public int ComputeCost(String drink, bool student, int amount)
{
if (!menu.ContainsKey(drink))
{
throw new Exception("No such drink exists");
}
IBeverage beverage = menu[drink];
if (amount > MAX_NUMBER_OF_DRINKS && beverage.isAmountLimited())
{
throw new Exception("Too many drinks, max " + MAX_NUMBER_OF_DRINKS);
}
int price = beverage.GetPrice();
if (student && beverage.isEligableForStudentDiscount())
{
price = price - price / STUDENT_DISCOUNT;
}
return(price * amount);
}