Добавлена функция проверки наличия продукции в логику хранения

SecuritySystem/SecuritySystemFileImplement/Implements/ShopStorage.cs

@@ -125,5 +125,50 @@ namespace SecuritySystemFileImplement.Implements
 
             return true;
         }
+
+        public bool CheckCountSecure(ISecureModel model, int count)
+        {
+            int store = source.Shops.Select(x => x.ShopSecures.Select(y => (y.Value.Item1.Id == model.Id ? y.Value.Item2 : 0)).Sum()).Sum();
+            return store >= count;
+        }
+
+        public bool SellSecures(ISecureModel model, int count)
+        {
+            var secure = source.Secures.FirstOrDefault(x => x.Id == model.Id);
+
+            if (secure == null || !CheckCountSecure(model, count))
+            {
+                throw new ArgumentNullException("В магазинах нет такого количества товара");
+            }
+
+            foreach (var shop in source.Shops)
+            {
+                var secures = shop.ShopSecures;
+                foreach (var elem in secures.Where(x => x.Value.Item1.Id == secure.Id))
+                {
+                    var selling = Math.Min(elem.Value.Item2, count);
+                    secures[elem.Value.Item1.Id] = (elem.Value.Item1, elem.Value.Item2 - selling);
+                    count -= selling;
+
+                    if (count <= 0)
+                    {
+                        break;
+                    }
+                }
+
+                shop.Update(new ShopBindingModel
+                {
+                    Id = model.Id,
+                    Name = shop.Name,
+                    Address = shop.Address,
+                    OpeningDate = shop.OpeningDate,
+                    ShopSecures = secures,
+                    MaxSecuresCount = shop.MaxSecuresCount
+                });
+            }
+
+            source.SaveShops();
+            return true;
+        }
     }
 }