// Programmer: Dylan McDonald
// Class & Section: CS 54, Section <n>
// Date: January 30, 2007
// Purpose: To gain weight at Clayton's Cafeteria

#include <iostream>
using namespace std;

int main()
{
  /* delcare constants used in all parts */
  const int DONUTCAL = 450, ICECAL = 350, PICAL = 500;
  const int DONUTFAT = 18, ICEFAT = 20, PIFAT = 15;
  const double DONUTPRICE = 1.5, ICEPRICE = 2.2, PIPRICE = 3.141592;
  const double GRAM2KILO = 0.001, GRAM2LB = 0.0022046;
  int choice;
  double weightGain = 0.0;

  /* part I - display menu */
  /* part III added choice 4 */
  cout << "Welcome to Clayton's Cafeteria!" << endl;
  cout << "1) Jelly Donuts $1.50" << endl;
  cout << "2) Ice Cream $2.20" << endl;
  cout << "3) Cherry Pie $3.141592" << endl;
  cout << "4) Exit" << endl << endl;

  /* part III - wrap previous parts in a loop */
  do
  {
    /* part II - ask for what they want and validate it */
    /* part I is the same without the do...while loop */
    do
    {
      cout << "And what is your pleasure today? ";
      cin >> choice;
    } while (choice != 1 && choice != 2 && choice != 3 && choice != 4);
  
    /* part I - take the choice and print out the information */
    /* ...for donuts */
    if (choice == 1)
    {
      cout << "Your order costs $" << DONUTPRICE << ", has "
           << DONUTCAL << " calories, and "
           << DONUTFAT << " grams of fat." << endl;

      /* part III calculations */
      weightGain = weightGain + 4.2 * DONUTCAL + 75 * DONUTFAT;
    }
    /* ...for ice cream */
    else if (choice == 2)
    {
      cout << "Your order costs $" << ICEPRICE << ", has "
           << ICECAL << " calories, and "
           << ICEFAT << " grams of fat." << endl;

      /* part III calculations */
      weightGain = weightGain + 4.2 * ICECAL + 75 * ICEFAT;
    }
    /* ...for pie */
    else if (choice == 3)
    {
      cout << "Your order costs $" << PIPRICE << ", has "
           << PICAL << " calories, and "
           << PIFAT << " grams of fat." << endl;

      /* part III calculations */
      weightGain = weightGain + 4.2 * PICAL + 75 * PIFAT;
    }
    /* ...do nothing for the exit option */
    else if (choice == 4)
    {
      /* this semi colon is known as a "NULL statement" */
      /* it's a statement that just does nothing */
      ;
    }
    /* ...for items with DNE problems */
    else
    {
      cout << "There exists no such item!" << endl;
    }
  } while (choice != 4);

  /* part III conversion from grams to kilograms */
  /* (you could have also done grams to pounds) */
  weightGain = weightGain * GRAM2KILO;
  cout << "You can expect to gain " << weightGain << " kg." << endl;
  return 0;
}