public IActionResult Tamamla(PaymentForm form)
        {
            try
            {
                var user  = _userService.GetById(form.UserId);
                var order = new Order {
                    Cart            = _cartService.GetUserCart(user.Id).Result,
                    OrderDate       = DateTime.Now,
                    ShippingAddress = form.GetAddress()
                };

                // sipariş geçmişine ekle
                user.Orders.Add(order);
                _userService.Update(user);

                // sepeti boşalt
                order.Cart.Items         = new List <CartItem>();
                order.Cart.SubTotal      = 0;
                order.Cart.TotalDiscount = 0;
                order.Cart.TotalTax      = 0;
                order.Cart.TotalPrice    = 0;
                _cartService.Update(order.Cart);

                return(RedirectToAction("Index"));
            }
            catch (Exception exc)
            {
                return(View("Error"));
            }
        }