// Запрос на списание конкретного товара
        public ActionResult ProductToWritingOff(int productId)
        {
            int sellerLocation = GetSellerLocation();
            var item = _context.SalePoints.Find(sellerLocation).Storage;
            double count = item.First(p => p.ProductId == productId).Count;
            string name = item.First(p => p.ProductId == productId).Product.Name;

            ViewBag.Count = count;
            ViewBag.ProductName = name;

            var woff = new WritingOffProduct { ProductId = productId };

            return View(woff);
        }
        public ActionResult ProductToWritingOff(WritingOffProduct product)
        {
            if (ModelState.IsValid)
            {
                ViewBag.ProductName = _context.Products.Find(product.ProductId).Name;
                return View("ConfirmWritingOff", product);
            }

            return View(product);
        }
        public ActionResult ConfirmWritingOff(WritingOffProduct product)
        {
            int sellerLocation = GetSellerLocation();
            var storage = _context.SalePoints.Find(sellerLocation).Storage
                .First(p => p.ProductId == product.ProductId).Count -= product.Count;
            product.Date = DateTime.Now;
            product.SalePointId = sellerLocation;
            product.UserId = _context.Users.First(u => u.UserName == User.Identity.Name).Id;
            _context.WritingOffProducts.Add(product);
            _context.SaveChanges();

            var listOfProducts = _context.SalePoints.Find(sellerLocation).Storage.ToList();

            return View("WritingOff",listOfProducts);
        }