using System;

​

public enum Action { Rock, Paper, Scissor };

public enum Result { Tie, PlayerWon, ComputerWon }

​

public class Program {

    public static Random rand;

    public static void Main() {

        // static variable used in GetComputerChoice

        rand = new Random();

        int playerPoints = 0;

        int computerPoints = 0;

        Console.WriteLine("How many rounds would you like to play?");

        int rounds = GetDesiredRounds();

        for(var round = 1; round <= rounds; round++) {

            Console.WriteLine("Round {0} Begins", round);

            Console.WriteLine("Which hand do you choose(Rock, Paper, Scissor)? ");

            var playerAction = GetPlayerAction();

            Console.WriteLine("You picked: {0}", playerAction.ToString());

            var computerAction = GetComputerAction();

            Console.WriteLine("Your opponent picked: {0}", computerAction.ToString());

​

            switch(CalculateResult(playerAction, computerAction)) {

                case Result.PlayerWon:

                    Console.WriteLine("You won the round! You gained a point.");

                    playerPoints++;

                    break;

                case Result.ComputerWon:

                    Console.WriteLine("Computer won the round! Computer gained a point.");

                    computerPoints++;

                    break;

                case Result.Tie:

                    Console.WriteLine("Round tied. You and the computer gained a point.");

                    playerPoints++;

                    computerPoints++;

                    break;

            }

            Console.WriteLine();

        }

        Console.WriteLine("Results - Player {0}, Computer {1}", playerPoints, computerPoints);

        if (playerPoints == computerPoints) {

            Console.WriteLine("Tie Game");  

        } else {

            bool isPlayerWinner = playerPoints > computerPoints;

            Console.WriteLine("{0} won the game!", isPlayerWinner ? "Player" : "Computer"); 

        }

    }

    public static int GetDesiredRounds() {

        int result;

        do {

            var input = Console.ReadLine();

            if(Int32.TryParse(input, out result)) {

                return result;

            } else {

                Console.WriteLine("Invalid input. Please input a number.");

            }

        } while(true);

    }

    public static Action GetPlayerAction() {

        Action result;

        do {

            var input = Console.ReadLine();

            // Second param tells to ignore case of string

            if(Action.TryParse(input, true, out result)) {

                return result;  

            } else {

                Console.WriteLine("Invalid action {0}. Please input 'Rock', 'Paper' or 'Scissors'.", input);

            }

        } while(true);

    }

    public static Action GetComputerAction() {

        // Gets a random number between 1 (Action.Rock) and 4 (Action.Scissor + 1)

        // This will result in the values 1 (Rock), 2 (Paper), or 3 (Scissor)

        return (Action)rand.Next((int)Action.Rock, (int)Action.Scissor + 1);

    }

    public static Result CalculateResult(Action p, Action c) {

        switch(p) {

            case Action.Rock:

                switch (c) {

                    case Action.Rock:    return Result.Tie;

                    case Action.Paper:   return Result.ComputerWon;

                    case Action.Scissor: return Result.PlayerWon;

                }

                break;

            case Action.Paper:

                switch (c) {

                    case Action.Rock:    return Result.PlayerWon;

                    case Action.Paper:   return Result.Tie;

                    case Action.Scissor: return Result.ComputerWon;

                }

                break;

            case Action.Scissor:

                switch (c) {

                    case Action.Rock:    return Result.ComputerWon;

                    case Action.Paper:   return Result.PlayerWon;

                    case Action.Scissor: return Result.Tie;

                }

                break;

        }

        throw new Exception(string.Format("Unhandled action pair occured: {0}, {1}", p, c));

    }

}