using System;
using System.Linq;

namespace XOX
{
    internal class Program
    {
        private static void Main()
        {
            new Game().Init();

            Console.WriteLine("\n\nPress any key to quit.");
            Console.ReadKey();
        }
    }

    internal class Game
    {
        public void Init()
        {
            var controller = new Controller();
            controller.InitEmptyGameField();
            controller.GameLoop();
        }
    }

    internal class Model
    {
        public static GameFieldStatus[] GameField = new GameFieldStatus[9];
        public static GameStatusEnum GameStatus = GameStatusEnum.Playing;
        public enum GameFieldStatus
        {
            Empty = 0,
            X,
            O
        }

        public enum GameStatusEnum
        {
            Playing,
            XWon,
            OWon,
            Tie
        }
    }

    internal class View
    {
        public static void PrintGameField()
        {
            for (var i = 1; i <= Model.GameField.Length; i++)
            {
                Console.Write($"| {ParseGameFieldStatus(Model.GameField[i - 1], i)} |");
                if (i != 0 && i % 3 == 0)
                    Console.Write("\n");
            }
        }

        public static void PrintErrorNotANumber()
        {
            Console.Clear();
            Console.WriteLine("\nError: This was not a number. Please try again. \n");
        }

        public static void PrintErrorFieldTaken()
        {
            Console.Clear();
            Console.WriteLine("\nError: This field is already taken. Please try again. \n");
        }

        public static void PrintErrorWrongNumber()
        {
            Console.Clear();
            Console.WriteLine("Please enter a valid number. \n");
        }


        public static void PrintWaitForInput()
        {
            Console.WriteLine("Please enter the fieldnumber you want to mark with X: ");
        }

        public static void ClearConsole()
        {
            Console.Clear();
        }

        public static void PrintGameStatus()
        {
            switch (Model.GameStatus)
            {
                case Model.GameStatusEnum.Playing:
                    break;
                case Model.GameStatusEnum.XWon:
                    Console.WriteLine("Player won the game! :)\n\n");
                    break;
                case Model.GameStatusEnum.OWon:
                    Console.WriteLine("PC won the game! :(\n\n");
                    break;
                case Model.GameStatusEnum.Tie:
                    Console.WriteLine("Nobody won, tie. :|\n\n");
                    break;
                default:
                    throw new ArgumentOutOfRangeException();
            }
        }

        private static string ParseGameFieldStatus(Model.GameFieldStatus status, int position = 0)
        {
            switch (status)
            {
                case Model.GameFieldStatus.Empty:
                    return $" {position} ";
                case Model.GameFieldStatus.X:
                    return " X ";
                case Model.GameFieldStatus.O:
                    return " O ";
                default:
                    throw new ArgumentOutOfRangeException(nameof(status), status, null);
            }
        }
    }

    internal class Controller
    {
        private static bool _wrongPlayerMove;

        public void GameLoop()
        {
            for (;;)
            {
                View.PrintGameField();
                View.PrintWaitForInput();

                ParsePlayerInput(Console.ReadKey());

                CheckForWinCondition();
                if (ParseWinCondition())
                    break;

                if(!_wrongPlayerMove) // only move when player has entered a sane and vaild input
                    MakeEnemyMove();

                CheckForWinCondition();
                if (ParseWinCondition())
                    break;

            }

            View.PrintGameField(); // print the game one more time to celebrate wins visually ;)
        }

        public void InitEmptyGameField()
        {

            for (var i = 0; i < Model.GameField.Length; i++)
            {
                Model.GameField[i] = Model.GameFieldStatus.Empty;
            }
        }

        private static void ParsePlayerInput(ConsoleKeyInfo input)
        {
            if (int.TryParse(input.KeyChar.ToString(), out var intResult))
            {
                _wrongPlayerMove = false; // reset dirty flag

                if (intResult < 1)
                {
                    _wrongPlayerMove = true;
                    View.PrintErrorWrongNumber();
                    return;
                }

                if (Model.GameField[intResult - 1] == Model.GameFieldStatus.Empty)
                    Model.GameField[intResult - 1] = Model.GameFieldStatus.X;
                else
                {
                    View.PrintErrorFieldTaken();
                    _wrongPlayerMove = true;
                    return;
                }


                View.ClearConsole();
            }
            else
            {
                _wrongPlayerMove = true;
                View.PrintErrorNotANumber();
            }
        }

        private static bool ParseWinCondition()
        {
            if (Model.GameStatus == Model.GameStatusEnum.Playing) return false;

            View.PrintGameStatus();
            return true;
        }


        private static void MakeEnemyMove()
        {
            // get available fields array positions, read: an array of array positions, where GameFieldStatus is empty
            var emptyFieldsArrayPosition = Model.GameField.Select((s, i) => new {i, s})
                .Where(t => t.s == Model.GameFieldStatus.Empty)
                .Select(t => t.i)
                .ToArray();

            // TODO: Make enemy smarter
            // chose one array position of the earlier created array
            var randomEmptyArrayPosition = new Random().Next(0, emptyFieldsArrayPosition.Length-1);
            var chosenField = emptyFieldsArrayPosition[randomEmptyArrayPosition];

            Model.GameField[chosenField] = Model.GameFieldStatus.O;
        }

        private static void CheckForWinCondition()
        {

            if (CheckHorizontal(Model.GameFieldStatus.X) || CheckVertical(Model.GameFieldStatus.X) ||
                CheckDiagonal(Model.GameFieldStatus.X))
            {
                Model.GameStatus = Model.GameStatusEnum.XWon;
                return;
            }


            if (CheckHorizontal(Model.GameFieldStatus.O) || CheckVertical(Model.GameFieldStatus.O) ||
                CheckDiagonal(Model.GameFieldStatus.O))
            {
                Model.GameStatus = Model.GameStatusEnum.OWon;
                return;
            }


            if (Model.GameField.Any(x => x == (int) Model.GameStatusEnum.Playing)) return; // not all fields filled yet, early out

            Model.GameStatus = Model.GameStatusEnum.Tie; // all fields filled, no winner -> tie

        }

        private static bool CheckHorizontal(Model.GameFieldStatus checkForThisPlayer)
        {
            for (var i = 0; i < Model.GameField.Length; i += 3)
            {
                if (Model.GameField[i] == checkForThisPlayer && Model.GameField[i + 1] == checkForThisPlayer &&
                    Model.GameField[i + 2] == checkForThisPlayer)
                    return true;
            }

            return false;
        }

        private static bool CheckVertical(Model.GameFieldStatus checkForThisPlayer)
        {
            for (var i = 0; i < 3; i++)
            {
                if (Model.GameField[i] == checkForThisPlayer && Model.GameField[i + 3] == checkForThisPlayer &&
                    Model.GameField[i + 6] == checkForThisPlayer)
                    return true;
            }

            return false;
        }

        private static bool CheckDiagonal(Model.GameFieldStatus checkForThisPlayer)
        {
            if (Model.GameField[0] == checkForThisPlayer && Model.GameField[4] == checkForThisPlayer &&
                Model.GameField[8] == checkForThisPlayer)
                return true;

            if (Model.GameField[2] == checkForThisPlayer && Model.GameField[4] == checkForThisPlayer &&
                Model.GameField[6] == checkForThisPlayer)
                return true;

            return false;
        }
    }
}