function resolveEpoch(state, action) { var newState = JSON.parse(JSON.stringify(state)); function getPieceColor(piece) { if (!piece) return null; return piece[0] === 'w' ? 'white' : 'black'; } function getPieceType(piece) { if (!piece) return null; return piece[1]; } function isOwnPiece(piece, color) { return getPieceColor(piece) === color; } function isEnemyPiece(piece, color) { var pieceColor = getPieceColor(piece); return pieceColor !== null && pieceColor !== color; } function getKingPosition(board, color) { var kingPiece = color === 'white' ? 'wK' : 'bK'; for (var i = 0; i < 64; i++) { if (board[i].piece === kingPiece) return i; } return -1; } function isSquareAttacked(board, targetIdx, byColor) { var tx = targetIdx % 8; var ty = Math.floor(targetIdx / 8); for (var i = 0; i < 64; i++) { var piece = board[i].piece; if (!piece || getPieceColor(piece) !== byColor) continue; var fx = i % 8; var fy = Math.floor(i / 8); var dx = tx - fx; var dy = ty - fy; var adx = Math.abs(dx); var ady = Math.abs(dy); var type = getPieceType(piece); if (type === 'P') { var pawnDir = byColor === 'white' ? 1 : -1; if (dy === pawnDir && adx === 1) return true; } else if (type === 'N') { if ((adx === 2 && ady === 1) || (adx === 1 && ady === 2)) return true; } else if (type === 'B') { if (adx === ady && adx > 0) { if (isPathClear(board, fx, fy, tx, ty)) return true; } } else if (type === 'R') { if ((dx === 0 || dy === 0) && (adx > 0 || ady > 0)) { if (isPathClear(board, fx, fy, tx, ty)) return true; } } else if (type === 'Q') { if ((adx === ady && adx > 0) || ((dx === 0 || dy === 0) && (adx > 0 || ady > 0))) { if (isPathClear(board, fx, fy, tx, ty)) return true; } } else if (type === 'K') { if (adx <= 1 && ady <= 1 && (adx > 0 || ady > 0)) return true; } } return false; } function isPathClear(board, fx, fy, tx, ty) { var dx = tx - fx; var dy = ty - fy; var steps = Math.max(Math.abs(dx), Math.abs(dy)); var stepX = dx === 0 ? 0 : dx / Math.abs(dx); var stepY = dy === 0 ? 0 : dy / Math.abs(dy); for (var s = 1; s < steps; s++) { var cx = fx + stepX * s; var cy = fy + stepY * s; var idx = cy * 8 + cx; if (board[idx].piece) return false; } return true; } function isInCheck(board, color) { var kingPos = getKingPosition(board, color); if (kingPos === -1) return false; var enemyColor = color === 'white' ? 'black' : 'white'; return isSquareAttacked(board, kingPos, enemyColor); } function wouldBeInCheck(board, fromIdx, toIdx, color) { var testBoard = JSON.parse(JSON.stringify(board)); testBoard[toIdx].piece = testBoard[fromIdx].piece; testBoard[toIdx].icon = testBoard[fromIdx].icon; testBoard[fromIdx].piece = ''; testBoard[fromIdx].icon = ''; return isInCheck(testBoard, color); } function getValidMoves(board, fromIdx, currentPlayer, enPassantTarget, castlingRights) { var moves = []; var piece = board[fromIdx].piece; if (!piece || !isOwnPiece(piece, currentPlayer)) return moves; var fx = fromIdx % 8; var fy = Math.floor(fromIdx / 8); var type = getPieceType(piece); var color = getPieceColor(piece); if (type === 'P') { var dir = color === 'white' ? 1 : -1; var startRow = color === 'white' ? 1 : 6; var oneStep = fromIdx + dir * 8; if (oneStep >= 0 && oneStep < 64 && !board[oneStep].piece) { moves.push(oneStep); if (fy === startRow) { var twoStep = fromIdx + dir * 16; if (!board[twoStep].piece) moves.push(twoStep); } } var captures = [fromIdx + dir * 8 - 1, fromIdx + dir * 8 + 1]; for (var c = 0; c < captures.length; c++) { var capIdx = captures[c]; var capX = capIdx % 8; if (capIdx >= 0 && capIdx < 64 && Math.abs(capX - fx) === 1) { if (isEnemyPiece(board[capIdx].piece, color) || capIdx === enPassantTarget) { moves.push(capIdx); } } } } else if (type === 'N') { var knightMoves = [[-2, -1], [-2, 1], [-1, -2], [-1, 2], [1, -2], [1, 2], [2, -1], [2, 1]]; for (var k = 0; k < knightMoves.length; k++) { var nx = fx + knightMoves[k][0]; var ny = fy + knightMoves[k][1]; if (nx >= 0 && nx < 8 && ny >= 0 && ny < 8) { var nIdx = ny * 8 + nx; if (!isOwnPiece(board[nIdx].piece, color)) moves.push(nIdx); } } } else if (type === 'B' || type === 'R' || type === 'Q') { var directions = []; if (type === 'B' || type === 'Q') { directions.push([-1, -1], [-1, 1], [1, -1], [1, 1]); } if (type === 'R' || type === 'Q') { directions.push([-1, 0], [1, 0], [0, -1], [0, 1]); } for (var d = 0; d < directions.length; d++) { var ddx = directions[d][0]; var ddy = directions[d][1]; for (var dist = 1; dist < 8; dist++) { var sx = fx + ddx * dist; var sy = fy + ddy * dist; if (sx < 0 || sx >= 8 || sy < 0 || sy >= 8) break; var sIdx = sy * 8 + sx; if (isOwnPiece(board[sIdx].piece, color)) break; moves.push(sIdx); if (isEnemyPiece(board[sIdx].piece, color)) break; } } } else if (type === 'K') { var kingMoves = [[-1, -1], [-1, 0], [-1, 1], [0, -1], [0, 1], [1, -1], [1, 0], [1, 1]]; for (var km = 0; km < kingMoves.length; km++) { var kx = fx + kingMoves[km][0]; var ky = fy + kingMoves[km][1]; if (kx >= 0 && kx < 8 && ky >= 0 && ky < 8) { var kIdx = ky * 8 + kx; if (!isOwnPiece(board[kIdx].piece, color)) moves.push(kIdx); } } var enemyColor = color === 'white' ? 'black' : 'white'; var row = color === 'white' ? 0 : 7; if (castlingRights[color].kingSide) { if (!board[row * 8 + 5].piece && !board[row * 8 + 6].piece) { if (!isSquareAttacked(board, row * 8 + 4, enemyColor) && !isSquareAttacked(board, row * 8 + 5, enemyColor) && !isSquareAttacked(board, row * 8 + 6, enemyColor)) { moves.push(row * 8 + 6); } } } if (castlingRights[color].queenSide) { if (!board[row * 8 + 1].piece && !board[row * 8 + 2].piece && !board[row * 8 + 3].piece) { if (!isSquareAttacked(board, row * 8 + 4, enemyColor) && !isSquareAttacked(board, row * 8 + 3, enemyColor) && !isSquareAttacked(board, row * 8 + 2, enemyColor)) { moves.push(row * 8 + 2); } } } } var legalMoves = []; for (var m = 0; m < moves.length; m++) { if (!wouldBeInCheck(board, fromIdx, moves[m], color)) { legalMoves.push(moves[m]); } } return legalMoves; } function getAllLegalMoves(board, color, enPassantTarget, castlingRights) { var allMoves = []; for (var i = 0; i < 64; i++) { if (isOwnPiece(board[i].piece, color)) { var pieceMoves = getValidMoves(board, i, color, enPassantTarget, castlingRights); for (var m = 0; m < pieceMoves.length; m++) { allMoves.push({ from: i, to: pieceMoves[m] }); } } } return allMoves; } function getPieceIcon(piece) { var icons = { 'wK': '♔', 'wQ': '♕', 'wR': '♖', 'wB': '♗', 'wN': '♘', 'wP': '♙', 'bK': '♚', 'bQ': '♛', 'bR': '♜', 'bB': '♝', 'bN': '♞', 'bP': '♟' }; return icons[piece] || ''; } function updateBoardHighlights(board, selectedCell, validMoves) { for (var i = 0; i < 64; i++) { var row = Math.floor(i / 8); var col = i % 8; var isLight = (row + col) % 2 === 1; board[i].bg = isLight ? 'var(--game-surface-light)' : 'var(--game-surface-dark)'; board[i].ringWidth = 'none'; board[i].ringColor = ''; board[i].transform = 'none'; } if (selectedCell >= 0 && selectedCell < 64) { board[selectedCell].bg = 'var(--game-highlight-primary)'; board[selectedCell].transform = 'scale-110'; } for (var v = 0; v < validMoves.length; v++) { var idx = validMoves[v]; if (board[idx].piece) { board[idx].ringWidth = 'thick'; board[idx].ringColor = 'var(--game-highlight-success)'; } else { board[idx].ringWidth = 'thin'; board[idx].ringColor = 'var(--game-highlight-success)'; } } } switch (action.type) { case '$INIT': { var board = []; var backRow = ['R', 'N', 'B', 'Q', 'K', 'B', 'N', 'R']; for (var i = 0; i < 64; i++) { var row = Math.floor(i / 8); var col = i % 8; var isLight = (row + col) % 2 === 1; var piece = ''; if (row === 0) piece = 'w' + backRow[col]; else if (row === 1) piece = 'wP'; else if (row === 6) piece = 'bP'; else if (row === 7) piece = 'b' + backRow[col]; board.push({ piece: piece, icon: getPieceIcon(piece), bg: isLight ? 'var(--game-surface-light)' : 'var(--game-surface-dark)', color: piece ? (piece[0] === 'w' ? '#FFF8DC' : '#2F1810') : 'var(--game-text)', ringWidth: 'none', ringColor: '', transform: 'none' }); } newState.board = board; newState.castlingRights = { white: { kingSide: true, queenSide: true }, black: { kingSide: true, queenSide: true } }; newState.enPassantTarget = -1; newState.halfMoveClock = 0; newState.moveHistory = []; return newState; } case 'SELECT_CELL': { if (newState.phase !== 'playing' || newState.gameOver) return state; var cellIndex = action.payload.cellIndex; if (cellIndex < 0 || cellIndex >= 64) return state; var currentColor = newState.currentPlayer; var clickedPiece = newState.board[cellIndex].piece; if (newState.selectedCell === -1) { if (isOwnPiece(clickedPiece, currentColor)) { var moves = getValidMoves(newState.board, cellIndex, currentColor, newState.enPassantTarget, newState.castlingRights); if (moves.length > 0) { newState.selectedCell = cellIndex; newState.validMoves = moves; updateBoardHighlights(newState.board, newState.selectedCell, newState.validMoves); } } } else { if (newState.validMoves.indexOf(cellIndex) !== -1) { var fromIdx = newState.selectedCell; var toIdx = cellIndex; var movingPiece = newState.board[fromIdx].piece; var pieceType = getPieceType(movingPiece); var pieceColor = getPieceColor(movingPiece); newState.enPassantTarget = -1; if (pieceType === 'P') { var moveDir = pieceColor === 'white' ? 1 : -1; if (Math.abs(toIdx - fromIdx) === 16) { newState.enPassantTarget = fromIdx + moveDir * 8; } if (Math.abs((toIdx % 8) - (fromIdx % 8)) === 1 && !newState.board[toIdx].piece) { var capturedPawnIdx = toIdx - moveDir * 8; newState.board[capturedPawnIdx].piece = ''; newState.board[capturedPawnIdx].icon = ''; newState.board[capturedPawnIdx].color = 'var(--game-text)'; } } if (pieceType === 'K') { newState.castlingRights[pieceColor].kingSide = false; newState.castlingRights[pieceColor].queenSide = false; if (Math.abs((toIdx % 8) - (fromIdx % 8)) === 2) { var kingRow = Math.floor(fromIdx / 8); if (toIdx % 8 === 6) { newState.board[kingRow * 8 + 5].piece = newState.board[kingRow * 8 + 7].piece; newState.board[kingRow * 8 + 5].icon = newState.board[kingRow * 8 + 7].icon; newState.board[kingRow * 8 + 5].color = newState.board[kingRow * 8 + 7].color; newState.board[kingRow * 8 + 7].piece = ''; newState.board[kingRow * 8 + 7].icon = ''; newState.board[kingRow * 8 + 7].color = 'var(--game-text)'; } else if (toIdx % 8 === 2) { newState.board[kingRow * 8 + 3].piece = newState.board[kingRow * 8 + 0].piece; newState.board[kingRow * 8 + 3].icon = newState.board[kingRow * 8 + 0].icon; newState.board[kingRow * 8 + 3].color = newState.board[kingRow * 8 + 0].color; newState.board[kingRow * 8 + 0].piece = ''; newState.board[kingRow * 8 + 0].icon = ''; newState.board[kingRow * 8 + 0].color = 'var(--game-text)'; } } } if (pieceType === 'R') { var rookRow = Math.floor(fromIdx / 8); var rookCol = fromIdx % 8; if (rookRow === 0 && pieceColor === 'white') { if (rookCol === 0) newState.castlingRights.white.queenSide = false; if (rookCol === 7) newState.castlingRights.white.kingSide = false; } if (rookRow === 7 && pieceColor === 'black') { if (rookCol === 0) newState.castlingRights.black.queenSide = false; if (rookCol === 7) newState.castlingRights.black.kingSide = false; } } newState.board[toIdx].piece = movingPiece; newState.board[toIdx].icon = getPieceIcon(movingPiece); newState.board[toIdx].color = pieceColor === 'white' ? '#FFF8DC' : '#2F1810'; newState.board[fromIdx].piece = ''; newState.board[fromIdx].icon = ''; newState.board[fromIdx].color = 'var(--game-text)'; var promotionRow = pieceColor === 'white' ? 7 : 0; if (pieceType === 'P' && Math.floor(toIdx / 8) === promotionRow) { newState.phase = 'promotion'; newState.promotionCell = toIdx; newState.selectedCell = -1; newState.validMoves = []; updateBoardHighlights(newState.board, -1, []); return newState; } newState.currentPlayer = currentColor === 'white' ? 'black' : 'white'; newState.selectedCell = -1; newState.validMoves = []; var nextColor = newState.currentPlayer; newState.inCheck = isInCheck(newState.board, nextColor); var nextMoves = getAllLegalMoves(newState.board, nextColor, newState.enPassantTarget, newState.castlingRights); if (nextMoves.length === 0) { newState.gameOver = true; newState.phase = 'gameOver'; if (newState.inCheck) { newState.winner = currentColor; newState.resultMessage = 'Checkmate! ' + (currentColor === 'white' ? 'White' : 'Black') + ' wins!'; } else { newState.winner = 'draw'; newState.resultMessage = 'Stalemate - Draw!'; } } updateBoardHighlights(newState.board, -1, []); } else if (isOwnPiece(clickedPiece, currentColor)) { var newMoves = getValidMoves(newState.board, cellIndex, currentColor, newState.enPassantTarget, newState.castlingRights); if (newMoves.length > 0) { newState.selectedCell = cellIndex; newState.validMoves = newMoves; } else { newState.selectedCell = -1; newState.validMoves = []; } updateBoardHighlights(newState.board, newState.selectedCell, newState.validMoves); } else { newState.selectedCell = -1; newState.validMoves = []; updateBoardHighlights(newState.board, -1, []); } } return newState; } case 'PROMOTE': { if (newState.phase !== 'promotion' || newState.promotionCell === -1) return state; var promoteType = action.payload.pieceType; if (['Q', 'R', 'B', 'N'].indexOf(promoteType) === -1) return state; var pawnColor = getPieceColor(newState.board[newState.promotionCell].piece); var newPiece = pawnColor[0] + promoteType; newState.board[newState.promotionCell].piece = newPiece; newState.board[newState.promotionCell].icon = getPieceIcon(newPiece); newState.promotionCell = -1; newState.phase = 'playing'; newState.currentPlayer = pawnColor === 'white' ? 'black' : 'white'; var nextColor2 = newState.currentPlayer; newState.inCheck = isInCheck(newState.board, nextColor2); var nextMoves2 = getAllLegalMoves(newState.board, nextColor2, newState.enPassantTarget, newState.castlingRights); if (nextMoves2.length === 0) { newState.gameOver = true; newState.phase = 'gameOver'; if (newState.inCheck) { newState.winner = pawnColor; newState.resultMessage = 'Checkmate! ' + (pawnColor === 'white' ? 'White' : 'Black') + ' wins!'; } else { newState.winner = 'draw'; newState.resultMessage = 'Stalemate - Draw!'; } } updateBoardHighlights(newState.board, -1, []); return newState; } case 'RESIGN': { if (newState.gameOver) return state; var resigningPlayer = action.payload.player || newState.currentPlayer; newState.winner = resigningPlayer === 'white' ? 'black' : 'white'; newState.gameOver = true; newState.phase = 'gameOver'; newState.resultMessage = (newState.winner === 'white' ? 'White' : 'Black') + ' wins by resignation!'; return newState; } case '$TIMEOUT': { if (newState.gameOver) return state; if (newState.phase === 'promotion') { newState = resolveEpoch(newState, { type: 'PROMOTE', payload: { pieceType: 'Q' } }); return newState; } var timeoutColor = newState.currentPlayer; var legalMoves = getAllLegalMoves(newState.board, timeoutColor, newState.enPassantTarget, newState.castlingRights); if (legalMoves.length > 0) { var seed = action.payload && action.payload.seed ? action.payload.seed : 0.5; var randomIdx = Math.floor(seed * legalMoves.length); var randomMove = legalMoves[randomIdx]; newState = resolveEpoch(newState, { type: 'SELECT_CELL', payload: { cellIndex: randomMove.from } }); newState = resolveEpoch(newState, { type: 'SELECT_CELL', payload: { cellIndex: randomMove.to } }); } else { newState.winner = timeoutColor === 'white' ? 'black' : 'white'; newState.gameOver = true; newState.phase = 'gameOver'; newState.resultMessage = (newState.winner === 'white' ? 'White' : 'Black') + ' wins on time!'; } return newState; } default: return state; } }

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