feat: implement Chess Game with AI using C++ (#17)

Author: saumya1317

Src/Chess_Game_AI/Board.cpp

@@ -0,0 +1,288 @@
+#include "Board.h"
+#include <iostream>
+#include <algorithm>
+
+Board::Board() {
+    // Initialize empty board
+    for (int i = 0; i < 8; i++) {
+        for (int j = 0; j < 8; j++) {
+            board[i][j] = nullptr;
+        }
+    }
+}
+
+void Board::initialize() {
+    // Clear board
+    for (int i = 0; i < 8; i++) {
+        for (int j = 0; j < 8; j++) {
+            board[i][j] = nullptr;
+        }
+    }
+    
+    // Place black pieces (row 0-1)
+    board[0][0] = std::make_unique<Rook>(Color::BLACK, Position(0, 0));
+    board[0][1] = std::make_unique<Knight>(Color::BLACK, Position(0, 1));
+    board[0][2] = std::make_unique<Bishop>(Color::BLACK, Position(0, 2));
+    board[0][3] = std::make_unique<Queen>(Color::BLACK, Position(0, 3));
+    board[0][4] = std::make_unique<King>(Color::BLACK, Position(0, 4));
+    board[0][5] = std::make_unique<Bishop>(Color::BLACK, Position(0, 5));
+    board[0][6] = std::make_unique<Knight>(Color::BLACK, Position(0, 6));
+    board[0][7] = std::make_unique<Rook>(Color::BLACK, Position(0, 7));
+    
+    for (int col = 0; col < 8; col++) {
+        board[1][col] = std::make_unique<Pawn>(Color::BLACK, Position(1, col));
+    }
+    
+    // Place white pieces (row 6-7)
+    for (int col = 0; col < 8; col++) {
+        board[6][col] = std::make_unique<Pawn>(Color::WHITE, Position(6, col));
+    }
+    
+    board[7][0] = std::make_unique<Rook>(Color::WHITE, Position(7, 0));
+    board[7][1] = std::make_unique<Knight>(Color::WHITE, Position(7, 1));
+    board[7][2] = std::make_unique<Bishop>(Color::WHITE, Position(7, 2));
+    board[7][3] = std::make_unique<Queen>(Color::WHITE, Position(7, 3));
+    board[7][4] = std::make_unique<King>(Color::WHITE, Position(7, 4));
+    board[7][5] = std::make_unique<Bishop>(Color::WHITE, Position(7, 5));
+    board[7][6] = std::make_unique<Knight>(Color::WHITE, Position(7, 6));
+    board[7][7] = std::make_unique<Rook>(Color::WHITE, Position(7, 7));
+    
+    // Set king positions
+    whiteKingPos = Position(7, 4);
+    blackKingPos = Position(0, 4);
+}
+
+Piece* Board::getPiece(const Position& pos) const {
+    if (!pos.isValid()) return nullptr;
+    return board[pos.row][pos.col].get();
+}
+
+bool Board::isEmpty(const Position& pos) const {
+    if (!pos.isValid()) return false;
+    return board[pos.row][pos.col] == nullptr;
+}
+
+bool Board::hasEnemyPiece(const Position& pos, Color playerColor) const {
+    if (!pos.isValid()) return false;
+    Piece* piece = board[pos.row][pos.col].get();
+    return piece != nullptr && piece->getColor() != playerColor;
+}
+
+bool Board::makeMove(const Position& from, const Position& to) {
+    if (!from.isValid() || !to.isValid()) return false;
+    
+    Piece* piece = getPiece(from);
+    if (!piece) return false;
+    
+    // Check if move is legal
+    if (!isMoveLegal(from, to, piece->getColor())) {
+        return false;
+    }
+    
+    // Capture enemy piece if present
+    if (getPiece(to)) {
+        board[to.row][to.col] = nullptr;
+    }
+    
+    // Move the piece
+    board[to.row][to.col] = std::move(board[from.row][from.col]);
+    board[to.row][to.col]->setPosition(to);
+    board[to.row][to.col]->setHasMoved(true);
+    
+    // Update king position if king moved
+    if (board[to.row][to.col]->getType() == PieceType::KING) {
+        if (board[to.row][to.col]->getColor() == Color::WHITE) {
+            whiteKingPos = to;
+        } else {
+            blackKingPos = to;
+        }
+    }
+    
+    return true;
+}
+
+bool Board::isKingInCheck(Color kingColor) const {
+    Position kingPos = (kingColor == Color::WHITE) ? whiteKingPos : blackKingPos;
+    Color enemyColor = (kingColor == Color::WHITE) ? Color::BLACK : Color::WHITE;
+    
+    return isPositionUnderAttack(kingPos, enemyColor);
+}
+
+bool Board::isPositionUnderAttack(const Position& pos, Color attackerColor) const {
+    // Check all pieces of the attacking color
+    for (int row = 0; row < 8; row++) {
+        for (int col = 0; col < 8; col++) {
+            Piece* piece = board[row][col].get();
+            if (piece && piece->getColor() == attackerColor) {
+                std::vector<Position> moves = piece->getValidMoves(*this);
+                for (const Position& move : moves) {
+                    if (move == pos) {
+                        return true;
+                    }
+                }
+            }
+        }
+    }
+    return false;
+}
+
+bool Board::wouldKingBeSafe(const Position& from, const Position& to, Color playerColor) const {
+    // Create a temporary board state
+    Board tempBoard;
+    
+    // Copy current board state
+    for (int row = 0; row < 8; row++) {
+        for (int col = 0; col < 8; col++) {
+            if (board[row][col]) {
+                tempBoard.board[row][col] = board[row][col]->clone();
+            }
+        }
+    }
+    tempBoard.whiteKingPos = whiteKingPos;
+    tempBoard.blackKingPos = blackKingPos;
+    
+    // Make the move on temporary board
+    if (tempBoard.board[to.row][to.col]) {
+        tempBoard.board[to.row][to.col] = nullptr;
+    }
+    tempBoard.board[to.row][to.col] = std::move(tempBoard.board[from.row][from.col]);
+    tempBoard.board[to.row][to.col]->setPosition(to);
+    
+    // Update king position if king moved
+    if (tempBoard.board[to.row][to.col]->getType() == PieceType::KING) {
+        if (playerColor == Color::WHITE) {
+            tempBoard.whiteKingPos = to;
+        } else {
+            tempBoard.blackKingPos = to;
+        }
+    }
+    
+    // Check if king is in check after the move
+    return !tempBoard.isKingInCheck(playerColor);
+}
+
+bool Board::isMoveLegal(const Position& from, const Position& to, Color playerColor) const {
+    Piece* piece = getPiece(from);
+    if (!piece || piece->getColor() != playerColor) return false;
+    
+    // Check if the move is in the piece's valid moves
+    std::vector<Position> validMoves = piece->getValidMoves(*this);
+    bool isValidMove = false;
+    for (const Position& move : validMoves) {
+        if (move == to) {
+            isValidMove = true;
+            break;
+        }
+    }
+    
+    if (!isValidMove) return false;
+    
+    // Check if the move would leave the king in check
+    return wouldKingBeSafe(from, to, playerColor);
+}
+
+std::vector<std::pair<Position, Position>> Board::getAllValidMoves(Color playerColor) const {
+    std::vector<std::pair<Position, Position>> allMoves;
+    
+    for (int row = 0; row < 8; row++) {
+        for (int col = 0; col < 8; col++) {
+            Piece* piece = board[row][col].get();
+            if (piece && piece->getColor() == playerColor) {
+                Position from(row, col);
+                std::vector<Position> validMoves = piece->getValidMoves(*this);
+                
+                for (const Position& to : validMoves) {
+                    if (isMoveLegal(from, to, playerColor)) {
+                        allMoves.push_back({from, to});
+                    }
+                }
+            }
+        }
+    }
+    
+    return allMoves;
+}
+
+bool Board::isCheckmate(Color playerColor) const {
+    // If not in check, it's not checkmate
+    if (!isKingInCheck(playerColor)) return false;
+    
+    // If there are any valid moves, it's not checkmate
+    return getAllValidMoves(playerColor).empty();
+}
+
+bool Board::isStalemate(Color playerColor) const {
+    // If in check, it's not stalemate
+    if (isKingInCheck(playerColor)) return false;
+    
+    // If there are no valid moves, it's stalemate
+    return getAllValidMoves(playerColor).empty();
+}
+
+Position Board::getKingPosition(Color kingColor) const {
+    return (kingColor == Color::WHITE) ? whiteKingPos : blackKingPos;
+}
+
+int Board::evaluatePosition() const {
+    int score = 0;
+    
+    for (int row = 0; row < 8; row++) {
+        for (int col = 0; col < 8; col++) {
+            Piece* piece = board[row][col].get();
+            if (piece) {
+                int pieceValue = piece->getValue();
+                if (piece->getColor() == Color::WHITE) {
+                    score += pieceValue;
+                } else {
+                    score -= pieceValue;
+                }
+            }
+        }
+    }
+    
+    return score;
+}
+
+void Board::display() const {
+    std::cout << "\n    a   b   c   d   e   f   g   h\n";
+    std::cout << "  +---+---+---+---+---+---+---+---+\n";
+    
+    for (int row = 0; row < 8; row++) {
+        std::cout << 8 - row << " |";
+        for (int col = 0; col < 8; col++) {
+            Piece* piece = board[row][col].get();
+            if (piece) {
+                std::cout << " " << piece->getSymbol() << " |";
+            } else {
+                std::cout << "   |";
+            }
+        }
+        std::cout << " " << 8 - row << "\n";
+        std::cout << "  +---+---+---+---+---+---+---+---+\n";
+    }
+    
+    std::cout << "    a   b   c   d   e   f   g   h\n\n";
+}
+
+void Board::placePiece(std::unique_ptr<Piece> piece, const Position& pos) {
+    if (pos.isValid()) {
+        board[pos.row][pos.col] = std::move(piece);
+    }
+}
+
+std::unique_ptr<Board> Board::clone() const {
+    auto clonedBoard = std::make_unique<Board>();
+    
+    for (int row = 0; row < 8; row++) {
+        for (int col = 0; col < 8; col++) {
+            if (board[row][col]) {
+                clonedBoard->board[row][col] = board[row][col]->clone();
+            }
+        }
+    }
+    
+    clonedBoard->whiteKingPos = whiteKingPos;
+    clonedBoard->blackKingPos = blackKingPos;
+    
+    return clonedBoard;
+}

Src/Chess_Game_AI/Board.h

@@ -0,0 +1,86 @@
+#ifndef BOARD_H
+#define BOARD_H
+
+#include "Piece.h"
+#include <array>
+#include <memory>
+#include <vector>
+
+struct Move {
+    Position from;
+    Position to;
+    std::unique_ptr<Piece> capturedPiece;
+    bool isCastling;
+    bool isEnPassant;
+    
+    Move(Position f, Position t) 
+        : from(f), to(t), capturedPiece(nullptr), isCastling(false), isEnPassant(false) {}
+};
+
+class Board {
+private:
+    std::array<std::array<std::unique_ptr<Piece>, 8>, 8> board;
+    std::vector<Move> moveHistory;
+    Position whiteKingPos;
+    Position blackKingPos;
+
+public:
+    Board();
+    
+    // Initialize the board with standard chess setup
+    void initialize();
+    
+    // Get piece at position
+    Piece* getPiece(const Position& pos) const;
+    
+    // Check if position is empty
+    bool isEmpty(const Position& pos) const;
+    
+    // Check if position has enemy piece
+    bool hasEnemyPiece(const Position& pos, Color playerColor) const;
+    
+    // Make a move
+    bool makeMove(const Position& from, const Position& to);
+    
+    // Undo last move
+    void undoMove();
+    
+    // Check if king is in check
+    bool isKingInCheck(Color kingColor) const;
+    
+    // Check if it's checkmate
+    bool isCheckmate(Color playerColor) const;
+    
+    // Check if it's stalemate
+    bool isStalemate(Color playerColor) const;
+    
+    // Get all valid moves for a player
+    std::vector<std::pair<Position, Position>> getAllValidMoves(Color playerColor) const;
+    
+    // Validate if a move is legal (doesn't leave king in check)
+    bool isMoveLegal(const Position& from, const Position& to, Color playerColor) const;
+    
+    // Display the board
+    void display() const;
+    
+    // Get king position
+    Position getKingPosition(Color kingColor) const;
+    
+    // Evaluate board position for AI
+    int evaluatePosition() const;
+    
+    // Clone board for simulation
+    std::unique_ptr<Board> clone() const;
+
+private:
+    // Helper function to check if position is under attack
+    bool isPositionUnderAttack(const Position& pos, Color attackerColor) const;
+    
+    // Helper to simulate a move and check if king is safe
+    bool wouldKingBeSafe(const Position& from, const Position& to, Color playerColor) const;
+    
+    // Place a piece on the board
+    void placePiece(std::unique_ptr<Piece> piece, const Position& pos);
+};
+
+#endif // BOARD_H

Src/Chess_Game_AI/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.10)
+project(ChessGameAI)
+
+# Set C++ standard
+set(CMAKE_CXX_STANDARD 14)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+# Add executable
+add_executable(chess_game
+    main.cpp
+    Piece.cpp
+    Board.cpp
+    Player.cpp
+    Game.cpp
+)
+
+# Enable warnings
+if(MSVC)
+    target_compile_options(chess_game PRIVATE /W4)
+else()
+    target_compile_options(chess_game PRIVATE -Wall -Wextra -pedantic)
+endif()