRegistry.RUBY_BARREL.get(), windowId);

        this.tileEntity = tileEntity;

        assert tileEntity.getWorld() != null;

        this.canInteractWithCallable = IWorldPosCallable.of(tileEntity.getWorld(), tileEntity.getPos());

        int startX = 8;
        int startY = 18;
        int slotSizePlus2 = 18;

        // Barrel inventory slot assignment
        for (int row = 0; row < 5; ++row) {
            for (int column = 0; column < 9; ++column) {
                this.addSlot(new Slot(tileEntity,
                        (row * 9) + column,
                        startX + (column * slotSizePlus2),
                        startY + (row * slotSizePlus2))
                );
            }
        }

        // Player inventory slot assignment
        int startPlayerInvY = startY * 5 + 32;

        for (int row = 0; row < 3; ++row) {
            for (int column = 0; column < 9; ++column) {
                this.addSlot(new Slot(playerInventory,
                        9 + (row * 9) + column,
                        startX + (column * slotSizePlus2),
                        startPlayerInvY + (row * slotSizePlus2))
                );
            }
        }

        // Hotbar inventory slot assignment
        int hotbarY = startPlayerInvY + (startPlayerInvY / 2) - 3;

        for (int column = 0; column < 9; column++) {
            this.addSlot(new Slot(playerInventory,
                    column,
                    startX + (column * slotSizePlus2),
                    hotbarY)
            );
        }
    }

    public RubyBarrelContainer(
            final int windowId, final PlayerInventory playerInventory, final PacketBuffer data) {
        this(windowId, playerInventory,
                getTileEntity(playerInventory, data));
    }

    private static RubyBarrelTileEntity getTileEntity(final PlayerInventory playerInventory,
                                                      final PacketBuffer data) {

        Objects.requireNonNull(playerInventory, "playerInventory cannot be null");
        Objects.requireNonNull(data, "data cannot be null");
        final TileEntity tileAtPos = playerInventory.player.world.getTileEntity(data.readBlockPos());

        if (tileAtPos instanceof RubyBarrelTileEntity) {
            return (RubyBarrelTileEntity) tileAtPos;
        }

        throw new IllegalStateException("Tile entity is not correct! " + tileAtPos);
    }

    @Override
    public boolean canInteractWith(@NotNull PlayerEntity playerIn) {
        return isWithinUsableDistance(
                canInteractWithCallable, playerIn, BlocksRegistry.RUBY_BARREL.get());
    }

    @Override
    public @NotNull ItemStack transferStackInSlot(@NotNull PlayerEntity playerIn, int index) {
        ItemStack itemstack = ItemStack.EMPTY;
        Slot slot = this.inventorySlots.get(index);
        if (slot != null && slot.getHasStack()) {
            ItemStack itemStack1 = slot.getStack();
            itemstack = itemStack1.copy();
            if (index < 36) {
                if (!this.mergeItemStack(itemStack1, 36, this.inventorySlots.size(), true)) {
                    return ItemStack.EMPTY;
                }
            } else if (!this.mergeItemStack(itemStack1, 0, 36, false)) {
                return ItemStack.EMPTY;
            }

            if (itemStack1.isEmpty()) {
                slot.putStack(ItemStack.EMPTY);
            } else {
                slot.onSlotChanged();
            }
        }
        return itemstack;
    }
}