public Receipt Checkout(ShoppingCart shoppingCart)
{
Receipt receipt = new Receipt();
if (shoppingCart == null)
{
throw new ArgumentNullException();
}
receipt.ReceiptId = _shoppingRepository.GetReceiptId();
receipt.ReceiptItems = shoppingCart.ShoppingItems;
receipt.TotalQuantity = receipt.ReceiptItems.Sum(x => x.ProductQuantity);
receipt.TotalAmount = receipt.ReceiptItems.Sum(x => x.ProductTotalPrice);
return(receipt);
}
