client/src/variants/Eightpieces.js

   1 import { ArrayFun } from "@/utils/array";
   2 import { randInt } from "@/utils/alea";
   3 import { ChessRules, PiPo, Move } from "@/base_rules";
   4
   5 export const VariantRules = class EightpiecesRules extends ChessRules {
   6   static get JAILER() {
   7     return "j";
   8   }
   9   static get SENTRY() {
  10     return "s";
  11   }
  12   static get LANCER() {
  13     return "l";
  14   }
  15
  16   static get IMAGE_EXTENSION() {
  17     // Temporarily, for the time SVG pieces are being designed:
  18     return ".png";
  19   }
  20
  21   // Lancer directions *from white perspective*
  22   static get LANCER_DIRS() {
  23     return {
  24       'c': [-1, 0], //north
  25       'd': [-1, 1], //N-E
  26       'e': [0, 1], //east
  27       'f': [1, 1], //S-E
  28       'g': [1, 0], //south
  29       'h': [1, -1], //S-W
  30       'm': [0, -1], //west
  31       'o': [-1, -1] //N-W
  32     };
  33   }
  34
  35   static get PIECES() {
  36     return ChessRules.PIECES
  37       .concat([V.JAILER, V.SENTRY])
  38       .concat(Object.keys(V.LANCER_DIRS));
  39   }
  40
  41   getPiece(i, j) {
  42     const piece = this.board[i][j].charAt(1);
  43     // Special lancer case: 8 possible orientations
  44     if (Object.keys(V.LANCER_DIRS).includes(piece)) return V.LANCER;
  45     return piece;
  46   }
  47
  48   getPpath(b, color, score, orientation) {
  49     if ([V.JAILER, V.SENTRY].includes(b[1])) return "Eightpieces/tmp_png/" + b;
  50     if (Object.keys(V.LANCER_DIRS).includes(b[1])) {
  51       if (orientation == 'w') return "Eightpieces/tmp_png/" + b;
  52       // Find opposite direction for adequate display:
  53       let oppDir = '';
  54       switch (b[1]) {
  55         case 'c':
  56           oppDir = 'g';
  57           break;
  58         case 'g':
  59           oppDir = 'c';
  60           break;
  61         case 'd':
  62           oppDir = 'h';
  63           break;
  64         case 'h':
  65           oppDir = 'd';
  66           break;
  67         case 'e':
  68           oppDir = 'm';
  69           break;
  70         case 'm':
  71           oppDir = 'e';
  72           break;
  73         case 'f':
  74           oppDir = 'o';
  75           break;
  76         case 'o':
  77           oppDir = 'f';
  78           break;
  79       }
  80       return "Eightpieces/tmp_png/" + b[0] + oppDir;
  81     }
  82     // TODO: after we have SVG pieces, remove the folder and next prefix:
  83     return "Eightpieces/tmp_png/" + b;
  84   }
  85
  86   getPPpath(b, orientation) {
  87     return this.getPpath(b, null, null, orientation);
  88   }
  89
  90   static ParseFen(fen) {
  91     const fenParts = fen.split(" ");
  92     return Object.assign(
  93       ChessRules.ParseFen(fen),
  94       { sentrypush: fenParts[5] }
  95     );
  96   }
  97
  98   static IsGoodFen(fen) {
  99     if (!ChessRules.IsGoodFen(fen)) return false;
 100     const fenParsed = V.ParseFen(fen);
 101     // 5) Check sentry push (if any)
 102     if (
 103       fenParsed.sentrypush != "-" &&
 104       !fenParsed.sentrypush.match(/^([a-h][1-8],?)+$/)
 105     ) {
 106       return false;
 107     }
 108     return true;
 109   }
 110
 111   getFen() {
 112     return super.getFen() + " " + this.getSentrypushFen();
 113   }
 114
 115   getFenForRepeat() {
 116     return super.getFenForRepeat() + "_" + this.getSentrypushFen();
 117   }
 118
 119   getSentrypushFen() {
 120     const L = this.sentryPush.length;
 121     if (!this.sentryPush[L-1]) return "-";
 122     let res = "";
 123     this.sentryPush[L-1].forEach(coords =>
 124       res += V.CoordsToSquare(coords) + ",");
 125     return res.slice(0, -1);
 126   }
 127
 128   setOtherVariables(fen) {
 129     super.setOtherVariables(fen);
 130     // subTurn == 2 only when a sentry moved, and is about to push something
 131     this.subTurn = 1;
 132     // Sentry position just after a "capture" (subTurn from 1 to 2)
 133     this.sentryPos = null;
 134     // Stack pieces' forbidden squares after a sentry move at each turn
 135     const parsedFen = V.ParseFen(fen);
 136     if (parsedFen.sentrypush == "-") this.sentryPush = [null];
 137     else {
 138       this.sentryPush = [
 139         parsedFen.sentrypush.split(",").map(sq => {
 140           return V.SquareToCoords(sq);
 141         })
 142       ];
 143     }
 144   }
 145
 146   static GenRandInitFen(randomness) {
 147     if (randomness == 0)
 148       // Deterministic:
 149       return "jsfqkbnr/pppppppp/8/8/8/8/PPPPPPPP/JSDQKBNR w 0 ahah - -";
 150
 151     let pieces = { w: new Array(8), b: new Array(8) };
 152     let flags = "";
 153     // Shuffle pieces on first (and last rank if randomness == 2)
 154     for (let c of ["w", "b"]) {
 155       if (c == 'b' && randomness == 1) {
 156         const lancerIdx = pieces['w'].findIndex(p => {
 157           return Object.keys(V.LANCER_DIRS).includes(p);
 158         });
 159         pieces['b'] =
 160           pieces['w'].slice(0, lancerIdx)
 161           .concat(['g'])
 162           .concat(pieces['w'].slice(lancerIdx + 1));
 163         flags += flags;
 164         break;
 165       }
 166
 167       let positions = ArrayFun.range(8);
 168
 169       // Get random squares for bishop and sentry
 170       let randIndex = 2 * randInt(4);
 171       let bishopPos = positions[randIndex];
 172       // The sentry must be on a square of different color
 173       let randIndex_tmp = 2 * randInt(4) + 1;
 174       let sentryPos = positions[randIndex_tmp];
 175       if (c == 'b') {
 176         // Check if white sentry is on the same color as ours.
 177         // If yes: swap bishop and sentry positions.
 178         if ((pieces['w'].indexOf('s') - sentryPos) % 2 == 0)
 179           [bishopPos, sentryPos] = [sentryPos, bishopPos];
 180       }
 181       positions.splice(Math.max(randIndex, randIndex_tmp), 1);
 182       positions.splice(Math.min(randIndex, randIndex_tmp), 1);
 183
 184       // Get random squares for knight and lancer
 185       randIndex = randInt(6);
 186       const knightPos = positions[randIndex];
 187       positions.splice(randIndex, 1);
 188       randIndex = randInt(5);
 189       const lancerPos = positions[randIndex];
 190       positions.splice(randIndex, 1);
 191
 192       // Get random square for queen
 193       randIndex = randInt(4);
 194       const queenPos = positions[randIndex];
 195       positions.splice(randIndex, 1);
 196
 197       // Rook, jailer and king positions are now almost fixed,
 198       // only the ordering rook-> jailer or jailer->rook must be decided.
 199       let rookPos = positions[0];
 200       let jailerPos = positions[2];
 201       const kingPos = positions[1];
 202       flags += V.CoordToColumn(rookPos) + V.CoordToColumn(jailerPos);
 203       if (Math.random() < 0.5) [rookPos, jailerPos] = [jailerPos, rookPos];
 204
 205       pieces[c][rookPos] = "r";
 206       pieces[c][knightPos] = "n";
 207       pieces[c][bishopPos] = "b";
 208       pieces[c][queenPos] = "q";
 209       pieces[c][kingPos] = "k";
 210       pieces[c][sentryPos] = "s";
 211       // Lancer faces north for white, and south for black:
 212       pieces[c][lancerPos] = c == 'w' ? 'c' : 'g';
 213       pieces[c][jailerPos] = "j";
 214     }
 215     return (
 216       pieces["b"].join("") +
 217       "/pppppppp/8/8/8/8/PPPPPPPP/" +
 218       pieces["w"].join("").toUpperCase() +
 219       " w 0 " + flags + " - -"
 220     );
 221   }
 222
 223   canTake([x1, y1], [x2, y2]) {
 224     if (this.subTurn == 2)
 225       // Only self captures on this subturn:
 226       return this.getColor(x1, y1) == this.getColor(x2, y2);
 227     return super.canTake([x1, y1], [x2, y2]);
 228   }
 229
 230   // Is piece on square (x,y) immobilized?
 231   isImmobilized([x, y]) {
 232     const color = this.getColor(x, y);
 233     const oppCol = V.GetOppCol(color);
 234     for (let step of V.steps[V.ROOK]) {
 235       const [i, j] = [x + step[0], y + step[1]];
 236       if (
 237         V.OnBoard(i, j) &&
 238         this.board[i][j] != V.EMPTY &&
 239         this.getColor(i, j) == oppCol
 240       ) {
 241         if (this.getPiece(i, j) == V.JAILER) return [i, j];
 242       }
 243     }
 244     return null;
 245   }
 246
 247   // Because of the lancers, getPiece() could be wrong:
 248   // use board[x][y][1] instead (always valid).
 249   getBasicMove([sx, sy], [ex, ey], tr) {
 250     let mv = new Move({
 251       appear: [
 252         new PiPo({
 253           x: ex,
 254           y: ey,
 255           c: tr ? tr.c : this.getColor(sx, sy),
 256           p: tr ? tr.p : this.board[sx][sy].charAt(1)
 257         })
 258       ],
 259       vanish: [
 260         new PiPo({
 261           x: sx,
 262           y: sy,
 263           c: this.getColor(sx, sy),
 264           p: this.board[sx][sy].charAt(1)
 265         })
 266       ]
 267     });
 268
 269     // The opponent piece disappears if we take it
 270     if (this.board[ex][ey] != V.EMPTY) {
 271       mv.vanish.push(
 272         new PiPo({
 273           x: ex,
 274           y: ey,
 275           c: this.getColor(ex, ey),
 276           p: this.board[ex][ey].charAt(1)
 277         })
 278       );
 279     }
 280
 281     return mv;
 282   }
 283
 284   canIplay(side, [x, y]) {
 285     return (
 286       (this.subTurn == 1 && this.turn == side && this.getColor(x, y) == side) ||
 287       (this.subTurn == 2 && x == this.sentryPos.x && y == this.sentryPos.y)
 288     );
 289   }
 290
 291   getPotentialMovesFrom([x, y]) {
 292     // At subTurn == 2, jailers aren't effective (Jeff K)
 293     if (this.subTurn == 1) {
 294       const jsq = this.isImmobilized([x, y]);
 295       if (!!jsq) {
 296         let moves = [];
 297         // Special pass move if king:
 298         if (this.getPiece(x, y) == V.KING) {
 299           moves.push(
 300             new Move({
 301               appear: [],
 302               vanish: [],
 303               start: { x: x, y: y },
 304               end: { x: jsq[0], y: jsq[1] }
 305             })
 306           );
 307         }
 308         return moves;
 309       }
 310     }
 311     let moves = [];
 312     switch (this.getPiece(x, y)) {
 313       case V.JAILER:
 314         moves = this.getPotentialJailerMoves([x, y]);
 315         break;
 316       case V.SENTRY:
 317         moves = this.getPotentialSentryMoves([x, y]);
 318         break;
 319       case V.LANCER:
 320         moves = this.getPotentialLancerMoves([x, y]);
 321         break;
 322       default:
 323         moves = super.getPotentialMovesFrom([x, y]);
 324         break;
 325     }
 326     const L = this.sentryPush.length;
 327     if (!!this.sentryPush[L-1]) {
 328       // Delete moves walking back on sentry push path
 329       moves = moves.filter(m => {
 330         if (
 331           m.vanish[0].p != V.PAWN &&
 332           this.sentryPush[L-1].some(sq => sq.x == m.end.x && sq.y == m.end.y)
 333         ) {
 334           return false;
 335         }
 336         return true;
 337       });
 338     } else if (this.subTurn == 2) {
 339       // Put back the sentinel on board:
 340       const color = this.turn;
 341       moves.forEach(m => {
 342         m.appear.push({x: x, y: y, p: V.SENTRY, c: color});
 343       });
 344     }
 345     return moves;
 346   }
 347
 348   getPotentialPawnMoves([x, y]) {
 349     const color = this.getColor(x, y);
 350     let moves = [];
 351     const [sizeX, sizeY] = [V.size.x, V.size.y];
 352     let shiftX = (color == "w" ? -1 : 1);
 353     if (this.subTurn == 2) shiftX *= -1;
 354     const firstRank = color == "w" ? sizeX - 1 : 0;
 355     const startRank = color == "w" ? sizeX - 2 : 1;
 356     const lastRank = color == "w" ? 0 : sizeX - 1;
 357
 358     // Pawns might be pushed on 1st rank and attempt to move again:
 359     if (!V.OnBoard(x + shiftX, y)) return [];
 360
 361     const finalPieces =
 362       // A push cannot put a pawn on last rank (it goes backward)
 363       x + shiftX == lastRank
 364         ? Object.keys(V.LANCER_DIRS).concat(
 365           [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN, V.SENTRY, V.JAILER])
 366         : [V.PAWN];
 367     if (this.board[x + shiftX][y] == V.EMPTY) {
 368       // One square forward
 369       for (let piece of finalPieces) {
 370         moves.push(
 371           this.getBasicMove([x, y], [x + shiftX, y], {
 372             c: color,
 373             p: piece
 374           })
 375         );
 376       }
 377       if (
 378         // 2-squares jumps forbidden if pawn push
 379         this.subTurn == 1 &&
 380         [startRank, firstRank].includes(x) &&
 381         this.board[x + 2 * shiftX][y] == V.EMPTY
 382       ) {
 383         // Two squares jump
 384         moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
 385       }
 386     }
 387     // Captures
 388     for (let shiftY of [-1, 1]) {
 389       if (
 390         y + shiftY >= 0 &&
 391         y + shiftY < sizeY &&
 392         this.board[x + shiftX][y + shiftY] != V.EMPTY &&
 393         this.canTake([x, y], [x + shiftX, y + shiftY])
 394       ) {
 395         for (let piece of finalPieces) {
 396           moves.push(
 397             this.getBasicMove([x, y], [x + shiftX, y + shiftY], {
 398               c: color,
 399               p: piece
 400             })
 401           );
 402         }
 403       }
 404     }
 405
 406     // En passant: only on subTurn == 1
 407     const Lep = this.epSquares.length;
 408     const epSquare = this.epSquares[Lep - 1];
 409     if (
 410       this.subTurn == 1 &&
 411       !!epSquare &&
 412       epSquare.x == x + shiftX &&
 413       Math.abs(epSquare.y - y) == 1
 414     ) {
 415       let enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
 416       enpassantMove.vanish.push({
 417         x: x,
 418         y: epSquare.y,
 419         p: "p",
 420         c: this.getColor(x, epSquare.y)
 421       });
 422       moves.push(enpassantMove);
 423     }
 424
 425     return moves;
 426   }
 427
 428   // Obtain all lancer moves in "step" direction
 429   getPotentialLancerMoves_aux([x, y], step, tr) {
 430     let moves = [];
 431     // Add all moves to vacant squares until opponent is met:
 432     const color = this.getColor(x, y);
 433     const oppCol =
 434       this.subTurn == 1
 435         ? V.GetOppCol(color)
 436         // at subTurn == 2, consider own pieces as opponent
 437         : color;
 438     let sq = [x + step[0], y + step[1]];
 439     while (V.OnBoard(sq[0], sq[1]) && this.getColor(sq[0], sq[1]) != oppCol) {
 440       if (this.board[sq[0]][sq[1]] == V.EMPTY)
 441         moves.push(this.getBasicMove([x, y], sq, tr));
 442       sq[0] += step[0];
 443       sq[1] += step[1];
 444     }
 445     if (V.OnBoard(sq[0], sq[1]))
 446       // Add capturing move
 447       moves.push(this.getBasicMove([x, y], sq, tr));
 448     return moves;
 449   }
 450
 451   getPotentialLancerMoves([x, y]) {
 452     let moves = [];
 453     // Add all lancer possible orientations, similar to pawn promotions.
 454     // Except if just after a push: allow all movements from init square then
 455     const L = this.sentryPush.length;
 456     const color = this.getColor(x, y);
 457     if (!!this.sentryPush[L-1]) {
 458       // Maybe I was pushed
 459       const pl = this.sentryPush[L-1].length;
 460       if (
 461         this.sentryPush[L-1][pl-1].x == x &&
 462         this.sentryPush[L-1][pl-1].y == y
 463       ) {
 464         // I was pushed: allow all directions (for this move only), but
 465         // do not change direction after moving, *except* if I keep the
 466         // same orientation in which I was pushed.
 467         const curDir = V.LANCER_DIRS[this.board[x][y].charAt(1)];
 468         Object.values(V.LANCER_DIRS).forEach(step => {
 469           const dirCode = Object.keys(V.LANCER_DIRS).find(k => {
 470             return (
 471               V.LANCER_DIRS[k][0] == step[0] &&
 472               V.LANCER_DIRS[k][1] == step[1]
 473             );
 474           });
 475           const dirMoves =
 476             this.getPotentialLancerMoves_aux(
 477               [x, y],
 478               step,
 479               { p: dirCode, c: color }
 480             );
 481           if (curDir[0] == step[0] && curDir[1] == step[1]) {
 482             // Keeping same orientation: can choose after
 483             let chooseMoves = [];
 484             dirMoves.forEach(m => {
 485               Object.keys(V.LANCER_DIRS).forEach(k => {
 486                 let mk = JSON.parse(JSON.stringify(m));
 487                 mk.appear[0].p = k;
 488                 moves.push(mk);
 489               });
 490             });
 491             Array.prototype.push.apply(moves, chooseMoves);
 492           } else Array.prototype.push.apply(moves, dirMoves);
 493         });
 494         return moves;
 495       }
 496     }
 497     // I wasn't pushed: standard lancer move
 498     const dirCode = this.board[x][y][1];
 499     const monodirMoves =
 500       this.getPotentialLancerMoves_aux([x, y], V.LANCER_DIRS[dirCode]);
 501     // Add all possible orientations aftermove except if I'm being pushed
 502     if (this.subTurn == 1) {
 503       monodirMoves.forEach(m => {
 504         Object.keys(V.LANCER_DIRS).forEach(k => {
 505           let mk = JSON.parse(JSON.stringify(m));
 506           mk.appear[0].p = k;
 507           moves.push(mk);
 508         });
 509       });
 510       return moves;
 511     } else {
 512       // I'm pushed: add potential nudges
 513       let potentialNudges = [];
 514       for (let step of V.steps[V.ROOK].concat(V.steps[V.BISHOP])) {
 515         if (
 516           V.OnBoard(x + step[0], y + step[1]) &&
 517           this.board[x + step[0]][y + step[1]] == V.EMPTY
 518         ) {
 519           const newDirCode = Object.keys(V.LANCER_DIRS).find(k => {
 520             const codeStep = V.LANCER_DIRS[k];
 521             return (codeStep[0] == step[0] && codeStep[1] == step[1]);
 522           });
 523           potentialNudges.push(
 524             this.getBasicMove(
 525               [x, y],
 526               [x + step[0], y + step[1]],
 527               { c: color, p: newDirCode }
 528             )
 529           );
 530         }
 531       }
 532       return monodirMoves.concat(potentialNudges);
 533     }
 534   }
 535
 536   getPotentialSentryMoves([x, y]) {
 537     // The sentry moves a priori like a bishop:
 538     let moves = super.getPotentialBishopMoves([x, y]);
 539     // ...but captures are replaced by special move, if and only if
 540     // "captured" piece can move now, considered as the capturer unit.
 541     // --> except is subTurn == 2, in this case I don't push anything.
 542     if (this.subTurn == 2) return moves.filter(m => m.vanish.length == 1);
 543     moves.forEach(m => {
 544       if (m.vanish.length == 2) {
 545         // Temporarily cancel the sentry capture:
 546         m.appear.pop();
 547         m.vanish.pop();
 548       }
 549     });
 550     const color = this.getColor(x, y);
 551     const fMoves = moves.filter(m => {
 552       // Can the pushed unit make any move? ...resulting in a non-self-check?
 553       if (m.appear.length == 0) {
 554         let res = false;
 555         this.play(m);
 556         let moves2 = this.getPotentialMovesFrom([m.end.x, m.end.y]);
 557         for (let m2 of moves2) {
 558           this.play(m2);
 559           res = !this.underCheck(color);
 560           this.undo(m2);
 561           if (res) break;
 562         }
 563         this.undo(m);
 564         return res;
 565       }
 566       return true;
 567     });
 568     return fMoves;
 569   }
 570
 571   getPotentialJailerMoves([x, y]) {
 572     return super.getPotentialRookMoves([x, y]).filter(m => {
 573       // Remove jailer captures
 574       return m.vanish[0].p != V.JAILER || m.vanish.length == 1;
 575     });
 576   }
 577
 578   getPotentialKingMoves(sq) {
 579     const moves = this.getSlideNJumpMoves(
 580       sq,
 581       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
 582       "oneStep"
 583     );
 584     return (
 585       this.subTurn == 1
 586         ? moves.concat(this.getCastleMoves(sq))
 587         : moves
 588     );
 589   }
 590
 591   // Adapted: castle with jailer possible
 592   getCastleMoves([x, y]) {
 593     const c = this.getColor(x, y);
 594     const firstRank = (c == "w" ? V.size.x - 1 : 0);
 595     if (x != firstRank || y != this.INIT_COL_KING[c])
 596       return [];
 597
 598     const oppCol = V.GetOppCol(c);
 599     let moves = [];
 600     let i = 0;
 601     // King, then rook or jailer:
 602     const finalSquares = [
 603       [2, 3],
 604       [V.size.y - 2, V.size.y - 3]
 605     ];
 606     castlingCheck: for (
 607       let castleSide = 0;
 608       castleSide < 2;
 609       castleSide++
 610     ) {
 611       if (this.castleFlags[c][castleSide] >= 8) continue;
 612       // Rook (or jailer) and king are on initial position
 613       const finDist = finalSquares[castleSide][0] - y;
 614       let step = finDist / Math.max(1, Math.abs(finDist));
 615       i = y;
 616       do {
 617         if (
 618           this.isAttacked([x, i], [oppCol]) ||
 619           (this.board[x][i] != V.EMPTY &&
 620             (this.getColor(x, i) != c ||
 621               ![V.KING, V.ROOK, V.JAILER].includes(this.getPiece(x, i))))
 622         ) {
 623           continue castlingCheck;
 624         }
 625         i += step;
 626       } while (i != finalSquares[castleSide][0]);
 627       step = castleSide == 0 ? -1 : 1;
 628       const rookOrJailerPos = this.castleFlags[c][castleSide];
 629       for (i = y + step; i != rookOrJailerPos; i += step)
 630         if (this.board[x][i] != V.EMPTY) continue castlingCheck;
 631
 632       // Nothing on final squares, except maybe king and castling rook or jailer?
 633       for (i = 0; i < 2; i++) {
 634         if (
 635           this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
 636           this.getPiece(x, finalSquares[castleSide][i]) != V.KING &&
 637           finalSquares[castleSide][i] != rookOrJailerPos
 638         ) {
 639           continue castlingCheck;
 640         }
 641       }
 642
 643       // If this code is reached, castle is valid
 644       const castlingPiece = this.getPiece(firstRank, rookOrJailerPos);
 645       moves.push(
 646         new Move({
 647           appear: [
 648             new PiPo({ x: x, y: finalSquares[castleSide][0], p: V.KING, c: c }),
 649             new PiPo({ x: x, y: finalSquares[castleSide][1], p: castlingPiece, c: c })
 650           ],
 651           vanish: [
 652             new PiPo({ x: x, y: y, p: V.KING, c: c }),
 653             new PiPo({ x: x, y: rookOrJailerPos, p: castlingPiece, c: c })
 654           ],
 655           end:
 656             Math.abs(y - rookOrJailerPos) <= 2
 657               ? { x: x, y: rookOrJailerPos }
 658               : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) }
 659         })
 660       );
 661     }
 662
 663     return moves;
 664   }
 665
 666   atLeastOneMove() {
 667     // If in second-half of a move, we already know that a move is possible
 668     if (this.subTurn == 2) return true;
 669     return super.atLeastOneMove();
 670   }
 671
 672   filterValid(moves) {
 673     if (moves.length == 0) return [];
 674     const basicFilter = (m, c) => {
 675       this.play(m);
 676       const res = !this.underCheck(c);
 677       this.undo(m);
 678       return res;
 679     };
 680     // Disable check tests for sentry pushes,
 681     // because in this case the move isn't finished
 682     let movesWithoutSentryPushes = [];
 683     let movesWithSentryPushes = [];
 684     moves.forEach(m => {
 685       // Second condition below for special king "pass" moves
 686       if (m.appear.length > 0 || m.vanish.length == 0)
 687         movesWithoutSentryPushes.push(m);
 688       else movesWithSentryPushes.push(m);
 689     });
 690     const color = this.turn;
 691     const oppCol = V.GetOppCol(color);
 692     const filteredMoves =
 693       movesWithoutSentryPushes.filter(m => basicFilter(m, color));
 694     // If at least one full move made, everything is allowed.
 695     // Else: forbid checks and captures.
 696     return (
 697       this.movesCount >= 2
 698         ? filteredMoves
 699         : filteredMoves.filter(m => {
 700           return (m.vanish.length <= 1 && basicFilter(m, oppCol));
 701         })
 702     ).concat(movesWithSentryPushes);
 703   }
 704
 705   getAllValidMoves() {
 706     if (this.subTurn == 1) return super.getAllValidMoves();
 707     // Sentry push:
 708     const sentrySq = [this.sentryPos.x, this.sentryPos.y];
 709     return this.filterValid(this.getPotentialMovesFrom(sentrySq));
 710   }
 711
 712   prePlay(move) {
 713     if (move.appear.length == 0 && move.vanish.length == 1)
 714       // The sentry is about to push a piece: subTurn goes from 1 to 2
 715       this.sentryPos = { x: move.end.x, y: move.end.y };
 716     if (this.subTurn == 2 && move.vanish[0].p != V.PAWN) {
 717       // A piece is pushed: forbid array of squares between start and end
 718       // of move, included (except if it's a pawn)
 719       let squares = [];
 720       if ([V.KNIGHT,V.KING].includes(move.vanish[0].p))
 721         // short-range pieces: just forbid initial square
 722         squares.push({ x: move.start.x, y: move.start.y });
 723       else {
 724         const deltaX = move.end.x - move.start.x;
 725         const deltaY = move.end.y - move.start.y;
 726         const step = [
 727           deltaX / Math.abs(deltaX) || 0,
 728           deltaY / Math.abs(deltaY) || 0
 729         ];
 730         for (
 731           let sq = {x: move.start.x, y: move.start.y};
 732           sq.x != move.end.x || sq.y != move.end.y;
 733           sq.x += step[0], sq.y += step[1]
 734         ) {
 735           squares.push({ x: sq.x, y: sq.y });
 736         }
 737       }
 738       // Add end square as well, to know if I was pushed (useful for lancers)
 739       squares.push({ x: move.end.x, y: move.end.y });
 740       this.sentryPush.push(squares);
 741     } else this.sentryPush.push(null);
 742   }
 743
 744   play(move) {
 745 //    if (!this.states) this.states = [];
 746 //    const stateFen = this.getFen();
 747 //    this.states.push(stateFen);
 748
 749     this.prePlay(move);
 750     move.flags = JSON.stringify(this.aggregateFlags());
 751     this.epSquares.push(this.getEpSquare(move));
 752     V.PlayOnBoard(this.board, move);
 753     // Is it a sentry push? (useful for undo)
 754     move.sentryPush = (this.subTurn == 2);
 755     if (this.subTurn == 1) this.movesCount++;
 756     if (move.appear.length == 0 && move.vanish.length == 1) this.subTurn = 2;
 757     else {
 758       // Turn changes only if not a sentry "pre-push"
 759       this.turn = V.GetOppCol(this.turn);
 760       this.subTurn = 1;
 761     }
 762     this.postPlay(move);
 763   }
 764
 765   postPlay(move) {
 766     if (move.vanish.length == 0 || this.subTurn == 2)
 767       // Special pass move of the king, or sentry pre-push: nothing to update
 768       return;
 769     const c = move.vanish[0].c;
 770     const piece = move.vanish[0].p;
 771     const firstRank = c == "w" ? V.size.x - 1 : 0;
 772
 773     if (piece == V.KING) {
 774       this.kingPos[c][0] = move.appear[0].x;
 775       this.kingPos[c][1] = move.appear[0].y;
 776       this.castleFlags[c] = [V.size.y, V.size.y];
 777       return;
 778     }
 779     // Update castling flags if rooks are moved
 780     const oppCol = V.GetOppCol(c);
 781     const oppFirstRank = V.size.x - 1 - firstRank;
 782     if (
 783       move.start.x == firstRank && //our rook moves?
 784       this.castleFlags[c].includes(move.start.y)
 785     ) {
 786       const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
 787       this.castleFlags[c][flagIdx] = V.size.y;
 788     } else if (
 789       move.end.x == oppFirstRank && //we took opponent rook?
 790       this.castleFlags[oppCol].includes(move.end.y)
 791     ) {
 792       const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
 793       this.castleFlags[oppCol][flagIdx] = V.size.y;
 794     }
 795   }
 796
 797   undo(move) {
 798     this.epSquares.pop();
 799     this.disaggregateFlags(JSON.parse(move.flags));
 800     V.UndoOnBoard(this.board, move);
 801     // Decrement movesCount except if the move is a sentry push
 802     if (!move.sentryPush) this.movesCount--;
 803     if (this.subTurn == 2) this.subTurn = 1;
 804     else {
 805       this.turn = V.GetOppCol(this.turn);
 806       if (move.sentryPush) this.subTurn = 2;
 807     }
 808     this.postUndo(move);
 809
 810 //    const stateFen = this.getFen();
 811 //    if (stateFen != this.states[this.states.length-1]) debugger;
 812 //    this.states.pop();
 813   }
 814
 815   postUndo(move) {
 816     super.postUndo(move);
 817     this.sentryPush.pop();
 818   }
 819
 820   isAttacked(sq, colors) {
 821     return (
 822       super.isAttacked(sq, colors) ||
 823       this.isAttackedByLancer(sq, colors) ||
 824       this.isAttackedBySentry(sq, colors)
 825     );
 826   }
 827
 828   isAttackedBySlideNJump([x, y], colors, piece, steps, oneStep) {
 829     for (let step of steps) {
 830       let rx = x + step[0],
 831           ry = y + step[1];
 832       while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
 833         rx += step[0];
 834         ry += step[1];
 835       }
 836       if (
 837         V.OnBoard(rx, ry) &&
 838         this.getPiece(rx, ry) === piece &&
 839         colors.includes(this.getColor(rx, ry)) &&
 840         !this.isImmobilized([rx, ry])
 841       ) {
 842         return true;
 843       }
 844     }
 845     return false;
 846   }
 847
 848   isAttackedByPawn([x, y], colors) {
 849     for (let c of colors) {
 850       const pawnShift = c == "w" ? 1 : -1;
 851       if (x + pawnShift >= 0 && x + pawnShift < V.size.x) {
 852         for (let i of [-1, 1]) {
 853           if (
 854             y + i >= 0 &&
 855             y + i < V.size.y &&
 856             this.getPiece(x + pawnShift, y + i) == V.PAWN &&
 857             this.getColor(x + pawnShift, y + i) == c &&
 858             !this.isImmobilized([x + pawnShift, y + i])
 859           ) {
 860             return true;
 861           }
 862         }
 863       }
 864     }
 865     return false;
 866   }
 867
 868   isAttackedByLancer([x, y], colors) {
 869     for (let step of V.steps[V.ROOK].concat(V.steps[V.BISHOP])) {
 870       // If in this direction there are only enemy pieces and empty squares,
 871       // and we meet a lancer: can he reach us?
 872       // NOTE: do not stop at first lancer, there might be several!
 873       let coord = { x: x + step[0], y: y + step[1] };
 874       let lancerPos = [];
 875       while (
 876         V.OnBoard(coord.x, coord.y) &&
 877         (
 878           this.board[coord.x][coord.y] == V.EMPTY ||
 879           colors.includes(this.getColor(coord.x, coord.y))
 880         )
 881       ) {
 882         if (
 883           this.getPiece(coord.x, coord.y) == V.LANCER &&
 884           !this.isImmobilized([coord.x, coord.y])
 885         ) {
 886           lancerPos.push({x: coord.x, y: coord.y});
 887         }
 888         coord.x += step[0];
 889         coord.y += step[1];
 890       }
 891       for (let xy of lancerPos) {
 892         const dir = V.LANCER_DIRS[this.board[xy.x][xy.y].charAt(1)];
 893         if (dir[0] == -step[0] && dir[1] == -step[1]) return true;
 894       }
 895     }
 896     return false;
 897   }
 898
 899   // Helper to check sentries attacks:
 900   selfAttack([x1, y1], [x2, y2]) {
 901     const color = this.getColor(x1, y1);
 902     const sliderAttack = (allowedSteps, lancer) => {
 903       const deltaX = x2 - x1,
 904             absDeltaX = Math.abs(deltaX);
 905       const deltaY = y2 - y1,
 906             absDeltaY = Math.abs(deltaY);
 907       const step = [ deltaX / absDeltaX, deltaY / absDeltaY ];
 908       if (
 909         // Check that the step is a priori valid:
 910         (absDeltaX != absDeltaY && deltaX != 0 && deltaY != 0) ||
 911         allowedSteps.every(st => st[0] != step[0] || st[1] != step[1])
 912       ) {
 913         return false;
 914       }
 915       let sq = [ x1 + step[0], y1 + step[1] ];
 916       while (sq[0] != x2 && sq[1] != y2) {
 917         if (
 918           // NOTE: no need to check OnBoard in this special case
 919           (!lancer && this.board[sq[0]][sq[1]] != V.EMPTY) ||
 920           (!!lancer && this.getColor(sq[0], sq[1]) != color)
 921         ) {
 922           return false;
 923         }
 924         sq[0] += step[0];
 925         sq[1] += step[1];
 926       }
 927       return true;
 928     };
 929     switch (this.getPiece(x1, y1)) {
 930       case V.PAWN: {
 931         // Pushed pawns move as enemy pawns
 932         const shift = (color == 'w' ? 1 : -1);
 933         return (x1 + shift == x2 && Math.abs(y1 - y2) == 1);
 934       }
 935       case V.KNIGHT: {
 936         const deltaX = Math.abs(x1 - x2);
 937         const deltaY = Math.abs(y1 - y2);
 938         return (
 939           deltaX + deltaY == 3 &&
 940           [1, 2].includes(deltaX) &&
 941           [1, 2].includes(deltaY)
 942         );
 943       }
 944       case V.ROOK:
 945         return sliderAttack(V.steps[V.ROOK]);
 946       case V.BISHOP:
 947         return sliderAttack(V.steps[V.BISHOP]);
 948       case V.QUEEN:
 949         return sliderAttack(V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
 950       case V.LANCER: {
 951         // Special case: as long as no enemy units stands in-between, it attacks
 952         // (if it points toward the king).
 953         const allowedStep = V.LANCER_DIRS[this.board[x1][y1].charAt(1)];
 954         return sliderAttack([allowedStep], "lancer");
 955       }
 956       // No sentries or jailer tests: they cannot self-capture
 957     }
 958     return false;
 959   }
 960
 961   isAttackedBySentry([x, y], colors) {
 962     // Attacked by sentry means it can self-take our king.
 963     // Just check diagonals of enemy sentry(ies), and if it reaches
 964     // one of our pieces: can I self-take?
 965     const color = V.GetOppCol(colors[0]);
 966     let candidates = [];
 967     for (let i=0; i<V.size.x; i++) {
 968       for (let j=0; j<V.size.y; j++) {
 969         if (
 970           this.getPiece(i,j) == V.SENTRY &&
 971           colors.includes(this.getColor(i,j)) &&
 972           !this.isImmobilized([i, j])
 973         ) {
 974           for (let step of V.steps[V.BISHOP]) {
 975             let sq = [ i + step[0], j + step[1] ];
 976             while (
 977               V.OnBoard(sq[0], sq[1]) &&
 978               this.board[sq[0]][sq[1]] == V.EMPTY
 979             ) {
 980               sq[0] += step[0];
 981               sq[1] += step[1];
 982             }
 983             if (
 984               V.OnBoard(sq[0], sq[1]) &&
 985               this.getColor(sq[0], sq[1]) == color
 986             ) {
 987               candidates.push([ sq[0], sq[1] ]);
 988             }
 989           }
 990         }
 991       }
 992     }
 993     for (let c of candidates)
 994       if (this.selfAttack(c, [x, y])) return true;
 995     return false;
 996   }
 997
 998   // Jailer doesn't capture or give check
 999
1000   static get VALUES() {
1001     return Object.assign(
1002       { l: 4.8, s: 2.8, j: 3.8 }, //Jeff K. estimations
1003       ChessRules.VALUES
1004     );
1005   }
1006
1007   getComputerMove() {
1008     const maxeval = V.INFINITY;
1009     const color = this.turn;
1010     let moves1 = this.getAllValidMoves();
1011
1012     if (moves1.length == 0)
1013       // TODO: this situation should not happen
1014       return null;
1015
1016     const setEval = (move, next) => {
1017       const score = this.getCurrentScore();
1018       const curEval = move.eval;
1019       if (score != "*") {
1020         move.eval =
1021           score == "1/2"
1022             ? 0
1023             : (score == "1-0" ? 1 : -1) * maxeval;
1024       } else move.eval = this.evalPosition();
1025       if (
1026         // "next" is defined after sentry pushes
1027         !!next && (
1028           !curEval ||
1029           color == 'w' && move.eval > curEval ||
1030           color == 'b' && move.eval < curEval
1031         )
1032       ) {
1033         move.second = next;
1034       }
1035     };
1036
1037     // Just search_depth == 1 (because of sentries. TODO: can do better...)
1038     moves1.forEach(m1 => {
1039       this.play(m1);
1040       if (this.subTurn == 1) setEval(m1);
1041       else {
1042         // Need to play every pushes and count:
1043         const moves2 = this.getAllValidMoves();
1044         moves2.forEach(m2 => {
1045           this.play(m2);
1046           setEval(m1, m2);
1047           this.undo(m2);
1048         });
1049       }
1050       this.undo(m1);
1051     });
1052
1053     moves1.sort((a, b) => {
1054       return (color == "w" ? 1 : -1) * (b.eval - a.eval);
1055     });
1056     let candidates = [0];
1057     for (let j = 1; j < moves1.length && moves1[j].eval == moves1[0].eval; j++)
1058       candidates.push(j);
1059     const choice = moves1[candidates[randInt(candidates.length)]];
1060     return (!choice.second ? choice : [choice, choice.second]);
1061   }
1062
1063   getNotation(move) {
1064     // Special case "king takes jailer" is a pass move
1065     if (move.appear.length == 0 && move.vanish.length == 0) return "pass";
1066     if (this.subTurn == 2) {
1067       // Do not consider appear[1] (sentry) for sentry pushes
1068       const simpleMove = {
1069         appear: [move.appear[0]],
1070         vanish: move.vanish,
1071         start: move.start,
1072         end: move.end
1073       };
1074       return super.getNotation(simpleMove);
1075     }
1076     return super.getNotation(move);
1077   }
1078 };