using System;

​

public class Program

{

    public enum PromoTier

    {

        TierOne,

        TierTwo,

        TierThree

    }

​

    //delegate definition 

    public delegate string PromoLvl(double amnt);

    //class containing methods that difine and processes discount tiers

    public class Promotion

    {

        public double t1Percent = 0.10;

        public double t2Percent = 0.15;

        public double t3Percent = 0.25;

        public double UsrAmnt { get; set; }

​

        public double ProcessDiscount(double amnt, double percentage)

        {

            var discount = amnt * percentage;

            Console.WriteLine("You saved: $" + string.Format("{0:n}", discount));

            return amnt - discount;

        }

​

        public string LvlOne(double amnt)

        {

            var result = ProcessDiscount(amnt, t1Percent);

            return "Tier One 10% discount. You pay $" + string.Format("{0:n}", result);

        }

​

        public string LvlTwo(double amnt)

        {

            var result = ProcessDiscount(amnt, t2Percent);

            return "Tier Two 15% discount. You pay $" + string.Format("{0:n}", result);

        }

​

        public string LvlThree(double amnt)

        {

            var result = ProcessDiscount(amnt, t3Percent);

            return "Tier Three 25% discount. You Pay $" + string.Format("{0:n}", result);

        }

    }

    //prompts user for amount

    public double GetAmount()

    {

        Promotion promo = new Promotion();

        string amnt = string.Empty;

        bool isNum = false;

        do

        {

            Console.WriteLine("Enter a numeric value... press Enter");

            amnt = Console.ReadLine();

            double num;

            if(double.TryParse(amnt, out num)) 

            {

                isNum = true;

            }

        }

        while (string.IsNullOrEmpty(amnt) | !isNum);

        promo.UsrAmnt = double.Parse(amnt);

        return promo.UsrAmnt;

    }

    // returns a random tier selection

    public PromoTier GetPromoTier()

    {

        Random rand = new Random();

        int randNum = rand.Next(0, 3);

        PromoTier randTier = PromoTier.TierOne;

        switch (randNum)

        {

            case 0:

                randTier = PromoTier.TierOne;

                break;

            case 1:

                randTier = PromoTier.TierTwo;

                break;

            case 2:

                randTier = PromoTier.TierThree;

                break;

        }

​

        return randTier;

    }

    public void DisplayAmnt(double amnt)

    {

      Console.WriteLine(string.Format("Total before discount ${0}", amnt));

    }

    //method that uses the PromoLvl delegate to call a method from the Promotion class and displays the result in the console

    public void displayDiscount(PromoTier tier, double total)

    {

        Promotion promo = new Promotion();

        if (tier == PromoTier.TierOne)

        {

            PromoLvl myPromo = new PromoLvl(promo.LvlOne);

            DisplayAmnt(total);

            Console.WriteLine(myPromo(total));

        }

        else if (tier == PromoTier.TierTwo)

        {

            PromoLvl myPromo = new PromoLvl(promo.LvlTwo);

            DisplayAmnt(total);

            Console.WriteLine(myPromo(total));

        }

        else

        {

            PromoLvl myPromo = new PromoLvl(promo.LvlThree);

             DisplayAmnt(total);

            Console.WriteLine(myPromo(total));

        }

    }

​

    public static void Main()

    {

        Console.WriteLine("Awesome Promotion Discount Calculator");

        Program prgrm = new Program();

        PromoTier promoTier = prgrm.GetPromoTier();

        double amount = prgrm.GetAmount();

        if (amount > 0)

        {

            prgrm.displayDiscount(promoTier, amount);

        }

    }

}