/* 
 * Two player game utilizing threads.
 *
 * Players alternate taking turns adding their
 * symbol to a board.  The players with the most
 * 3-in-a-rows, vertical or horizontal, wins.
 *
 * In the board shown to     +----+
 * the right:                |XOOO| 
 * X has 3 3-in-a-rows, and  |OXXO|
 * O has 3 3-in-a-rows.      |XXXO|
 * That game is a draw.      |OXXO|
 *                           +----+
 *
 * Your job is to modify the program below so that the
 * computer is always working in the background, trying
 * to find the best move in response to each of the 
 * moves that the human might make at that step.
 *
 * For example, suppse that
 * the board shown to the    +----+
 * right is the position     |O X | 
 * after 10 moves, and the   |OXX |
 * computer is waiting for   |O OX|
 * the human (X) to make his |X  O|
 * move.  There are 6 poss-  +----+
 * ible moves that the human
 * could make, and for each of them, the computer should
 * be descending the game tree deciding which move would
 * be best for the computer, in each case.  
 *
 * As soon as the human makes a move, the computer must 
 * immediately cease game computation and make its move.
 *
 * The computer should spawn one thread for each move that
 * the human might make.  These threads need to communicate
 * so that no thread descends to level n+1 in the tree
 * before every thread has completed its computation down
 * to level n.
 */

#include<iostream>
#include<string>
#include "game.h"

using namespace std;

int main(int argc, char* argv[]){
    char board[SIZE][SIZE];

    initialize(board);
    play(board);
    terminate(board);

}

void initialize(char board[SIZE][SIZE]){
    for(int i = 0; i < SIZE; i++)
	for(int j = 0; j < SIZE; j++)
	    board[i][j] = ' ';
    srand(time(NULL));
}

void play(char board[SIZE][SIZE]){
    int numMoves = 0;
    string input;
    Player turn;		// enum Player {HUMAN, COMPUTER}

    cout << "\nPlaying on a " << SIZE << "x" << SIZE << " board" << endl;
    printBoard(board);

    cout << "Who first?  Human (X) or Computer (O)? ";
    cin >> input;
    turn = (tolower(input[0]) == 'x' || tolower(input[0]) == 'h') 
	? HUMAN : COMPUTER;

    while(numMoves < SIZE*SIZE){
	if(turn == HUMAN){
	    makeHumanMove(board);
	    turn = COMPUTER;
	}
	else{
	    makeComputerMove(board);
	    turn = HUMAN;
	}
	numMoves++;
	printBoard(board);
    }
}

void makeHumanMove(char board[SIZE][SIZE]){
    string move;
    int r, c;			// row and column

    cout << "Your move (in form 'a1')? ";
    cin >> move;
    r = (int)(tolower(move[0])) - 96;
    c = (int)move[1] - '1' + 1;

    while(board[r - 1][c - 1] != ' '){
	cout << "  Occupied already!" << endl;
	cout << "Your move (in form 'a1')? ";
	cin >> move;
	r = (int)(tolower(move[0])) - 96;
	c = (int)move[1] - '1' + 1;
    }

    board[r - 1][c - 1] = 'X';
}

void makeComputerMove(char board[SIZE][SIZE]){
    int openr[SIZE*SIZE];	// Available spaces
    int openc[SIZE*SIZE];	// Available spaces
    int found = 0;		// counts available spaces
    int r, c;			// row and column
    int computerMove;

    for(r = 0; r < SIZE; r++)
	for(c = 0; c < SIZE; c++)
	    if(board[r][c] == ' '){
		openr[found] = r;
		openc[found] = c;
		found++;
	    }

    computerMove = rand() % found;
    cout << "My move: ";
    cout << (char)(openr[computerMove] + 97);
    cout << openc[computerMove] + 1 << endl;
    board[openr[computerMove]][openc[computerMove]] = 'O';
}
    

void printBoard(char board[SIZE][SIZE]){
    int r, c;			// row and column counters
    cout << "  ";
    for(c = 0; c < SIZE; c++) cout << c+1;
    cout << endl << " +";
    for(c = 0; c < SIZE; c++) cout << "-";
    cout << "+" << endl;
    for(r = 0; r < SIZE; r++){
	cout << (char) (r + 97) << "|";
	for(c = 0; c < SIZE; c++)
	    cout << board[r][c];
	cout << "|" << endl;
    }
    cout << " +";
    for(c = 0; c < SIZE; c++) cout << "-";
    cout << "+" << endl;
}

void terminate(char board[SIZE][SIZE]){
    int r, c;			// row and column
    int numH = 0, numC = 0;	// number of 3-in-a-rows

    // Count horizontal winners
    for(r = 0; r < SIZE; r++)
	for(c = 0; c < SIZE - 2; c++){
	    if(board[r][c]   == 'X' &&
	       board[r][c+1] == 'X' &&
	       board[r][c+2] == 'X')
		numH++;
	    if(board[r][c]   == 'O' &&
	       board[r][c+1] == 'O' &&
	       board[r][c+2] == 'O')
		numC++;
	}
    // Count vertical winners
    for(c = 0; c < SIZE; c++)
	for(r = 0; r < SIZE - 2; r++){
	    if(board[r][c]   == 'X' &&
	       board[r+1][c] == 'X' &&
	       board[r+2][c] == 'X')
		numH++;
	    if(board[r][c]   == 'O' &&
	       board[r+1][c] == 'O' &&
	       board[r+2][c] == 'O')
		numC++;
	}

    cout << "*** You had " << numH << " points, I had "
	 << numC << " points." << endl;
    if(numH > numC)
	cout << "*** HUMAN WINS ***" << endl;
    else if(numC > numH)
	cout << "*** COMPUTER WINS ***" << endl;
    else
	cout << "*** DRAW ***" << endl;
}