/// 112 年工科賽第 3 題
/// 簡單的 3 乘 3 井字棋程式
/// 漆家豪 於海青資訊科 2024/2/8
using System;

namespace TicTacToe //井字棋
{
    class Program
    {
        static string[] checkerBoard = Enumerable.Repeat("口", 9).ToArray();
        static bool playerTurn = true;

        static void clearBoard()//清除棋盤
        {
            for (int i = 0; i < checkerBoard.Length; i++)
            {
                checkerBoard[i] = "口";
            }
        }
        static void printBoard()
        {
            Console.WriteLine(string.Concat(checkerBoard.Skip(6).Take(3)));
            Console.WriteLine(string.Concat(checkerBoard.Skip(3).Take(3)));
            Console.WriteLine(string.Concat(checkerBoard.Take(3)));
        }

        static void playerMove()//玩家下棋
        {
            Console.Write("請輸入 1~9 (按 0 鍵結束)：");
            int move = int.Parse(Console.ReadLine());
            if (move == 0)
            {
                Environment.Exit(0);
            }
            if (checkerBoard[move - 1] == "口")//可以填入
            {
                checkerBoard[move - 1] = "Ｏ";
            }
            else
            {
                Console.WriteLine("下的位置已有棋子");
                playerMove();
            }
        }
        static void computerMove()//電腦隨機下棋
        {
            Random rand = new Random();
            int move;
            do
            {
                move = rand.Next(1, 10);
            } while (checkerBoard[move - 1] != "口");

            checkerBoard[move - 1] = "Ｘ";
            Console.WriteLine($"電腦下在位置 {move}");
        }
        static bool checkWin(string symbol)//檢查棋盤是否獲勝
        {
            return (checkerBoard[0] == symbol && checkerBoard[1] == symbol && checkerBoard[2] == symbol) ||
                   (checkerBoard[3] == symbol && checkerBoard[4] == symbol && checkerBoard[5] == symbol) ||
                   (checkerBoard[6] == symbol && checkerBoard[7] == symbol && checkerBoard[8] == symbol) ||
                   (checkerBoard[0] == symbol && checkerBoard[3] == symbol && checkerBoard[6] == symbol) ||
                   (checkerBoard[1] == symbol && checkerBoard[4] == symbol && checkerBoard[7] == symbol) ||
                   (checkerBoard[2] == symbol && checkerBoard[5] == symbol && checkerBoard[8] == symbol) ||
                   (checkerBoard[0] == symbol && checkerBoard[4] == symbol && checkerBoard[8] == symbol) ||
                   (checkerBoard[2] == symbol && checkerBoard[4] == symbol && checkerBoard[6] == symbol);
        }
        static bool isCheckerBoardFull()//是否下滿了
        {
            foreach (string c in checkerBoard)
            {
                if (c == "口")
                {
                    return false;
                }
            }
            return true;
        }

        static void Main(string[] args)
        {
            printBoard();
            while (true)
            {
                if (playerTurn)
                {
                    playerMove();
                }
                else
                {
                    computerMove();
                }
                printBoard();
                if (checkWin("Ｏ"))
                {
                    Console.WriteLine("你○方獲勝 再來一盤");
                    clearBoard();
                    playerTurn = false;
                    printBoard();
                }
                else if (checkWin("Ｘ"))
                {
                    Console.WriteLine("電腦 Ｘ 方獲勝 再來一盤!");
                    clearBoard();
                    playerTurn = true;
                    printBoard();
                }
                else if (isCheckerBoardFull())
                {
                    Console.WriteLine("雙方平手 再來一盤!");
                    clearBoard();
                    printBoard();
                }
                playerTurn = !playerTurn;
            }
        }
    }
}