main.cpp

#include <iostream>
#include "board.h"

int evaluateWindow(int window[4], int piece) {
    int score = 0;
    int pieceCount = 0;
    int emptyCount = 0;
    int opponentCount = 0;
    
    for (int i = 0; i < 4; i++) {
        if (window[i] == piece) pieceCount++;
        else if (window[i] == 0) emptyCount++;
        else opponentCount++;
    }
    
    // AI piece (2) scoring
    if (piece == 2) {
        if (pieceCount == 4) return 1000;      // Win
        if (pieceCount == 3 && emptyCount == 1) return 100;   // 3-in-a-row
        if (pieceCount == 2 && emptyCount == 2) return 10;    // 2-in-a-row
        if (pieceCount == 1 && emptyCount == 3) return 1;     // 1 piece
    }
    // Player piece (1) scoring - defensive
    else if (piece == 1) {
        if (opponentCount == 4) return -1000;  // Opponent wins
        if (opponentCount == 3 && emptyCount == 1) return -100;  // Block 3-in-a-row
        if (opponentCount == 2 && emptyCount == 2) return -10;   // Block 2-in-a-row
    }
    
    return score;
}

// Heuristic evaluation function
int scoreBoard(Board board, int piece) {
    int score = 0;
    
    // Horizontal evaluation
    for (int i = 0; i < 6; i++) {
        for (int j = 0; j < 4; j++) {
            int window[4] = {board.getCell(i, j), board.getCell(i, j+1), 
                           board.getCell(i, j+2), board.getCell(i, j+3)};
            score += evaluateWindow(window, 2);
            score += evaluateWindow(window, 1);
        }
    }
    
    // Vertical evaluation
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 7; j++) {
            int window[4] = {board.getCell(i, j), board.getCell(i+1, j), 
                           board.getCell(i+2, j), board.getCell(i+3, j)};
            score += evaluateWindow(window, 2);
            score += evaluateWindow(window, 1);
        }
    }
    
    // Diagonal evaluation (top-left to bottom-right)
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 4; j++) {
            int window[4] = {board.getCell(i, j), board.getCell(i+1, j+1), 
                           board.getCell(i+2, j+2), board.getCell(i+3, j+3)};
            score += evaluateWindow(window, 2);
            score += evaluateWindow(window, 1);
        }
    }
    
    // Diagonal evaluation (top-right to bottom-left)
    for (int i = 0; i < 3; i++) {
        for (int j = 3; j < 7; j++) {
            int window[4] = {board.getCell(i, j), board.getCell(i+1, j-1), 
                           board.getCell(i+2, j-2), board.getCell(i+3, j-3)};
            score += evaluateWindow(window, 2);
            score += evaluateWindow(window, 1);
        }
    }
    
    // Center column bonus
    for (int i = 0; i < 6; i++) {
        if (board.getCell(i, 3) == 2) score += 5;
        if (board.getCell(i, 2) == 2) score += 3;
        if (board.getCell(i, 4) == 2) score += 3;
    }
    
    return score;
}

int minimax(Board board, int depth, int alpha, int beta, bool maximizingPlayer) {
    // Base cases
    if (board.checkWin(2)) return 10000 - depth;
    if (board.checkWin(1)) return depth - 10000;
    if (board.isFull()) return 0;
    if (depth == 0) return scoreBoard(board, 2);
    
    if (maximizingPlayer) {
        int maxEval = -100000;
        for (int col = 0; col < 7; col++) {
            Board tempBoard = board;
            if (tempBoard.makeMove(col, 2)) {
                int eval = minimax(tempBoard, depth - 1, alpha, beta, false);
                maxEval = (eval > maxEval) ? eval : maxEval;
                alpha = (eval > alpha) ? eval : alpha;
                if (beta <= alpha) break;
            }
        }
        return maxEval;
    } else {
        int minEval = 100000;
        for (int col = 0; col < 7; col++) {
            Board tempBoard = board;
            if (tempBoard.makeMove(col, 1)) {
                int eval = minimax(tempBoard, depth - 1, alpha, beta, true);
                minEval = (eval < minEval) ? eval : minEval;
                beta = (eval < beta) ? eval : beta;
                if (beta <= alpha) break;
            }
        }
        return minEval;
    }
}

int main(){
    std::cout << "Hello world!" << std::endl;

    Board board;
    int playerTurn = 1;

    //Game Loop
    while(!board.isFull()){
        board.printBoard();
        
        //Player Turn
        if(playerTurn == 1){
            std::cout << "Make a move (Enter column number for move 1-7): " << std::endl;

            int moveCol;
            std::cin >> moveCol;
            if(moveCol < 1 || moveCol > 7){
                std::cout << "Make valid move (1-7): " << std::endl;
                std::cin >> moveCol;
            }

            board.makeMove(moveCol - 1, playerTurn);

            if(board.checkWin(1)){
                board.printBoard();
                std::cout << "Player Won The Game!!!" << std::endl;
                break;
            }

            playerTurn = 2;
        }
        //AI Turn
        else{
            std::cout << "AI is thinking..." << std::endl;
            int bestMove = 0;
            int bestScore = -1000;

            for (int col = 0; col < 7; col++) {
                Board tempBoard = board;
                if (tempBoard.makeMove(col, 2)) {
                    int score = minimax(tempBoard, 8, -100000, 100000, false);
                    if (score > bestScore) {
                        bestScore = score;
                        bestMove = col;
                    }
                }
            }

            board.makeMove(bestMove, 2);

            if(board.checkWin(2)){
                board.printBoard();
                std::cout << "Bot Won The Game!!!" << std::endl;
                break;
            }

            playerTurn = 1;
        }
    }

    return 0;
}