using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CSharpDelegate
{
    public enum comparison
    {
        theFirstComesFirst = 1,
        theSecondComesFirst = 2
    }

    // A simple class to hold two items
    public class Pair
    {
        // Private array to hold the two objects
        private object[] thePair = new object[2];

        // The delegate declaration
        public delegate comparison
            WhichIsFirst(object obj1, object obj2);

        // Passed in constructor takes two objects,
        // added in order received
        public Pair(
            object firstObject,
            object secondObject)
        {
            thePair[0] = firstObject;
            thePair[1] = secondObject;
        }

        // Public method that orders the
        // two objects by whatever criteria the objects like!
        public void Sort(
            WhichIsFirst theDelegatedFunc)
        {
            if (theDelegatedFunc(thePair[0], thePair[1])
                == comparison.theSecondComesFirst)
            {
                object temp = thePair[0];
                thePair[0] = thePair[1];
                thePair[1] = temp;
            }
        }

        // Public method that orders the
        // two objects by the reverse of whatever criteria the
        // objects likes!
        public void ReverseSort(
            WhichIsFirst theDelegatedFunc)
        {
            if (theDelegatedFunc(thePair[0], thePair[1]) ==
                comparison.theFirstComesFirst)
            {
                object temp = thePair[0];
                thePair[0] = thePair[1];
                thePair[1] = temp;
            }
        }

        // Ask the two objects to give their string values
        public override string ToString()
        {
            return thePair[0].ToString() + ", "
                + thePair[1].ToString();
        }
    }

    public class Dog
    {
        private int weight;

        public Dog(int weight)
        {
            this.weight = weight;
        }

        // Dogs are sorted by weight
        public static comparison WhichDogComesFirst(
            Object o1, Object o2)
        {
            Dog d1 = (Dog)o1;
            Dog d2 = (Dog)o2;
            return d1.weight > d2.weight ?
                comparison.theSecondComesFirst :
                comparison.theFirstComesFirst;
        }
        public override string ToString()
        {
            return weight.ToString();
        }
    }

    class Tester
    {
        public void Run()
        {
            // Create  two dogs
            // and add them to a Pair object
            Dog Milo = new Dog(65);
            Dog Fred = new Dog(12);

            Pair dogPair = new Pair(Milo, Fred);
            Console.WriteLine("dogPair\t\t\t\t: {0}",
                dogPair.ToString());

            // Instantiate the delegate
            Pair.WhichIsFirst theDogDelegate =
                new Pair.WhichIsFirst(
                Dog.WhichDogComesFirst);

            // Sort using the delegate
            dogPair.Sort(theDogDelegate);
            Console.WriteLine("After Sort dogPair\t\t: {0}",
                dogPair.ToString());
            dogPair.ReverseSort(theDogDelegate);
            Console.WriteLine("After ReverseSort dogPair\t: {0}",
                dogPair.ToString());
        }

        static void Main()
        {
            Tester t = new Tester();
            t.Run();
            Console.ReadLine();
        }
    }
}