/*	TTTGame.cpp
 *
 *
 *  	Written February, 2004 by Pat Troy for CS 422
 */

#include "TTTGame.h"
#include <iostream>
using namespace std;

int posArray[8][3] = {  {1,2,3},    /* positions in the first row */
                        {4,5,6},    /* positions in the second row */
                        {7,8,9},    /* positions in the third row */
                        {1,4,7},    /* positions in the first column */
                        {2,5,8},    /* positions in the second column */
                        {3,6,9},    /* positions in the third column */
                        {1,5,9},    /* positions in the first diagonal */
                        {3,5,7}};   /* positions in the second diagonal */

/* There is also a static pointer to TTTGame to keep 
   track of the single instance of the class.			*/
TTTGame *TTTGame::game = NULL;

/* The constructors will be protected to force the use
   of the static createTTTGame method.				*/
TTTGame::TTTGame()
{
 /* set the game statistics to zero */
 turn = 0;
 startingPlayer = 0;
 moveNumber = 0;
 numStarted = 0;
 numWon = 0;
 numLost = 0;
 numCats = 0;	/* A "Cat's Game" is a game with no winner 	*/
  
 /* initialize the board */
 for (int i = 0; i < 10; ++i)
    board[i] = '0' + i;
}

/* These static methods will create and/or return the instance
   of the game maintained in the static pointer			*/
TTTGame *TTTGame::createTTTGame ( void )
{
 if (!game)
    game = new TTTGame ();
 return game;
}

TTTGame *TTTGame::getGame ( void )
{
 return game;
}

/* Here are the normal methods of the class			*/
int TTTGame::newGame (int startPlayer)
{
 /* initialize the board */
 for (int i = 0; i < 10; ++i)
    board[i] = '0' + i;

 /* Initialize the other values */
 moveNumber = 0;
 if ((startPlayer == USERPLAYER) || (startPlayer == COMPUTERPLAYER))
     startingPlayer = startPlayer;
 else if (startingPlayer == USERPLAYER)
     startingPlayer = COMPUTERPLAYER;
 else
     startingPlayer = USERPLAYER;
 turn = startingPlayer;

 /* increment the number started statistic			*/
 ++numStarted;
 
 /* return the value of startingPlayer */
 return startingPlayer;
}

char TTTGame::getPosition ( int pos )
{
 return board[pos];
} 

int TTTGame::userMove (char move)
{
 /* check for Cats's Game */
 if (moveNumber >= 9)
   {
    ++ numCats;
    return CATSGAME;
   }

 /* invalid or off-board move */
 if ((move < '1') || move > '9')
    return INVALIDMOVE;

 /* check if position is already in use */
 if (board[move-'0'] != move)
    return POSITIONINUSE;

 board[move-'0'] = 'X';
 ++ moveNumber;
 turn = COMPUTERPLAYER;

 /* check for 3 in a row */
 if ( isGameWon() >= 0)
   {
    ++ numWon;
    return WINGAME;
   }
 else if (moveNumber >= 9)
   {
    ++ numCats;
    return CATSGAME;
   }
 else 
    return VALIDMOVE;
}

int TTTGame::isGameWon()
{
 int i;

 for (i = 0; i < 8; i++)
    {
     if ((board[posArray[i][0]] == board[posArray[i][1]]) &&
         (board[posArray[i][0]] == board[posArray[i][2]]))
	return i;
    }
 return -1;
}

int TTTGame::findWinningMove (char player, int posOrCount)
{
 int count = 0;
 int i,j;
 char value[3];

 /* loop for each row in posArray */
 for (i = 0; i < 8; ++i)
   {
    for (j = 0; j < 3; ++j)
       value[j] = board[posArray[i][j]];
 
    for (j = 0; j < 3; ++j)
       {
        if ((isdigit(value[j])) &&
            (value[(j+1)%3] == player) &&
            (value[(j+2)%3] == player))
          {
           if (posOrCount == POS)
              return (value[j] - '0');
           else
              ++count;
          }
       }
   }
 if (posOrCount == POS)
    return 0;
 else
    return count;
}

int TTTGame::determineComputerMove()
{
 int move;
 int i;
 int pos, count;

 /* check for a winning move by the computer */
 move = findWinningMove ('O', POS);
 if (move > 0)
    return move;
 
 /* check for a blocking move */
 move = findWinningMove ('X', POS);
 if (move > 0)
    return move;

 /* check to set-up a possible winning move */
 pos = 0; 
 count = 0;
 for (i = 1; i <= 9; ++i)
    if (board[i] == (i + '0'))
       {
        board[i] = 'O';
        move = findWinningMove ('O', COUNT);
        if (move > count)
           {
            pos = i;
            count = move;
           }
        board[i] = i + '0';
       }
 if (pos != 0)
    return pos;

 /* make another move */
 if (board[5] == '5')
    return 5;
 else if (board[1] == '1')
    return 1;
 else if (board[3] == '3')
    return 3;
 else if (board[7] == '7')
    return 7;
 else if (board[9] == '9')
    return 9;
 else if (board[2] == '2')
    return 2;
 else if (board[4] == '4')
    return 4;
 else if (board[6] == '6')
    return 6;
 else if (board[8] == '8')
    return 8;
} 
 
int TTTGame::computerMove ( void )
{
 int move;

 /* check for Cats's Game */
 if (moveNumber >= 9)
   {
    ++ numCats;
    return CATSGAME;
   }

 /* make move by the computer */
 move = determineComputerMove();
 board[move] = 'O';
 ++ moveNumber;
 turn = USERPLAYER;

 /* check for 3 in a row */
 if ( isGameWon() >= 0)
   {
    ++ numLost;
    return LOSEGAME;
   }
 /* check for Cats's Game */
 else if (moveNumber >= 9)
   {
    ++ numCats;
    return CATSGAME;
   }
 else 
   {
    return VALIDMOVE;
   }
 
}

int TTTGame::getTurn ( void )
{
 return turn;
}

int TTTGame::getNumStarted ( void )
{
 return numStarted;
}

int TTTGame::getNumWon ( void )
{
 return numWon;
}

int TTTGame::getNumLost ( void )
{
 return numLost;
}

int TTTGame::getNumCats ( void )
{
 return numCats;
}