// Variants generally inherit from it, and modify some parts.
import { ArrayFun } from "@/utils/array";
-import { random, sample, shuffle } from "@/utils/alea";
-
-export const PiPo = class PiPo //Piece+Position
-{
- // o: {piece[p], color[c], posX[x], posY[y]}
- constructor(o)
- {
- this.p = o.p;
- this.c = o.c;
- this.x = o.x;
- this.y = o.y;
- }
-}
-
-// TODO: for animation, moves should contains "moving" and "fading" maybe...
-export const Move = class Move
-{
- // o: {appear, vanish, [start,] [end,]}
- // appear,vanish = arrays of PiPo
- // start,end = coordinates to apply to trigger move visually (think castle)
- constructor(o)
- {
- this.appear = o.appear;
- this.vanish = o.vanish;
- this.start = !!o.start ? o.start : {x:o.vanish[0].x, y:o.vanish[0].y};
- this.end = !!o.end ? o.end : {x:o.appear[0].x, y:o.appear[0].y};
- }
-}
+import { randInt, shuffle } from "@/utils/alea";
+
+// class "PiPo": Piece + Position
+export const PiPo = class PiPo {
+ // o: {piece[p], color[c], posX[x], posY[y]}
+ constructor(o) {
+ this.p = o.p;
+ this.c = o.c;
+ this.x = o.x;
+ this.y = o.y;
+ }
+};
+
+export const Move = class Move {
+ // o: {appear, vanish, [start,] [end,]}
+ // appear,vanish = arrays of PiPo
+ // start,end = coordinates to apply to trigger move visually (think castle)
+ constructor(o) {
+ this.appear = o.appear;
+ this.vanish = o.vanish;
+ this.start = o.start ? o.start : { x: o.vanish[0].x, y: o.vanish[0].y };
+ this.end = o.end ? o.end : { x: o.appear[0].x, y: o.appear[0].y };
+ }
+};
// NOTE: x coords = top to bottom; y = left to right (from white player perspective)
-export const ChessRules = class ChessRules
-{
- //////////////
- // MISC UTILS
-
- static get HasFlags() { return true; } //some variants don't have flags
-
- static get HasEnpassant() { return true; } //some variants don't have ep.
-
- // Path to pieces
- static getPpath(b)
- {
- return b; //usual pieces in pieces/ folder
- }
-
- // Turn "wb" into "B" (for FEN)
- static board2fen(b)
- {
- return b[0]=='w' ? b[1].toUpperCase() : b[1];
- }
-
- // Turn "p" into "bp" (for board)
- static fen2board(f)
- {
- return f.charCodeAt()<=90 ? "w"+f.toLowerCase() : "b"+f;
- }
-
- // Check if FEN describe a position
- static IsGoodFen(fen)
- {
- const fenParsed = V.ParseFen(fen);
- // 1) Check position
- if (!V.IsGoodPosition(fenParsed.position))
- return false;
- // 2) Check turn
- if (!fenParsed.turn || !V.IsGoodTurn(fenParsed.turn))
- return false;
- // 3) Check moves count
- if (!fenParsed.movesCount || !(parseInt(fenParsed.movesCount) >= 0))
- return false;
- // 4) Check flags
- if (V.HasFlags && (!fenParsed.flags || !V.IsGoodFlags(fenParsed.flags)))
- return false;
- // 5) Check enpassant
- if (V.HasEnpassant &&
- (!fenParsed.enpassant || !V.IsGoodEnpassant(fenParsed.enpassant)))
- {
- return false;
- }
- return true;
- }
-
- // Is position part of the FEN a priori correct?
- static IsGoodPosition(position)
- {
- if (position.length == 0)
- return false;
- const rows = position.split("/");
- if (rows.length != V.size.x)
- return false;
- for (let row of rows)
- {
- let sumElts = 0;
- for (let i=0; i<row.length; i++)
- {
- if (V.PIECES.includes(row[i].toLowerCase()))
- sumElts++;
- else
- {
- const num = parseInt(row[i]);
- if (isNaN(num))
- return false;
- sumElts += num;
- }
- }
- if (sumElts != V.size.y)
- return false;
- }
- return true;
- }
-
- // For FEN checking
- static IsGoodTurn(turn)
- {
- return ["w","b"].includes(turn);
- }
-
- // For FEN checking
- static IsGoodFlags(flags)
- {
- return !!flags.match(/^[01]{4,4}$/);
- }
-
- static IsGoodEnpassant(enpassant)
- {
- if (enpassant != "-")
- {
- const ep = V.SquareToCoords(fenParsed.enpassant);
- if (isNaN(ep.x) || !V.OnBoard(ep))
- return false;
- }
- return true;
- }
-
- // 3 --> d (column number to letter)
- static CoordToColumn(colnum)
- {
- return String.fromCharCode(97 + colnum);
- }
-
- // d --> 3 (column letter to number)
- static ColumnToCoord(column)
- {
- return column.charCodeAt(0) - 97;
- }
-
- // a4 --> {x:3,y:0}
- static SquareToCoords(sq)
- {
- return {
- // NOTE: column is always one char => max 26 columns
- // row is counted from black side => subtraction
- x: V.size.x - parseInt(sq.substr(1)),
- y: sq[0].charCodeAt() - 97
- };
- }
-
- // {x:0,y:4} --> e8
- static CoordsToSquare(coords)
- {
- return V.CoordToColumn(coords.y) + (V.size.x - coords.x);
- }
-
- // Aggregates flags into one object
- aggregateFlags()
- {
- return this.castleFlags;
- }
-
- // Reverse operation
- disaggregateFlags(flags)
- {
- this.castleFlags = flags;
- }
-
- // En-passant square, if any
- getEpSquare(moveOrSquare)
- {
- if (!moveOrSquare)
- return undefined;
- if (typeof moveOrSquare === "string")
- {
- const square = moveOrSquare;
- if (square == "-")
- return undefined;
- return V.SquareToCoords(square);
- }
- // Argument is a move:
- const move = moveOrSquare;
- const [sx,sy,ex] = [move.start.x,move.start.y,move.end.x];
- // TODO: next conditions are first for Atomic, and third for Checkered
- if (move.appear.length > 0 && move.appear[0].p == V.PAWN && ["w","b"].includes(move.appear[0].c) && Math.abs(sx - ex) == 2)
- {
- return {
- x: (sx + ex)/2,
- y: sy
- };
- }
- return undefined; //default
- }
-
- // Can thing on square1 take thing on square2
- canTake([x1,y1], [x2,y2])
- {
- return this.getColor(x1,y1) !== this.getColor(x2,y2);
- }
-
- // Is (x,y) on the chessboard?
- static OnBoard(x,y)
- {
- return (x>=0 && x<V.size.x && y>=0 && y<V.size.y);
- }
-
- // Used in interface: 'side' arg == player color
- canIplay(side, [x,y])
- {
- return (this.turn == side && this.getColor(x,y) == side);
- }
-
- // On which squares is color under check ? (for interface)
- getCheckSquares(color)
- {
- return this.isAttacked(this.kingPos[color], [V.GetOppCol(color)])
- ? [JSON.parse(JSON.stringify(this.kingPos[color]))] //need to duplicate!
- : [];
- }
-
- /////////////
- // FEN UTILS
-
- // Setup the initial random (assymetric) position
- static GenRandInitFen()
- {
- let pieces = { "w": new Array(8), "b": new Array(8) };
- // Shuffle pieces on first and last rank
- for (let c of ["w","b"])
- {
- let positions = ArrayFun.range(8);
-
- // Get random squares for bishops
- let randIndex = 2 * random(4);
- const bishop1Pos = positions[randIndex];
- // The second bishop must be on a square of different color
- let randIndex_tmp = 2 * random(4) + 1;
- const bishop2Pos = positions[randIndex_tmp];
- // Remove chosen squares
- positions.splice(Math.max(randIndex,randIndex_tmp), 1);
- positions.splice(Math.min(randIndex,randIndex_tmp), 1);
-
- // Get random squares for knights
- randIndex = random(6);
- const knight1Pos = positions[randIndex];
- positions.splice(randIndex, 1);
- randIndex = random(5);
- const knight2Pos = positions[randIndex];
- positions.splice(randIndex, 1);
-
- // Get random square for queen
- randIndex = random(4);
- const queenPos = positions[randIndex];
- positions.splice(randIndex, 1);
-
- // Rooks and king positions are now fixed,
- // because of the ordering rook-king-rook
- const rook1Pos = positions[0];
- const kingPos = positions[1];
- const rook2Pos = positions[2];
-
- // Finally put the shuffled pieces in the board array
- pieces[c][rook1Pos] = 'r';
- pieces[c][knight1Pos] = 'n';
- pieces[c][bishop1Pos] = 'b';
- pieces[c][queenPos] = 'q';
- pieces[c][kingPos] = 'k';
- pieces[c][bishop2Pos] = 'b';
- pieces[c][knight2Pos] = 'n';
- pieces[c][rook2Pos] = 'r';
- }
- return pieces["b"].join("") +
- "/pppppppp/8/8/8/8/PPPPPPPP/" +
- pieces["w"].join("").toUpperCase() +
- " w 0 1111 -"; //add turn + flags + enpassant
- }
-
- // "Parse" FEN: just return untransformed string data
- static ParseFen(fen)
- {
- const fenParts = fen.split(" ");
- let res =
- {
- position: fenParts[0],
- turn: fenParts[1],
- movesCount: fenParts[2],
- };
- let nextIdx = 3;
- if (V.HasFlags)
- Object.assign(res, {flags: fenParts[nextIdx++]});
- if (V.HasEnpassant)
- Object.assign(res, {enpassant: fenParts[nextIdx]});
- return res;
- }
-
- // Return current fen (game state)
- getFen()
- {
- return this.getBaseFen() + " " +
- this.getTurnFen() + " " + this.movesCount +
- (V.HasFlags ? (" " + this.getFlagsFen()) : "") +
- (V.HasEnpassant ? (" " + this.getEnpassantFen()) : "");
- }
-
- // Position part of the FEN string
- getBaseFen()
- {
- let position = "";
- for (let i=0; i<V.size.x; i++)
- {
- let emptyCount = 0;
- for (let j=0; j<V.size.y; j++)
- {
- if (this.board[i][j] == V.EMPTY)
- emptyCount++;
- else
- {
- if (emptyCount > 0)
- {
- // Add empty squares in-between
- position += emptyCount;
- emptyCount = 0;
- }
- position += V.board2fen(this.board[i][j]);
- }
- }
- if (emptyCount > 0)
- {
- // "Flush remainder"
- position += emptyCount;
- }
- if (i < V.size.x - 1)
- position += "/"; //separate rows
- }
- return position;
- }
-
- getTurnFen()
- {
- return this.turn;
- }
-
- // Flags part of the FEN string
- getFlagsFen()
- {
- let flags = "";
- // Add castling flags
- for (let i of ['w','b'])
- {
- for (let j=0; j<2; j++)
- flags += (this.castleFlags[i][j] ? '1' : '0');
- }
- return flags;
- }
-
- // Enpassant part of the FEN string
- getEnpassantFen()
- {
- const L = this.epSquares.length;
- if (!this.epSquares[L-1])
- return "-"; //no en-passant
- return V.CoordsToSquare(this.epSquares[L-1]);
- }
-
- // Turn position fen into double array ["wb","wp","bk",...]
- static GetBoard(position)
- {
- const rows = position.split("/");
- let board = ArrayFun.init(V.size.x, V.size.y, "");
- for (let i=0; i<rows.length; i++)
- {
- let j = 0;
- for (let indexInRow = 0; indexInRow < rows[i].length; indexInRow++)
- {
- const character = rows[i][indexInRow];
- const num = parseInt(character);
- if (!isNaN(num))
- j += num; //just shift j
- else //something at position i,j
- board[i][j++] = V.fen2board(character);
- }
- }
- return board;
- }
-
- // Extract (relevant) flags from fen
- setFlags(fenflags)
- {
- // white a-castle, h-castle, black a-castle, h-castle
- this.castleFlags = {'w': [true,true], 'b': [true,true]};
- if (!fenflags)
- return;
- for (let i=0; i<4; i++)
- this.castleFlags[i < 2 ? 'w' : 'b'][i%2] = (fenflags.charAt(i) == '1');
- }
-
- //////////////////
- // INITIALIZATION
-
- // Fen string fully describes the game state
- constructor(fen)
- {
- const fenParsed = V.ParseFen(fen);
- this.board = V.GetBoard(fenParsed.position);
- this.turn = fenParsed.turn[0]; //[0] to work with MarseilleRules
- this.movesCount = parseInt(fenParsed.movesCount);
- this.setOtherVariables(fen);
- }
-
- // Scan board for kings and rooks positions
- scanKingsRooks(fen)
- {
- this.INIT_COL_KING = {'w':-1, 'b':-1};
- this.INIT_COL_ROOK = {'w':[-1,-1], 'b':[-1,-1]};
- this.kingPos = {'w':[-1,-1], 'b':[-1,-1]}; //squares of white and black king
- const fenRows = V.ParseFen(fen).position.split("/");
- for (let i=0; i<fenRows.length; i++)
- {
- let k = 0; //column index on board
- for (let j=0; j<fenRows[i].length; j++)
- {
- switch (fenRows[i].charAt(j))
- {
- case 'k':
- this.kingPos['b'] = [i,k];
- this.INIT_COL_KING['b'] = k;
- break;
- case 'K':
- this.kingPos['w'] = [i,k];
- this.INIT_COL_KING['w'] = k;
- break;
- case 'r':
- if (this.INIT_COL_ROOK['b'][0] < 0)
- this.INIT_COL_ROOK['b'][0] = k;
- else
- this.INIT_COL_ROOK['b'][1] = k;
- break;
- case 'R':
- if (this.INIT_COL_ROOK['w'][0] < 0)
- this.INIT_COL_ROOK['w'][0] = k;
- else
- this.INIT_COL_ROOK['w'][1] = k;
- break;
- default:
- const num = parseInt(fenRows[i].charAt(j));
- if (!isNaN(num))
- k += (num-1);
- }
- k++;
- }
- }
- }
-
- // Some additional variables from FEN (variant dependant)
- setOtherVariables(fen)
- {
- // Set flags and enpassant:
- const parsedFen = V.ParseFen(fen);
- if (V.HasFlags)
- this.setFlags(parsedFen.flags);
- if (V.HasEnpassant)
- {
- const epSq = parsedFen.enpassant != "-"
- ? V.SquareToCoords(parsedFen.enpassant)
- : undefined;
- this.epSquares = [ epSq ];
- }
- // Search for king and rooks positions:
- this.scanKingsRooks(fen);
- }
-
- /////////////////////
- // GETTERS & SETTERS
-
- static get size()
- {
- return {x:8, y:8};
- }
-
- // Color of thing on suqare (i,j). 'undefined' if square is empty
- getColor(i,j)
- {
- return this.board[i][j].charAt(0);
- }
-
- // Piece type on square (i,j). 'undefined' if square is empty
- getPiece(i,j)
- {
- return this.board[i][j].charAt(1);
- }
-
- // Get opponent color
- static GetOppCol(color)
- {
- return (color=="w" ? "b" : "w");
- }
-
- // Get next color (for compatibility with 3 and 4 players games)
- static GetNextCol(color)
- {
- return V.GetOppCol(color);
- }
-
- // Pieces codes (for a clearer code)
- static get PAWN() { return 'p'; }
- static get ROOK() { return 'r'; }
- static get KNIGHT() { return 'n'; }
- static get BISHOP() { return 'b'; }
- static get QUEEN() { return 'q'; }
- static get KING() { return 'k'; }
-
- // For FEN checking:
- static get PIECES()
- {
- return [V.PAWN,V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN,V.KING];
- }
-
- // Empty square
- static get EMPTY() { return ""; }
-
- // Some pieces movements
- static get steps()
- {
- return {
- 'r': [ [-1,0],[1,0],[0,-1],[0,1] ],
- 'n': [ [-1,-2],[-1,2],[1,-2],[1,2],[-2,-1],[-2,1],[2,-1],[2,1] ],
- 'b': [ [-1,-1],[-1,1],[1,-1],[1,1] ],
- };
- }
-
- ////////////////////
- // MOVES GENERATION
-
- // All possible moves from selected square (assumption: color is OK)
- getPotentialMovesFrom([x,y])
- {
- switch (this.getPiece(x,y))
- {
- case V.PAWN:
- return this.getPotentialPawnMoves([x,y]);
- case V.ROOK:
- return this.getPotentialRookMoves([x,y]);
- case V.KNIGHT:
- return this.getPotentialKnightMoves([x,y]);
- case V.BISHOP:
- return this.getPotentialBishopMoves([x,y]);
- case V.QUEEN:
- return this.getPotentialQueenMoves([x,y]);
- case V.KING:
- return this.getPotentialKingMoves([x,y]);
- }
- }
-
- // Build a regular move from its initial and destination squares.
- // tr: transformation
- getBasicMove([sx,sy], [ex,ey], tr)
- {
- let mv = new Move({
- appear: [
- new PiPo({
- x: ex,
- y: ey,
- c: !!tr ? tr.c : this.getColor(sx,sy),
- p: !!tr ? tr.p : this.getPiece(sx,sy)
- })
- ],
- vanish: [
- new PiPo({
- x: sx,
- y: sy,
- c: this.getColor(sx,sy),
- p: this.getPiece(sx,sy)
- })
- ]
- });
-
- // The opponent piece disappears if we take it
- if (this.board[ex][ey] != V.EMPTY)
- {
- mv.vanish.push(
- new PiPo({
- x: ex,
- y: ey,
- c: this.getColor(ex,ey),
- p: this.getPiece(ex,ey)
- })
- );
- }
- return mv;
- }
-
- // Generic method to find possible moves of non-pawn pieces:
- // "sliding or jumping"
- getSlideNJumpMoves([x,y], steps, oneStep)
- {
- const color = this.getColor(x,y);
- let moves = [];
- outerLoop:
- for (let step of steps)
- {
- let i = x + step[0];
- let j = y + step[1];
- while (V.OnBoard(i,j) && this.board[i][j] == V.EMPTY)
- {
- moves.push(this.getBasicMove([x,y], [i,j]));
- if (oneStep !== undefined)
- continue outerLoop;
- i += step[0];
- j += step[1];
- }
- if (V.OnBoard(i,j) && this.canTake([x,y], [i,j]))
- moves.push(this.getBasicMove([x,y], [i,j]));
- }
- return moves;
- }
-
- // What are the pawn moves from square x,y ?
- getPotentialPawnMoves([x,y])
- {
- const color = this.turn;
- let moves = [];
- const [sizeX,sizeY] = [V.size.x,V.size.y];
- const shiftX = (color == "w" ? -1 : 1);
- const firstRank = (color == 'w' ? sizeX-1 : 0);
- const startRank = (color == "w" ? sizeX-2 : 1);
- const lastRank = (color == "w" ? 0 : sizeX-1);
- const pawnColor = this.getColor(x,y); //can be different for checkered
-
- // NOTE: next condition is generally true (no pawn on last rank)
- if (x+shiftX >= 0 && x+shiftX < sizeX)
- {
- const finalPieces = x + shiftX == lastRank
- ? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN]
- : [V.PAWN]
- // One square forward
- if (this.board[x+shiftX][y] == V.EMPTY)
- {
- for (let piece of finalPieces)
- {
- moves.push(this.getBasicMove([x,y], [x+shiftX,y],
- {c:pawnColor,p:piece}));
- }
- // Next condition because pawns on 1st rank can generally jump
- if ([startRank,firstRank].includes(x)
- && this.board[x+2*shiftX][y] == V.EMPTY)
- {
- // Two squares jump
- moves.push(this.getBasicMove([x,y], [x+2*shiftX,y]));
- }
- }
- // Captures
- for (let shiftY of [-1,1])
- {
- if (y + shiftY >= 0 && y + shiftY < sizeY
- && this.board[x+shiftX][y+shiftY] != V.EMPTY
- && this.canTake([x,y], [x+shiftX,y+shiftY]))
- {
- for (let piece of finalPieces)
- {
- moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
- {c:pawnColor,p:piece}));
- }
- }
- }
- }
-
- if (V.HasEnpassant)
- {
- // En passant
- const Lep = this.epSquares.length;
- const epSquare = this.epSquares[Lep-1]; //always at least one element
- if (!!epSquare && epSquare.x == x+shiftX && Math.abs(epSquare.y - y) == 1)
- {
- let enpassantMove = this.getBasicMove([x,y], [epSquare.x,epSquare.y]);
- enpassantMove.vanish.push({
- x: x,
- y: epSquare.y,
- p: 'p',
- c: this.getColor(x,epSquare.y)
- });
- moves.push(enpassantMove);
- }
- }
-
- return moves;
- }
-
- // What are the rook moves from square x,y ?
- getPotentialRookMoves(sq)
- {
- return this.getSlideNJumpMoves(sq, V.steps[V.ROOK]);
- }
-
- // What are the knight moves from square x,y ?
- getPotentialKnightMoves(sq)
- {
- return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep");
- }
-
- // What are the bishop moves from square x,y ?
- getPotentialBishopMoves(sq)
- {
- return this.getSlideNJumpMoves(sq, V.steps[V.BISHOP]);
- }
-
- // What are the queen moves from square x,y ?
- getPotentialQueenMoves(sq)
- {
- return this.getSlideNJumpMoves(sq,
- V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
- }
-
- // What are the king moves from square x,y ?
- getPotentialKingMoves(sq)
- {
- // Initialize with normal moves
- let moves = this.getSlideNJumpMoves(sq,
- V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep");
- return moves.concat(this.getCastleMoves(sq));
- }
-
- getCastleMoves([x,y])
- {
- const c = this.getColor(x,y);
- if (x != (c=="w" ? V.size.x-1 : 0) || y != this.INIT_COL_KING[c])
- return []; //x isn't first rank, or king has moved (shortcut)
-
- // Castling ?
- const oppCol = V.GetOppCol(c);
- let moves = [];
- let i = 0;
- const finalSquares = [ [2,3], [V.size.y-2,V.size.y-3] ]; //king, then rook
- castlingCheck:
- for (let castleSide=0; castleSide < 2; castleSide++) //large, then small
- {
- if (!this.castleFlags[c][castleSide])
- continue;
- // If this code is reached, rooks and king are on initial position
-
- // Nothing on the path of the king ?
- // (And no checks; OK also if y==finalSquare)
- let step = finalSquares[castleSide][0] < y ? -1 : 1;
- for (i=y; i!=finalSquares[castleSide][0]; i+=step)
- {
- if (this.isAttacked([x,i], [oppCol]) || (this.board[x][i] != V.EMPTY &&
- // NOTE: next check is enough, because of chessboard constraints
- (this.getColor(x,i) != c
- || ![V.KING,V.ROOK].includes(this.getPiece(x,i)))))
- {
- continue castlingCheck;
- }
- }
-
- // Nothing on the path to the rook?
- step = castleSide == 0 ? -1 : 1;
- for (i = y + step; i != this.INIT_COL_ROOK[c][castleSide]; i += step)
- {
- if (this.board[x][i] != V.EMPTY)
- continue castlingCheck;
- }
- const rookPos = this.INIT_COL_ROOK[c][castleSide];
-
- // Nothing on final squares, except maybe king and castling rook?
- for (i=0; i<2; i++)
- {
- if (this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
- this.getPiece(x,finalSquares[castleSide][i]) != V.KING &&
- finalSquares[castleSide][i] != rookPos)
- {
- continue castlingCheck;
- }
- }
-
- // If this code is reached, castle is valid
- moves.push( new Move({
- appear: [
- new PiPo({x:x,y:finalSquares[castleSide][0],p:V.KING,c:c}),
- new PiPo({x:x,y:finalSquares[castleSide][1],p:V.ROOK,c:c})],
- vanish: [
- new PiPo({x:x,y:y,p:V.KING,c:c}),
- new PiPo({x:x,y:rookPos,p:V.ROOK,c:c})],
- end: Math.abs(y - rookPos) <= 2
- ? {x:x, y:rookPos}
- : {x:x, y:y + 2 * (castleSide==0 ? -1 : 1)}
- }) );
- }
-
- return moves;
- }
-
- ////////////////////
- // MOVES VALIDATION
-
- // For the interface: possible moves for the current turn from square sq
- getPossibleMovesFrom(sq)
- {
- return this.filterValid( this.getPotentialMovesFrom(sq) );
- }
-
- // TODO: promotions (into R,B,N,Q) should be filtered only once
- filterValid(moves)
- {
- if (moves.length == 0)
- return [];
- const color = this.turn;
- return moves.filter(m => {
- this.play(m);
- const res = !this.underCheck(color);
- this.undo(m);
- return res;
- });
- }
-
- // Search for all valid moves considering current turn
- // (for engine and game end)
- getAllValidMoves()
- {
- const color = this.turn;
- const oppCol = V.GetOppCol(color);
- let potentialMoves = [];
- for (let i=0; i<V.size.x; i++)
- {
- for (let j=0; j<V.size.y; j++)
- {
- // Next condition "!= oppCol" to work with checkered variant
- if (this.board[i][j] != V.EMPTY && this.getColor(i,j) != oppCol)
- {
- Array.prototype.push.apply(potentialMoves,
- this.getPotentialMovesFrom([i,j]));
- }
- }
- }
- return this.filterValid(potentialMoves);
- }
-
- // Stop at the first move found
- atLeastOneMove()
- {
- const color = this.turn;
- const oppCol = V.GetOppCol(color);
- for (let i=0; i<V.size.x; i++)
- {
- for (let j=0; j<V.size.y; j++)
- {
- if (this.board[i][j] != V.EMPTY && this.getColor(i,j) != oppCol)
- {
- const moves = this.getPotentialMovesFrom([i,j]);
- if (moves.length > 0)
- {
- for (let k=0; k<moves.length; k++)
- {
- if (this.filterValid([moves[k]]).length > 0)
- return true;
- }
- }
- }
- }
- }
- return false;
- }
-
- // Check if pieces of color in 'colors' are attacking (king) on square x,y
- isAttacked(sq, colors)
- {
- return (this.isAttackedByPawn(sq, colors)
- || this.isAttackedByRook(sq, colors)
- || this.isAttackedByKnight(sq, colors)
- || this.isAttackedByBishop(sq, colors)
- || this.isAttackedByQueen(sq, colors)
- || this.isAttackedByKing(sq, colors));
- }
-
- // Is square x,y attacked by 'colors' pawns ?
- isAttackedByPawn([x,y], colors)
- {
- for (let c of colors)
- {
- let pawnShift = (c=="w" ? 1 : -1);
- if (x+pawnShift>=0 && x+pawnShift<V.size.x)
- {
- for (let i of [-1,1])
- {
- if (y+i>=0 && y+i<V.size.y && this.getPiece(x+pawnShift,y+i)==V.PAWN
- && this.getColor(x+pawnShift,y+i)==c)
- {
- return true;
- }
- }
- }
- }
- return false;
- }
-
- // Is square x,y attacked by 'colors' rooks ?
- isAttackedByRook(sq, colors)
- {
- return this.isAttackedBySlideNJump(sq, colors, V.ROOK, V.steps[V.ROOK]);
- }
-
- // Is square x,y attacked by 'colors' knights ?
- isAttackedByKnight(sq, colors)
- {
- return this.isAttackedBySlideNJump(sq, colors,
- V.KNIGHT, V.steps[V.KNIGHT], "oneStep");
- }
-
- // Is square x,y attacked by 'colors' bishops ?
- isAttackedByBishop(sq, colors)
- {
- return this.isAttackedBySlideNJump(sq, colors, V.BISHOP, V.steps[V.BISHOP]);
- }
-
- // Is square x,y attacked by 'colors' queens ?
- isAttackedByQueen(sq, colors)
- {
- return this.isAttackedBySlideNJump(sq, colors, V.QUEEN,
- V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
- }
-
- // Is square x,y attacked by 'colors' king(s) ?
- isAttackedByKing(sq, colors)
- {
- return this.isAttackedBySlideNJump(sq, colors, V.KING,
- V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep");
- }
-
- // Generic method for non-pawn pieces ("sliding or jumping"):
- // is x,y attacked by a piece of color in array 'colors' ?
- isAttackedBySlideNJump([x,y], colors, piece, steps, oneStep)
- {
- for (let step of steps)
- {
- let rx = x+step[0], ry = y+step[1];
- while (V.OnBoard(rx,ry) && this.board[rx][ry] == V.EMPTY && !oneStep)
- {
- rx += step[0];
- ry += step[1];
- }
- if (V.OnBoard(rx,ry) && this.getPiece(rx,ry) === piece
- && colors.includes(this.getColor(rx,ry)))
- {
- return true;
- }
- }
- return false;
- }
-
- // Is color under check after his move ?
- underCheck(color)
- {
- return this.isAttacked(this.kingPos[color], [V.GetOppCol(color)]);
- }
-
- /////////////////
- // MOVES PLAYING
-
- // Apply a move on board
- static PlayOnBoard(board, move)
- {
- for (let psq of move.vanish)
- board[psq.x][psq.y] = V.EMPTY;
- for (let psq of move.appear)
- board[psq.x][psq.y] = psq.c + psq.p;
- }
- // Un-apply the played move
- static UndoOnBoard(board, move)
- {
- for (let psq of move.appear)
- board[psq.x][psq.y] = V.EMPTY;
- for (let psq of move.vanish)
- board[psq.x][psq.y] = psq.c + psq.p;
- }
-
- // After move is played, update variables + flags
- updateVariables(move)
- {
- let piece = undefined;
- let c = undefined;
- if (move.vanish.length >= 1)
- {
- // Usual case, something is moved
- piece = move.vanish[0].p;
- c = move.vanish[0].c;
- }
- else
- {
- // Crazyhouse-like variants
- piece = move.appear[0].p;
- c = move.appear[0].c;
- }
- if (c == "c") //if (!["w","b"].includes(c))
- {
- // 'c = move.vanish[0].c' doesn't work for Checkered
- c = V.GetOppCol(this.turn);
- }
- const firstRank = (c == "w" ? V.size.x-1 : 0);
-
- // Update king position + flags
- if (piece == V.KING && move.appear.length > 0)
- {
- this.kingPos[c][0] = move.appear[0].x;
- this.kingPos[c][1] = move.appear[0].y;
- if (V.HasFlags)
- this.castleFlags[c] = [false,false];
- return;
- }
- if (V.HasFlags)
- {
- // Update castling flags if rooks are moved
- const oppCol = V.GetOppCol(c);
- const oppFirstRank = (V.size.x-1) - firstRank;
- if (move.start.x == firstRank //our rook moves?
- && this.INIT_COL_ROOK[c].includes(move.start.y))
- {
- const flagIdx = (move.start.y == this.INIT_COL_ROOK[c][0] ? 0 : 1);
- this.castleFlags[c][flagIdx] = false;
- }
- else if (move.end.x == oppFirstRank //we took opponent rook?
- && this.INIT_COL_ROOK[oppCol].includes(move.end.y))
- {
- const flagIdx = (move.end.y == this.INIT_COL_ROOK[oppCol][0] ? 0 : 1);
- this.castleFlags[oppCol][flagIdx] = false;
- }
- }
- }
-
- // After move is undo-ed *and flags resetted*, un-update other variables
- // TODO: more symmetry, by storing flags increment in move (?!)
- unupdateVariables(move)
- {
- // (Potentially) Reset king position
- const c = this.getColor(move.start.x,move.start.y);
- if (this.getPiece(move.start.x,move.start.y) == V.KING)
- this.kingPos[c] = [move.start.x, move.start.y];
- }
-
- play(move)
- {
- // DEBUG:
-// if (!this.states) this.states = [];
-// const stateFen = this.getBaseFen() + this.getTurnFen() + this.getFlagsFen();
-// this.states.push(stateFen);
-
- if (V.HasFlags)
- move.flags = JSON.stringify(this.aggregateFlags()); //save flags (for undo)
- if (V.HasEnpassant)
- this.epSquares.push( this.getEpSquare(move) );
- if (!move.color)
- move.color = this.turn; //for interface
- V.PlayOnBoard(this.board, move);
- this.turn = V.GetOppCol(this.turn);
- this.movesCount++;
- this.updateVariables(move);
- }
-
- undo(move)
- {
- if (V.HasEnpassant)
- this.epSquares.pop();
- if (V.HasFlags)
- this.disaggregateFlags(JSON.parse(move.flags));
- V.UndoOnBoard(this.board, move);
- this.turn = V.GetOppCol(this.turn);
- this.movesCount--;
- this.unupdateVariables(move);
-
- // DEBUG:
-// const stateFen = this.getBaseFen() + this.getTurnFen() + this.getFlagsFen();
-// if (stateFen != this.states[this.states.length-1]) debugger;
-// this.states.pop();
- }
-
- ///////////////
- // END OF GAME
-
- // What is the score ? (Interesting if game is over)
- getCurrentScore()
- {
- if (this.atLeastOneMove()) // game not over
- return "*";
-
- // Game over
- const color = this.turn;
- // No valid move: stalemate or checkmate?
- if (!this.isAttacked(this.kingPos[color], [V.GetOppCol(color)]))
- return "1/2";
- // OK, checkmate
- return (color == "w" ? "0-1" : "1-0");
- }
-
- ///////////////
- // ENGINE PLAY
-
- // Pieces values
- static get VALUES()
- {
- return {
- 'p': 1,
- 'r': 5,
- 'n': 3,
- 'b': 3,
- 'q': 9,
- 'k': 1000
- };
- }
-
- // "Checkmate" (unreachable eval)
- static get INFINITY() { return 9999; }
-
- // At this value or above, the game is over
- static get THRESHOLD_MATE() { return V.INFINITY; }
-
- // Search depth: 2 for high branching factor, 4 for small (Loser chess, eg.)
- static get SEARCH_DEPTH() { return 3; }
-
- // Assumption: at least one legal move
- // NOTE: works also for extinction chess because depth is 3...
- getComputerMove()
- {
- const maxeval = V.INFINITY;
- const color = this.turn;
- // Some variants may show a bigger moves list to the human (Switching),
- // thus the argument "computer" below (which is generally ignored)
- let moves1 = this.getAllValidMoves("computer");
-
- // Can I mate in 1 ? (for Magnetic & Extinction)
- for (let i of shuffle(ArrayFun.range(moves1.length)))
- {
- this.play(moves1[i]);
- let finish = (Math.abs(this.evalPosition()) >= V.THRESHOLD_MATE);
- if (!finish)
- {
- const score = this.getCurrentScore();
- if (["1-0","0-1"].includes(score))
- finish = true;
- }
- this.undo(moves1[i]);
- if (finish)
- return moves1[i];
- }
-
- // Rank moves using a min-max at depth 2
- for (let i=0; i<moves1.length; i++)
- {
- // Initial self evaluation is very low: "I'm checkmated"
- moves1[i].eval = (color=="w" ? -1 : 1) * maxeval;
- this.play(moves1[i]);
- const score1 = this.getCurrentScore();
- let eval2 = undefined;
- if (score1 == "*")
- {
- // Initial enemy evaluation is very low too, for him
- eval2 = (color=="w" ? 1 : -1) * maxeval;
- // Second half-move:
- let moves2 = this.getAllValidMoves("computer");
- for (let j=0; j<moves2.length; j++)
- {
- this.play(moves2[j]);
- const score2 = this.getCurrentScore();
- const evalPos = score2 == "*"
- ? this.evalPosition()
- : (score2=="1/2" ? 0 : (score2=="1-0" ? 1 : -1) * maxeval);
- if ((color == "w" && evalPos < eval2)
- || (color=="b" && evalPos > eval2))
- {
- eval2 = evalPos;
- }
- this.undo(moves2[j]);
- }
- }
- else
- eval2 = (score1=="1/2" ? 0 : (score1=="1-0" ? 1 : -1) * maxeval);
- if ((color=="w" && eval2 > moves1[i].eval)
- || (color=="b" && eval2 < moves1[i].eval))
- {
- moves1[i].eval = eval2;
- }
- this.undo(moves1[i]);
- }
- moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
-
- let candidates = [0]; //indices of candidates moves
- for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
- candidates.push(j);
- let currentBest = moves1[sample(candidates)];
-
- // From here, depth >= 3: may take a while, so we control time
- const timeStart = Date.now();
-
- // Skip depth 3+ if we found a checkmate (or if we are checkmated in 1...)
- if (V.SEARCH_DEPTH >= 3 && Math.abs(moves1[0].eval) < V.THRESHOLD_MATE)
- {
- for (let i=0; i<moves1.length; i++)
- {
- if (Date.now()-timeStart >= 5000) //more than 5 seconds
- return currentBest; //depth 2 at least
- this.play(moves1[i]);
- // 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
- moves1[i].eval = 0.1*moves1[i].eval +
- this.alphabeta(V.SEARCH_DEPTH-1, -maxeval, maxeval);
- this.undo(moves1[i]);
- }
- moves1.sort( (a,b) => {
- return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
- }
- else
- return currentBest;
-// console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
-
- candidates = [0];
- for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
- candidates.push(j);
- return moves1[sample(candidates)];
- }
-
- alphabeta(depth, alpha, beta)
- {
- const maxeval = V.INFINITY;
- const color = this.turn;
- const score = this.getCurrentScore();
- if (score != "*")
- return (score=="1/2" ? 0 : (score=="1-0" ? 1 : -1) * maxeval);
- if (depth == 0)
- return this.evalPosition();
- const moves = this.getAllValidMoves("computer");
- let v = color=="w" ? -maxeval : maxeval;
- if (color == "w")
- {
- for (let i=0; i<moves.length; i++)
- {
- this.play(moves[i]);
- v = Math.max(v, this.alphabeta(depth-1, alpha, beta));
- this.undo(moves[i]);
- alpha = Math.max(alpha, v);
- if (alpha >= beta)
- break; //beta cutoff
- }
- }
- else //color=="b"
- {
- for (let i=0; i<moves.length; i++)
- {
- this.play(moves[i]);
- v = Math.min(v, this.alphabeta(depth-1, alpha, beta));
- this.undo(moves[i]);
- beta = Math.min(beta, v);
- if (alpha >= beta)
- break; //alpha cutoff
- }
- }
- return v;
- }
-
- evalPosition()
- {
- let evaluation = 0;
- // Just count material for now
- for (let i=0; i<V.size.x; i++)
- {
- for (let j=0; j<V.size.y; j++)
- {
- if (this.board[i][j] != V.EMPTY)
- {
- const sign = this.getColor(i,j) == "w" ? 1 : -1;
- evaluation += sign * V.VALUES[this.getPiece(i,j)];
- }
- }
- }
- return evaluation;
- }
-
- /////////////////////////
- // MOVES + GAME NOTATION
- /////////////////////////
-
- // Context: just before move is played, turn hasn't changed
- // TODO: un-ambiguous notation (switch on piece type, check directions...)
- getNotation(move)
- {
- if (move.appear.length == 2 && move.appear[0].p == V.KING) //castle
- return (move.end.y < move.start.y ? "0-0-0" : "0-0");
-
- // Translate final square
- const finalSquare = V.CoordsToSquare(move.end);
-
- const piece = this.getPiece(move.start.x, move.start.y);
- if (piece == V.PAWN)
- {
- // Pawn move
- let notation = "";
- if (move.vanish.length > move.appear.length)
- {
- // Capture
- const startColumn = V.CoordToColumn(move.start.y);
- notation = startColumn + "x" + finalSquare;
- }
- else //no capture
- notation = finalSquare;
- if (move.appear.length > 0 && move.appear[0].p != V.PAWN) //promotion
- notation += "=" + move.appear[0].p.toUpperCase();
- return notation;
- }
-
- else
- {
- // Piece movement
- return piece.toUpperCase() +
- (move.vanish.length > move.appear.length ? "x" : "") + finalSquare;
- }
- }
-}
+export const ChessRules = class ChessRules {
+ //////////////
+ // MISC UTILS
+
+ // Some variants don't have flags:
+ static get HasFlags() {
+ return true;
+ }
+
+ // Or castle
+ static get HasCastle() {
+ return V.HasFlags;
+ }
+
+ // Pawns specifications
+ static get PawnSpecs() {
+ return {
+ directions: { 'w': -1, 'b': 1 },
+ twoSquares: true,
+ promotions: [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN],
+ canCapture: true,
+ captureBackward: false,
+ bidirectional: false
+ };
+ }
+
+ // En-passant captures need a stack of squares:
+ static get HasEnpassant() {
+ return true;
+ }
+
+ // Some variants cannot have analyse mode
+ static get CanAnalyze() {
+ return true;
+ }
+ // Patch: issues with javascript OOP, objects can't access static fields.
+ get canAnalyze() {
+ return V.CanAnalyze;
+ }
+
+ // Some variants show incomplete information,
+ // and thus show only a partial moves list or no list at all.
+ static get ShowMoves() {
+ return "all";
+ }
+ get showMoves() {
+ return V.ShowMoves;
+ }
+
+ // Some variants always show the same orientation
+ static get CanFlip() {
+ return true;
+ }
+ get canFlip() {
+ return V.CanFlip;
+ }
+
+ // Some variants require turn indicator
+ // (generally when analysis or flip is diabled)
+ static get ShowTurn() {
+ return !V.CanAnalyze || V.ShowMoves != "all" || !V.CanFlip;
+ }
+ get showTurn() {
+ return V.ShowTurn;
+ }
+
+ static get IMAGE_EXTENSION() {
+ // All pieces should be in the SVG format
+ return ".svg";
+ }
+
+ // Turn "wb" into "B" (for FEN)
+ static board2fen(b) {
+ return b[0] == "w" ? b[1].toUpperCase() : b[1];
+ }
+
+ // Turn "p" into "bp" (for board)
+ static fen2board(f) {
+ return f.charCodeAt() <= 90 ? "w" + f.toLowerCase() : "b" + f;
+ }
+
+ // Check if FEN describes a board situation correctly
+ static IsGoodFen(fen) {
+ const fenParsed = V.ParseFen(fen);
+ // 1) Check position
+ if (!V.IsGoodPosition(fenParsed.position)) return false;
+ // 2) Check turn
+ if (!fenParsed.turn || !V.IsGoodTurn(fenParsed.turn)) return false;
+ // 3) Check moves count
+ if (!fenParsed.movesCount || !(parseInt(fenParsed.movesCount) >= 0))
+ return false;
+ // 4) Check flags
+ if (V.HasFlags && (!fenParsed.flags || !V.IsGoodFlags(fenParsed.flags)))
+ return false;
+ // 5) Check enpassant
+ if (
+ V.HasEnpassant &&
+ (!fenParsed.enpassant || !V.IsGoodEnpassant(fenParsed.enpassant))
+ ) {
+ return false;
+ }
+ return true;
+ }
+
+ // Is position part of the FEN a priori correct?
+ static IsGoodPosition(position) {
+ if (position.length == 0) return false;
+ const rows = position.split("/");
+ if (rows.length != V.size.x) return false;
+ let kings = { "k": 0, "K": 0 };
+ for (let row of rows) {
+ let sumElts = 0;
+ for (let i = 0; i < row.length; i++) {
+ if (['K','k'].includes(row[i])) kings[row[i]]++;
+ if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
+ else {
+ const num = parseInt(row[i]);
+ if (isNaN(num)) return false;
+ sumElts += num;
+ }
+ }
+ if (sumElts != V.size.y) return false;
+ }
+ // Both kings should be on board. Exactly one per color.
+ if (Object.values(kings).some(v => v != 1)) return false;
+ return true;
+ }
+
+ // For FEN checking
+ static IsGoodTurn(turn) {
+ return ["w", "b"].includes(turn);
+ }
+
+ // For FEN checking
+ static IsGoodFlags(flags) {
+ // NOTE: a little too permissive to work with more variants
+ return !!flags.match(/^[a-z]{4,4}$/);
+ }
+
+ static IsGoodEnpassant(enpassant) {
+ if (enpassant != "-") {
+ const ep = V.SquareToCoords(enpassant);
+ if (isNaN(ep.x) || !V.OnBoard(ep)) return false;
+ }
+ return true;
+ }
+
+ // 3 --> d (column number to letter)
+ static CoordToColumn(colnum) {
+ return String.fromCharCode(97 + colnum);
+ }
+
+ // d --> 3 (column letter to number)
+ static ColumnToCoord(column) {
+ return column.charCodeAt(0) - 97;
+ }
+
+ // a4 --> {x:3,y:0}
+ static SquareToCoords(sq) {
+ return {
+ // NOTE: column is always one char => max 26 columns
+ // row is counted from black side => subtraction
+ x: V.size.x - parseInt(sq.substr(1)),
+ y: sq[0].charCodeAt() - 97
+ };
+ }
+
+ // {x:0,y:4} --> e8
+ static CoordsToSquare(coords) {
+ return V.CoordToColumn(coords.y) + (V.size.x - coords.x);
+ }
+
+ // Path to pieces (standard ones in pieces/ folder)
+ getPpath(b) {
+ return b;
+ }
+
+ // Path to promotion pieces (usually the same)
+ getPPpath(b) {
+ return this.getPpath(b);
+ }
+
+ // Aggregates flags into one object
+ aggregateFlags() {
+ return this.castleFlags;
+ }
+
+ // Reverse operation
+ disaggregateFlags(flags) {
+ this.castleFlags = flags;
+ }
+
+ // En-passant square, if any
+ getEpSquare(moveOrSquare) {
+ if (!moveOrSquare) return undefined;
+ if (typeof moveOrSquare === "string") {
+ const square = moveOrSquare;
+ if (square == "-") return undefined;
+ return V.SquareToCoords(square);
+ }
+ // Argument is a move:
+ const move = moveOrSquare;
+ const s = move.start,
+ e = move.end;
+ if (
+ Math.abs(s.x - e.x) == 2 &&
+ s.y == e.y &&
+ move.appear[0].p == V.PAWN
+ ) {
+ return {
+ x: (s.x + e.x) / 2,
+ y: s.y
+ };
+ }
+ return undefined; //default
+ }
+
+ // Can thing on square1 take thing on square2
+ canTake([x1, y1], [x2, y2]) {
+ return this.getColor(x1, y1) !== this.getColor(x2, y2);
+ }
+
+ // Is (x,y) on the chessboard?
+ static OnBoard(x, y) {
+ return x >= 0 && x < V.size.x && y >= 0 && y < V.size.y;
+ }
+
+ // Used in interface: 'side' arg == player color
+ canIplay(side, [x, y]) {
+ return this.turn == side && this.getColor(x, y) == side;
+ }
+
+ // On which squares is color under check ? (for interface)
+ getCheckSquares(color) {
+ return (
+ this.underCheck(color)
+ ? [JSON.parse(JSON.stringify(this.kingPos[color]))] //need to duplicate!
+ : []
+ );
+ }
+
+ /////////////
+ // FEN UTILS
+
+ // Setup the initial random (asymmetric) position
+ static GenRandInitFen(randomness) {
+ if (randomness == 0)
+ // Deterministic:
+ return "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w 0 ahah -";
+
+ let pieces = { w: new Array(8), b: new Array(8) };
+ let flags = "";
+ // Shuffle pieces on first (and last rank if randomness == 2)
+ for (let c of ["w", "b"]) {
+ if (c == 'b' && randomness == 1) {
+ pieces['b'] = pieces['w'];
+ flags += flags;
+ break;
+ }
+
+ let positions = ArrayFun.range(8);
+
+ // Get random squares for bishops
+ let randIndex = 2 * randInt(4);
+ const bishop1Pos = positions[randIndex];
+ // The second bishop must be on a square of different color
+ let randIndex_tmp = 2 * randInt(4) + 1;
+ const bishop2Pos = positions[randIndex_tmp];
+ // Remove chosen squares
+ positions.splice(Math.max(randIndex, randIndex_tmp), 1);
+ positions.splice(Math.min(randIndex, randIndex_tmp), 1);
+
+ // Get random squares for knights
+ randIndex = randInt(6);
+ const knight1Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+ randIndex = randInt(5);
+ const knight2Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+
+ // Get random square for queen
+ randIndex = randInt(4);
+ const queenPos = positions[randIndex];
+ positions.splice(randIndex, 1);
+
+ // Rooks and king positions are now fixed,
+ // because of the ordering rook-king-rook
+ const rook1Pos = positions[0];
+ const kingPos = positions[1];
+ const rook2Pos = positions[2];
+
+ // Finally put the shuffled pieces in the board array
+ pieces[c][rook1Pos] = "r";
+ pieces[c][knight1Pos] = "n";
+ pieces[c][bishop1Pos] = "b";
+ pieces[c][queenPos] = "q";
+ pieces[c][kingPos] = "k";
+ pieces[c][bishop2Pos] = "b";
+ pieces[c][knight2Pos] = "n";
+ pieces[c][rook2Pos] = "r";
+ flags += V.CoordToColumn(rook1Pos) + V.CoordToColumn(rook2Pos);
+ }
+ // Add turn + flags + enpassant
+ return (
+ pieces["b"].join("") +
+ "/pppppppp/8/8/8/8/PPPPPPPP/" +
+ pieces["w"].join("").toUpperCase() +
+ " w 0 " + flags + " -"
+ );
+ }
+
+ // "Parse" FEN: just return untransformed string data
+ static ParseFen(fen) {
+ const fenParts = fen.split(" ");
+ let res = {
+ position: fenParts[0],
+ turn: fenParts[1],
+ movesCount: fenParts[2]
+ };
+ let nextIdx = 3;
+ if (V.HasFlags) Object.assign(res, { flags: fenParts[nextIdx++] });
+ if (V.HasEnpassant) Object.assign(res, { enpassant: fenParts[nextIdx] });
+ return res;
+ }
+
+ // Return current fen (game state)
+ getFen() {
+ return (
+ this.getBaseFen() + " " +
+ this.getTurnFen() + " " +
+ this.movesCount +
+ (V.HasFlags ? " " + this.getFlagsFen() : "") +
+ (V.HasEnpassant ? " " + this.getEnpassantFen() : "")
+ );
+ }
+
+ getFenForRepeat() {
+ // Omit movesCount, only variable allowed to differ
+ return (
+ this.getBaseFen() + "_" +
+ this.getTurnFen() +
+ (V.HasFlags ? "_" + this.getFlagsFen() : "") +
+ (V.HasEnpassant ? "_" + this.getEnpassantFen() : "")
+ );
+ }
+
+ // Position part of the FEN string
+ getBaseFen() {
+ const format = (count) => {
+ // if more than 9 consecutive free spaces, break the integer,
+ // otherwise FEN parsing will fail.
+ if (count <= 9) return count;
+ // Currently only boards of size up to 11 or 12:
+ return "9" + (count - 9);
+ };
+ let position = "";
+ for (let i = 0; i < V.size.x; i++) {
+ let emptyCount = 0;
+ for (let j = 0; j < V.size.y; j++) {
+ if (this.board[i][j] == V.EMPTY) emptyCount++;
+ else {
+ if (emptyCount > 0) {
+ // Add empty squares in-between
+ position += format(emptyCount);
+ emptyCount = 0;
+ }
+ position += V.board2fen(this.board[i][j]);
+ }
+ }
+ if (emptyCount > 0) {
+ // "Flush remainder"
+ position += format(emptyCount);
+ }
+ if (i < V.size.x - 1) position += "/"; //separate rows
+ }
+ return position;
+ }
+
+ getTurnFen() {
+ return this.turn;
+ }
+
+ // Flags part of the FEN string
+ getFlagsFen() {
+ let flags = "";
+ // Castling flags
+ for (let c of ["w", "b"])
+ flags += this.castleFlags[c].map(V.CoordToColumn).join("");
+ return flags;
+ }
+
+ // Enpassant part of the FEN string
+ getEnpassantFen() {
+ const L = this.epSquares.length;
+ if (!this.epSquares[L - 1]) return "-"; //no en-passant
+ return V.CoordsToSquare(this.epSquares[L - 1]);
+ }
+
+ // Turn position fen into double array ["wb","wp","bk",...]
+ static GetBoard(position) {
+ const rows = position.split("/");
+ let board = ArrayFun.init(V.size.x, V.size.y, "");
+ for (let i = 0; i < rows.length; i++) {
+ let j = 0;
+ for (let indexInRow = 0; indexInRow < rows[i].length; indexInRow++) {
+ const character = rows[i][indexInRow];
+ const num = parseInt(character);
+ // If num is a number, just shift j:
+ if (!isNaN(num)) j += num;
+ // Else: something at position i,j
+ else board[i][j++] = V.fen2board(character);
+ }
+ }
+ return board;
+ }
+
+ // Extract (relevant) flags from fen
+ setFlags(fenflags) {
+ // white a-castle, h-castle, black a-castle, h-castle
+ this.castleFlags = { w: [-1, -1], b: [-1, -1] };
+ for (let i = 0; i < 4; i++) {
+ this.castleFlags[i < 2 ? "w" : "b"][i % 2] =
+ V.ColumnToCoord(fenflags.charAt(i));
+ }
+ }
+
+ //////////////////
+ // INITIALIZATION
+
+ // Fen string fully describes the game state
+ constructor(fen) {
+ if (!fen)
+ // In printDiagram() fen isn't supply because only getPpath() is used
+ // TODO: find a better solution!
+ return;
+ const fenParsed = V.ParseFen(fen);
+ this.board = V.GetBoard(fenParsed.position);
+ this.turn = fenParsed.turn[0]; //[0] to work with MarseilleRules
+ this.movesCount = parseInt(fenParsed.movesCount);
+ this.setOtherVariables(fen);
+ }
+
+ // Scan board for kings positions
+ scanKings(fen) {
+ this.INIT_COL_KING = { w: -1, b: -1 };
+ this.kingPos = { w: [-1, -1], b: [-1, -1] }; //squares of white and black king
+ const fenRows = V.ParseFen(fen).position.split("/");
+ const startRow = { 'w': V.size.x - 1, 'b': 0 };
+ for (let i = 0; i < fenRows.length; i++) {
+ let k = 0; //column index on board
+ for (let j = 0; j < fenRows[i].length; j++) {
+ switch (fenRows[i].charAt(j)) {
+ case "k":
+ this.kingPos["b"] = [i, k];
+ this.INIT_COL_KING["b"] = k;
+ break;
+ case "K":
+ this.kingPos["w"] = [i, k];
+ this.INIT_COL_KING["w"] = k;
+ break;
+ default: {
+ const num = parseInt(fenRows[i].charAt(j));
+ if (!isNaN(num)) k += num - 1;
+ }
+ }
+ k++;
+ }
+ }
+ }
+
+ // Some additional variables from FEN (variant dependant)
+ setOtherVariables(fen) {
+ // Set flags and enpassant:
+ const parsedFen = V.ParseFen(fen);
+ if (V.HasFlags) this.setFlags(parsedFen.flags);
+ if (V.HasEnpassant) {
+ const epSq =
+ parsedFen.enpassant != "-"
+ ? this.getEpSquare(parsedFen.enpassant)
+ : undefined;
+ this.epSquares = [epSq];
+ }
+ // Search for kings positions:
+ this.scanKings(fen);
+ }
+
+ /////////////////////
+ // GETTERS & SETTERS
+
+ static get size() {
+ return { x: 8, y: 8 };
+ }
+
+ // Color of thing on square (i,j). 'undefined' if square is empty
+ getColor(i, j) {
+ return this.board[i][j].charAt(0);
+ }
+
+ // Piece type on square (i,j). 'undefined' if square is empty
+ getPiece(i, j) {
+ return this.board[i][j].charAt(1);
+ }
+
+ // Get opponent color
+ static GetOppCol(color) {
+ return color == "w" ? "b" : "w";
+ }
+
+ // Pieces codes (for a clearer code)
+ static get PAWN() {
+ return "p";
+ }
+ static get ROOK() {
+ return "r";
+ }
+ static get KNIGHT() {
+ return "n";
+ }
+ static get BISHOP() {
+ return "b";
+ }
+ static get QUEEN() {
+ return "q";
+ }
+ static get KING() {
+ return "k";
+ }
+
+ // For FEN checking:
+ static get PIECES() {
+ return [V.PAWN, V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN, V.KING];
+ }
+
+ // Empty square
+ static get EMPTY() {
+ return "";
+ }
+
+ // Some pieces movements
+ static get steps() {
+ return {
+ r: [
+ [-1, 0],
+ [1, 0],
+ [0, -1],
+ [0, 1]
+ ],
+ n: [
+ [-1, -2],
+ [-1, 2],
+ [1, -2],
+ [1, 2],
+ [-2, -1],
+ [-2, 1],
+ [2, -1],
+ [2, 1]
+ ],
+ b: [
+ [-1, -1],
+ [-1, 1],
+ [1, -1],
+ [1, 1]
+ ]
+ };
+ }
+
+ ////////////////////
+ // MOVES GENERATION
+
+ // All possible moves from selected square
+ getPotentialMovesFrom([x, y]) {
+ switch (this.getPiece(x, y)) {
+ case V.PAWN:
+ return this.getPotentialPawnMoves([x, y]);
+ case V.ROOK:
+ return this.getPotentialRookMoves([x, y]);
+ case V.KNIGHT:
+ return this.getPotentialKnightMoves([x, y]);
+ case V.BISHOP:
+ return this.getPotentialBishopMoves([x, y]);
+ case V.QUEEN:
+ return this.getPotentialQueenMoves([x, y]);
+ case V.KING:
+ return this.getPotentialKingMoves([x, y]);
+ }
+ return []; //never reached
+ }
+
+ // Build a regular move from its initial and destination squares.
+ // tr: transformation
+ getBasicMove([sx, sy], [ex, ey], tr) {
+ const initColor = this.getColor(sx, sy);
+ const initPiece = this.getPiece(sx, sy);
+ let mv = new Move({
+ appear: [
+ new PiPo({
+ x: ex,
+ y: ey,
+ c: tr ? tr.c : initColor,
+ p: tr ? tr.p : initPiece
+ })
+ ],
+ vanish: [
+ new PiPo({
+ x: sx,
+ y: sy,
+ c: initColor,
+ p: initPiece
+ })
+ ]
+ });
+
+ // The opponent piece disappears if we take it
+ if (this.board[ex][ey] != V.EMPTY) {
+ mv.vanish.push(
+ new PiPo({
+ x: ex,
+ y: ey,
+ c: this.getColor(ex, ey),
+ p: this.getPiece(ex, ey)
+ })
+ );
+ }
+
+ return mv;
+ }
+
+ // Generic method to find possible moves of non-pawn pieces:
+ // "sliding or jumping"
+ getSlideNJumpMoves([x, y], steps, oneStep) {
+ let moves = [];
+ outerLoop: for (let step of steps) {
+ let i = x + step[0];
+ let j = y + step[1];
+ while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
+ moves.push(this.getBasicMove([x, y], [i, j]));
+ if (oneStep) continue outerLoop;
+ i += step[0];
+ j += step[1];
+ }
+ if (V.OnBoard(i, j) && this.canTake([x, y], [i, j]))
+ moves.push(this.getBasicMove([x, y], [i, j]));
+ }
+ return moves;
+ }
+
+ // Special case of en-passant captures: treated separately
+ getEnpassantCaptures([x, y], shiftX) {
+ const Lep = this.epSquares.length;
+ const epSquare = this.epSquares[Lep - 1]; //always at least one element
+ let enpassantMove = null;
+ if (
+ !!epSquare &&
+ epSquare.x == x + shiftX &&
+ Math.abs(epSquare.y - y) == 1
+ ) {
+ enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
+ enpassantMove.vanish.push({
+ x: x,
+ y: epSquare.y,
+ // Captured piece is usually a pawn, but next line seems harmless
+ p: this.getPiece(x, epSquare.y),
+ c: this.getColor(x, epSquare.y)
+ });
+ }
+ return !!enpassantMove ? [enpassantMove] : [];
+ }
+
+ // Consider all potential promotions:
+ addPawnMoves([x1, y1], [x2, y2], moves, promotions) {
+ let finalPieces = [V.PAWN];
+ const color = this.turn;
+ const lastRank = (color == "w" ? 0 : V.size.x - 1);
+ if (x2 == lastRank) {
+ // promotions arg: special override for Hiddenqueen variant
+ if (!!promotions) finalPieces = promotions;
+ else if (!!V.PawnSpecs.promotions)
+ finalPieces = V.PawnSpecs.promotions;
+ }
+ let tr = null;
+ for (let piece of finalPieces) {
+ tr = (piece != V.PAWN ? { c: color, p: piece } : null);
+ moves.push(this.getBasicMove([x1, y1], [x2, y2], tr));
+ }
+ }
+
+ // What are the pawn moves from square x,y ?
+ getPotentialPawnMoves([x, y], promotions) {
+ const color = this.turn;
+ const [sizeX, sizeY] = [V.size.x, V.size.y];
+ const pawnShiftX = V.PawnSpecs.directions[color];
+ const firstRank = (color == "w" ? sizeX - 1 : 0);
+ const startRank = (color == "w" ? sizeX - 2 : 1);
+
+ // Pawn movements in shiftX direction:
+ const getPawnMoves = (shiftX) => {
+ let moves = [];
+ // NOTE: next condition is generally true (no pawn on last rank)
+ if (x + shiftX >= 0 && x + shiftX < sizeX) {
+ if (this.board[x + shiftX][y] == V.EMPTY) {
+ // One square forward
+ this.addPawnMoves([x, y], [x + shiftX, y], moves, promotions);
+ // Next condition because pawns on 1st rank can generally jump
+ if (
+ V.PawnSpecs.twoSquares &&
+ [startRank, firstRank].includes(x) &&
+ this.board[x + 2 * shiftX][y] == V.EMPTY
+ ) {
+ // Two squares jump
+ moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
+ }
+ }
+ // Captures
+ if (V.PawnSpecs.canCapture) {
+ for (let shiftY of [-1, 1]) {
+ if (
+ y + shiftY >= 0 &&
+ y + shiftY < sizeY
+ ) {
+ if (
+ this.board[x + shiftX][y + shiftY] != V.EMPTY &&
+ this.canTake([x, y], [x + shiftX, y + shiftY])
+ ) {
+ this.addPawnMoves(
+ [x, y], [x + shiftX, y + shiftY],
+ moves, promotions
+ );
+ }
+ if (
+ V.PawnSpecs.captureBackward &&
+ x - shiftX >= 0 && x - shiftX < V.size.x &&
+ this.board[x - shiftX][y + shiftY] != V.EMPTY &&
+ this.canTake([x, y], [x - shiftX, y + shiftY])
+ ) {
+ this.addPawnMoves(
+ [x, y], [x + shiftX, y + shiftY],
+ moves, promotions
+ );
+ }
+ }
+ }
+ }
+ }
+ return moves;
+ }
+
+ let pMoves = getPawnMoves(pawnShiftX);
+ if (V.PawnSpecs.bidirectional)
+ pMoves = pMoves.concat(getPawnMoves(-pawnShiftX));
+
+ if (V.HasEnpassant) {
+ // NOTE: backward en-passant captures are not considered
+ // because no rules define them (for now).
+ Array.prototype.push.apply(
+ pMoves,
+ this.getEnpassantCaptures([x, y], pawnShiftX)
+ );
+ }
+
+ return pMoves;
+ }
+
+ // What are the rook moves from square x,y ?
+ getPotentialRookMoves(sq) {
+ return this.getSlideNJumpMoves(sq, V.steps[V.ROOK]);
+ }
+
+ // What are the knight moves from square x,y ?
+ getPotentialKnightMoves(sq) {
+ return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep");
+ }
+
+ // What are the bishop moves from square x,y ?
+ getPotentialBishopMoves(sq) {
+ return this.getSlideNJumpMoves(sq, V.steps[V.BISHOP]);
+ }
+
+ // What are the queen moves from square x,y ?
+ getPotentialQueenMoves(sq) {
+ return this.getSlideNJumpMoves(
+ sq,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP])
+ );
+ }
+
+ // What are the king moves from square x,y ?
+ getPotentialKingMoves(sq) {
+ // Initialize with normal moves
+ let moves = this.getSlideNJumpMoves(
+ sq,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
+ "oneStep"
+ );
+ if (V.HasCastle) moves = moves.concat(this.getCastleMoves(sq));
+ return moves;
+ }
+
+ // "castleInCheck" arg to let some variants castle under check
+ getCastleMoves([x, y], castleInCheck) {
+ const c = this.getColor(x, y);
+ if (x != (c == "w" ? V.size.x - 1 : 0) || y != this.INIT_COL_KING[c])
+ return []; //x isn't first rank, or king has moved (shortcut)
+
+ // Castling ?
+ const oppCol = V.GetOppCol(c);
+ let moves = [];
+ let i = 0;
+ // King, then rook:
+ const finalSquares = [
+ [2, 3],
+ [V.size.y - 2, V.size.y - 3]
+ ];
+ castlingCheck: for (
+ let castleSide = 0;
+ castleSide < 2;
+ castleSide++ //large, then small
+ ) {
+ if (this.castleFlags[c][castleSide] >= V.size.y) continue;
+ // If this code is reached, rook and king are on initial position
+
+ // NOTE: in some variants this is not a rook, but let's keep variable name
+ const rookPos = this.castleFlags[c][castleSide];
+ const castlingPiece = this.getPiece(x, rookPos);
+ if (this.getColor(x, rookPos) != c)
+ // Rook is here but changed color (see Benedict)
+ continue;
+
+ // Nothing on the path of the king ? (and no checks)
+ const finDist = finalSquares[castleSide][0] - y;
+ let step = finDist / Math.max(1, Math.abs(finDist));
+ i = y;
+ do {
+ if (
+ (!castleInCheck && this.isAttacked([x, i], oppCol)) ||
+ (this.board[x][i] != V.EMPTY &&
+ // NOTE: next check is enough, because of chessboard constraints
+ (this.getColor(x, i) != c ||
+ ![V.KING, castlingPiece].includes(this.getPiece(x, i))))
+ ) {
+ continue castlingCheck;
+ }
+ i += step;
+ } while (i != finalSquares[castleSide][0]);
+
+ // Nothing on the path to the rook?
+ step = castleSide == 0 ? -1 : 1;
+ for (i = y + step; i != rookPos; i += step) {
+ if (this.board[x][i] != V.EMPTY) continue castlingCheck;
+ }
+
+ // Nothing on final squares, except maybe king and castling rook?
+ for (i = 0; i < 2; i++) {
+ if (
+ this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
+ this.getPiece(x, finalSquares[castleSide][i]) != V.KING &&
+ finalSquares[castleSide][i] != rookPos
+ ) {
+ continue castlingCheck;
+ }
+ }
+
+ // If this code is reached, castle is valid
+ moves.push(
+ new Move({
+ appear: [
+ new PiPo({ x: x, y: finalSquares[castleSide][0], p: V.KING, c: c }),
+ new PiPo({ x: x, y: finalSquares[castleSide][1], p: castlingPiece, c: c })
+ ],
+ vanish: [
+ new PiPo({ x: x, y: y, p: V.KING, c: c }),
+ new PiPo({ x: x, y: rookPos, p: castlingPiece, c: c })
+ ],
+ end:
+ Math.abs(y - rookPos) <= 2
+ ? { x: x, y: rookPos }
+ : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) }
+ })
+ );
+ }
+
+ return moves;
+ }
+
+ ////////////////////
+ // MOVES VALIDATION
+
+ // For the interface: possible moves for the current turn from square sq
+ getPossibleMovesFrom(sq) {
+ return this.filterValid(this.getPotentialMovesFrom(sq));
+ }
+
+ // TODO: promotions (into R,B,N,Q) should be filtered only once
+ filterValid(moves) {
+ if (moves.length == 0) return [];
+ const color = this.turn;
+ return moves.filter(m => {
+ this.play(m);
+ const res = !this.underCheck(color);
+ this.undo(m);
+ return res;
+ });
+ }
+
+ // Search for all valid moves considering current turn
+ // (for engine and game end)
+ getAllValidMoves() {
+ const color = this.turn;
+ let potentialMoves = [];
+ for (let i = 0; i < V.size.x; i++) {
+ for (let j = 0; j < V.size.y; j++) {
+ if (this.getColor(i, j) == color) {
+ Array.prototype.push.apply(
+ potentialMoves,
+ this.getPotentialMovesFrom([i, j])
+ );
+ }
+ }
+ }
+ return this.filterValid(potentialMoves);
+ }
+
+ // Stop at the first move found
+ atLeastOneMove() {
+ const color = this.turn;
+ for (let i = 0; i < V.size.x; i++) {
+ for (let j = 0; j < V.size.y; j++) {
+ if (this.getColor(i, j) == color) {
+ const moves = this.getPotentialMovesFrom([i, j]);
+ if (moves.length > 0) {
+ for (let k = 0; k < moves.length; k++) {
+ if (this.filterValid([moves[k]]).length > 0) return true;
+ }
+ }
+ }
+ }
+ }
+ return false;
+ }
+
+ // Check if pieces of given color are attacking (king) on square x,y
+ isAttacked(sq, color) {
+ return (
+ this.isAttackedByPawn(sq, color) ||
+ this.isAttackedByRook(sq, color) ||
+ this.isAttackedByKnight(sq, color) ||
+ this.isAttackedByBishop(sq, color) ||
+ this.isAttackedByQueen(sq, color) ||
+ this.isAttackedByKing(sq, color)
+ );
+ }
+
+ // Generic method for non-pawn pieces ("sliding or jumping"):
+ // is x,y attacked by a piece of given color ?
+ isAttackedBySlideNJump([x, y], color, piece, steps, oneStep) {
+ for (let step of steps) {
+ let rx = x + step[0],
+ ry = y + step[1];
+ while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
+ rx += step[0];
+ ry += step[1];
+ }
+ if (
+ V.OnBoard(rx, ry) &&
+ this.getPiece(rx, ry) == piece &&
+ this.getColor(rx, ry) == color
+ ) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ // Is square x,y attacked by 'color' pawns ?
+ isAttackedByPawn([x, y], color) {
+ const pawnShift = (color == "w" ? 1 : -1);
+ if (x + pawnShift >= 0 && x + pawnShift < V.size.x) {
+ for (let i of [-1, 1]) {
+ if (
+ y + i >= 0 &&
+ y + i < V.size.y &&
+ this.getPiece(x + pawnShift, y + i) == V.PAWN &&
+ this.getColor(x + pawnShift, y + i) == color
+ ) {
+ return true;
+ }
+ }
+ }
+ return false;
+ }
+
+ // Is square x,y attacked by 'color' rooks ?
+ isAttackedByRook(sq, color) {
+ return this.isAttackedBySlideNJump(sq, color, V.ROOK, V.steps[V.ROOK]);
+ }
+
+ // Is square x,y attacked by 'color' knights ?
+ isAttackedByKnight(sq, color) {
+ return this.isAttackedBySlideNJump(
+ sq,
+ color,
+ V.KNIGHT,
+ V.steps[V.KNIGHT],
+ "oneStep"
+ );
+ }
+
+ // Is square x,y attacked by 'color' bishops ?
+ isAttackedByBishop(sq, color) {
+ return this.isAttackedBySlideNJump(sq, color, V.BISHOP, V.steps[V.BISHOP]);
+ }
+
+ // Is square x,y attacked by 'color' queens ?
+ isAttackedByQueen(sq, color) {
+ return this.isAttackedBySlideNJump(
+ sq,
+ color,
+ V.QUEEN,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP])
+ );
+ }
+
+ // Is square x,y attacked by 'color' king(s) ?
+ isAttackedByKing(sq, color) {
+ return this.isAttackedBySlideNJump(
+ sq,
+ color,
+ V.KING,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
+ "oneStep"
+ );
+ }
+
+ // Is color under check after his move ?
+ underCheck(color) {
+ return this.isAttacked(this.kingPos[color], V.GetOppCol(color));
+ }
+
+ /////////////////
+ // MOVES PLAYING
+
+ // Apply a move on board
+ static PlayOnBoard(board, move) {
+ for (let psq of move.vanish) board[psq.x][psq.y] = V.EMPTY;
+ for (let psq of move.appear) board[psq.x][psq.y] = psq.c + psq.p;
+ }
+ // Un-apply the played move
+ static UndoOnBoard(board, move) {
+ for (let psq of move.appear) board[psq.x][psq.y] = V.EMPTY;
+ for (let psq of move.vanish) board[psq.x][psq.y] = psq.c + psq.p;
+ }
+
+ prePlay() {}
+
+ play(move) {
+ // DEBUG:
+// if (!this.states) this.states = [];
+// const stateFen = this.getFen() + JSON.stringify(this.kingPos);
+// this.states.push(stateFen);
+
+ this.prePlay(move);
+ if (V.HasFlags) move.flags = JSON.stringify(this.aggregateFlags()); //save flags (for undo)
+ if (V.HasEnpassant) this.epSquares.push(this.getEpSquare(move));
+ V.PlayOnBoard(this.board, move);
+ this.turn = V.GetOppCol(this.turn);
+ this.movesCount++;
+ this.postPlay(move);
+ }
+
+ updateCastleFlags(move, piece) {
+ const c = V.GetOppCol(this.turn);
+ const firstRank = (c == "w" ? V.size.x - 1 : 0);
+ // Update castling flags if rooks are moved
+ const oppCol = V.GetOppCol(c);
+ const oppFirstRank = V.size.x - 1 - firstRank;
+ if (piece == V.KING && move.appear.length > 0)
+ this.castleFlags[c] = [V.size.y, V.size.y];
+ else if (
+ move.start.x == firstRank && //our rook moves?
+ this.castleFlags[c].includes(move.start.y)
+ ) {
+ const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
+ this.castleFlags[c][flagIdx] = V.size.y;
+ }
+ // NOTE: not "else if" because a rook could take an opposing rook
+ if (
+ move.end.x == oppFirstRank && //we took opponent rook?
+ this.castleFlags[oppCol].includes(move.end.y)
+ ) {
+ const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
+ this.castleFlags[oppCol][flagIdx] = V.size.y;
+ }
+ }
+
+ // After move is played, update variables + flags
+ postPlay(move) {
+ const c = V.GetOppCol(this.turn);
+ let piece = undefined;
+ if (move.vanish.length >= 1)
+ // Usual case, something is moved
+ piece = move.vanish[0].p;
+ else
+ // Crazyhouse-like variants
+ piece = move.appear[0].p;
+
+ // Update king position + flags
+ if (piece == V.KING && move.appear.length > 0) {
+ this.kingPos[c][0] = move.appear[0].x;
+ this.kingPos[c][1] = move.appear[0].y;
+ return;
+ }
+ if (V.HasCastle) this.updateCastleFlags(move, piece);
+ }
+
+ preUndo() {}
+
+ undo(move) {
+ this.preUndo(move);
+ if (V.HasEnpassant) this.epSquares.pop();
+ if (V.HasFlags) this.disaggregateFlags(JSON.parse(move.flags));
+ V.UndoOnBoard(this.board, move);
+ this.turn = V.GetOppCol(this.turn);
+ this.movesCount--;
+ this.postUndo(move);
+
+ // DEBUG:
+// const stateFen = this.getFen() + JSON.stringify(this.kingPos);
+// if (stateFen != this.states[this.states.length-1]) debugger;
+// this.states.pop();
+ }
+
+ // After move is undo-ed *and flags resetted*, un-update other variables
+ // TODO: more symmetry, by storing flags increment in move (?!)
+ postUndo(move) {
+ // (Potentially) Reset king position
+ const c = this.getColor(move.start.x, move.start.y);
+ if (this.getPiece(move.start.x, move.start.y) == V.KING)
+ this.kingPos[c] = [move.start.x, move.start.y];
+ }
+
+ ///////////////
+ // END OF GAME
+
+ // What is the score ? (Interesting if game is over)
+ getCurrentScore() {
+ if (this.atLeastOneMove()) return "*";
+ // Game over
+ const color = this.turn;
+ // No valid move: stalemate or checkmate?
+ if (!this.underCheck(color)) return "1/2";
+ // OK, checkmate
+ return (color == "w" ? "0-1" : "1-0");
+ }
+
+ ///////////////
+ // ENGINE PLAY
+
+ // Pieces values
+ static get VALUES() {
+ return {
+ p: 1,
+ r: 5,
+ n: 3,
+ b: 3,
+ q: 9,
+ k: 1000
+ };
+ }
+
+ // "Checkmate" (unreachable eval)
+ static get INFINITY() {
+ return 9999;
+ }
+
+ // At this value or above, the game is over
+ static get THRESHOLD_MATE() {
+ return V.INFINITY;
+ }
+
+ // Search depth: 1,2 for high branching factor, 4 for small (Loser chess, eg.)
+ static get SEARCH_DEPTH() {
+ return 3;
+ }
+
+ getComputerMove() {
+ const maxeval = V.INFINITY;
+ const color = this.turn;
+ let moves1 = this.getAllValidMoves();
+
+ if (moves1.length == 0)
+ // TODO: this situation should not happen
+ return null;
+
+ // Rank moves using a min-max at depth 2 (if search_depth >= 2!)
+ for (let i = 0; i < moves1.length; i++) {
+ this.play(moves1[i]);
+ const score1 = this.getCurrentScore();
+ if (score1 != "*") {
+ moves1[i].eval =
+ score1 == "1/2"
+ ? 0
+ : (score1 == "1-0" ? 1 : -1) * maxeval;
+ }
+ if (V.SEARCH_DEPTH == 1 || score1 != "*") {
+ if (!moves1[i].eval) moves1[i].eval = this.evalPosition();
+ this.undo(moves1[i]);
+ continue;
+ }
+ // Initial self evaluation is very low: "I'm checkmated"
+ moves1[i].eval = (color == "w" ? -1 : 1) * maxeval;
+ // Initial enemy evaluation is very low too, for him
+ let eval2 = (color == "w" ? 1 : -1) * maxeval;
+ // Second half-move:
+ let moves2 = this.getAllValidMoves();
+ for (let j = 0; j < moves2.length; j++) {
+ this.play(moves2[j]);
+ const score2 = this.getCurrentScore();
+ let evalPos = 0; //1/2 value
+ switch (score2) {
+ case "*":
+ evalPos = this.evalPosition();
+ break;
+ case "1-0":
+ evalPos = maxeval;
+ break;
+ case "0-1":
+ evalPos = -maxeval;
+ break;
+ }
+ if (
+ (color == "w" && evalPos < eval2) ||
+ (color == "b" && evalPos > eval2)
+ ) {
+ eval2 = evalPos;
+ }
+ this.undo(moves2[j]);
+ }
+ if (
+ (color == "w" && eval2 > moves1[i].eval) ||
+ (color == "b" && eval2 < moves1[i].eval)
+ ) {
+ moves1[i].eval = eval2;
+ }
+ this.undo(moves1[i]);
+ }
+ moves1.sort((a, b) => {
+ return (color == "w" ? 1 : -1) * (b.eval - a.eval);
+ });
+// console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
+
+ // Skip depth 3+ if we found a checkmate (or if we are checkmated in 1...)
+ if (V.SEARCH_DEPTH >= 3 && Math.abs(moves1[0].eval) < V.THRESHOLD_MATE) {
+ for (let i = 0; i < moves1.length; i++) {
+ this.play(moves1[i]);
+ // 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
+ moves1[i].eval =
+ 0.1 * moves1[i].eval +
+ this.alphabeta(V.SEARCH_DEPTH - 1, -maxeval, maxeval);
+ this.undo(moves1[i]);
+ }
+ moves1.sort((a, b) => {
+ return (color == "w" ? 1 : -1) * (b.eval - a.eval);
+ });
+ }
+
+ let candidates = [0];
+ for (let i = 1; i < moves1.length && moves1[i].eval == moves1[0].eval; i++)
+ candidates.push(i);
+ return moves1[candidates[randInt(candidates.length)]];
+ }
+
+ alphabeta(depth, alpha, beta) {
+ const maxeval = V.INFINITY;
+ const color = this.turn;
+ const score = this.getCurrentScore();
+ if (score != "*")
+ return score == "1/2" ? 0 : (score == "1-0" ? 1 : -1) * maxeval;
+ if (depth == 0) return this.evalPosition();
+ const moves = this.getAllValidMoves();
+ let v = color == "w" ? -maxeval : maxeval;
+ if (color == "w") {
+ for (let i = 0; i < moves.length; i++) {
+ this.play(moves[i]);
+ v = Math.max(v, this.alphabeta(depth - 1, alpha, beta));
+ this.undo(moves[i]);
+ alpha = Math.max(alpha, v);
+ if (alpha >= beta) break; //beta cutoff
+ }
+ }
+ else {
+ // color=="b"
+ for (let i = 0; i < moves.length; i++) {
+ this.play(moves[i]);
+ v = Math.min(v, this.alphabeta(depth - 1, alpha, beta));
+ this.undo(moves[i]);
+ beta = Math.min(beta, v);
+ if (alpha >= beta) break; //alpha cutoff
+ }
+ }
+ return v;
+ }
+
+ evalPosition() {
+ let evaluation = 0;
+ // Just count material for now
+ for (let i = 0; i < V.size.x; i++) {
+ for (let j = 0; j < V.size.y; j++) {
+ if (this.board[i][j] != V.EMPTY) {
+ const sign = this.getColor(i, j) == "w" ? 1 : -1;
+ evaluation += sign * V.VALUES[this.getPiece(i, j)];
+ }
+ }
+ }
+ return evaluation;
+ }
+
+ /////////////////////////
+ // MOVES + GAME NOTATION
+ /////////////////////////
+
+ // Context: just before move is played, turn hasn't changed
+ // TODO: un-ambiguous notation (switch on piece type, check directions...)
+ getNotation(move) {
+ if (move.appear.length == 2 && move.appear[0].p == V.KING)
+ // Castle
+ return move.end.y < move.start.y ? "0-0-0" : "0-0";
+
+ // Translate final square
+ const finalSquare = V.CoordsToSquare(move.end);
+
+ const piece = this.getPiece(move.start.x, move.start.y);
+ if (piece == V.PAWN) {
+ // Pawn move
+ let notation = "";
+ if (move.vanish.length > move.appear.length) {
+ // Capture
+ const startColumn = V.CoordToColumn(move.start.y);
+ notation = startColumn + "x" + finalSquare;
+ }
+ else notation = finalSquare;
+ if (move.appear.length > 0 && move.appear[0].p != V.PAWN)
+ // Promotion
+ notation += "=" + move.appear[0].p.toUpperCase();
+ return notation;
+ }
+ // Piece movement
+ return (
+ piece.toUpperCase() +
+ (move.vanish.length > move.appear.length ? "x" : "") +
+ finalSquare
+ );
+ }
+};
projects / vchess.git / blobdiff