client/src/variants/Dynamo.js

   1 import { ChessRules, Move, PiPo } from "@/base_rules";
   2 import { randInt } from "@/utils/alea";
   3
   4 export class DynamoRules extends ChessRules {
   5   // TODO: later, allow to push out pawns on a and h files
   6   static get HasEnpassant() {
   7     return false;
   8   }
   9
  10   canIplay(side, [x, y]) {
  11     // Sometimes opponent's pieces can be moved directly
  12     return true;
  13   }
  14
  15   setOtherVariables(fen) {
  16     super.setOtherVariables(fen);
  17     this.subTurn = 1;
  18     // Local stack of "action moves"
  19     this.amoves = [];
  20     const amove = V.ParseFen(fen).amove;
  21     if (amove != "-") {
  22       const amoveParts = amove.split("/");
  23       let move = {
  24         // No need for start & end
  25         appear: [],
  26         vanish: []
  27       };
  28       [0, 1].map(i => {
  29         if (amoveParts[i] != "-") {
  30           amoveParts[i].split(".").forEach(av => {
  31             // Format is "bpe3"
  32             const xy = V.SquareToCoords(av.substr(2));
  33             move[i == 0 ? "appear" : "vanish"].push(
  34               new PiPo({
  35                 x: xy.x,
  36                 y: xy.y,
  37                 c: av[0],
  38                 p: av[1]
  39               })
  40             );
  41           });
  42         }
  43       });
  44       this.amoves.push(move);
  45     }
  46     this.subTurn = 1;
  47     // Stack "first moves" (on subTurn 1) to merge and check opposite moves
  48     this.firstMove = [];
  49   }
  50
  51   static ParseFen(fen) {
  52     return Object.assign(
  53       ChessRules.ParseFen(fen),
  54       { amove: fen.split(" ")[4] }
  55     );
  56   }
  57
  58   static IsGoodFen(fen) {
  59     if (!ChessRules.IsGoodFen(fen)) return false;
  60     const fenParts = fen.split(" ");
  61     if (fenParts.length != 5) return false;
  62     if (fenParts[4] != "-") {
  63       // TODO: a single regexp instead.
  64       // Format is [bpa2[.wpd3]] || '-'/[bbc3[.wrd5]] || '-'
  65       const amoveParts = fenParts[4].split("/");
  66       if (amoveParts.length != 2) return false;
  67       for (let part of amoveParts) {
  68         if (part != "-") {
  69           for (let psq of part.split("."))
  70             if (!psq.match(/^[a-r]{3}[1-8]$/)) return false;
  71         }
  72       }
  73     }
  74     return true;
  75   }
  76
  77   getFen() {
  78     return super.getFen() + " " + this.getAmoveFen();
  79   }
  80
  81   getFenForRepeat() {
  82     return super.getFenForRepeat() + "_" + this.getAmoveFen();
  83   }
  84
  85   getAmoveFen() {
  86     const L = this.amoves.length;
  87     if (L == 0) return "-";
  88     return (
  89       ["appear","vanish"].map(
  90         mpart => {
  91           if (mpart.length == 0) return "-";
  92           return (
  93             this.amoves[L-1][mpart].map(
  94               av => {
  95                 const square = V.CoordsToSquare({ x: av.x, y: av.y });
  96                 return av.c + av.p + square;
  97               }
  98             ).join(".")
  99           );
 100         }
 101       ).join("/")
 102     );
 103   }
 104
 105   canTake() {
 106     // Captures don't occur (only pulls & pushes)
 107     return false;
 108   }
 109
 110   // Step is right, just add (push/pull) moves in this direction
 111   // Direction is assumed normalized.
 112   getMovesInDirection([x, y], [dx, dy], nbSteps) {
 113     nbSteps = nbSteps || 8; //max 8 steps anyway
 114     let [i, j] = [x + dx, y + dy];
 115     let moves = [];
 116     const color = this.getColor(x, y);
 117     const piece = this.getPiece(x, y);
 118     const lastRank = (color == 'w' ? 0 : 7);
 119     let counter = 1;
 120     while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
 121       if (i == lastRank && piece == V.PAWN) {
 122         // Promotion by push or pull
 123         V.PawnSpecs.promotions.forEach(p => {
 124           let move = super.getBasicMove([x, y], [i, j], { c: color, p: p });
 125           moves.push(move);
 126         });
 127       }
 128       else moves.push(super.getBasicMove([x, y], [i, j]));
 129       if (++counter > nbSteps) break;
 130       i += dx;
 131       j += dy;
 132     }
 133     if (!V.OnBoard(i, j) && piece != V.KING) {
 134       // Add special "exit" move, by "taking king"
 135       moves.push(
 136         new Move({
 137           start: { x: x, y: y },
 138           end: { x: this.kingPos[color][0], y: this.kingPos[color][1] },
 139           appear: [],
 140           vanish: [{ x: x, y: y, c: color, p: piece }]
 141         })
 142       );
 143     }
 144     return moves;
 145   }
 146
 147   // Normalize direction to know the step
 148   getNormalizedDirection([dx, dy]) {
 149     const absDir = [Math.abs(dx), Math.abs(dy)];
 150     let divisor = 0;
 151     if (absDir[0] != 0 && absDir[1] != 0 && absDir[0] != absDir[1])
 152       // Knight
 153       divisor = Math.min(absDir[0], absDir[1]);
 154     else
 155       // Standard slider (or maybe a pawn or king: same)
 156       divisor = Math.max(absDir[0], absDir[1]);
 157     return [dx / divisor, dy / divisor];
 158   }
 159
 160   // There was something on x2,y2, maybe our color, pushed/pulled.
 161   // Also, the pushed/pulled piece must exit the board.
 162   isAprioriValidExit([x1, y1], [x2, y2], color2) {
 163     const color1 = this.getColor(x1, y1);
 164     const pawnShift = (color1 == 'w' ? -1 : 1);
 165     const lastRank = (color1 == 'w' ? 0 : 7);
 166     const deltaX = Math.abs(x1 - x2);
 167     const deltaY = Math.abs(y1 - y2);
 168     const checkSlider = () => {
 169       const dir = this.getNormalizedDirection([x2 - x1, y2 - y1]);
 170       let [i, j] = [x1 + dir[0], y1 + dir[1]];
 171       while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
 172         i += dir[0];
 173         j += dir[1];
 174       }
 175       return !V.OnBoard(i, j);
 176     };
 177     switch (this.getPiece(x1, y1)) {
 178       case V.PAWN:
 179         return (
 180           x1 + pawnShift == x2 &&
 181           (
 182             (color1 == color2 && x2 == lastRank && y1 == y2) ||
 183             (color1 != color2 && deltaY == 1 && !V.OnBoard(x2, 2 * y2 - y1))
 184           )
 185         );
 186       case V.ROOK:
 187         if (x1 != x2 && y1 != y2) return false;
 188         return checkSlider();
 189       case V.KNIGHT:
 190         return (
 191           deltaX + deltaY == 3 &&
 192           (deltaX == 1 || deltaY == 1) &&
 193           !V.OnBoard(2 * x2 - x1, 2 * y2 - y1)
 194         );
 195       case V.BISHOP:
 196         if (deltaX != deltaY) return false;
 197         return checkSlider();
 198       case V.QUEEN:
 199         if (deltaX != 0 && deltaY != 0 && deltaX != deltaY) return false;
 200         return checkSlider();
 201       case V.KING:
 202         return (
 203           deltaX <= 1 &&
 204           deltaY <= 1 &&
 205           !V.OnBoard(2 * x2 - x1, 2 * y2 - y1)
 206         );
 207     }
 208     return false;
 209   }
 210
 211   // NOTE: for pushes, play the pushed piece first.
 212   //       for pulls: play the piece doing the action first
 213   // NOTE: to push a piece out of the board, make it slide until its king
 214   getPotentialMovesFrom([x, y]) {
 215     const color = this.turn;
 216     if (this.subTurn == 1) {
 217       const getMoveHash = (m) => {
 218         return V.CoordsToSquare(m.start) + V.CoordsToSquare(m.end);
 219       };
 220       const addMoves = (dir, nbSteps) => {
 221         const newMoves =
 222           this.getMovesInDirection([x, y], [-dir[0], -dir[1]], nbSteps)
 223           .filter(m => !movesHash[getMoveHash(m)]);
 224         newMoves.forEach(m => { movesHash[getMoveHash(m)] = true; });
 225         Array.prototype.push.apply(moves, newMoves);
 226       };
 227       // Free to play any move:
 228       const moves = super.getPotentialMovesFrom([x, y])
 229       const pawnShift = (color == 'w' ? -1 : 1);
 230       const pawnStartRank = (color == 'w' ? 6 : 1);
 231       // Structure to avoid adding moves twice (can be action & move)
 232       let movesHash = {};
 233       moves.forEach(m => { movesHash[getMoveHash(m)] = true; });
 234       // [x, y] is pushed by 'color'
 235       for (let step of V.steps[V.KNIGHT]) {
 236         const [i, j] = [x + step[0], y + step[1]];
 237         if (
 238           V.OnBoard(i, j) &&
 239           this.board[i][j] != V.EMPTY &&
 240           this.getColor(i, j) == color &&
 241           this.getPiece(i, j) == V.KNIGHT
 242         ) {
 243           addMoves(step, 1);
 244         }
 245       }
 246       for (let step of V.steps[V.ROOK].concat(V.steps[V.BISHOP])) {
 247         let [i, j] = [x + step[0], y + step[1]];
 248         while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
 249           i += step[0];
 250           j += step[1];
 251         }
 252         if (
 253           V.OnBoard(i, j) &&
 254           this.board[i][j] != V.EMPTY &&
 255           this.getColor(i, j) == color
 256         ) {
 257           const deltaX = Math.abs(i - x);
 258           const deltaY = Math.abs(j - y);
 259           // Can a priori go both ways, except with pawns
 260           switch (this.getPiece(i, j)) {
 261             case V.PAWN:
 262               if (
 263                 (x - i) / deltaX == pawnShift &&
 264                 deltaX <= 2 &&
 265                 deltaY <= 1
 266               ) {
 267                 const pColor = this.getColor(x, y);
 268                 if (pColor == color && deltaY == 0) {
 269                   // Pushed forward
 270                   const maxSteps = (i == pawnStartRank && deltaX == 1 ? 2 : 1);
 271                   addMoves(step, maxSteps);
 272                 }
 273                 else if (pColor != color && deltaY == 1 && deltaX == 1)
 274                   // Pushed diagonally
 275                   addMoves(step, 1);
 276               }
 277               break;
 278             case V.ROOK:
 279               if (deltaX == 0 || deltaY == 0) addMoves(step);
 280               break;
 281             case V.BISHOP:
 282               if (deltaX == deltaY) addMoves(step);
 283               break;
 284             case V.QUEEN:
 285               if (deltaX == 0 || deltaY == 0 || deltaX == deltaY)
 286                 addMoves(step);
 287               break;
 288             case V.KING:
 289               if (deltaX <= 1 && deltaY <= 1) addMoves(step, 1);
 290               break;
 291           }
 292         }
 293       }
 294       return moves;
 295     }
 296     // If subTurn == 2 then we should have a first move,
 297     // which restrict what we can play now: only in the first move direction
 298     // NOTE: no need for knight or pawn checks, because the move will be
 299     // naturally limited in those cases.
 300     const L = this.firstMove.length;
 301     const fm = this.firstMove[L-1];
 302     if (fm.appear.length == 2 && fm.vanish.length == 2)
 303       // Castle: no real move playable then.
 304       return [];
 305     if (fm.appear.length == 0) {
 306       // Piece at subTurn 1 just exited the board.
 307       // Can I be a piece which caused the exit?
 308       if (
 309         this.isAprioriValidExit(
 310           [x, y],
 311           [fm.start.x, fm.start.y],
 312           fm.vanish[0].c
 313         )
 314       ) {
 315         // Seems so:
 316         const dir = this.getNormalizedDirection(
 317           [fm.start.x - x, fm.start.y - y]);
 318         return this.getMovesInDirection([x, y], dir);
 319       }
 320     }
 321     else {
 322       const dirM = this.getNormalizedDirection(
 323         [fm.end.x - fm.start.x, fm.end.y - fm.start.y]);
 324       const dir = this.getNormalizedDirection(
 325         [fm.start.x - x, fm.start.y - y]);
 326       // Normalized directions should match
 327       if (dir[0] == dirM[0] && dir[1] == dirM[1]) {
 328         // And nothing should stand between [x, y] and the square fm.start
 329         let [i, j] = [x + dir[0], y + dir[1]];
 330         while (
 331           (i != fm.start.x || j != fm.start.y) &&
 332           this.board[i][j] == V.EMPTY
 333         ) {
 334           i += dir[0];
 335           j += dir[1];
 336         }
 337         if (i == fm.start.x && j == fm.start.y)
 338           return this.getMovesInDirection([x, y], dir);
 339       }
 340     }
 341     return [];
 342   }
 343
 344   // Does m2 un-do m1 ? (to disallow undoing actions)
 345   oppositeMoves(m1, m2) {
 346     const isEqual = (av1, av2) => {
 347       // Precondition: av1 and av2 length = 2
 348       for (let av of av1) {
 349         const avInAv2 = av2.find(elt => {
 350           return (
 351             elt.x == av.x &&
 352             elt.y == av.y &&
 353             elt.c == av.c &&
 354             elt.p == av.p
 355           );
 356         });
 357         if (!avInAv2) return false;
 358       }
 359       return true;
 360     };
 361     return (
 362       m1.appear.length == 2 &&
 363       m2.appear.length == 2 &&
 364       m1.vanish.length == 2 &&
 365       m2.vanish.length == 2 &&
 366       isEqual(m1.appear, m2.vanish) &&
 367       isEqual(m1.vanish, m2.appear)
 368     );
 369   }
 370
 371   getAmove(move1, move2) {
 372     // Just merge (one is action one is move, one may be empty)
 373     return {
 374       appear: move1.appear.concat(move2.appear),
 375       vanish: move1.vanish.concat(move2.vanish)
 376     }
 377   }
 378
 379   filterValid(moves) {
 380     const color = this.turn;
 381     if (this.subTurn == 1) {
 382       return moves.filter(m => {
 383         // A move is valid either if it doesn't result in a check,
 384         // or if a second move is possible to counter the check
 385         // (not undoing a potential move + action of the opponent)
 386         this.play(m);
 387         let res = this.underCheck(color);
 388         if (res) {
 389           const moves2 = this.getAllPotentialMoves();
 390           for (let m2 of moves2) {
 391             this.play(m2);
 392             const res2 = this.underCheck(color);
 393             this.undo(m2);
 394             if (!res2) {
 395               res = false;
 396               break;
 397             }
 398           }
 399         }
 400         this.undo(m);
 401         return !res;
 402       });
 403     }
 404     const Lf = this.firstMove.length;
 405     const La = this.amoves.length;
 406     if (La == 0) return super.filterValid(moves);
 407     return (
 408       super.filterValid(
 409         moves.filter(m => {
 410           // Move shouldn't undo another:
 411           const amove = this.getAmove(this.firstMove[Lf-1], m);
 412           return !this.oppositeMoves(this.amoves[La-1], amove);
 413         })
 414       )
 415     );
 416   }
 417
 418   isAttackedBySlideNJump([x, y], color, piece, steps, oneStep) {
 419     for (let step of steps) {
 420       let rx = x + step[0],
 421           ry = y + step[1];
 422       while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
 423         rx += step[0];
 424         ry += step[1];
 425       }
 426       if (
 427         V.OnBoard(rx, ry) &&
 428         this.getPiece(rx, ry) == piece &&
 429         this.getColor(rx, ry) == color
 430       ) {
 431         // Now step in the other direction: if end of the world, then attacked
 432         rx = x - step[0];
 433         ry = y - step[1];
 434         while (
 435           V.OnBoard(rx, ry) &&
 436           this.board[rx][ry] == V.EMPTY &&
 437           !oneStep
 438         ) {
 439           rx -= step[0];
 440           ry -= step[1];
 441         }
 442         if (!V.OnBoard(rx, ry)) return true;
 443       }
 444     }
 445     return false;
 446   }
 447
 448   isAttackedByPawn([x, y], color) {
 449     const lastRank = (color == 'w' ? 0 : 7);
 450     if (x != lastRank)
 451       // The king can be pushed out by a pawn only on last rank
 452       return false;
 453     const pawnShift = (color == "w" ? 1 : -1);
 454     for (let i of [-1, 1]) {
 455       if (
 456         y + i >= 0 &&
 457         y + i < V.size.y &&
 458         this.getPiece(x + pawnShift, y + i) == V.PAWN &&
 459         this.getColor(x + pawnShift, y + i) == color
 460       ) {
 461         return true;
 462       }
 463     }
 464     return false;
 465   }
 466
 467   getCurrentScore() {
 468     if (this.subTurn == 2)
 469       // Move not over
 470       return "*";
 471     return super.getCurrentScore();
 472   }
 473
 474   doClick(square) {
 475     // If subTurn == 2 && square is empty && !underCheck,
 476     // then return an empty move, allowing to "pass" subTurn2
 477     if (
 478       this.subTurn == 2 &&
 479       this.board[square[0]][square[1]] == V.EMPTY &&
 480       !this.underCheck(this.turn)
 481     ) {
 482       return {
 483         start: { x: -1, y: -1 },
 484         end: { x: -1, y: -1 },
 485         appear: [],
 486         vanish: []
 487       };
 488     }
 489     return null;
 490   }
 491
 492   play(move) {
 493     move.flags = JSON.stringify(this.aggregateFlags());
 494     V.PlayOnBoard(this.board, move);
 495     if (this.subTurn == 2) {
 496       const L = this.firstMove.length;
 497       this.amoves.push(this.getAmove(this.firstMove[L-1], move));
 498       this.turn = V.GetOppCol(this.turn);
 499       this.movesCount++;
 500     }
 501     else this.firstMove.push(move);
 502     this.subTurn = 3 - this.subTurn;
 503     this.postPlay(move);
 504   }
 505
 506   postPlay(move) {
 507     if (move.start.x < 0) return;
 508     for (let a of move.appear)
 509       if (a.p == V.KING) this.kingPos[a.c] = [a.x, a.y];
 510     this.updateCastleFlags(move);
 511   }
 512
 513   updateCastleFlags(move) {
 514     const firstRank = { 'w': V.size.x - 1, 'b': 0 };
 515     for (let v of move.vanish) {
 516       if (v.p == V.KING) this.castleFlags[v.c] = [V.size.y, V.size.y];
 517       else if (v.x == firstRank[v.c] && this.castleFlags[v.c].includes(v.y)) {
 518         const flagIdx = (v.y == this.castleFlags[v.c][0] ? 0 : 1);
 519         this.castleFlags[v.c][flagIdx] = V.size.y;
 520       }
 521     }
 522   }
 523
 524   undo(move) {
 525     this.disaggregateFlags(JSON.parse(move.flags));
 526     V.UndoOnBoard(this.board, move);
 527     if (this.subTurn == 1) {
 528       this.turn = V.GetOppCol(this.turn);
 529       this.movesCount--;
 530     }
 531     else this.firstMove.pop();
 532     this.subTurn = 3 - this.subTurn;
 533     this.postUndo(move);
 534   }
 535
 536   postUndo(move) {
 537     // (Potentially) Reset king position
 538     for (let v of move.vanish)
 539       if (v.p == V.KING) this.kingPos[v.c] = [v.x, v.y];
 540   }
 541
 542   getComputerMove() {
 543     let moves = this.getAllValidMoves();
 544     if (moves.length == 0) return null;
 545     // "Search" at depth 1 for now
 546     const maxeval = V.INFINITY;
 547     const color = this.turn;
 548     const emptyMove = {
 549       start: { x: -1, y: -1 },
 550       end: { x: -1, y: -1 },
 551       appear: [],
 552       vanish: []
 553     };
 554     moves.forEach(m => {
 555       this.play(m);
 556       m.eval = (color == "w" ? -1 : 1) * maxeval;
 557       const moves2 = this.getAllValidMoves().concat([emptyMove]);
 558       m.next = moves2[0];
 559       moves2.forEach(m2 => {
 560         this.play(m2);
 561         const score = this.getCurrentScore();
 562         let mvEval = 0;
 563         if (score != "1/2") {
 564           if (score != "*") mvEval = (score == "1-0" ? 1 : -1) * maxeval;
 565           else mvEval = this.evalPosition();
 566         }
 567         if (
 568           (color == 'w' && mvEval > m.eval) ||
 569           (color == 'b' && mvEval < m.eval)
 570         ) {
 571           m.eval = mvEval;
 572           m.next = m2;
 573         }
 574         this.undo(m2);
 575       });
 576       this.undo(m);
 577     });
 578     moves.sort((a, b) => {
 579       return (color == "w" ? 1 : -1) * (b.eval - a.eval);
 580     });
 581     let candidates = [0];
 582     for (let i = 1; i < moves.length && moves[i].eval == moves[0].eval; i++)
 583       candidates.push(i);
 584     const mIdx = candidates[randInt(candidates.length)];
 585     const move2 = moves[mIdx].next;
 586     delete moves[mIdx]["next"];
 587     return [moves[mIdx], move2];
 588   }
 589
 590   getNotation(move) {
 591     if (move.start.x < 0)
 592       // A second move is always required, but may be empty
 593       return "-";
 594     const initialSquare = V.CoordsToSquare(move.start);
 595     const finalSquare = V.CoordsToSquare(move.end);
 596     if (move.appear.length == 0)
 597       // Pushed or pulled out of the board
 598       return initialSquare + "R";
 599     return move.appear[0].p.toUpperCase() + initialSquare + finalSquare;
 600   }
 601 };