@wirelineio/shogiboardjsx/dist/es/Shogiboard/helpers.js

Shogiboardjsx is a shogiboard for React. Inspired by Chessboardjsx

function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }

import diff from 'deep-diff';
export var ItemTypes = {
  PIECE: 'piece'
};
export var COLUMNS = 'abcdefghi'.split('');
export var constructPositionAttributes = function constructPositionAttributes(currentPosition, position) {
  var difference = diff(currentPosition, position);
  var squaresAffected = difference.length;
  var sourceSquare = difference && difference[1] && difference && difference[1].kind === 'D' ? difference[1].path && difference[1].path[0] : difference[0].path && difference[0].path[0];
  var targetSquare = difference && difference[1] && difference && difference[1].kind === 'D' ? difference[0] && difference[0].path[0] : difference[1] && difference[1].path[0];
  var sourcePiece = difference && difference[1] && difference && difference[1].kind === 'D' ? difference[1] && difference[1].lhs : difference[1] && difference[1].rhs;
  return {
    sourceSquare: sourceSquare,
    targetSquare: targetSquare,
    sourcePiece: sourcePiece,
    squaresAffected: squaresAffected
  };
};

function isString(s) {
  return typeof s === 'string';
}

export function fenToObj(fen) {
  if (!validFen(fen)) return false; // cut off any move, castling, etc info from the end
  // we're only interested in position information

  fen = fen.replace(/ .+$/, '');
  var rows = fen.split('/');
  var position = {};
  var currentRow = 9;

  for (var i = 0; i < 9; i++) {
    var row = rows[i].split('');
    var colIdx = 0; // loop through each character in the FEN section

    for (var j = 0; j < row.length; j++) {
      // number / empty squares
      if (row[j].search(/[1-9]/) !== -1) {
        var numEmptySquares = parseInt(row[j], 10);
        colIdx = colIdx + numEmptySquares;
      } else {
        // piece
        var square = COLUMNS[colIdx] + currentRow;
        position[square] = fenToPieceCode(row[j]);
        colIdx = colIdx + 1;
      }
    }

    currentRow = currentRow - 1;
  }

  return position;
}

function expandFenEmptySquares(fen) {
  return fen.replace(/9/g, '111111111').replace(/8/g, '11111111').replace(/7/g, '1111111').replace(/6/g, '111111').replace(/5/g, '11111').replace(/4/g, '1111').replace(/3/g, '111').replace(/2/g, '11');
}

export function validFen(fen) {
  if (!isString(fen)) return false; // cut off any move, castling, etc info from the end
  // we're only interested in position information

  fen = fen.replace(/ .+$/, ''); // expand the empty square numbers to just 1s

  fen = expandFenEmptySquares(fen); // SFEN should be 9 sections separated by slashes

  var chunks = fen.split('/');
  if (chunks.length !== 9) return false; // TODO(burdon): Promoted pieces are prefixed with "+".
  // check each section

  for (var i = 0; i < 9; i++) {
    if (chunks[i].length !== 9 || chunks[i].search(/[^lnsgkrbpLNSGKRBP1]/) !== -1) {
      return false;
    }
  }

  return true;
} // TODO(burdon): Promoted pieces (+X)
// convert FEN piece code to bP, wK, etc

function fenToPieceCode(piece) {
  // black piece
  if (piece.toLowerCase() === piece) {
    return 'b' + piece.toUpperCase();
  } // white piece


  return 'w' + piece.toUpperCase();
}

function validSquare(square) {
  return isString(square) && square.search(/^[a-i][1-9]$/) !== -1;
} // TODO(burdon): Promoted pieces (+X)


function validPieceCode(code) {
  return isString(code) && code.search(/^[bw][LNSGKRB]$/) !== -1;
}

export function validPositionObject(pos) {
  if (pos === null || _typeof(pos) !== 'object') return false;

  for (var i in pos) {
    if (!pos.hasOwnProperty(i)) continue;

    if (!validSquare(i) || !validPieceCode(pos[i])) {
      return false;
    }
  }

  return true;
}

function squeezeFenEmptySquares(fen) {
  return fen.replace(/111111111/g, '9').replace(/11111111/g, '8').replace(/1111111/g, '7').replace(/111111/g, '6').replace(/11111/g, '5').replace(/1111/g, '4').replace(/111/g, '3').replace(/11/g, '2');
} // TODO(burdon): "+" for promoted piece.
// convert bP, wK, etc code to FEN structure


function pieceCodeToFen(piece) {
  var pieceCodeLetters = piece.split(''); // white piece

  if (pieceCodeLetters[0] === 'w') {
    return pieceCodeLetters[1].toUpperCase();
  } // black piece


  return pieceCodeLetters[1].toLowerCase();
} // position object to FEN string
// returns false if the obj is not a valid position object


export function objToFen(obj) {
  if (!validPositionObject(obj)) return false;
  var fen = '';
  var currentRow = 9;

  for (var i = 0; i < 9; i++) {
    for (var j = 0; j < 9; j++) {
      var square = COLUMNS[j] + currentRow; // piece exists

      if (obj.hasOwnProperty(square)) {
        fen = fen + pieceCodeToFen(obj[square]);
      } else {
        // empty space
        fen = fen + '1';
      }
    }

    if (i !== 7) {
      fen = fen + '/';
    }

    currentRow = currentRow - 1;
  } // squeeze the empty numbers together


  fen = squeezeFenEmptySquares(fen);
  return fen;
}