/// <summary>
/// This method subtract money from the accountBalance. This also adds to the receipt printout. Since we have a built-in summation of products, this also prevents inaccurate repeats.
/// </summary>
/// <param name="catering"></param>
/// <param name="cateringItem"></param>
/// <param name="userQuantity"></param>
public void SubtractPurchase(Catering catering, CateringItem cateringItem, int userQuantity)
{
accountBalance -= userQuantity * cateringItem.Price;
if (cateringItem.QuantityInStock - userQuantity >= 0)
{
cateringItem.QuantityInStock -= userQuantity;
if (!catering.AllPurchasedItems.Contains(cateringItem))
{
catering.PurchasedAdd(cateringItem);
}
}
}
