public Decimal AddItem(Product product, Decimal quantity)
{
if (cardItems.ContainsKey(product))
{
if (cardItems[product] + quantity > 0)
{
cardItems[product] += quantity;
}
else
{
throw new Exception(product.Name +" quantity should be greater than zero.");
}
}
else
{
if (quantity > 0)
{
cardItems.Add(product, quantity);
}
else
{
throw new Exception(product.Name + " quantity should be greater than zero.");
}
}
return cardItems[product];
}
public void RemoveItem(Product product)
{
cardItems.Remove(product);
}