function resolveEpoch(state, action) { // Helper functions function cloneState(s) { return JSON.parse(JSON.stringify(s)); } function getSquareId(x, y) { var files = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']; return files[x] + (8 - y); } function parseSquareId(id) { var files = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']; var x = files.indexOf(id[0]); var y = 8 - parseInt(id[1]); return { x: x, y: y }; } function getIndex(x, y) { return y * 8 + x; } function getPieceIcon(piece, color) { var icons = { white: { K: 'chess-king', Q: 'chess-queen', R: 'chess-rook', B: 'chess-bishop', N: 'chess-knight', P: 'chess-pawn' }, black: { K: 'chess-king', Q: 'chess-queen', R: 'chess-rook', B: 'chess-bishop', N: 'chess-knight', P: 'chess-pawn' } }; if (!piece || !color) return ''; return icons[color][piece] || ''; } function getBaseBgColor(x, y) { var isLight = (x + y) % 2 === 0; return isLight ? 'var(--game-surface-light)' : 'var(--game-surface-dark)'; } function isValidPosition(x, y) { return x >= 0 && x < 8 && y >= 0 && y < 8; } function findKing(board, color) { for (var i = 0; i < 64; i++) { if (board[i].piece === 'K' && board[i].pieceColor === color) { return i; } } return -1; } function isSquareAttacked(board, x, y, byColor) { // Check if square (x,y) is attacked by any piece of byColor for (var i = 0; i < 64; i++) { var cell = board[i]; if (cell.piece && cell.pieceColor === byColor) { var pos = parseSquareId(cell.id); var moves = getRawMoves(board, pos.x, pos.y, cell.piece, byColor, true); for (var j = 0; j < moves.length; j++) { if (moves[j].x === x && moves[j].y === y) { return true; } } } } return false; } function getRawMoves(board, x, y, piece, color, attackOnly) { var moves = []; var enemy = color === 'white' ? 'black' : 'white'; var directions, dx, dy, nx, ny, i; switch (piece) { case 'P': var dir = color === 'white' ? -1 : 1; var startRow = color === 'white' ? 6 : 1; if (!attackOnly) { // Forward move nx = x; ny = y + dir; if (isValidPosition(nx, ny) && !board[getIndex(nx, ny)].piece) { moves.push({ x: nx, y: ny }); // Double move from start if (y === startRow) { ny = y + 2 * dir; if (!board[getIndex(nx, ny)].piece) { moves.push({ x: nx, y: ny }); } } } } // Captures (diagonal) for (dx = -1; dx <= 1; dx += 2) { nx = x + dx; ny = y + dir; if (isValidPosition(nx, ny)) { var target = board[getIndex(nx, ny)]; if (attackOnly || (target.piece && target.pieceColor === enemy)) { moves.push({ x: nx, y: ny }); } } } break; case 'N': var knightMoves = [ { dx: 1, dy: 2 }, { dx: 2, dy: 1 }, { dx: 2, dy: -1 }, { dx: 1, dy: -2 }, { dx: -1, dy: -2 }, { dx: -2, dy: -1 }, { dx: -2, dy: 1 }, { dx: -1, dy: 2 } ]; for (i = 0; i < knightMoves.length; i++) { nx = x + knightMoves[i].dx; ny = y + knightMoves[i].dy; if (isValidPosition(nx, ny)) { var targetCell = board[getIndex(nx, ny)]; if (!targetCell.piece || targetCell.pieceColor === enemy) { moves.push({ x: nx, y: ny }); } } } break; case 'B': directions = [{ dx: 1, dy: 1 }, { dx: 1, dy: -1 }, { dx: -1, dy: 1 }, { dx: -1, dy: -1 }]; for (i = 0; i < directions.length; i++) { dx = directions[i].dx; dy = directions[i].dy; nx = x + dx; ny = y + dy; while (isValidPosition(nx, ny)) { var bCell = board[getIndex(nx, ny)]; if (!bCell.piece) { moves.push({ x: nx, y: ny }); } else { if (bCell.pieceColor === enemy) { moves.push({ x: nx, y: ny }); } break; } nx += dx; ny += dy; } } break; case 'R': directions = [{ dx: 1, dy: 0 }, { dx: -1, dy: 0 }, { dx: 0, dy: 1 }, { dx: 0, dy: -1 }]; for (i = 0; i < directions.length; i++) { dx = directions[i].dx; dy = directions[i].dy; nx = x + dx; ny = y + dy; while (isValidPosition(nx, ny)) { var rCell = board[getIndex(nx, ny)]; if (!rCell.piece) { moves.push({ x: nx, y: ny }); } else { if (rCell.pieceColor === enemy) { moves.push({ x: nx, y: ny }); } break; } nx += dx; ny += dy; } } break; case 'Q': directions = [ { dx: 1, dy: 0 }, { dx: -1, dy: 0 }, { dx: 0, dy: 1 }, { dx: 0, dy: -1 }, { dx: 1, dy: 1 }, { dx: 1, dy: -1 }, { dx: -1, dy: 1 }, { dx: -1, dy: -1 } ]; for (i = 0; i < directions.length; i++) { dx = directions[i].dx; dy = directions[i].dy; nx = x + dx; ny = y + dy; while (isValidPosition(nx, ny)) { var qCell = board[getIndex(nx, ny)]; if (!qCell.piece) { moves.push({ x: nx, y: ny }); } else { if (qCell.pieceColor === enemy) { moves.push({ x: nx, y: ny }); } break; } nx += dx; ny += dy; } } break; case 'K': directions = [ { dx: 1, dy: 0 }, { dx: -1, dy: 0 }, { dx: 0, dy: 1 }, { dx: 0, dy: -1 }, { dx: 1, dy: 1 }, { dx: 1, dy: -1 }, { dx: -1, dy: 1 }, { dx: -1, dy: -1 } ]; for (i = 0; i < directions.length; i++) { nx = x + directions[i].dx; ny = y + directions[i].dy; if (isValidPosition(nx, ny)) { var kCell = board[getIndex(nx, ny)]; if (!kCell.piece || kCell.pieceColor === enemy) { moves.push({ x: nx, y: ny }); } } } break; } return moves; } function getLegalMoves(board, fromX, fromY, piece, color) { var rawMoves = getRawMoves(board, fromX, fromY, piece, color, false); var legalMoves = []; var enemy = color === 'white' ? 'black' : 'white'; for (var i = 0; i < rawMoves.length; i++) { var move = rawMoves[i]; // Simulate the move var testBoard = JSON.parse(JSON.stringify(board)); var fromIdx = getIndex(fromX, fromY); var toIdx = getIndex(move.x, move.y); testBoard[toIdx].piece = testBoard[fromIdx].piece; testBoard[toIdx].pieceColor = testBoard[fromIdx].pieceColor; testBoard[fromIdx].piece = null; testBoard[fromIdx].pieceColor = null; // Check if own king is in check after move var kingIdx = findKing(testBoard, color); var kingPos = parseSquareId(testBoard[kingIdx].id); if (!isSquareAttacked(testBoard, kingPos.x, kingPos.y, enemy)) { legalMoves.push(move); } } return legalMoves; } function isInCheck(board, color) { var kingIdx = findKing(board, color); if (kingIdx === -1) return false; var kingPos = parseSquareId(board[kingIdx].id); var enemy = color === 'white' ? 'black' : 'white'; return isSquareAttacked(board, kingPos.x, kingPos.y, enemy); } function hasLegalMoves(board, color) { for (var i = 0; i < 64; i++) { var cell = board[i]; if (cell.piece && cell.pieceColor === color) { var pos = parseSquareId(cell.id); var moves = getLegalMoves(board, pos.x, pos.y, cell.piece, color); if (moves.length > 0) { return true; } } } return false; } function clearHighlights(board) { for (var i = 0; i < 64; i++) { var pos = parseSquareId(board[i].id); board[i].bgColor = getBaseBgColor(pos.x, pos.y); board[i].isSelected = false; board[i].isValidMove = false; board[i].ringWidth = 'none'; board[i].ringColor = ''; board[i].transform = 'none'; } } function updateBoardDisplay(newState) { var board = newState.board; clearHighlights(board); // Highlight last move if (newState.lastMove) { var fromPos = parseSquareId(newState.lastMove.from); var toPos = parseSquareId(newState.lastMove.to); board[getIndex(fromPos.x, fromPos.y)].isLastMove = true; board[getIndex(toPos.x, toPos.y)].isLastMove = true; board[getIndex(fromPos.x, fromPos.y)].bgColor = 'var(--game-highlight-primary)'; board[getIndex(toPos.x, toPos.y)].bgColor = 'var(--game-highlight-primary)'; } // Highlight selected square and valid moves if (newState.selectedSquare) { var selPos = parseSquareId(newState.selectedSquare); var selIdx = getIndex(selPos.x, selPos.y); var selCell = board[selIdx]; board[selIdx].isSelected = true; board[selIdx].bgColor = 'var(--game-highlight-primary)'; board[selIdx].transform = 'scale-105'; // Show valid moves var validMoves = getLegalMoves(board, selPos.x, selPos.y, selCell.piece, selCell.pieceColor); for (var i = 0; i < validMoves.length; i++) { var moveIdx = getIndex(validMoves[i].x, validMoves[i].y); board[moveIdx].isValidMove = true; if (board[moveIdx].piece) { board[moveIdx].ringWidth = 'thick'; board[moveIdx].ringColor = 'var(--game-highlight-success)'; } else { board[moveIdx].ringWidth = 'thin'; board[moveIdx].ringColor = 'var(--game-highlight-success)'; } } } // Highlight king in check if (newState.inCheck) { var kingIdx = findKing(board, newState.inCheck); if (kingIdx !== -1) { board[kingIdx].bgColor = '#dc2626'; } } // Update icons for (var j = 0; j < 64; j++) { board[j].icon = getPieceIcon(board[j].piece, board[j].pieceColor); board[j].iconColor = board[j].pieceColor === 'white' ? '#ffffff' : '#1a1a1a'; } } switch (action.type) { case '$INIT': { var newState = cloneState(state); var board = []; var backRow = ['R', 'N', 'B', 'Q', 'K', 'B', 'N', 'R']; for (var y = 0; y < 8; y++) { for (var x = 0; x < 8; x++) { var id = getSquareId(x, y); var piece = null; var pieceColor = null; if (y === 0) { piece = backRow[x]; pieceColor = 'black'; } else if (y === 1) { piece = 'P'; pieceColor = 'black'; } else if (y === 6) { piece = 'P'; pieceColor = 'white'; } else if (y === 7) { piece = backRow[x]; pieceColor = 'white'; } board.push({ id: id, piece: piece, pieceColor: pieceColor, icon: getPieceIcon(piece, pieceColor), iconColor: pieceColor === 'white' ? '#ffffff' : '#1a1a1a', bgColor: getBaseBgColor(x, y), isSelected: false, isValidMove: false, isLastMove: false, ringWidth: 'none', ringColor: '', transform: 'none' }); } } newState.board = board; newState.phase = 'playing'; newState.gameOver = false; newState.currentPlayer = 'white'; newState.selectedSquare = null; newState.capturedWhite = []; newState.capturedBlack = []; newState.inCheck = null; newState.winner = null; newState.lastMove = null; newState.statusMessage = "White's turn"; newState.lastMoveNotation = ''; return newState; } case 'SELECT_SQUARE': { if (state.gameOver) return state; var newState = cloneState(state); var squareId = action.payload.squareId; var pos = parseSquareId(squareId); var idx = getIndex(pos.x, pos.y); var clickedCell = newState.board[idx]; if (!newState.selectedSquare) { // No piece selected yet if (clickedCell.piece && clickedCell.pieceColor === newState.currentPlayer) { var moves = getLegalMoves(newState.board, pos.x, pos.y, clickedCell.piece, clickedCell.pieceColor); if (moves.length > 0) { newState.selectedSquare = squareId; } } } else { // A piece is already selected var selPos = parseSquareId(newState.selectedSquare); var selIdx = getIndex(selPos.x, selPos.y); var selectedCell = newState.board[selIdx]; var legalMoves = getLegalMoves(newState.board, selPos.x, selPos.y, selectedCell.piece, selectedCell.pieceColor); // Check if clicked square is a valid move var isValidMove = false; for (var i = 0; i < legalMoves.length; i++) { if (legalMoves[i].x === pos.x && legalMoves[i].y === pos.y) { isValidMove = true; break; } } if (isValidMove) { // Execute the move var capturedPiece = clickedCell.piece; var capturedColor = clickedCell.pieceColor; // Store captured piece if (capturedPiece) { var capturedIcon = getPieceIcon(capturedPiece, capturedColor); if (capturedColor === 'white') { newState.capturedWhite.push(capturedIcon); } else { newState.capturedBlack.push(capturedIcon); } } // Move the piece newState.board[idx].piece = selectedCell.piece; newState.board[idx].pieceColor = selectedCell.pieceColor; newState.board[selIdx].piece = null; newState.board[selIdx].pieceColor = null; // Pawn promotion if (newState.board[idx].piece === 'P') { if ((newState.board[idx].pieceColor === 'white' && pos.y === 0) || (newState.board[idx].pieceColor === 'black' && pos.y === 7)) { newState.board[idx].piece = 'Q'; } } // Record last move newState.lastMove = { from: newState.selectedSquare, to: squareId, piece: selectedCell.piece, captured: capturedPiece }; newState.lastMoveNotation = newState.selectedSquare + ' → ' + squareId; // Clear selection newState.selectedSquare = null; // Switch player var nextPlayer = newState.currentPlayer === 'white' ? 'black' : 'white'; newState.currentPlayer = nextPlayer; // Check game state var inCheck = isInCheck(newState.board, nextPlayer); var hasMovesLeft = hasLegalMoves(newState.board, nextPlayer); newState.inCheck = inCheck ? nextPlayer : null; if (!hasMovesLeft) { newState.gameOver = true; newState.phase = 'gameOver'; if (inCheck) { // Checkmate newState.winner = nextPlayer === 'white' ? 'black' : 'white'; newState.statusMessage = 'Checkmate! ' + (newState.winner === 'white' ? 'White' : 'Black') + ' wins!'; } else { // Stalemate newState.winner = 'draw'; newState.statusMessage = 'Stalemate! Game is a draw.'; } } else if (inCheck) { newState.statusMessage = (nextPlayer === 'white' ? 'White' : 'Black') + ' is in check!'; } else { newState.statusMessage = (nextPlayer === 'white' ? "White's" : "Black's") + ' turn'; } } else if (clickedCell.piece && clickedCell.pieceColor === newState.currentPlayer) { // Select a different piece var newMoves = getLegalMoves(newState.board, pos.x, pos.y, clickedCell.piece, clickedCell.pieceColor); if (newMoves.length > 0) { newState.selectedSquare = squareId; } else { newState.selectedSquare = null; } } else { // Deselect newState.selectedSquare = null; } } updateBoardDisplay(newState); return newState; } case 'RESIGN': { if (state.gameOver) return state; var newState = cloneState(state); newState.gameOver = true; newState.phase = 'gameOver'; newState.winner = newState.currentPlayer === 'white' ? 'black' : 'white'; newState.statusMessage = (newState.currentPlayer === 'white' ? 'White' : 'Black') + ' resigned. ' + (newState.winner === 'white' ? 'White' : 'Black') + ' wins!'; newState.selectedSquare = null; updateBoardDisplay(newState); return newState; } case 'TIMEOUT': { if (state.gameOver) return state; var newState = cloneState(state); newState.gameOver = true; newState.phase = 'gameOver'; newState.winner = newState.currentPlayer === 'white' ? 'black' : 'white'; newState.statusMessage = (newState.currentPlayer === 'white' ? 'White' : 'Black') + ' ran out of time. ' + (newState.winner === 'white' ? 'White' : 'Black') + ' wins!'; newState.selectedSquare = null; updateBoardDisplay(newState); return newState; } default: return state; } }

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