| 1 | class PiPo //Piece+Position |
| 2 | { |
| 3 | // o: {piece[p], color[c], posX[x], posY[y]} |
| 4 | constructor(o) |
| 5 | { |
| 6 | this.p = o.p; |
| 7 | this.c = o.c; |
| 8 | this.x = o.x; |
| 9 | this.y = o.y; |
| 10 | } |
| 11 | } |
| 12 | |
| 13 | class Move |
| 14 | { |
| 15 | // o: {appear, vanish, [start,] [end,]} |
| 16 | // appear,vanish = arrays of PiPo |
| 17 | // start,end = coordinates to apply to trigger move visually (think castle) |
| 18 | constructor(o) |
| 19 | { |
| 20 | this.appear = o.appear; |
| 21 | this.vanish = o.vanish; |
| 22 | this.start = !!o.start ? o.start : {x:o.vanish[0].x, y:o.vanish[0].y}; |
| 23 | this.end = !!o.end ? o.end : {x:o.appear[0].x, y:o.appear[0].y}; |
| 24 | } |
| 25 | } |
| 26 | |
| 27 | // NOTE: x coords = top to bottom; y = left to right (from white player perspective) |
| 28 | class ChessRules |
| 29 | { |
| 30 | // Path to pieces |
| 31 | static getPpath(b) |
| 32 | { |
| 33 | return b; //usual pieces in pieces/ folder |
| 34 | } |
| 35 | // Turn "wb" into "B" (for FEN) |
| 36 | static board2fen(b) |
| 37 | { |
| 38 | return b[0]=='w' ? b[1].toUpperCase() : b[1]; |
| 39 | } |
| 40 | // Turn "p" into "bp" (for board) |
| 41 | static fen2board(f) |
| 42 | { |
| 43 | return f.charCodeAt()<=90 ? "w"+f.toLowerCase() : "b"+f; |
| 44 | } |
| 45 | |
| 46 | ///////////////// |
| 47 | // INITIALIZATION |
| 48 | |
| 49 | // fen == "position flags" |
| 50 | constructor(fen, moves) |
| 51 | { |
| 52 | this.moves = moves; |
| 53 | // Use fen string to initialize variables, flags and board |
| 54 | this.board = VariantRules.GetBoard(fen); |
| 55 | this.setFlags(fen); |
| 56 | this.initVariables(fen); |
| 57 | } |
| 58 | |
| 59 | initVariables(fen) |
| 60 | { |
| 61 | this.INIT_COL_KING = {'w':-1, 'b':-1}; |
| 62 | this.INIT_COL_ROOK = {'w':[-1,-1], 'b':[-1,-1]}; |
| 63 | this.kingPos = {'w':[-1,-1], 'b':[-1,-1]}; //respective squares of white and black king |
| 64 | const fenParts = fen.split(" "); |
| 65 | const position = fenParts[0].split("/"); |
| 66 | for (let i=0; i<position.length; i++) |
| 67 | { |
| 68 | let k = 0; //column index on board |
| 69 | for (let j=0; j<position[i].length; j++) |
| 70 | { |
| 71 | switch (position[i].charAt(j)) |
| 72 | { |
| 73 | case 'k': |
| 74 | this.kingPos['b'] = [i,k]; |
| 75 | this.INIT_COL_KING['b'] = k; |
| 76 | break; |
| 77 | case 'K': |
| 78 | this.kingPos['w'] = [i,k]; |
| 79 | this.INIT_COL_KING['w'] = k; |
| 80 | break; |
| 81 | case 'r': |
| 82 | if (this.INIT_COL_ROOK['b'][0] < 0) |
| 83 | this.INIT_COL_ROOK['b'][0] = k; |
| 84 | else |
| 85 | this.INIT_COL_ROOK['b'][1] = k; |
| 86 | break; |
| 87 | case 'R': |
| 88 | if (this.INIT_COL_ROOK['w'][0] < 0) |
| 89 | this.INIT_COL_ROOK['w'][0] = k; |
| 90 | else |
| 91 | this.INIT_COL_ROOK['w'][1] = k; |
| 92 | break; |
| 93 | default: |
| 94 | let num = parseInt(position[i].charAt(j)); |
| 95 | if (!isNaN(num)) |
| 96 | k += (num-1); |
| 97 | } |
| 98 | k++; |
| 99 | } |
| 100 | } |
| 101 | const epSq = this.moves.length > 0 ? this.getEpSquare(this.lastMove) : undefined; |
| 102 | this.epSquares = [ epSq ]; |
| 103 | } |
| 104 | |
| 105 | // Turn diagram fen into double array ["wb","wp","bk",...] |
| 106 | static GetBoard(fen) |
| 107 | { |
| 108 | let rows = fen.split(" ")[0].split("/"); |
| 109 | const [sizeX,sizeY] = VariantRules.size; |
| 110 | let board = doubleArray(sizeX, sizeY, ""); |
| 111 | for (let i=0; i<rows.length; i++) |
| 112 | { |
| 113 | let j = 0; |
| 114 | for (let indexInRow = 0; indexInRow < rows[i].length; indexInRow++) |
| 115 | { |
| 116 | let character = rows[i][indexInRow]; |
| 117 | let num = parseInt(character); |
| 118 | if (!isNaN(num)) |
| 119 | j += num; //just shift j |
| 120 | else //something at position i,j |
| 121 | board[i][j++] = VariantRules.fen2board(character); |
| 122 | } |
| 123 | } |
| 124 | return board; |
| 125 | } |
| 126 | |
| 127 | // Overridable: flags can change a lot |
| 128 | setFlags(fen) |
| 129 | { |
| 130 | // white a-castle, h-castle, black a-castle, h-castle |
| 131 | this.castleFlags = {'w': new Array(2), 'b': new Array(2)}; |
| 132 | let flags = fen.split(" ")[1]; //flags right after position |
| 133 | for (let i=0; i<4; i++) |
| 134 | this.castleFlags[i < 2 ? 'w' : 'b'][i%2] = (flags.charAt(i) == '1'); |
| 135 | } |
| 136 | |
| 137 | /////////////////// |
| 138 | // GETTERS, SETTERS |
| 139 | |
| 140 | // Simple useful getters |
| 141 | static get size() { return [8,8]; } |
| 142 | // Two next functions return 'undefined' if called on empty square |
| 143 | getColor(i,j) { return this.board[i][j].charAt(0); } |
| 144 | getPiece(i,j) { return this.board[i][j].charAt(1); } |
| 145 | |
| 146 | // Color |
| 147 | getOppCol(color) { return color=="w" ? "b" : "w"; } |
| 148 | |
| 149 | get lastMove() { |
| 150 | const L = this.moves.length; |
| 151 | return L>0 ? this.moves[L-1] : null; |
| 152 | } |
| 153 | get turn() { |
| 154 | return this.moves.length%2==0 ? 'w' : 'b'; |
| 155 | } |
| 156 | |
| 157 | // Pieces codes |
| 158 | static get PAWN() { return 'p'; } |
| 159 | static get ROOK() { return 'r'; } |
| 160 | static get KNIGHT() { return 'n'; } |
| 161 | static get BISHOP() { return 'b'; } |
| 162 | static get QUEEN() { return 'q'; } |
| 163 | static get KING() { return 'k'; } |
| 164 | |
| 165 | // Empty square |
| 166 | static get EMPTY() { return ''; } |
| 167 | |
| 168 | // Some pieces movements |
| 169 | static get steps() { |
| 170 | return { |
| 171 | 'r': [ [-1,0],[1,0],[0,-1],[0,1] ], |
| 172 | 'n': [ [-1,-2],[-1,2],[1,-2],[1,2],[-2,-1],[-2,1],[2,-1],[2,1] ], |
| 173 | 'b': [ [-1,-1],[-1,1],[1,-1],[1,1] ], |
| 174 | 'q': [ [-1,0],[1,0],[0,-1],[0,1],[-1,-1],[-1,1],[1,-1],[1,1] ] |
| 175 | }; |
| 176 | } |
| 177 | |
| 178 | // Aggregates flags into one object |
| 179 | get flags() { |
| 180 | return this.castleFlags; |
| 181 | } |
| 182 | |
| 183 | // Reverse operation |
| 184 | parseFlags(flags) |
| 185 | { |
| 186 | this.castleFlags = flags; |
| 187 | } |
| 188 | |
| 189 | // En-passant square, if any |
| 190 | getEpSquare(move) |
| 191 | { |
| 192 | const [sx,sy,ex] = [move.start.x,move.start.y,move.end.x]; |
| 193 | if (this.getPiece(sx,sy) == VariantRules.PAWN && Math.abs(sx - ex) == 2) |
| 194 | { |
| 195 | return { |
| 196 | x: (sx + ex)/2, |
| 197 | y: sy |
| 198 | }; |
| 199 | } |
| 200 | return undefined; //default |
| 201 | } |
| 202 | |
| 203 | // can thing on square1 take thing on square2 |
| 204 | canTake([x1,y1], [x2,y2]) |
| 205 | { |
| 206 | return this.getColor(x1,y1) != this.getColor(x2,y2); |
| 207 | } |
| 208 | |
| 209 | /////////////////// |
| 210 | // MOVES GENERATION |
| 211 | |
| 212 | // All possible moves from selected square (assumption: color is OK) |
| 213 | getPotentialMovesFrom([x,y]) |
| 214 | { |
| 215 | switch (this.getPiece(x,y)) |
| 216 | { |
| 217 | case VariantRules.PAWN: |
| 218 | return this.getPotentialPawnMoves([x,y]); |
| 219 | case VariantRules.ROOK: |
| 220 | return this.getPotentialRookMoves([x,y]); |
| 221 | case VariantRules.KNIGHT: |
| 222 | return this.getPotentialKnightMoves([x,y]); |
| 223 | case VariantRules.BISHOP: |
| 224 | return this.getPotentialBishopMoves([x,y]); |
| 225 | case VariantRules.QUEEN: |
| 226 | return this.getPotentialQueenMoves([x,y]); |
| 227 | case VariantRules.KING: |
| 228 | return this.getPotentialKingMoves([x,y]); |
| 229 | } |
| 230 | } |
| 231 | |
| 232 | // Build a regular move from its initial and destination squares; tr: transformation |
| 233 | getBasicMove([sx,sy], [ex,ey], tr) |
| 234 | { |
| 235 | let mv = new Move({ |
| 236 | appear: [ |
| 237 | new PiPo({ |
| 238 | x: ex, |
| 239 | y: ey, |
| 240 | c: !!tr ? tr.c : this.getColor(sx,sy), |
| 241 | p: !!tr ? tr.p : this.getPiece(sx,sy) |
| 242 | }) |
| 243 | ], |
| 244 | vanish: [ |
| 245 | new PiPo({ |
| 246 | x: sx, |
| 247 | y: sy, |
| 248 | c: this.getColor(sx,sy), |
| 249 | p: this.getPiece(sx,sy) |
| 250 | }) |
| 251 | ] |
| 252 | }); |
| 253 | |
| 254 | // The opponent piece disappears if we take it |
| 255 | if (this.board[ex][ey] != VariantRules.EMPTY) |
| 256 | { |
| 257 | mv.vanish.push( |
| 258 | new PiPo({ |
| 259 | x: ex, |
| 260 | y: ey, |
| 261 | c: this.getColor(ex,ey), |
| 262 | p: this.getPiece(ex,ey) |
| 263 | }) |
| 264 | ); |
| 265 | } |
| 266 | return mv; |
| 267 | } |
| 268 | |
| 269 | // Generic method to find possible moves of non-pawn pieces ("sliding or jumping") |
| 270 | getSlideNJumpMoves([x,y], steps, oneStep) |
| 271 | { |
| 272 | const color = this.getColor(x,y); |
| 273 | let moves = []; |
| 274 | const [sizeX,sizeY] = VariantRules.size; |
| 275 | outerLoop: |
| 276 | for (let step of steps) |
| 277 | { |
| 278 | let i = x + step[0]; |
| 279 | let j = y + step[1]; |
| 280 | while (i>=0 && i<sizeX && j>=0 && j<sizeY && this.board[i][j] == VariantRules.EMPTY) |
| 281 | { |
| 282 | moves.push(this.getBasicMove([x,y], [i,j])); |
| 283 | if (oneStep !== undefined) |
| 284 | continue outerLoop; |
| 285 | i += step[0]; |
| 286 | j += step[1]; |
| 287 | } |
| 288 | if (i>=0 && i<8 && j>=0 && j<8 && this.canTake([x,y], [i,j])) |
| 289 | moves.push(this.getBasicMove([x,y], [i,j])); |
| 290 | } |
| 291 | return moves; |
| 292 | } |
| 293 | |
| 294 | // What are the pawn moves from square x,y considering color "color" ? |
| 295 | getPotentialPawnMoves([x,y]) |
| 296 | { |
| 297 | const color = this.turn; |
| 298 | let moves = []; |
| 299 | const V = VariantRules; |
| 300 | const [sizeX,sizeY] = VariantRules.size; |
| 301 | const shift = (color == "w" ? -1 : 1); |
| 302 | const firstRank = (color == 'w' ? sizeY-1 : 0); |
| 303 | const startRank = (color == "w" ? sizeY-2 : 1); |
| 304 | const lastRank = (color == "w" ? 0 : sizeY-1); |
| 305 | |
| 306 | if (x+shift >= 0 && x+shift < sizeX && x+shift != lastRank) |
| 307 | { |
| 308 | // Normal moves |
| 309 | if (this.board[x+shift][y] == V.EMPTY) |
| 310 | { |
| 311 | moves.push(this.getBasicMove([x,y], [x+shift,y])); |
| 312 | // Next condition because variants with pawns on 1st rank generally allow them to jump |
| 313 | if ([startRank,firstRank].includes(x) && this.board[x+2*shift][y] == V.EMPTY) |
| 314 | { |
| 315 | // Two squares jump |
| 316 | moves.push(this.getBasicMove([x,y], [x+2*shift,y])); |
| 317 | } |
| 318 | } |
| 319 | // Captures |
| 320 | if (y>0 && this.canTake([x,y], [x+shift,y-1]) && this.board[x+shift][y-1] != V.EMPTY) |
| 321 | moves.push(this.getBasicMove([x,y], [x+shift,y-1])); |
| 322 | if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1]) && this.board[x+shift][y+1] != V.EMPTY) |
| 323 | moves.push(this.getBasicMove([x,y], [x+shift,y+1])); |
| 324 | } |
| 325 | |
| 326 | if (x+shift == lastRank) |
| 327 | { |
| 328 | // Promotion |
| 329 | let promotionPieces = [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN]; |
| 330 | promotionPieces.forEach(p => { |
| 331 | // Normal move |
| 332 | if (this.board[x+shift][y] == V.EMPTY) |
| 333 | moves.push(this.getBasicMove([x,y], [x+shift,y], {c:color,p:p})); |
| 334 | // Captures |
| 335 | if (y>0 && this.canTake([x,y], [x+shift,y-1]) && this.board[x+shift][y-1] != V.EMPTY) |
| 336 | moves.push(this.getBasicMove([x,y], [x+shift,y-1], {c:color,p:p})); |
| 337 | if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1]) && this.board[x+shift][y+1] != V.EMPTY) |
| 338 | moves.push(this.getBasicMove([x,y], [x+shift,y+1], {c:color,p:p})); |
| 339 | }); |
| 340 | } |
| 341 | |
| 342 | // En passant |
| 343 | const Lep = this.epSquares.length; |
| 344 | const epSquare = Lep>0 ? this.epSquares[Lep-1] : undefined; |
| 345 | if (!!epSquare && epSquare.x == x+shift && Math.abs(epSquare.y - y) == 1) |
| 346 | { |
| 347 | let epStep = epSquare.y - y; |
| 348 | var enpassantMove = this.getBasicMove([x,y], [x+shift,y+epStep]); |
| 349 | enpassantMove.vanish.push({ |
| 350 | x: x, |
| 351 | y: y+epStep, |
| 352 | p: 'p', |
| 353 | c: this.getColor(x,y+epStep) |
| 354 | }); |
| 355 | moves.push(enpassantMove); |
| 356 | } |
| 357 | |
| 358 | return moves; |
| 359 | } |
| 360 | |
| 361 | // What are the rook moves from square x,y ? |
| 362 | getPotentialRookMoves(sq) |
| 363 | { |
| 364 | return this.getSlideNJumpMoves(sq, VariantRules.steps[VariantRules.ROOK]); |
| 365 | } |
| 366 | |
| 367 | // What are the knight moves from square x,y ? |
| 368 | getPotentialKnightMoves(sq) |
| 369 | { |
| 370 | return this.getSlideNJumpMoves(sq, VariantRules.steps[VariantRules.KNIGHT], "oneStep"); |
| 371 | } |
| 372 | |
| 373 | // What are the bishop moves from square x,y ? |
| 374 | getPotentialBishopMoves(sq) |
| 375 | { |
| 376 | return this.getSlideNJumpMoves(sq, VariantRules.steps[VariantRules.BISHOP]); |
| 377 | } |
| 378 | |
| 379 | // What are the queen moves from square x,y ? |
| 380 | getPotentialQueenMoves(sq) |
| 381 | { |
| 382 | return this.getSlideNJumpMoves(sq, VariantRules.steps[VariantRules.QUEEN]); |
| 383 | } |
| 384 | |
| 385 | // What are the king moves from square x,y ? |
| 386 | getPotentialKingMoves(sq) |
| 387 | { |
| 388 | // Initialize with normal moves |
| 389 | let moves = this.getSlideNJumpMoves(sq, VariantRules.steps[VariantRules.QUEEN], "oneStep"); |
| 390 | return moves.concat(this.getCastleMoves(sq)); |
| 391 | } |
| 392 | |
| 393 | getCastleMoves([x,y]) |
| 394 | { |
| 395 | const c = this.getColor(x,y); |
| 396 | if (x != (c=="w" ? 7 : 0) || y != this.INIT_COL_KING[c]) |
| 397 | return []; //x isn't first rank, or king has moved (shortcut) |
| 398 | |
| 399 | const V = VariantRules; |
| 400 | |
| 401 | // Castling ? |
| 402 | const oppCol = this.getOppCol(c); |
| 403 | let moves = []; |
| 404 | let i = 0; |
| 405 | const finalSquares = [ [2,3], [6,5] ]; //king, then rook |
| 406 | castlingCheck: |
| 407 | for (let castleSide=0; castleSide < 2; castleSide++) //large, then small |
| 408 | { |
| 409 | if (!this.castleFlags[c][castleSide]) |
| 410 | continue; |
| 411 | // If this code is reached, rooks and king are on initial position |
| 412 | |
| 413 | // Nothing on the path of the king (and no checks; OK also if y==finalSquare)? |
| 414 | let step = finalSquares[castleSide][0] < y ? -1 : 1; |
| 415 | for (i=y; i!=finalSquares[castleSide][0]; i+=step) |
| 416 | { |
| 417 | if (this.isAttacked([x,i], oppCol) || (this.board[x][i] != V.EMPTY && |
| 418 | // NOTE: next check is enough, because of chessboard constraints |
| 419 | (this.getColor(x,i) != c || ![V.KING,V.ROOK].includes(this.getPiece(x,i))))) |
| 420 | { |
| 421 | continue castlingCheck; |
| 422 | } |
| 423 | } |
| 424 | |
| 425 | // Nothing on the path to the rook? |
| 426 | step = castleSide == 0 ? -1 : 1; |
| 427 | for (i = y + step; i != this.INIT_COL_ROOK[c][castleSide]; i += step) |
| 428 | { |
| 429 | if (this.board[x][i] != V.EMPTY) |
| 430 | continue castlingCheck; |
| 431 | } |
| 432 | const rookPos = this.INIT_COL_ROOK[c][castleSide]; |
| 433 | |
| 434 | // Nothing on final squares, except maybe king and castling rook? |
| 435 | for (i=0; i<2; i++) |
| 436 | { |
| 437 | if (this.board[x][finalSquares[castleSide][i]] != V.EMPTY && |
| 438 | this.getPiece(x,finalSquares[castleSide][i]) != V.KING && |
| 439 | finalSquares[castleSide][i] != rookPos) |
| 440 | { |
| 441 | continue castlingCheck; |
| 442 | } |
| 443 | } |
| 444 | |
| 445 | // If this code is reached, castle is valid |
| 446 | moves.push( new Move({ |
| 447 | appear: [ |
| 448 | new PiPo({x:x,y:finalSquares[castleSide][0],p:V.KING,c:c}), |
| 449 | new PiPo({x:x,y:finalSquares[castleSide][1],p:V.ROOK,c:c})], |
| 450 | vanish: [ |
| 451 | new PiPo({x:x,y:y,p:V.KING,c:c}), |
| 452 | new PiPo({x:x,y:rookPos,p:V.ROOK,c:c})], |
| 453 | end: Math.abs(y - rookPos) <= 2 |
| 454 | ? {x:x, y:rookPos} |
| 455 | : {x:x, y:y + 2 * (castleSide==0 ? -1 : 1)} |
| 456 | }) ); |
| 457 | } |
| 458 | |
| 459 | return moves; |
| 460 | } |
| 461 | |
| 462 | /////////////////// |
| 463 | // MOVES VALIDATION |
| 464 | |
| 465 | canIplay(side, [x,y]) |
| 466 | { |
| 467 | return ((side=='w' && this.moves.length%2==0) || (side=='b' && this.moves.length%2==1)) |
| 468 | && this.getColor(x,y) == side; |
| 469 | } |
| 470 | |
| 471 | getPossibleMovesFrom(sq) |
| 472 | { |
| 473 | // Assuming color is right (already checked) |
| 474 | return this.filterValid( this.getPotentialMovesFrom(sq) ); |
| 475 | } |
| 476 | |
| 477 | // TODO: once a promotion is filtered, the others results are same: useless computations |
| 478 | filterValid(moves) |
| 479 | { |
| 480 | if (moves.length == 0) |
| 481 | return []; |
| 482 | let color = this.turn; |
| 483 | return moves.filter(m => { return !this.underCheck(m, color); }); |
| 484 | } |
| 485 | |
| 486 | // Search for all valid moves considering current turn (for engine and game end) |
| 487 | getAllValidMoves() |
| 488 | { |
| 489 | const color = this.turn; |
| 490 | const oppCol = this.getOppCol(color); |
| 491 | var potentialMoves = []; |
| 492 | let [sizeX,sizeY] = VariantRules.size; |
| 493 | for (var i=0; i<sizeX; i++) |
| 494 | { |
| 495 | for (var j=0; j<sizeY; j++) |
| 496 | { |
| 497 | // Next condition ... != oppCol is a little HACK to work with checkered variant |
| 498 | if (this.board[i][j] != VariantRules.EMPTY && this.getColor(i,j) != oppCol) |
| 499 | Array.prototype.push.apply(potentialMoves, this.getPotentialMovesFrom([i,j])); |
| 500 | } |
| 501 | } |
| 502 | // NOTE: prefer lazy undercheck tests, letting the king being taken? |
| 503 | // No: if happen on last 1/2 move, could lead to forbidden moves, wrong evals |
| 504 | return this.filterValid(potentialMoves); |
| 505 | } |
| 506 | |
| 507 | // Stop at the first move found |
| 508 | atLeastOneMove() |
| 509 | { |
| 510 | const color = this.turn; |
| 511 | const oppCol = this.getOppCol(color); |
| 512 | let [sizeX,sizeY] = VariantRules.size; |
| 513 | for (var i=0; i<sizeX; i++) |
| 514 | { |
| 515 | for (var j=0; j<sizeY; j++) |
| 516 | { |
| 517 | if (this.board[i][j] != VariantRules.EMPTY && this.getColor(i,j) != oppCol) |
| 518 | { |
| 519 | const moves = this.getPotentialMovesFrom([i,j]); |
| 520 | if (moves.length > 0) |
| 521 | { |
| 522 | for (let i=0; i<moves.length; i++) |
| 523 | { |
| 524 | if (this.filterValid([moves[i]]).length > 0) |
| 525 | return true; |
| 526 | } |
| 527 | } |
| 528 | } |
| 529 | } |
| 530 | } |
| 531 | return false; |
| 532 | } |
| 533 | |
| 534 | // Check if pieces of color 'colors' are attacking square x,y |
| 535 | isAttacked(sq, colors) |
| 536 | { |
| 537 | return (this.isAttackedByPawn(sq, colors) |
| 538 | || this.isAttackedByRook(sq, colors) |
| 539 | || this.isAttackedByKnight(sq, colors) |
| 540 | || this.isAttackedByBishop(sq, colors) |
| 541 | || this.isAttackedByQueen(sq, colors) |
| 542 | || this.isAttackedByKing(sq, colors)); |
| 543 | } |
| 544 | |
| 545 | // Is square x,y attacked by pawns of color c ? |
| 546 | isAttackedByPawn([x,y], colors) |
| 547 | { |
| 548 | for (let c of colors) |
| 549 | { |
| 550 | let pawnShift = (c=="w" ? 1 : -1); |
| 551 | if (x+pawnShift>=0 && x+pawnShift<8) |
| 552 | { |
| 553 | for (let i of [-1,1]) |
| 554 | { |
| 555 | if (y+i>=0 && y+i<8 && this.getPiece(x+pawnShift,y+i)==VariantRules.PAWN |
| 556 | && this.getColor(x+pawnShift,y+i)==c) |
| 557 | { |
| 558 | return true; |
| 559 | } |
| 560 | } |
| 561 | } |
| 562 | } |
| 563 | return false; |
| 564 | } |
| 565 | |
| 566 | // Is square x,y attacked by rooks of color c ? |
| 567 | isAttackedByRook(sq, colors) |
| 568 | { |
| 569 | return this.isAttackedBySlideNJump(sq, colors, |
| 570 | VariantRules.ROOK, VariantRules.steps[VariantRules.ROOK]); |
| 571 | } |
| 572 | |
| 573 | // Is square x,y attacked by knights of color c ? |
| 574 | isAttackedByKnight(sq, colors) |
| 575 | { |
| 576 | return this.isAttackedBySlideNJump(sq, colors, |
| 577 | VariantRules.KNIGHT, VariantRules.steps[VariantRules.KNIGHT], "oneStep"); |
| 578 | } |
| 579 | |
| 580 | // Is square x,y attacked by bishops of color c ? |
| 581 | isAttackedByBishop(sq, colors) |
| 582 | { |
| 583 | return this.isAttackedBySlideNJump(sq, colors, |
| 584 | VariantRules.BISHOP, VariantRules.steps[VariantRules.BISHOP]); |
| 585 | } |
| 586 | |
| 587 | // Is square x,y attacked by queens of color c ? |
| 588 | isAttackedByQueen(sq, colors) |
| 589 | { |
| 590 | return this.isAttackedBySlideNJump(sq, colors, |
| 591 | VariantRules.QUEEN, VariantRules.steps[VariantRules.QUEEN]); |
| 592 | } |
| 593 | |
| 594 | // Is square x,y attacked by king of color c ? |
| 595 | isAttackedByKing(sq, colors) |
| 596 | { |
| 597 | return this.isAttackedBySlideNJump(sq, colors, |
| 598 | VariantRules.KING, VariantRules.steps[VariantRules.QUEEN], "oneStep"); |
| 599 | } |
| 600 | |
| 601 | // Generic method for non-pawn pieces ("sliding or jumping"): is x,y attacked by piece != color ? |
| 602 | isAttackedBySlideNJump([x,y], colors, piece, steps, oneStep) |
| 603 | { |
| 604 | for (let step of steps) |
| 605 | { |
| 606 | let rx = x+step[0], ry = y+step[1]; |
| 607 | while (rx>=0 && rx<8 && ry>=0 && ry<8 && this.board[rx][ry] == VariantRules.EMPTY |
| 608 | && !oneStep) |
| 609 | { |
| 610 | rx += step[0]; |
| 611 | ry += step[1]; |
| 612 | } |
| 613 | if (rx>=0 && rx<8 && ry>=0 && ry<8 && this.board[rx][ry] != VariantRules.EMPTY |
| 614 | && this.getPiece(rx,ry) == piece && colors.includes(this.getColor(rx,ry))) |
| 615 | { |
| 616 | return true; |
| 617 | } |
| 618 | } |
| 619 | return false; |
| 620 | } |
| 621 | |
| 622 | // Is color c under check after move ? |
| 623 | underCheck(move) |
| 624 | { |
| 625 | const color = this.turn; |
| 626 | this.play(move); |
| 627 | let res = this.isAttacked(this.kingPos[color], this.getOppCol(color)); |
| 628 | this.undo(move); |
| 629 | return res; |
| 630 | } |
| 631 | |
| 632 | // On which squares is color c under check (after move) ? |
| 633 | getCheckSquares(move) |
| 634 | { |
| 635 | this.play(move); |
| 636 | const color = this.turn; //opponent |
| 637 | let res = this.isAttacked(this.kingPos[color], this.getOppCol(color)) |
| 638 | ? [ JSON.parse(JSON.stringify(this.kingPos[color])) ] //need to duplicate! |
| 639 | : [ ]; |
| 640 | this.undo(move); |
| 641 | return res; |
| 642 | } |
| 643 | |
| 644 | // Apply a move on board |
| 645 | static PlayOnBoard(board, move) |
| 646 | { |
| 647 | for (let psq of move.vanish) |
| 648 | board[psq.x][psq.y] = VariantRules.EMPTY; |
| 649 | for (let psq of move.appear) |
| 650 | board[psq.x][psq.y] = psq.c + psq.p; |
| 651 | } |
| 652 | // Un-apply the played move |
| 653 | static UndoOnBoard(board, move) |
| 654 | { |
| 655 | for (let psq of move.appear) |
| 656 | board[psq.x][psq.y] = VariantRules.EMPTY; |
| 657 | for (let psq of move.vanish) |
| 658 | board[psq.x][psq.y] = psq.c + psq.p; |
| 659 | } |
| 660 | |
| 661 | // Before move is played, update variables + flags |
| 662 | updateVariables(move) |
| 663 | { |
| 664 | const piece = this.getPiece(move.start.x,move.start.y); |
| 665 | const c = this.getColor(move.start.x,move.start.y); |
| 666 | const firstRank = (c == "w" ? 7 : 0); |
| 667 | |
| 668 | // Update king position + flags |
| 669 | if (piece == VariantRules.KING && move.appear.length > 0) |
| 670 | { |
| 671 | this.kingPos[c][0] = move.appear[0].x; |
| 672 | this.kingPos[c][1] = move.appear[0].y; |
| 673 | this.castleFlags[c] = [false,false]; |
| 674 | return; |
| 675 | } |
| 676 | const oppCol = this.getOppCol(c); |
| 677 | const oppFirstRank = 7 - firstRank; |
| 678 | if (move.start.x == firstRank //our rook moves? |
| 679 | && this.INIT_COL_ROOK[c].includes(move.start.y)) |
| 680 | { |
| 681 | const flagIdx = (move.start.y == this.INIT_COL_ROOK[c][0] ? 0 : 1); |
| 682 | this.castleFlags[c][flagIdx] = false; |
| 683 | } |
| 684 | else if (move.end.x == oppFirstRank //we took opponent rook? |
| 685 | && this.INIT_COL_ROOK[oppCol].includes(move.end.y)) |
| 686 | { |
| 687 | const flagIdx = (move.end.y == this.INIT_COL_ROOK[oppCol][0] ? 0 : 1); |
| 688 | this.castleFlags[oppCol][flagIdx] = false; |
| 689 | } |
| 690 | } |
| 691 | |
| 692 | unupdateVariables(move) |
| 693 | { |
| 694 | // (Potentially) Reset king position |
| 695 | const c = this.getColor(move.start.x,move.start.y); |
| 696 | if (this.getPiece(move.start.x,move.start.y) == VariantRules.KING) |
| 697 | this.kingPos[c] = [move.start.x, move.start.y]; |
| 698 | } |
| 699 | |
| 700 | play(move, ingame) |
| 701 | { |
| 702 | if (!!ingame) |
| 703 | move.notation = this.getNotation(move); |
| 704 | |
| 705 | move.flags = JSON.stringify(this.flags); //save flags (for undo) |
| 706 | this.updateVariables(move); |
| 707 | this.moves.push(move); |
| 708 | this.epSquares.push( this.getEpSquare(move) ); |
| 709 | VariantRules.PlayOnBoard(this.board, move); |
| 710 | } |
| 711 | |
| 712 | undo(move) |
| 713 | { |
| 714 | VariantRules.UndoOnBoard(this.board, move); |
| 715 | this.epSquares.pop(); |
| 716 | this.moves.pop(); |
| 717 | this.unupdateVariables(move); |
| 718 | this.parseFlags(JSON.parse(move.flags)); |
| 719 | } |
| 720 | |
| 721 | ////////////// |
| 722 | // END OF GAME |
| 723 | |
| 724 | checkRepetition() |
| 725 | { |
| 726 | // Check for 3 repetitions |
| 727 | if (this.moves.length >= 8) |
| 728 | { |
| 729 | // NOTE: crude detection, only moves repetition |
| 730 | const L = this.moves.length; |
| 731 | if (_.isEqual(this.moves[L-1], this.moves[L-5]) && |
| 732 | _.isEqual(this.moves[L-2], this.moves[L-6]) && |
| 733 | _.isEqual(this.moves[L-3], this.moves[L-7]) && |
| 734 | _.isEqual(this.moves[L-4], this.moves[L-8])) |
| 735 | { |
| 736 | return true; |
| 737 | } |
| 738 | } |
| 739 | return false; |
| 740 | } |
| 741 | |
| 742 | checkGameOver() |
| 743 | { |
| 744 | if (this.checkRepetition()) |
| 745 | return "1/2"; |
| 746 | |
| 747 | if (this.atLeastOneMove()) // game not over |
| 748 | return "*"; |
| 749 | |
| 750 | // Game over |
| 751 | return this.checkGameEnd(); |
| 752 | } |
| 753 | |
| 754 | // No moves are possible: compute score |
| 755 | checkGameEnd() |
| 756 | { |
| 757 | const color = this.turn; |
| 758 | // No valid move: stalemate or checkmate? |
| 759 | if (!this.isAttacked(this.kingPos[color], this.getOppCol(color))) |
| 760 | return "1/2"; |
| 761 | // OK, checkmate |
| 762 | return color == "w" ? "0-1" : "1-0"; |
| 763 | } |
| 764 | |
| 765 | //////// |
| 766 | //ENGINE |
| 767 | |
| 768 | // Pieces values |
| 769 | static get VALUES() { |
| 770 | return { |
| 771 | 'p': 1, |
| 772 | 'r': 5, |
| 773 | 'n': 3, |
| 774 | 'b': 3, |
| 775 | 'q': 9, |
| 776 | 'k': 1000 |
| 777 | }; |
| 778 | } |
| 779 | |
| 780 | // Assumption: at least one legal move |
| 781 | getComputerMove() |
| 782 | { |
| 783 | const color = this.turn; |
| 784 | |
| 785 | // Rank moves using a min-max at depth 2 |
| 786 | let moves1 = this.getAllValidMoves(); |
| 787 | |
| 788 | for (let i=0; i<moves1.length; i++) |
| 789 | { |
| 790 | moves1[i].eval = (color=="w" ? -1 : 1) * 1000; //very low, I'm checkmated |
| 791 | let eval2 = (color=="w" ? 1 : -1) * 1000; //initialized with very high (checkmate) value |
| 792 | this.play(moves1[i]); |
| 793 | // Second half-move: |
| 794 | let moves2 = this.getAllValidMoves(); |
| 795 | // If no possible moves AND underCheck, eval2 is correct. |
| 796 | // If !underCheck, eval2 is 0 (stalemate). |
| 797 | if (moves2.length == 0 && this.checkGameEnd() == "1/2") |
| 798 | eval2 = 0; |
| 799 | for (let j=0; j<moves2.length; j++) |
| 800 | { |
| 801 | this.play(moves2[j]); |
| 802 | let evalPos = this.evalPosition(); |
| 803 | if ((color == "w" && evalPos < eval2) || (color=="b" && evalPos > eval2)) |
| 804 | eval2 = evalPos; |
| 805 | this.undo(moves2[j]); |
| 806 | } |
| 807 | if ((color=="w" && eval2 > moves1[i].eval) || (color=="b" && eval2 < moves1[i].eval)) |
| 808 | moves1[i].eval = eval2; |
| 809 | this.undo(moves1[i]); |
| 810 | } |
| 811 | moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); }); |
| 812 | |
| 813 | // TODO: show current analyzed move for depth 3, allow stopping eval (return moves1[0]) |
| 814 | for (let i=0; i<moves1.length; i++) |
| 815 | { |
| 816 | this.play(moves1[i]); |
| 817 | // 0.1 * oldEval : heuristic to avoid some bad moves (not all...) |
| 818 | moves1[i].eval = 0.1*moves1[i].eval + this.alphabeta(2, -1000, 1000); |
| 819 | this.undo(moves1[i]); |
| 820 | } |
| 821 | moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); }); |
| 822 | |
| 823 | let candidates = [0]; //indices of candidates moves |
| 824 | for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++) |
| 825 | candidates.push(j); |
| 826 | |
| 827 | //console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; })); |
| 828 | return moves1[_.sample(candidates, 1)]; |
| 829 | } |
| 830 | |
| 831 | alphabeta(depth, alpha, beta) |
| 832 | { |
| 833 | const color = this.turn; |
| 834 | if (!this.atLeastOneMove()) |
| 835 | { |
| 836 | switch (this.checkGameEnd()) |
| 837 | { |
| 838 | case "1/2": return 0; |
| 839 | default: return color=="w" ? -1000 : 1000; |
| 840 | } |
| 841 | } |
| 842 | if (depth == 0) |
| 843 | return this.evalPosition(); |
| 844 | const moves = this.getAllValidMoves(); |
| 845 | let v = color=="w" ? -1000 : 1000; |
| 846 | if (color == "w") |
| 847 | { |
| 848 | for (let i=0; i<moves.length; i++) |
| 849 | { |
| 850 | this.play(moves[i]); |
| 851 | v = Math.max(v, this.alphabeta(depth-1, alpha, beta)); |
| 852 | this.undo(moves[i]); |
| 853 | alpha = Math.max(alpha, v); |
| 854 | if (alpha >= beta) |
| 855 | break; //beta cutoff |
| 856 | } |
| 857 | } |
| 858 | else //color=="b" |
| 859 | { |
| 860 | for (let i=0; i<moves.length; i++) |
| 861 | { |
| 862 | this.play(moves[i]); |
| 863 | v = Math.min(v, this.alphabeta(depth-1, alpha, beta)); |
| 864 | this.undo(moves[i]); |
| 865 | beta = Math.min(beta, v); |
| 866 | if (alpha >= beta) |
| 867 | break; //alpha cutoff |
| 868 | } |
| 869 | } |
| 870 | return v; |
| 871 | } |
| 872 | |
| 873 | evalPosition() |
| 874 | { |
| 875 | const [sizeX,sizeY] = VariantRules.size; |
| 876 | let evaluation = 0; |
| 877 | //Just count material for now |
| 878 | for (let i=0; i<sizeX; i++) |
| 879 | { |
| 880 | for (let j=0; j<sizeY; j++) |
| 881 | { |
| 882 | if (this.board[i][j] != VariantRules.EMPTY) |
| 883 | { |
| 884 | const sign = this.getColor(i,j) == "w" ? 1 : -1; |
| 885 | evaluation += sign * VariantRules.VALUES[this.getPiece(i,j)]; |
| 886 | } |
| 887 | } |
| 888 | } |
| 889 | return evaluation; |
| 890 | } |
| 891 | |
| 892 | //////////// |
| 893 | // FEN utils |
| 894 | |
| 895 | // Overridable.. |
| 896 | static GenRandInitFen() |
| 897 | { |
| 898 | let pieces = [new Array(8), new Array(8)]; |
| 899 | // Shuffle pieces on first and last rank |
| 900 | for (let c = 0; c <= 1; c++) |
| 901 | { |
| 902 | let positions = _.range(8); |
| 903 | |
| 904 | // Get random squares for bishops |
| 905 | let randIndex = 2 * _.random(3); |
| 906 | let bishop1Pos = positions[randIndex]; |
| 907 | // The second bishop must be on a square of different color |
| 908 | let randIndex_tmp = 2 * _.random(3) + 1; |
| 909 | let bishop2Pos = positions[randIndex_tmp]; |
| 910 | // Remove chosen squares |
| 911 | positions.splice(Math.max(randIndex,randIndex_tmp), 1); |
| 912 | positions.splice(Math.min(randIndex,randIndex_tmp), 1); |
| 913 | |
| 914 | // Get random squares for knights |
| 915 | randIndex = _.random(5); |
| 916 | let knight1Pos = positions[randIndex]; |
| 917 | positions.splice(randIndex, 1); |
| 918 | randIndex = _.random(4); |
| 919 | let knight2Pos = positions[randIndex]; |
| 920 | positions.splice(randIndex, 1); |
| 921 | |
| 922 | // Get random square for queen |
| 923 | randIndex = _.random(3); |
| 924 | let queenPos = positions[randIndex]; |
| 925 | positions.splice(randIndex, 1); |
| 926 | |
| 927 | // Rooks and king positions are now fixed, because of the ordering rook-king-rook |
| 928 | let rook1Pos = positions[0]; |
| 929 | let kingPos = positions[1]; |
| 930 | let rook2Pos = positions[2]; |
| 931 | |
| 932 | // Finally put the shuffled pieces in the board array |
| 933 | pieces[c][rook1Pos] = 'r'; |
| 934 | pieces[c][knight1Pos] = 'n'; |
| 935 | pieces[c][bishop1Pos] = 'b'; |
| 936 | pieces[c][queenPos] = 'q'; |
| 937 | pieces[c][kingPos] = 'k'; |
| 938 | pieces[c][bishop2Pos] = 'b'; |
| 939 | pieces[c][knight2Pos] = 'n'; |
| 940 | pieces[c][rook2Pos] = 'r'; |
| 941 | } |
| 942 | let fen = pieces[0].join("") + |
| 943 | "/pppppppp/8/8/8/8/PPPPPPPP/" + |
| 944 | pieces[1].join("").toUpperCase() + |
| 945 | " 1111"; //add flags |
| 946 | return fen; |
| 947 | } |
| 948 | |
| 949 | // Return current fen according to pieces+colors state |
| 950 | getFen() |
| 951 | { |
| 952 | return this.getBaseFen() + " " + this.getFlagsFen(); |
| 953 | } |
| 954 | |
| 955 | getBaseFen() |
| 956 | { |
| 957 | let fen = ""; |
| 958 | let [sizeX,sizeY] = VariantRules.size; |
| 959 | for (let i=0; i<sizeX; i++) |
| 960 | { |
| 961 | let emptyCount = 0; |
| 962 | for (let j=0; j<sizeY; j++) |
| 963 | { |
| 964 | if (this.board[i][j] == VariantRules.EMPTY) |
| 965 | emptyCount++; |
| 966 | else |
| 967 | { |
| 968 | if (emptyCount > 0) |
| 969 | { |
| 970 | // Add empty squares in-between |
| 971 | fen += emptyCount; |
| 972 | emptyCount = 0; |
| 973 | } |
| 974 | fen += VariantRules.board2fen(this.board[i][j]); |
| 975 | } |
| 976 | } |
| 977 | if (emptyCount > 0) |
| 978 | { |
| 979 | // "Flush remainder" |
| 980 | fen += emptyCount; |
| 981 | } |
| 982 | if (i < sizeX - 1) |
| 983 | fen += "/"; //separate rows |
| 984 | } |
| 985 | return fen; |
| 986 | } |
| 987 | |
| 988 | // Overridable.. |
| 989 | getFlagsFen() |
| 990 | { |
| 991 | let fen = ""; |
| 992 | // Add castling flags |
| 993 | for (let i of ['w','b']) |
| 994 | { |
| 995 | for (let j=0; j<2; j++) |
| 996 | fen += this.castleFlags[i][j] ? '1' : '0'; |
| 997 | } |
| 998 | return fen; |
| 999 | } |
| 1000 | |
| 1001 | // Context: just before move is played, turn hasn't changed |
| 1002 | getNotation(move) |
| 1003 | { |
| 1004 | if (move.appear.length == 2 && move.appear[0].p == VariantRules.KING) |
| 1005 | { |
| 1006 | // Castle |
| 1007 | if (move.end.y < move.start.y) |
| 1008 | return "0-0-0"; |
| 1009 | else |
| 1010 | return "0-0"; |
| 1011 | } |
| 1012 | |
| 1013 | // Translate final square |
| 1014 | let finalSquare = |
| 1015 | String.fromCharCode(97 + move.end.y) + (VariantRules.size[0]-move.end.x); |
| 1016 | |
| 1017 | let piece = this.getPiece(move.start.x, move.start.y); |
| 1018 | if (piece == VariantRules.PAWN) |
| 1019 | { |
| 1020 | // Pawn move |
| 1021 | let notation = ""; |
| 1022 | if (move.vanish.length > move.appear.length) |
| 1023 | { |
| 1024 | // Capture |
| 1025 | let startColumn = String.fromCharCode(97 + move.start.y); |
| 1026 | notation = startColumn + "x" + finalSquare; |
| 1027 | } |
| 1028 | else //no capture |
| 1029 | notation = finalSquare; |
| 1030 | if (move.appear.length > 0 && piece != move.appear[0].p) //promotion |
| 1031 | notation += "=" + move.appear[0].p.toUpperCase(); |
| 1032 | return notation; |
| 1033 | } |
| 1034 | |
| 1035 | else |
| 1036 | { |
| 1037 | // Piece movement |
| 1038 | return piece.toUpperCase() + |
| 1039 | (move.vanish.length > move.appear.length ? "x" : "") + finalSquare; |
| 1040 | } |
| 1041 | } |
| 1042 | |
| 1043 | // The score is already computed when calling this function |
| 1044 | getPGN(mycolor, score, fenStart, mode) |
| 1045 | { |
| 1046 | let pgn = ""; |
| 1047 | pgn += '[Site "vchess.club"]<br>'; |
| 1048 | const d = new Date(); |
| 1049 | const opponent = mode=="human" ? "Anonymous" : "Computer"; |
| 1050 | pgn += '[Date "' + d.getFullYear() + '-' + (d.getMonth()+1) + '-' + d.getDate() + '"]<br>'; |
| 1051 | pgn += '[White "' + (mycolor=='w'?'Myself':opponent) + '"]<br>'; |
| 1052 | pgn += '[Black "' + (mycolor=='b'?'Myself':opponent) + '"]<br>'; |
| 1053 | pgn += '[Fen "' + fenStart + '"]<br>'; |
| 1054 | pgn += '[Result "' + score + '"]<br><br>'; |
| 1055 | |
| 1056 | for (let i=0; i<this.moves.length; i++) |
| 1057 | { |
| 1058 | if (i % 2 == 0) |
| 1059 | pgn += ((i/2)+1) + "."; |
| 1060 | pgn += this.moves[i].notation + " "; |
| 1061 | } |
| 1062 | |
| 1063 | pgn += score; |
| 1064 | return pgn; |
| 1065 | } |
| 1066 | } |