public IActionResult AddItem(int orderId, int productId, int quantity)
        {
            var product = _productsService.Get(productId);

            if (product != null)
            {
                if (_ordersService.AddItem(orderId, product.ProductId, quantity) &&
                    _ordersService.UpdateTotal(orderId, _productsService.Get()))
                {
                    return(Ok(_ordersService.Get(orderId)));
                }
                return(StatusCode((int)HttpStatusCode.Conflict));
            }

            return(NotFound());
        }