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Merge pull request #4 from RiteshS1/bestmove
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improved bestmove.js
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@RiteshS1
RiteshS1 authored Nov 12, 2024
2 parents 9f55101 + 04fe8be commit aacfcda
Showing 1 changed file with 98 additions and 62 deletions.
160 changes: 98 additions & 62 deletions scripts/bestmove.js
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Original file line number Diff line number Diff line change
@@ -1,72 +1,108 @@
let isWhiteTurn = true; // Track current turn

function suggestBestMove() {
console.log("Suggesting best move...");
updateBoardState(); // Update the current board state
const depth = 3; // Adjust the search depth as needed
const bestMove = findBestMove(depth);

if (bestMove) {
console.log("Best move found:", bestMove.moveNotation);
highlightBestMove(bestMove.from, bestMove.to);
} else {
console.log("No valid moves found");
class VirtualBoard {
constructor() {
this.board = new Array(8).fill(null).map(() => new Array(8).fill(null));
this.initialize();
}
}

function findBestMove(depth) {
const possibleMoves = generateAllPossibleMoves(isWhiteTurn);
if (possibleMoves.length === 0) {
const kingPos = findKingPosition(isWhiteTurn);
if (kingPos && isKingInCheck(kingPos.row, kingPos.col, isWhiteTurn)) {
console.log("Checkmate!");
} else {
console.log("Stalemate!");
}
return null;
initialize() {
// Copy current board state
document.querySelectorAll('.square').forEach(square => {
const piece = square.querySelector('.piece');
if (piece) {
const index = parseInt(square.getAttribute('data-index'));
const row = Math.floor(index / 8);
const col = index % 8;
this.board[row][col] = piece.getAttribute('data-piece');
}
});
}

let bestMove = null;
let bestValue = isWhiteTurn ? -Infinity : Infinity;

for (const move of possibleMoves) {
const value = evaluateMove(move, depth);
makeMove(from, to) {
const fromRow = Math.floor(from / 8);
const fromCol = from % 8;
const toRow = Math.floor(to / 8);
const toCol = to % 8;

if (isWhiteTurn && value > bestValue) {
bestValue = value;
bestMove = move;
} else if (!isWhiteTurn && value < bestValue) {
bestValue = value;
bestMove = move;
}
const piece = this.board[fromRow][fromCol];
this.board[fromRow][fromCol] = null;
this.board[toRow][toCol] = piece;
}

return bestMove;
}

function evaluateMove(move, depth) {
// Make the move temporarily
const sourceSquare = document.querySelector(`[data-index="${move.from}"]`);
const targetSquare = document.querySelector(`[data-index="${move.to}"]`);
const targetPiece = targetSquare.querySelector('.piece');

sourceSquare.removeChild(move.piece);
if (targetPiece) {
targetSquare.removeChild(targetPiece);
undoMove(from, to, capturedPiece) {
const fromRow = Math.floor(from / 8);
const fromCol = from % 8;
const toRow = Math.floor(to / 8);
const toCol = to % 8;

const piece = this.board[toRow][toCol];
this.board[fromRow][fromCol] = piece;
this.board[toRow][toCol] = capturedPiece;
}
targetSquare.appendChild(move.piece);
}

// Evaluate position
const value = minimax(depth - 1, -Infinity, Infinity, !isWhiteTurn);
function suggestBestMove() {
const button = document.getElementById('suggest-best-move');
button.disabled = true;
button.textContent = 'Calculating...';

setTimeout(() => {
try {
// Only look at immediate moves (depth 1)
const virtualBoard = new VirtualBoard();
const possibleMoves = generateAllPossibleMoves(isWhiteTurn);

// Evaluate only the top 10 moves based on basic piece capture value
const bestMoves = possibleMoves
.map(move => {
const targetSquare = document.querySelector(`[data-index="${move.to}"]`);
const targetPiece = targetSquare.querySelector('.piece');
const captureValue = targetPiece ? getPieceBasicValue(targetPiece.getAttribute('data-piece')) : 0;
return { ...move, value: captureValue };
})
.sort((a, b) => b.value - a.value)
.slice(0, 10);

// Find the best move among these candidates
let bestMove = bestMoves[0]; // Default to first move
let bestValue = -Infinity;

for (const move of bestMoves) {
virtualBoard.makeMove(move.from, move.to);
const value = evaluateBoard(virtualBoard);
virtualBoard.undoMove(move.from, move.to, null);

if (value > bestValue) {
bestValue = value;
bestMove = move;
}
}

// Undo the move
targetSquare.removeChild(move.piece);
if (targetPiece) {
targetSquare.appendChild(targetPiece);
}
sourceSquare.appendChild(move.piece);
if (bestMove) {
highlightBestMove(bestMove.from, bestMove.to);
}
} catch (error) {
console.error("Error calculating best move:", error);
} finally {
button.disabled = false;
button.textContent = 'Suggest Best Move';
}
}, 0);
}

return value;
// Helper function to get basic piece values
function getPieceBasicValue(pieceType) {
const values = {
'pawn': 1,
'knight': 3,
'bishop': 3,
'rook': 5,
'queen': 9,
'king': 0 // We don't want to prioritize capturing the king
};
const type = pieceType.split('_')[1];
return values[type] || 0;
}

function generateAllPossibleMoves(isWhite) {
Expand Down Expand Up @@ -159,9 +195,9 @@ function undoTemporaryMove(move, capturedPiece) {
updateBoardState(); // Update the internal board state
}

function minimax(depth, alpha, beta, isMaximizingPlayer) {
function minimax(virtualBoard, depth, alpha, beta, isMaximizingPlayer) {
if (depth === 0) {
return evaluatePosition();
return evaluatePosition(virtualBoard);
}

const possibleMoves = generateAllPossibleMoves(isMaximizingPlayer);
Expand All @@ -170,7 +206,7 @@ function minimax(depth, alpha, beta, isMaximizingPlayer) {
let maxEval = -Infinity;
for (const move of possibleMoves) {
const capturedPiece = makeTemporaryMove(move);
const eval = minimax(depth - 1, alpha, beta, false);
const eval = minimax(virtualBoard, depth - 1, alpha, beta, false);
undoTemporaryMove(move, capturedPiece);

maxEval = Math.max(maxEval, eval);
Expand All @@ -182,7 +218,7 @@ function minimax(depth, alpha, beta, isMaximizingPlayer) {
let minEval = Infinity;
for (const move of possibleMoves) {
const capturedPiece = makeTemporaryMove(move);
const eval = minimax(depth - 1, alpha, beta, true);
const eval = minimax(virtualBoard, depth - 1, alpha, beta, true);
undoTemporaryMove(move, capturedPiece);

minEval = Math.min(minEval, eval);
Expand All @@ -193,8 +229,8 @@ function minimax(depth, alpha, beta, isMaximizingPlayer) {
}
}

function evaluatePosition() {
return evaluateBoard(); // This function is from evaluation.js
function evaluatePosition(virtualBoard) {
return evaluateBoard(virtualBoard); // This function is from evaluation.js
}

function highlightBestMove(sourceIndex, targetIndex) {
Expand Down

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