using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;

namespace SwitchVsDictionaryBenchMark
{
    class Program
    {
        private static readonly Dictionary<string, Action> dictWithStrings = new Dictionary<string, Action>(3);
        private static readonly Dictionary<int, Action> dictWithInts = new Dictionary<int, Action>(20);
        private const int MillisecondsSleep = 10;

        static void Main(string[] args)
        {
            dictWithStrings.Add("Zero", Sleep);
            dictWithStrings.Add("One", Sleep);
            dictWithStrings.Add("Two", Sleep);

            const int iterations = 1000;

            var tsSwitch = Benchmark( () => SwitchTest("One"), iterations);

            var tsDict = Benchmark( () => DictTest("One"), iterations);
           
            Console.WriteLine("Difference in MS dict - switch with strings: {0}", tsDict - tsSwitch);

            var r = new Random();

            var switchWithIntMs = Benchmark(() => SwitchWithIntTest(r.Next(0, 20)), iterations);

            for (int i = 0; i < 20;i++ )
                dictWithInts.Add(i, Sleep);

            var dictWithIntsMs = Benchmark(() => DictWithIntTest(r.Next(0, 20)), iterations);

            Console.WriteLine("Difference in MS - dict - switch with ints: {0}", dictWithIntsMs - switchWithIntMs);

            Console.ReadLine();
        }

        private static long Benchmark(Action act, int iterations)
        {
            GC.Collect();
            act.Invoke(); // run once outside of loop to avoid initialization costs
            Stopwatch sw = Stopwatch.StartNew();
            for (int i = 0; i < iterations; i++)
            {
                act.Invoke();
            }
            sw.Stop();
            Console.WriteLine("MS per iteration: " + (sw.ElapsedMilliseconds / iterations).ToString());
            Console.WriteLine("total Elapsed MS: " + sw.ElapsedMilliseconds.ToString());

            return sw.ElapsedMilliseconds;
        }

        private static void SwitchTest(string testCase)
        {
            switch (testCase)
            {
                case "Zero":
                    Sleep();
                    break;
                case "One":
                    Sleep();
                    break;
                case "Two":
                    Sleep();
                    break;
                default:
                    Sleep();
                    break;
            }
        }

        private static void DictTest(string testCase)
        {
            Action command;
            if (dictWithStrings.TryGetValue(testCase, out command))
            {
                command();
            }    
        }

        private static void SwitchWithIntTest(int testCase)
        {
            switch (testCase)
            {
                case 0:
                    Sleep();
                    break;
                case 1:
                    Sleep();
                    break;
                case 2:
                    Sleep();
                    break;
                case 3:
                    Sleep();
                    break;
                case 4:
                    Sleep();
                    break;
                case 5:
                    Sleep();
                    break;
                case 6:
                    Sleep();
                    break;
                case 7:
                    Sleep();
                    break;
                case 8:
                    Sleep();
                    break;
                case 9:
                    Sleep();
                    break;
                case 10:
                    Sleep();
                    break;
                case 11:
                    Sleep();
                    break;
                case 12:
                    Sleep();
                    break;
                case 13:
                    Sleep();
                    break;
                case 14:
                    Sleep();
                    break;
                case 15:
                    Sleep();
                    break;
                case 16:
                    Sleep();
                    break;
                case 17:
                    Sleep();
                    break;
                case 18:
                    Sleep();
                    break;
                case 19:
                    Sleep();
                    break;
            }
        }

        private static void DictWithIntTest(int testCase)
        {
            Action command;
            if (dictWithInts.TryGetValue(testCase, out command))
            {
                command();
            }
        }

        private static void Sleep()
        {
            Thread.Sleep(MillisecondsSleep);
        }
    }
}