using UnityEngine;
using System.Collections;

public class chess : MonoBehaviour
{
  //四個錨點位置，用于計算棋子落點
  public GameObject LeftTop;
  public GameObject RightTop;
  public GameObject LeftBottom;
  public GameObject RightBottom;
  //主攝像機
  public Camera cam;
  //錨點在屏幕上的映射位置
  Vector3 LTPos;
  Vector3 RTPos;
  Vector3 LBPos;
  Vector3 RBPos;

  Vector3 PointPos;//當前點選的位置
  float gridWidth = 1; //棋盤網格寬度
  float gridHeight = 1; //棋盤網格高度
  float minGridDis; //網格寬和高中較小的一個
  Vector2[,] chessPos; //存儲棋盤上所有可以落子的位置
  int[,] chessState; //存儲棋盤位置上的落子狀態(tài)
  enum turn { black, white };
  turn chessTurn; //落子順序
  public Texture2D white; //白棋子
  public Texture2D black; //黑棋子
  public Texture2D blackWin; //白子獲勝提示圖
  public Texture2D whiteWin; //黑子獲勝提示圖
  int winner = 0; //獲勝方，1為黑子，-1為白子
  bool isPlaying = true; //是否處于對弈狀態(tài)

  void Start()
  {
    chessPos = new Vector2[15, 15];
    chessState = new int[17, 16];/*原來定義是new int[15, 15]，這里將原來數(shù)組chessState上、下和右邊各加一排數(shù)據，
    也就相當于在棋盤的上、下和右邊各填加一排隱形的棋道。原因后面解釋*/
    chessTurn = turn.black;

    //計算錨點位置
    LTPos = cam.WorldToScreenPoint(LeftTop.transform.position);
    RTPos = cam.WorldToScreenPoint(RightTop.transform.position);
    LBPos = cam.WorldToScreenPoint(LeftBottom.transform.position);
    RBPos = cam.WorldToScreenPoint(RightBottom.transform.position);

    //計算網格寬度
    gridWidth = (RTPos.x - LTPos.x) / 14;
    gridHeight = (LTPos.y - LBPos.y) / 14;
    minGridDis = gridWidth < gridHeight ? gridWidth : gridHeight;

    //計算落子點位置
    for (int i = 0; i < 15; i++)
    {
      for (int j = 0; j < 15; j++)
      {
        chessPos[i, j] = new Vector2(LBPos.x + gridWidth * j, LBPos.y + gridHeight * i);//這里和源程序定義稍有不同，這里i定位行，j為列
      }
    }
  }

  void Update()
  {
    //檢測鼠標輸入并確定落子狀態(tài)
    if (isPlaying && Input.GetMouseButtonDown(0))
    {
      PointPos = Input.mousePosition;
      for (int i = 0; i < 15; i++)
      {
        for (int j = 0; j < 15; j++)
        {
          //找到最接近鼠標點擊位置的落子點，如果空則落子
          if (Dis(PointPos, chessPos[i, j]) < minGridDis / 2 && chessState[i + 1, j] == 0)/*這里chessState行要加1，
            因為上、下和右邊各多加了一排，要空出來，chessPos的i行對應chessState的i+1行*/
          {
            //根據下棋順序確定落子顏色
            chessState[i + 1, j] = chessTurn == turn.black ? 1 : -1;//同理
            //落子成功，更換下棋順序
            chessTurn = chessTurn == turn.black ? turn.white : turn.black;
          }
        }
      }
      //調用判斷函數(shù)，確定是否有獲勝方
      int re = result();
      if (re == 1)
      {
        Debug.Log("黑棋勝");
        winner = 1;
        isPlaying = false;
      }
      else if (re == -1)
      {
        Debug.Log("白棋勝");
        winner = -1;
        isPlaying = false;
      }
    }
    //按下空格重新開始游戲
    if (Input.GetKeyDown(KeyCode.Space))
    {
      for (int i = 0; i < 15; i++)
      {
        for (int j = 0; j < 15; j++)
        {
          chessState[i + 1, j] = 0;//同理
        }
      }
      isPlaying = true;
      chessTurn = turn.black;
      winner = 0;
    }
  }
  //計算平面距離函數(shù)
  float Dis(Vector3 mPos, Vector2 gridPos)
  {
    return Mathf.Sqrt(Mathf.Pow(mPos.x - gridPos.x, 2) + Mathf.Pow(mPos.y - gridPos.y, 2));
  }

  void OnGUI()
  {
    //繪制棋子
    for (int i = 0; i < 15; i++)
    {
      for (int j = 0; j < 15; j++)
      {
        if (chessState[i + 1, j] == 1)//同理
        {
          GUI.DrawTexture(new Rect(chessPos[i, j].x - gridWidth / 2, Screen.height - chessPos[i, j].y - gridHeight / 2, gridWidth, gridHeight), black);
        }
        if (chessState[i + 1, j] == -1)//同理
        {
          GUI.DrawTexture(new Rect(chessPos[i, j].x - gridWidth / 2, Screen.height - chessPos[i, j].y - gridHeight / 2, gridWidth, gridHeight), white);
        }
      }
    }
    //根據獲勝狀態(tài)，彈出相應的勝利圖片
    if (winner == 1)
    {
      GUI.DrawTexture(new Rect(Screen.width * 0.25f, Screen.height * 0.25f, Screen.width * 0.5f, Screen.height * 0.25f), blackWin);
    }
    if (winner == -1)
      GUI.DrawTexture(new Rect(Screen.width * 0.25f, Screen.height * 0.25f, Screen.width * 0.5f, Screen.height * 0.25f), whiteWin);
  }
 //改寫result函數(shù)
 /*解釋：C語言中，這樣的表達式：chessState[i]&&chessState[i+1]&&chessState[i+2]&&chessState[i+3]&&chessState[i+4]，如果
   * chessState[i]為False,則不管B是真是假或者是異常都不會運行，利用這一點，在chessState的右邊、上邊和下邊各加一行為0的數(shù)據，
   * 這樣在判斷連續(xù)五個棋子的狀態(tài)時，就不用擔心chessState數(shù)組的索引值超出范圍。例如：chessState[i+4]的索引值i+4剛好超出范圍，
   * 通過在原來數(shù)組chessState的上、下和右邊個添加一排為0的數(shù)，這樣chessState[i+3]==0，于是就可以避免引起異常，從而簡化代碼*/
  int result()
  {
    int flag = 0;
    if (chessTurn == turn.white)
    {
      for (int i = 1; i <= 15; i++)//這里的i從1開始
      {
        for (int j = 0; j <= 14; j++)//j不用變
        {
          if ((chessState[i, j] == 1 && chessState[i, j + 1] == 1 && chessState[i, j + 2] == 1 && chessState[i, j + 3] == 1 && chessState[i, j + 4] == 1)//向右橫向
            || (chessState[i, j] == 1 && chessState[i + 1, j] == 1 && chessState[i + 2, j] == 1 && chessState[i + 3, j] == 1 && chessState[i + 4, j] == 1)//向上橫向
            || (chessState[i, j] == 1 && chessState[i + 1, j + 1] == 1 && chessState[i + 2, j + 2] == 1 && chessState[i + 3, j + 3] == 1 && chessState[i + 4, j + 4] == 1)//向右上斜向
            || (chessState[i, j] == 1 && chessState[i - 1, j + 1] == 1 && chessState[i - 2, j + 2] == 1 && chessState[i - 3, j + 3] == 1 && chessState[i - 4, j + 4] == 1))//向右下斜向
          {
            flag = 1;
          }
        }
      }
    }
    else if (chessTurn == turn.black)
    {
      for (int i = 1; i <= 15; i++)//這里的i從1開始
      {
        for (int j = 0; j <= 14; j++)
        {

          if ((chessState[i, j] == -1 && chessState[i, j + 1] == -1 && chessState[i, j + 2] == -1 && chessState[i, j + 3] == -1 && chessState[i, j + 4] == -1)
            || (chessState[i, j] == -1 && chessState[i + 1, j] == -1 && chessState[i + 2, j] == -1 && chessState[i + 3, j] == -1 && chessState[i + 4, j] == -1)
            || (chessState[i, j] == -1 && chessState[i + 1, j + 1] == -1 && chessState[i + 2, j + 2] == -1 && chessState[i + 3, j + 3] == -1 && chessState[i + 4, j + 4] == -1)
            || (chessState[i, j] == -1 && chessState[i - 1, j + 1] == -1 && chessState[i - 2, j + 2] == -1 && chessState[i - 3, j + 3] == -1 && chessState[i - 4, j + 4] == -1))
          {
            flag = -1;
          }
        }
      }
    }
    return flag;
  }
}