client/src/variants/Checkered1.js

   1 import { ChessRules, Move, PiPo } from "@/base_rules";
   2
   3 export class Checkered1Rules extends ChessRules {
   4   static board2fen(b) {
   5     const checkered_codes = {
   6       p: "s",
   7       q: "t",
   8       r: "u",
   9       b: "c",
  10       n: "o"
  11     };
  12     if (b[0] == "c") return checkered_codes[b[1]];
  13     return ChessRules.board2fen(b);
  14   }
  15
  16   static fen2board(f) {
  17     // Tolerate upper-case versions of checkered pieces (why not?)
  18     const checkered_pieces = {
  19       s: "p",
  20       S: "p",
  21       t: "q",
  22       T: "q",
  23       u: "r",
  24       U: "r",
  25       c: "b",
  26       C: "b",
  27       o: "n",
  28       O: "n"
  29     };
  30     if (Object.keys(checkered_pieces).includes(f))
  31       return "c" + checkered_pieces[f];
  32     return ChessRules.fen2board(f);
  33   }
  34
  35   static get PIECES() {
  36     return ChessRules.PIECES.concat(["s", "t", "u", "c", "o"]);
  37   }
  38
  39   getPpath(b) {
  40     return (b[0] == "c" ? "Checkered/" : "") + b;
  41   }
  42
  43   setOtherVariables(fen) {
  44     super.setOtherVariables(fen);
  45     // Local stack of non-capturing checkered moves:
  46     this.cmoves = [];
  47     const cmove = V.ParseFen(fen).cmove;
  48     if (cmove == "-") this.cmoves.push(null);
  49     else {
  50       this.cmoves.push({
  51         start: ChessRules.SquareToCoords(cmove.substr(0, 2)),
  52         end: ChessRules.SquareToCoords(cmove.substr(2))
  53       });
  54     }
  55     // Stage 1: as Checkered2. Stage 2: checkered pieces are autonomous
  56     const stageInfo = V.ParseFen(fen).stage;
  57     this.stage = parseInt(stageInfo[0], 10);
  58     this.sideCheckered = (this.stage == 2 ? stageInfo[1] : undefined);
  59   }
  60
  61   static IsGoodFen(fen) {
  62     if (!ChessRules.IsGoodFen(fen)) return false;
  63     const fenParts = fen.split(" ");
  64     if (fenParts.length != 7) return false;
  65     if (fenParts[5] != "-" && !fenParts[5].match(/^([a-h][1-8]){2}$/))
  66       return false;
  67     if (!fenParts[6].match(/^[12][wb]?$/)) return false;
  68     return true;
  69   }
  70
  71   static IsGoodFlags(flags) {
  72     // 4 for castle + 16 for pawns
  73     return !!flags.match(/^[a-z]{4,4}[01]{16,16}$/);
  74   }
  75
  76   setFlags(fenflags) {
  77     super.setFlags(fenflags); //castleFlags
  78     this.pawnFlags = {
  79       w: [...Array(8)], //pawns can move 2 squares?
  80       b: [...Array(8)]
  81     };
  82     const flags = fenflags.substr(4); //skip first 4 letters, for castle
  83     for (let c of ["w", "b"]) {
  84       for (let i = 0; i < 8; i++)
  85         this.pawnFlags[c][i] = flags.charAt((c == "w" ? 0 : 8) + i) == "1";
  86     }
  87   }
  88
  89   aggregateFlags() {
  90     return [this.castleFlags, this.pawnFlags];
  91   }
  92
  93   disaggregateFlags(flags) {
  94     this.castleFlags = flags[0];
  95     this.pawnFlags = flags[1];
  96   }
  97
  98   getEpSquare(moveOrSquare) {
  99     // At stage 2, all pawns can be captured en-passant
 100     if (
 101       this.stage == 2 ||
 102       typeof moveOrSquare !== "object" ||
 103       (moveOrSquare.appear.length > 0 && moveOrSquare.appear[0].c != 'c')
 104     )
 105       return super.getEpSquare(moveOrSquare);
 106     // Checkered or switch move: no en-passant
 107     return undefined;
 108   }
 109
 110   getCmove(move) {
 111     // No checkered move to undo at stage 2:
 112     if (this.stage == 1 && move.vanish.length == 1 && move.appear[0].c == "c")
 113       return { start: move.start, end: move.end };
 114     return null;
 115   }
 116
 117   canTake([x1, y1], [x2, y2]) {
 118     const color1 = this.getColor(x1, y1);
 119     const color2 = this.getColor(x2, y2);
 120     if (this.stage == 2) {
 121       // Black & White <-- takes --> Checkered
 122       const color1 = this.getColor(x1, y1);
 123       const color2 = this.getColor(x2, y2);
 124       return color1 != color2 && [color1, color2].includes('c');
 125     }
 126     // Checkered aren't captured
 127     return (
 128       color1 != color2 &&
 129       color2 != "c" &&
 130       (color1 != "c" || color2 != this.turn)
 131     );
 132   }
 133
 134   getPotentialMovesFrom([x, y], noswitch) {
 135     let standardMoves = super.getPotentialMovesFrom([x, y]);
 136     if (this.stage == 1) {
 137       const color = this.turn;
 138       // Post-processing: apply "checkerization" of standard moves
 139       const lastRank = (color == "w" ? 0 : 7);
 140       let moves = [];
 141       // King is treated differently: it never turn checkered
 142       if (this.getPiece(x, y) == V.KING) {
 143         // If at least one checkered piece, allow switching:
 144         if (
 145           !noswitch &&
 146           this.board.some(b => b.some(cell => cell[0] == 'c'))
 147         ) {
 148           const oppCol = V.GetOppCol(color);
 149           moves.push(
 150             new Move({
 151               start: { x: x, y: y },
 152               end: { x: this.kingPos[oppCol][0], y: this.kingPos[oppCol][1] },
 153               appear: [],
 154               vanish: []
 155             })
 156           );
 157         }
 158         return standardMoves.concat(moves);
 159       }
 160       standardMoves.forEach(m => {
 161         if (m.vanish[0].p == V.PAWN) {
 162           if (
 163             Math.abs(m.end.x - m.start.x) == 2 &&
 164             !this.pawnFlags[this.turn][m.start.y]
 165           ) {
 166             return; //skip forbidden 2-squares jumps
 167           }
 168           if (
 169             this.board[m.end.x][m.end.y] == V.EMPTY &&
 170             m.vanish.length == 2 &&
 171             this.getColor(m.start.x, m.start.y) == "c"
 172           ) {
 173             return; //checkered pawns cannot take en-passant
 174           }
 175         }
 176         if (m.vanish.length == 1)
 177           // No capture
 178           moves.push(m);
 179         else {
 180           // A capture occured (m.vanish.length == 2)
 181           m.appear[0].c = "c";
 182           moves.push(m);
 183           if (
 184             // Avoid promotions (already treated):
 185             m.appear[0].p != m.vanish[1].p &&
 186             (m.vanish[0].p != V.PAWN || m.end.x != lastRank)
 187           ) {
 188             // Add transformation into captured piece
 189             let m2 = JSON.parse(JSON.stringify(m));
 190             m2.appear[0].p = m.vanish[1].p;
 191             moves.push(m2);
 192           }
 193         }
 194       });
 195       return moves;
 196     }
 197     return standardMoves;
 198   }
 199
 200   getPotentialPawnMoves([x, y]) {
 201     const color = this.getColor(x, y);
 202     if (this.stage == 2) {
 203       const saveTurn = this.turn;
 204       if (this.sideCheckered == this.turn) {
 205         // Cannot change PawnSpecs.bidirectional, so cheat a little:
 206         this.turn = 'w';
 207         const wMoves = super.getPotentialPawnMoves([x, y]);
 208         this.turn = 'b';
 209         const bMoves = super.getPotentialPawnMoves([x, y]);
 210         this.turn = saveTurn;
 211         return wMoves.concat(bMoves);
 212       }
 213       // Playing with both colors:
 214       this.turn = color;
 215       const moves = super.getPotentialPawnMoves([x, y]);
 216       this.turn = saveTurn;
 217       return moves;
 218     }
 219     let moves = super.getPotentialPawnMoves([x, y]);
 220     // Post-process: set right color for checkered moves
 221     if (color == 'c') {
 222       moves.forEach(m => {
 223         m.appear[0].c = 'c'; //may be done twice if capture
 224         m.vanish[0].c = 'c';
 225       });
 226     }
 227     return moves;
 228   }
 229
 230   canIplay(side, [x, y]) {
 231     if (this.stage == 2) {
 232       const color = this.getColor(x, y);
 233       return (
 234         this.turn == this.sideCheckered
 235           ? color == 'c'
 236           : ['w', 'b'].includes(color)
 237       );
 238     }
 239     return side == this.turn && [side, "c"].includes(this.getColor(x, y));
 240   }
 241
 242   // Does m2 un-do m1 ? (to disallow undoing checkered moves)
 243   oppositeMoves(m1, m2) {
 244     return (
 245       !!m1 &&
 246       m2.appear[0].c == "c" &&
 247       m2.appear.length == 1 &&
 248       m2.vanish.length == 1 &&
 249       m1.start.x == m2.end.x &&
 250       m1.end.x == m2.start.x &&
 251       m1.start.y == m2.end.y &&
 252       m1.end.y == m2.start.y
 253     );
 254   }
 255
 256   filterValid(moves) {
 257     if (moves.length == 0) return [];
 258     const color = this.turn;
 259     const oppCol = V.GetOppCol(color);
 260     const L = this.cmoves.length; //at least 1: init from FEN
 261     const stage = this.stage; //may change if switch
 262     return moves.filter(m => {
 263       // Checkered cannot be under check (no king)
 264       if (stage == 2 && this.sideCheckered == color) return true;
 265       this.play(m);
 266       let res = true;
 267       if (stage == 1) {
 268         if (m.appear.length == 0 && m.vanish.length == 0) {
 269           // Special "switch" move: kings must not be attacked by checkered.
 270           // Not checking for oppositeMoves here: checkered are autonomous
 271           res = (
 272             !this.isAttacked(this.kingPos['w'], ['c']) &&
 273             !this.isAttacked(this.kingPos['b'], ['c']) &&
 274             this.getAllPotentialMoves().length > 0
 275           );
 276         }
 277         else res = !this.oppositeMoves(this.cmoves[L - 1], m);
 278       }
 279       if (res && m.appear.length > 0) res = !this.underCheck(color);
 280       // At stage 2, side with B & W can be undercheck with both kings:
 281       if (res && stage == 2) res = !this.underCheck(oppCol);
 282       this.undo(m);
 283       return res;
 284     });
 285   }
 286
 287   getAllPotentialMoves() {
 288     const color = this.turn;
 289     const oppCol = V.GetOppCol(color);
 290     let potentialMoves = [];
 291     for (let i = 0; i < V.size.x; i++) {
 292       for (let j = 0; j < V.size.y; j++) {
 293         const colIJ = this.getColor(i, j);
 294         if (
 295           this.board[i][j] != V.EMPTY &&
 296           (
 297             (this.stage == 1 && colIJ != oppCol) ||
 298             (this.stage == 2 &&
 299               (
 300                 (this.sideCheckered == color && colIJ == 'c') ||
 301                 (this.sideCheckered != color && ['w', 'b'].includes(colIJ))
 302               )
 303             )
 304           )
 305         ) {
 306           Array.prototype.push.apply(
 307             potentialMoves,
 308             this.getPotentialMovesFrom([i, j])
 309           );
 310         }
 311       }
 312     }
 313     return potentialMoves;
 314   }
 315
 316   atLeastOneMove() {
 317     const color = this.turn;
 318     const oppCol = V.GetOppCol(color);
 319     for (let i = 0; i < V.size.x; i++) {
 320       for (let j = 0; j < V.size.y; j++) {
 321         const colIJ = this.getColor(i, j);
 322         if (
 323           this.board[i][j] != V.EMPTY &&
 324           (
 325             (this.stage == 1 && colIJ != oppCol) ||
 326             (this.stage == 2 &&
 327               (
 328                 (this.sideCheckered == color && colIJ == 'c') ||
 329                 (this.sideCheckered != color && ['w', 'b'].includes(colIJ))
 330               )
 331             )
 332           )
 333         ) {
 334           const moves = this.getPotentialMovesFrom([i, j], "noswitch");
 335           if (moves.length > 0) {
 336             for (let k = 0; k < moves.length; k++)
 337               if (this.filterValid([moves[k]]).length > 0) return true;
 338           }
 339         }
 340       }
 341     }
 342     return false;
 343   }
 344
 345   // colors: array, 'w' and 'c' or 'b' and 'c' at stage 1,
 346   // just 'c' (or unused) at stage 2
 347   isAttacked(sq, colors) {
 348     if (!Array.isArray(colors)) colors = [colors];
 349     return (
 350       this.isAttackedByPawn(sq, colors) ||
 351       this.isAttackedByRook(sq, colors) ||
 352       this.isAttackedByKnight(sq, colors) ||
 353       this.isAttackedByBishop(sq, colors) ||
 354       this.isAttackedByQueen(sq, colors) ||
 355       this.isAttackedByKing(sq, colors)
 356     );
 357   }
 358
 359   isAttackedByPawn([x, y], colors) {
 360     for (let c of colors) {
 361       let shifts = [];
 362       if (this.stage == 1) {
 363         const color = (c == "c" ? this.turn : c);
 364         shifts = [color == "w" ? 1 : -1];
 365       }
 366       else {
 367         // Stage 2: checkered pawns are bidirectional
 368         if (c == 'c') shifts = [-1, 1];
 369         else shifts = [c == "w" ? 1 : -1];
 370       }
 371       for (let pawnShift of shifts) {
 372         if (x + pawnShift >= 0 && x + pawnShift < 8) {
 373           for (let i of [-1, 1]) {
 374             if (
 375               y + i >= 0 &&
 376               y + i < 8 &&
 377               this.getPiece(x + pawnShift, y + i) == V.PAWN &&
 378               this.getColor(x + pawnShift, y + i) == c
 379             ) {
 380               return true;
 381             }
 382           }
 383         }
 384       }
 385     }
 386     return false;
 387   }
 388
 389   isAttackedBySlideNJump([x, y], colors, piece, steps, oneStep) {
 390     for (let step of steps) {
 391       let rx = x + step[0],
 392           ry = y + step[1];
 393       while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
 394         rx += step[0];
 395         ry += step[1];
 396       }
 397       if (
 398         V.OnBoard(rx, ry) &&
 399         this.getPiece(rx, ry) === piece &&
 400         colors.includes(this.getColor(rx, ry))
 401       ) {
 402         return true;
 403       }
 404     }
 405     return false;
 406   }
 407
 408   isAttackedByRook(sq, colors) {
 409     return this.isAttackedBySlideNJump(sq, colors, V.ROOK, V.steps[V.ROOK]);
 410   }
 411
 412   isAttackedByKnight(sq, colors) {
 413     return this.isAttackedBySlideNJump(
 414       sq,
 415       colors,
 416       V.KNIGHT,
 417       V.steps[V.KNIGHT],
 418       "oneStep"
 419     );
 420   }
 421
 422   isAttackedByBishop(sq, colors) {
 423     return this.isAttackedBySlideNJump(
 424       sq, colors, V.BISHOP, V.steps[V.BISHOP]);
 425   }
 426
 427   isAttackedByQueen(sq, colors) {
 428     return this.isAttackedBySlideNJump(
 429       sq,
 430       colors,
 431       V.QUEEN,
 432       V.steps[V.ROOK].concat(V.steps[V.BISHOP])
 433     );
 434   }
 435
 436   isAttackedByKing(sq, colors) {
 437     return this.isAttackedBySlideNJump(
 438       sq,
 439       colors,
 440       V.KING,
 441       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
 442       "oneStep"
 443     );
 444   }
 445
 446   underCheck(color) {
 447     if (this.stage == 1)
 448       return this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"]);
 449     if (color == this.sideCheckered) return false;
 450     return (
 451       this.isAttacked(this.kingPos['w'], ["c"]) ||
 452       this.isAttacked(this.kingPos['b'], ["c"])
 453     );
 454   }
 455
 456   getCheckSquares() {
 457     const color = this.turn;
 458     if (this.stage == 1) {
 459       // Artifically change turn, for checkered pawns
 460       this.turn = V.GetOppCol(color);
 461       const kingAttacked =
 462         this.isAttacked(
 463           this.kingPos[color],
 464           [V.GetOppCol(color), "c"]
 465         );
 466       let res = kingAttacked
 467         ? [JSON.parse(JSON.stringify(this.kingPos[color]))]
 468         : [];
 469       this.turn = color;
 470       return res;
 471     }
 472     if (this.sideCheckered == color) return [];
 473     let res = [];
 474     for (let c of ['w', 'b']) {
 475       if (this.isAttacked(this.kingPos[c], ['c']))
 476         res.push(JSON.parse(JSON.stringify(this.kingPos[c])));
 477     }
 478     return res;
 479   }
 480
 481   play(move) {
 482     move.flags = JSON.stringify(this.aggregateFlags());
 483     this.epSquares.push(this.getEpSquare(move));
 484     V.PlayOnBoard(this.board, move);
 485     if (move.appear.length > 0 || move.vanish.length > 0)
 486     {
 487       this.turn = V.GetOppCol(this.turn);
 488       this.movesCount++;
 489     }
 490     this.postPlay(move);
 491   }
 492
 493   postPlay(move) {
 494     if (move.appear.length == 0 && move.vanish.length == 0) {
 495       this.stage = 2;
 496       this.sideCheckered = this.turn;
 497     }
 498     else {
 499       const c = move.vanish[0].c;
 500       const piece = move.vanish[0].p;
 501       if (piece == V.KING) {
 502         this.kingPos[c][0] = move.appear[0].x;
 503         this.kingPos[c][1] = move.appear[0].y;
 504       }
 505       super.updateCastleFlags(move, piece);
 506       // Does this move turn off a 2-squares pawn flag?
 507       if ([1, 6].includes(move.start.x) && move.vanish[0].p == V.PAWN)
 508         this.pawnFlags[move.start.x == 6 ? "w" : "b"][move.start.y] = false;
 509     }
 510     this.cmoves.push(this.getCmove(move));
 511   }
 512
 513   undo(move) {
 514     this.epSquares.pop();
 515     this.disaggregateFlags(JSON.parse(move.flags));
 516     V.UndoOnBoard(this.board, move);
 517     if (move.appear.length > 0 || move.vanish.length > 0)
 518     {
 519       this.turn = V.GetOppCol(this.turn);
 520       this.movesCount--;
 521     }
 522     this.postUndo(move);
 523   }
 524
 525   postUndo(move) {
 526     if (move.appear.length == 0 && move.vanish.length == 0) this.stage = 1;
 527     else super.postUndo(move);
 528     this.cmoves.pop();
 529   }
 530
 531   getCurrentScore() {
 532     const color = this.turn;
 533     if (this.stage == 1) {
 534       if (this.atLeastOneMove()) return "*";
 535       // Artifically change turn, for checkered pawns
 536       this.turn = V.GetOppCol(this.turn);
 537       const res =
 538         this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"])
 539           ? color == "w"
 540             ? "0-1"
 541             : "1-0"
 542           : "1/2";
 543       this.turn = V.GetOppCol(this.turn);
 544       return res;
 545     }
 546     // Stage == 2:
 547     if (this.sideCheckered == this.turn) {
 548       // Check if remaining checkered pieces: if none, I lost
 549       if (this.board.some(b => b.some(cell => cell[0] == 'c'))) {
 550         if (!this.atLeastOneMove()) return "1/2";
 551         return "*";
 552       }
 553       return color == 'w' ? "0-1" : "1-0";
 554     }
 555     if (this.atLeastOneMove()) return "*";
 556     let res = this.isAttacked(this.kingPos['w'], ["c"]);
 557     if (!res) res = this.isAttacked(this.kingPos['b'], ["c"]);
 558     if (res) return color == 'w' ? "0-1" : "1-0";
 559     return "1/2";
 560   }
 561
 562   evalPosition() {
 563     let evaluation = 0;
 564     // Just count material for now, considering checkered neutral at stage 1.
 565     const baseSign = (this.turn == 'w' ? 1 : -1);
 566     for (let i = 0; i < V.size.x; i++) {
 567       for (let j = 0; j < V.size.y; j++) {
 568         if (this.board[i][j] != V.EMPTY) {
 569           const sqColor = this.getColor(i, j);
 570           if (this.stage == 1) {
 571             if (["w", "b"].includes(sqColor)) {
 572               const sign = sqColor == "w" ? 1 : -1;
 573               evaluation += sign * V.VALUES[this.getPiece(i, j)];
 574             }
 575           }
 576           else {
 577             const sign =
 578               this.sideCheckered == this.turn
 579                 ? (sqColor == 'c' ? 1 : -1) * baseSign
 580                 : (sqColor == 'c' ? -1 : 1) * baseSign;
 581             evaluation += sign * V.VALUES[this.getPiece(i, j)];
 582           }
 583         }
 584       }
 585     }
 586     return evaluation;
 587   }
 588
 589   static GenRandInitFen(randomness) {
 590     // Add 16 pawns flags + empty cmove + stage == 1:
 591     return ChessRules.GenRandInitFen(randomness)
 592       .slice(0, -2) + "1111111111111111 - - 1";
 593   }
 594
 595   static ParseFen(fen) {
 596     const fenParts = fen.split(" ");
 597     return Object.assign(
 598       ChessRules.ParseFen(fen),
 599       {
 600         cmove: fenParts[5],
 601         stage: fenParts[6]
 602       }
 603     );
 604   }
 605
 606   getCmoveFen() {
 607     const L = this.cmoves.length;
 608     return (
 609       !this.cmoves[L - 1]
 610         ? "-"
 611         : ChessRules.CoordsToSquare(this.cmoves[L - 1].start) +
 612           ChessRules.CoordsToSquare(this.cmoves[L - 1].end)
 613     );
 614   }
 615
 616   getStageFen() {
 617     return (this.stage == 1 ? "1" : "2" + this.sideCheckered);
 618   }
 619
 620   getFen() {
 621     return (
 622       super.getFen() + " " + this.getCmoveFen() + " " + this.getStageFen()
 623     );
 624   }
 625
 626   getFenForRepeat() {
 627     return (
 628       super.getFenForRepeat() + "_" +
 629       this.getCmoveFen() + "_" + this.getStageFen()
 630     );
 631   }
 632
 633   getFlagsFen() {
 634     let fen = super.getFlagsFen();
 635     // Add pawns flags
 636     for (let c of ["w", "b"])
 637       for (let i = 0; i < 8; i++) fen += (this.pawnFlags[c][i] ? "1" : "0");
 638     return fen;
 639   }
 640
 641   static get SEARCH_DEPTH() {
 642     return 2;
 643   }
 644
 645   getComputerMove() {
 646     // To simplify, prevent the bot from switching (TODO...)
 647     return (
 648       super.getComputerMove(
 649         this.getAllValidMoves().filter(m => m.appear.length > 0)
 650       )
 651     );
 652   }
 653
 654   getNotation(move) {
 655     if (move.appear.length == 0 && move.vanish.length == 0) return "S";
 656     if (move.appear.length == 2) {
 657       // Castle
 658       if (move.end.y < move.start.y) return "0-0-0";
 659       return "0-0";
 660     }
 661
 662     const finalSquare = V.CoordsToSquare(move.end);
 663     const piece = this.getPiece(move.start.x, move.start.y);
 664     let notation = "";
 665     if (piece == V.PAWN) {
 666       if (move.vanish.length > 1) {
 667         const startColumn = V.CoordToColumn(move.start.y);
 668         notation = startColumn + "x" + finalSquare;
 669       } else notation = finalSquare;
 670     } else {
 671       // Piece movement
 672       notation =
 673         piece.toUpperCase() +
 674         (move.vanish.length > 1 ? "x" : "") +
 675         finalSquare;
 676     }
 677     if (move.appear[0].p != move.vanish[0].p)
 678       notation += "=" + move.appear[0].p.toUpperCase();
 679     return notation;
 680   }
 681 };