base_rules.js

   1 import { Random } from "/utils/alea.js";
   2 import { ArrayFun } from "/utils/array.js";
   3 import PiPo from "/utils/PiPo.js";
   4 import Move from "/utils/Move.js";
   5
   6 // Helper class for move animation
   7 class TargetObj {
   8
   9   constructor(callOnComplete) {
  10     this.value = 0;
  11     this.target = 0;
  12     this.callOnComplete = callOnComplete;
  13   }
  14   increment() {
  15     if (++this.value == this.target)
  16       this.callOnComplete();
  17   }
  18
  19 };
  20
  21 // NOTE: x coords: top to bottom (white perspective); y: left to right
  22 // NOTE: ChessRules is aliased as window.C, and variants as window.V
  23 export default class ChessRules {
  24
  25   static get Aliases() {
  26     return {'C': ChessRules};
  27   }
  28
  29   /////////////////////////
  30   // VARIANT SPECIFICATIONS
  31
  32   // Some variants have specific options, like the number of pawns in Monster,
  33   // or the board size for Pandemonium.
  34   // Users can generally select a randomness level from 0 to 2.
  35   static get Options() {
  36     return {
  37       select: [{
  38         label: "Randomness",
  39         variable: "randomness",
  40         defaut: 0,
  41         options: [
  42           {label: "Deterministic", value: 0},
  43           {label: "Symmetric random", value: 1},
  44           {label: "Asymmetric random", value: 2}
  45         ]
  46       }],
  47       input: [
  48         {
  49           label: "Capture king",
  50           variable: "taking",
  51           type: "checkbox",
  52           defaut: false
  53         },
  54         {
  55           label: "Falling pawn",
  56           variable: "pawnfall",
  57           type: "checkbox",
  58           defaut: false
  59         }
  60       ],
  61       // Game modifiers (using "elementary variants"). Default: false
  62       styles: [
  63         "atomic",
  64         "balance", //takes precedence over doublemove & progressive
  65         "cannibal",
  66         "capture",
  67         "crazyhouse",
  68         "cylinder", //ok with all
  69         "dark",
  70         "doublemove",
  71         "madrasi",
  72         "progressive", //(natural) priority over doublemove
  73         "recycle",
  74         "rifle",
  75         "teleport",
  76         "zen"
  77       ]
  78     };
  79   }
  80
  81   get pawnPromotions() {
  82     return ['q', 'r', 'n', 'b'];
  83   }
  84
  85   // Some variants don't have flags:
  86   get hasFlags() {
  87     return true;
  88   }
  89   // Or castle
  90   get hasCastle() {
  91     return this.hasFlags;
  92   }
  93
  94   // En-passant captures allowed?
  95   get hasEnpassant() {
  96     return true;
  97   }
  98
  99   get hasReserve() {
 100     return (
 101       !!this.options["crazyhouse"] ||
 102       (!!this.options["recycle"] && !this.options["teleport"])
 103     );
 104   }
 105   // Some variants do not store reserve state (Align4, Chakart...)
 106   get hasReserveFen() {
 107     return this.hasReserve;
 108   }
 109
 110   get noAnimate() {
 111     return !!this.options["dark"];
 112   }
 113
 114   // Some variants use only click information
 115   get clickOnly() {
 116     return false;
 117   }
 118
 119   // Some variants use click infos:
 120   doClick(coords) {
 121     if (typeof coords.x != "number")
 122       return null; //click on reserves
 123     if (
 124       this.options["teleport"] && this.subTurnTeleport == 2 &&
 125       this.board[coords.x][coords.y] == ""
 126     ) {
 127       let res = new Move({
 128         start: {x: this.captured.x, y: this.captured.y},
 129         appear: [
 130           new PiPo({
 131             x: coords.x,
 132             y: coords.y,
 133             c: this.captured.c,
 134             p: this.captured.p
 135           })
 136         ],
 137         vanish: []
 138       });
 139       res.drag = {c: this.captured.c, p: this.captured.p};
 140       return res;
 141     }
 142     return null;
 143   }
 144
 145   ////////////////////
 146   // COORDINATES UTILS
 147
 148   // 3a --> {x:3, y:10}
 149   static SquareToCoords(sq) {
 150     return ArrayFun.toObject(["x", "y"],
 151                              [0, 1].map(i => parseInt(sq[i], 36)));
 152   }
 153
 154   // {x:11, y:12} --> bc
 155   static CoordsToSquare(cd) {
 156     return Object.values(cd).map(c => c.toString(36)).join("");
 157   }
 158
 159   coordsToId(cd) {
 160     if (typeof cd.x == "number") {
 161       return (
 162         `${this.containerId}|sq-${cd.x.toString(36)}-${cd.y.toString(36)}`
 163       );
 164     }
 165     // Reserve :
 166     return `${this.containerId}|rsq-${cd.x}-${cd.y}`;
 167   }
 168
 169   idToCoords(targetId) {
 170     if (!targetId)
 171       return null; //outside page, maybe...
 172     const idParts = targetId.split('|'); //prefix|sq-2-3 (start at 0 => 3,4)
 173     if (
 174       idParts.length < 2 ||
 175       idParts[0] != this.containerId ||
 176       !idParts[1].match(/sq-[0-9a-zA-Z]-[0-9a-zA-Z]/)
 177     ) {
 178       return null;
 179     }
 180     const squares = idParts[1].split('-');
 181     if (squares[0] == "sq")
 182       return {x: parseInt(squares[1], 36), y: parseInt(squares[2], 36)};
 183     // squares[0] == "rsq" : reserve, 'c' + 'p' (letters color & piece)
 184     return {x: squares[1], y: squares[2]};
 185   }
 186
 187   /////////////
 188   // FEN UTILS
 189
 190   // Turn "wb" into "B" (for FEN)
 191   board2fen(b) {
 192     return (b[0] == "w" ? b[1].toUpperCase() : b[1]);
 193   }
 194
 195   // Turn "p" into "bp" (for board)
 196   fen2board(f) {
 197     return (f.charCodeAt(0) <= 90 ? "w" + f.toLowerCase() : "b" + f);
 198   }
 199
 200   // Setup the initial random-or-not (asymmetric-or-not) position
 201   genRandInitFen(seed) {
 202     let fen, flags = "0707";
 203     if (!this.options.randomness)
 204       // Deterministic:
 205       fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w 0";
 206
 207     else {
 208       // Randomize
 209       Random.setSeed(seed);
 210       let pieces = {w: new Array(8), b: new Array(8)};
 211       flags = "";
 212       // Shuffle pieces on first (and last rank if randomness == 2)
 213       for (let c of ["w", "b"]) {
 214         if (c == 'b' && this.options.randomness == 1) {
 215           pieces['b'] = pieces['w'];
 216           flags += flags;
 217           break;
 218         }
 219
 220         let positions = ArrayFun.range(8);
 221
 222         // Get random squares for bishops
 223         let randIndex = 2 * Random.randInt(4);
 224         const bishop1Pos = positions[randIndex];
 225         // The second bishop must be on a square of different color
 226         let randIndex_tmp = 2 * Random.randInt(4) + 1;
 227         const bishop2Pos = positions[randIndex_tmp];
 228         // Remove chosen squares
 229         positions.splice(Math.max(randIndex, randIndex_tmp), 1);
 230         positions.splice(Math.min(randIndex, randIndex_tmp), 1);
 231
 232         // Get random squares for knights
 233         randIndex = Random.randInt(6);
 234         const knight1Pos = positions[randIndex];
 235         positions.splice(randIndex, 1);
 236         randIndex = Random.randInt(5);
 237         const knight2Pos = positions[randIndex];
 238         positions.splice(randIndex, 1);
 239
 240         // Get random square for queen
 241         randIndex = Random.randInt(4);
 242         const queenPos = positions[randIndex];
 243         positions.splice(randIndex, 1);
 244
 245         // Rooks and king positions are now fixed,
 246         // because of the ordering rook-king-rook
 247         const rook1Pos = positions[0];
 248         const kingPos = positions[1];
 249         const rook2Pos = positions[2];
 250
 251         // Finally put the shuffled pieces in the board array
 252         pieces[c][rook1Pos] = "r";
 253         pieces[c][knight1Pos] = "n";
 254         pieces[c][bishop1Pos] = "b";
 255         pieces[c][queenPos] = "q";
 256         pieces[c][kingPos] = "k";
 257         pieces[c][bishop2Pos] = "b";
 258         pieces[c][knight2Pos] = "n";
 259         pieces[c][rook2Pos] = "r";
 260         flags += rook1Pos.toString() + rook2Pos.toString();
 261       }
 262       fen = (
 263         pieces["b"].join("") +
 264         "/pppppppp/8/8/8/8/PPPPPPPP/" +
 265         pieces["w"].join("").toUpperCase() +
 266         " w 0"
 267       );
 268     }
 269     // Add turn + flags + enpassant (+ reserve)
 270     let parts = [];
 271     if (this.hasFlags)
 272       parts.push(`"flags":"${flags}"`);
 273     if (this.hasEnpassant)
 274       parts.push('"enpassant":"-"');
 275     if (this.hasReserveFen)
 276       parts.push('"reserve":"000000000000"');
 277     if (this.options["crazyhouse"])
 278       parts.push('"ispawn":"-"');
 279     if (parts.length >= 1)
 280       fen += " {" + parts.join(",") + "}";
 281     return fen;
 282   }
 283
 284   // "Parse" FEN: just return untransformed string data
 285   parseFen(fen) {
 286     const fenParts = fen.split(" ");
 287     let res = {
 288       position: fenParts[0],
 289       turn: fenParts[1],
 290       movesCount: fenParts[2]
 291     };
 292     if (fenParts.length > 3)
 293       res = Object.assign(res, JSON.parse(fenParts[3]));
 294     return res;
 295   }
 296
 297   // Return current fen (game state)
 298   getFen() {
 299     let fen = (
 300       this.getPosition() + " " +
 301       this.getTurnFen() + " " +
 302       this.movesCount
 303     );
 304     let parts = [];
 305     if (this.hasFlags)
 306       parts.push(`"flags":"${this.getFlagsFen()}"`);
 307     if (this.hasEnpassant)
 308       parts.push(`"enpassant":"${this.getEnpassantFen()}"`);
 309     if (this.hasReserveFen)
 310       parts.push(`"reserve":"${this.getReserveFen()}"`);
 311     if (this.options["crazyhouse"])
 312       parts.push(`"ispawn":"${this.getIspawnFen()}"`);
 313     if (parts.length >= 1)
 314       fen += " {" + parts.join(",") + "}";
 315     return fen;
 316   }
 317
 318   static FenEmptySquares(count) {
 319     // if more than 9 consecutive free spaces, break the integer,
 320     // otherwise FEN parsing will fail.
 321     if (count <= 9)
 322       return count;
 323     // Most boards of size < 18:
 324     if (count <= 18)
 325       return "9" + (count - 9);
 326     // Except Gomoku:
 327     return "99" + (count - 18);
 328   }
 329
 330   // Position part of the FEN string
 331   getPosition() {
 332     let position = "";
 333     for (let i = 0; i < this.size.y; i++) {
 334       let emptyCount = 0;
 335       for (let j = 0; j < this.size.x; j++) {
 336         if (this.board[i][j] == "")
 337           emptyCount++;
 338         else {
 339           if (emptyCount > 0) {
 340             // Add empty squares in-between
 341             position += C.FenEmptySquares(emptyCount);
 342             emptyCount = 0;
 343           }
 344           position += this.board2fen(this.board[i][j]);
 345         }
 346       }
 347       if (emptyCount > 0)
 348         // "Flush remainder"
 349         position += C.FenEmptySquares(emptyCount);
 350       if (i < this.size.y - 1)
 351         position += "/"; //separate rows
 352     }
 353     return position;
 354   }
 355
 356   getTurnFen() {
 357     return this.turn;
 358   }
 359
 360   // Flags part of the FEN string
 361   getFlagsFen() {
 362     return ["w", "b"].map(c => {
 363       return this.castleFlags[c].map(x => x.toString(36)).join("");
 364     }).join("");
 365   }
 366
 367   // Enpassant part of the FEN string
 368   getEnpassantFen() {
 369     if (!this.epSquare)
 370       return "-"; //no en-passant
 371     return C.CoordsToSquare(this.epSquare);
 372   }
 373
 374   getReserveFen() {
 375     return (
 376       ["w","b"].map(c => Object.values(this.reserve[c]).join("")).join("")
 377     );
 378   }
 379
 380   getIspawnFen() {
 381     const squares = Object.keys(this.ispawn);
 382     if (squares.length == 0)
 383       return "-";
 384     return squares.join(",");
 385   }
 386
 387   // Set flags from fen (castle: white a,h then black a,h)
 388   setFlags(fenflags) {
 389     this.castleFlags = {
 390       w: [0, 1].map(i => parseInt(fenflags.charAt(i), 36)),
 391       b: [2, 3].map(i => parseInt(fenflags.charAt(i), 36))
 392     };
 393   }
 394
 395   //////////////////
 396   // INITIALIZATION
 397
 398   constructor(o) {
 399     this.options = o.options;
 400     // Fill missing options (always the case if random challenge)
 401     (V.Options.select || []).concat(V.Options.input || []).forEach(opt => {
 402       if (this.options[opt.variable] === undefined)
 403         this.options[opt.variable] = opt.defaut;
 404     });
 405     if (o.genFenOnly)
 406       // This object will be used only for initial FEN generation
 407       return;
 408     this.playerColor = o.color;
 409     this.afterPlay = o.afterPlay; //trigger some actions after playing a move
 410
 411     // Fen string fully describes the game state
 412     if (!o.fen)
 413       o.fen = this.genRandInitFen(o.seed);
 414     this.re_initFromFen(o.fen);
 415
 416     // Graphical (can use variables defined above)
 417     this.containerId = o.element;
 418     this.graphicalInit();
 419   }
 420
 421   re_initFromFen(fen, oldBoard) {
 422     const fenParsed = this.parseFen(fen);
 423     this.board = oldBoard || this.getBoard(fenParsed.position);
 424     this.turn = fenParsed.turn;
 425     this.movesCount = parseInt(fenParsed.movesCount, 10);
 426     this.setOtherVariables(fenParsed);
 427   }
 428
 429   // Turn position fen into double array ["wb","wp","bk",...]
 430   getBoard(position) {
 431     const rows = position.split("/");
 432     let board = ArrayFun.init(this.size.x, this.size.y, "");
 433     for (let i = 0; i < rows.length; i++) {
 434       let j = 0;
 435       for (let indexInRow = 0; indexInRow < rows[i].length; indexInRow++) {
 436         const character = rows[i][indexInRow];
 437         const num = parseInt(character, 10);
 438         // If num is a number, just shift j:
 439         if (!isNaN(num))
 440           j += num;
 441         // Else: something at position i,j
 442         else
 443           board[i][j++] = this.fen2board(character);
 444       }
 445     }
 446     return board;
 447   }
 448
 449   // Some additional variables from FEN (variant dependant)
 450   setOtherVariables(fenParsed) {
 451     // Set flags and enpassant:
 452     if (this.hasFlags)
 453       this.setFlags(fenParsed.flags);
 454     if (this.hasEnpassant)
 455       this.epSquare = this.getEpSquare(fenParsed.enpassant);
 456     if (this.hasReserve)
 457       this.initReserves(fenParsed.reserve);
 458     if (this.options["crazyhouse"])
 459       this.initIspawn(fenParsed.ispawn);
 460     if (this.options["teleport"]) {
 461       this.subTurnTeleport = 1;
 462       this.captured = null;
 463     }
 464     if (this.options["dark"]) {
 465       // Setup enlightened: squares reachable by player side
 466       this.enlightened = ArrayFun.init(this.size.x, this.size.y, false);
 467       this.updateEnlightened();
 468     }
 469     this.subTurn = 1; //may be unused
 470     if (!this.moveStack) //avoid resetting (unwanted)
 471       this.moveStack = [];
 472   }
 473
 474   // ordering as in pieces() p,r,n,b,q,k
 475   initReserves(reserveStr) {
 476     const counts = reserveStr.split("").map(c => parseInt(c, 36));
 477     this.reserve = { w: {}, b: {} };
 478     const pieceName = ['p', 'r', 'n', 'b', 'q', 'k'];
 479     const L = pieceName.length;
 480     for (let i of ArrayFun.range(2 * L)) {
 481       if (i < L)
 482         this.reserve['w'][pieceName[i]] = counts[i];
 483       else
 484         this.reserve['b'][pieceName[i-L]] = counts[i];
 485     }
 486   }
 487
 488   initIspawn(ispawnStr) {
 489     if (ispawnStr != "-")
 490       this.ispawn = ArrayFun.toObject(ispawnStr.split(","), true);
 491     else
 492       this.ispawn = {};
 493   }
 494
 495   ////////////////
 496   // VISUAL UTILS
 497
 498   getPieceWidth(rwidth) {
 499     return (rwidth / this.size.y);
 500   }
 501
 502   getReserveSquareSize(rwidth, nbR) {
 503     const sqSize = this.getPieceWidth(rwidth);
 504     return Math.min(sqSize, rwidth / nbR);
 505   }
 506
 507   getReserveNumId(color, piece) {
 508     return `${this.containerId}|rnum-${color}${piece}`;
 509   }
 510
 511   getNbReservePieces(color) {
 512     return (
 513       Object.values(this.reserve[color]).reduce(
 514         (oldV,newV) => oldV + (newV > 0 ? 1 : 0), 0)
 515     );
 516   }
 517
 518   getRankInReserve(c, p) {
 519     const pieces = Object.keys(this.pieces());
 520     const lastIndex = pieces.findIndex(pp => pp == p)
 521     let toTest = pieces.slice(0, lastIndex);
 522     return toTest.reduce(
 523       (oldV,newV) => oldV + (this.reserve[c][newV] > 0 ? 1 : 0), 0);
 524   }
 525
 526   static AddClass_es(piece, class_es) {
 527     if (!Array.isArray(class_es))
 528       class_es = [class_es];
 529     class_es.forEach(cl => {
 530       piece.classList.add(cl);
 531     });
 532   }
 533
 534   static RemoveClass_es(piece, class_es) {
 535     if (!Array.isArray(class_es))
 536       class_es = [class_es];
 537     class_es.forEach(cl => {
 538       piece.classList.remove(cl);
 539     });
 540   }
 541
 542   // Generally light square bottom-right
 543   getSquareColorClass(x, y) {
 544     return ((x+y) % 2 == 0 ? "light-square": "dark-square");
 545   }
 546
 547   getMaxDistance(r) {
 548     // Works for all rectangular boards:
 549     return Math.sqrt(r.width ** 2 + r.height ** 2);
 550   }
 551
 552   getDomPiece(x, y) {
 553     return (typeof x == "string" ? this.r_pieces : this.g_pieces)[x][y];
 554   }
 555
 556   //////////////////
 557   // VISUAL METHODS
 558
 559   graphicalInit() {
 560     // NOTE: not window.onresize = this.re_drawBoardElts because scope (this)
 561     window.onresize = () => this.re_drawBoardElements();
 562     this.re_drawBoardElements();
 563     this.initMouseEvents();
 564     const chessboard =
 565       document.getElementById(this.containerId).querySelector(".chessboard");
 566   }
 567
 568   re_drawBoardElements() {
 569     const board = this.getSvgChessboard();
 570     const oppCol = C.GetOppCol(this.playerColor);
 571     let chessboard =
 572       document.getElementById(this.containerId).querySelector(".chessboard");
 573     chessboard.innerHTML = "";
 574     chessboard.insertAdjacentHTML('beforeend', board);
 575     // Compare window ratio width / height to aspectRatio:
 576     const windowRatio = window.innerWidth / window.innerHeight;
 577     let cbWidth, cbHeight;
 578     const vRatio = this.size.ratio || 1;
 579     if (windowRatio <= vRatio) {
 580       // Limiting dimension is width:
 581       cbWidth = Math.min(window.innerWidth, 767);
 582       cbHeight = cbWidth / vRatio;
 583     }
 584     else {
 585       // Limiting dimension is height:
 586       cbHeight = Math.min(window.innerHeight, 767);
 587       cbWidth = cbHeight * vRatio;
 588     }
 589     if (this.hasReserve) {
 590       const sqSize = cbWidth / this.size.y;
 591       // NOTE: allocate space for reserves (up/down) even if they are empty
 592       // Cannot use getReserveSquareSize() here, but sqSize is an upper bound.
 593       if ((window.innerHeight - cbHeight) / 2 < sqSize + 5) {
 594         cbHeight = window.innerHeight - 2 * (sqSize + 5);
 595         cbWidth = cbHeight * vRatio;
 596       }
 597     }
 598     chessboard.style.width = cbWidth + "px";
 599     chessboard.style.height = cbHeight + "px";
 600     // Center chessboard:
 601     const spaceLeft = (window.innerWidth - cbWidth) / 2,
 602           spaceTop = (window.innerHeight - cbHeight) / 2;
 603     chessboard.style.left = spaceLeft + "px";
 604     chessboard.style.top = spaceTop + "px";
 605     // Give sizes instead of recomputing them,
 606     // because chessboard might not be drawn yet.
 607     this.setupPieces({
 608       width: cbWidth,
 609       height: cbHeight,
 610       x: spaceLeft,
 611       y: spaceTop
 612     });
 613   }
 614
 615   // Get SVG board (background, no pieces)
 616   getSvgChessboard() {
 617     const flipped = (this.playerColor == 'b');
 618     let board = `
 619       <svg
 620         viewBox="0 0 ${10*this.size.y} ${10*this.size.x}"
 621         class="chessboard_SVG">`;
 622     for (let i=0; i < this.size.x; i++) {
 623       for (let j=0; j < this.size.y; j++) {
 624         const ii = (flipped ? this.size.x - 1 - i : i);
 625         const jj = (flipped ? this.size.y - 1 - j : j);
 626         let classes = this.getSquareColorClass(ii, jj);
 627         if (this.enlightened && !this.enlightened[ii][jj])
 628           classes += " in-shadow";
 629         // NOTE: x / y reversed because coordinates system is reversed.
 630         board += `
 631           <rect
 632             class="${classes}"
 633             id="${this.coordsToId({x: ii, y: jj})}"
 634             width="10"
 635             height="10"
 636             x="${10*j}"
 637             y="${10*i}"
 638           />`;
 639       }
 640     }
 641     board += "</svg>";
 642     return board;
 643   }
 644
 645   setupPieces(r) {
 646     if (this.g_pieces) {
 647       // Refreshing: delete old pieces first
 648       for (let i=0; i<this.size.x; i++) {
 649         for (let j=0; j<this.size.y; j++) {
 650           if (this.g_pieces[i][j]) {
 651             this.g_pieces[i][j].remove();
 652             this.g_pieces[i][j] = null;
 653           }
 654         }
 655       }
 656     }
 657     else
 658       this.g_pieces = ArrayFun.init(this.size.x, this.size.y, null);
 659     let chessboard =
 660       document.getElementById(this.containerId).querySelector(".chessboard");
 661     if (!r)
 662       r = chessboard.getBoundingClientRect();
 663     const pieceWidth = this.getPieceWidth(r.width);
 664     for (let i=0; i < this.size.x; i++) {
 665       for (let j=0; j < this.size.y; j++) {
 666         if (this.board[i][j] != "") {
 667           const color = this.getColor(i, j);
 668           const piece = this.getPiece(i, j);
 669           this.g_pieces[i][j] = document.createElement("piece");
 670           C.AddClass_es(this.g_pieces[i][j],
 671                         this.pieces(color, i, j)[piece]["class"]);
 672           this.g_pieces[i][j].classList.add(C.GetColorClass(color));
 673           this.g_pieces[i][j].style.width = pieceWidth + "px";
 674           this.g_pieces[i][j].style.height = pieceWidth + "px";
 675           let [ip, jp] = this.getPixelPosition(i, j, r);
 676           // Translate coordinates to use chessboard as reference:
 677           this.g_pieces[i][j].style.transform =
 678             `translate(${ip - r.x}px,${jp - r.y}px)`;
 679           if (this.enlightened && !this.enlightened[i][j])
 680             this.g_pieces[i][j].classList.add("hidden");
 681           chessboard.appendChild(this.g_pieces[i][j]);
 682         }
 683       }
 684     }
 685     if (this.hasReserve)
 686       this.re_drawReserve(['w', 'b'], r);
 687   }
 688
 689   // NOTE: assume this.reserve != null
 690   re_drawReserve(colors, r) {
 691     if (this.r_pieces) {
 692       // Remove (old) reserve pieces
 693       for (let c of colors) {
 694         Object.keys(this.r_pieces[c]).forEach(p => {
 695           this.r_pieces[c][p].remove();
 696           delete this.r_pieces[c][p];
 697           const numId = this.getReserveNumId(c, p);
 698           document.getElementById(numId).remove();
 699         });
 700       }
 701     }
 702     else
 703       this.r_pieces = { w: {}, b: {} };
 704     let container = document.getElementById(this.containerId);
 705     if (!r)
 706       r = container.querySelector(".chessboard").getBoundingClientRect();
 707     for (let c of colors) {
 708       let reservesDiv = document.getElementById("reserves_" + c);
 709       if (reservesDiv)
 710         reservesDiv.remove();
 711       if (!this.reserve[c])
 712         continue;
 713       const nbR = this.getNbReservePieces(c);
 714       if (nbR == 0)
 715         continue;
 716       const sqResSize = this.getReserveSquareSize(r.width, nbR);
 717       let ridx = 0;
 718       const vShift = (c == this.playerColor ? r.height + 5 : -sqResSize - 5);
 719       const [i0, j0] = [r.x, r.y + vShift];
 720       let rcontainer = document.createElement("div");
 721       rcontainer.id = "reserves_" + c;
 722       rcontainer.classList.add("reserves");
 723       rcontainer.style.left = i0 + "px";
 724       rcontainer.style.top = j0 + "px";
 725       // NOTE: +1 fix display bug on Firefox at least
 726       rcontainer.style.width = (nbR * sqResSize + 1) + "px";
 727       rcontainer.style.height = sqResSize + "px";
 728       container.appendChild(rcontainer);
 729       for (let p of Object.keys(this.reserve[c])) {
 730         if (this.reserve[c][p] == 0)
 731           continue;
 732         let r_cell = document.createElement("div");
 733         r_cell.id = this.coordsToId({x: c, y: p});
 734         r_cell.classList.add("reserve-cell");
 735         r_cell.style.width = sqResSize + "px";
 736         r_cell.style.height = sqResSize + "px";
 737         rcontainer.appendChild(r_cell);
 738         let piece = document.createElement("piece");
 739         C.AddClass_es(piece, this.pieces(c, c, p)[p]["class"]);
 740         piece.classList.add(C.GetColorClass(c));
 741         piece.style.width = "100%";
 742         piece.style.height = "100%";
 743         this.r_pieces[c][p] = piece;
 744         r_cell.appendChild(piece);
 745         let number = document.createElement("div");
 746         number.textContent = this.reserve[c][p];
 747         number.classList.add("reserve-num");
 748         number.id = this.getReserveNumId(c, p);
 749         const fontSize = "1.3em";
 750         number.style.fontSize = fontSize;
 751         number.style.fontSize = fontSize;
 752         r_cell.appendChild(number);
 753         ridx++;
 754       }
 755     }
 756   }
 757
 758   updateReserve(color, piece, count) {
 759     if (this.options["cannibal"] && C.CannibalKings[piece])
 760       piece = "k"; //capturing cannibal king: back to king form
 761     const oldCount = this.reserve[color][piece];
 762     this.reserve[color][piece] = count;
 763     // Redrawing is much easier if count==0
 764     if ([oldCount, count].includes(0))
 765       this.re_drawReserve([color]);
 766     else {
 767       const numId = this.getReserveNumId(color, piece);
 768       document.getElementById(numId).textContent = count;
 769     }
 770   }
 771
 772   // Resize board: no need to destroy/recreate pieces
 773   rescale(mode) {
 774     let chessboard =
 775       document.getElementById(this.containerId).querySelector(".chessboard");
 776     const r = chessboard.getBoundingClientRect();
 777     const multFact = (mode == "up" ? 1.05 : 0.95);
 778     let [newWidth, newHeight] = [multFact * r.width, multFact * r.height];
 779     // Stay in window:
 780     const vRatio = this.size.ratio || 1;
 781     if (newWidth > window.innerWidth) {
 782       newWidth = window.innerWidth;
 783       newHeight = newWidth / vRatio;
 784     }
 785     if (newHeight > window.innerHeight) {
 786       newHeight = window.innerHeight;
 787       newWidth = newHeight * vRatio;
 788     }
 789     chessboard.style.width = newWidth + "px";
 790     chessboard.style.height = newHeight + "px";
 791     const newX = (window.innerWidth - newWidth) / 2;
 792     chessboard.style.left = newX + "px";
 793     const newY = (window.innerHeight - newHeight) / 2;
 794     chessboard.style.top = newY + "px";
 795     const newR = {x: newX, y: newY, width: newWidth, height: newHeight};
 796     const pieceWidth = this.getPieceWidth(newWidth);
 797     // NOTE: next "if" for variants which use squares filling
 798     // instead of "physical", moving pieces
 799     if (this.g_pieces) {
 800       for (let i=0; i < this.size.x; i++) {
 801         for (let j=0; j < this.size.y; j++) {
 802           if (this.g_pieces[i][j]) {
 803             // NOTE: could also use CSS transform "scale"
 804             this.g_pieces[i][j].style.width = pieceWidth + "px";
 805             this.g_pieces[i][j].style.height = pieceWidth + "px";
 806             const [ip, jp] = this.getPixelPosition(i, j, newR);
 807             // Translate coordinates to use chessboard as reference:
 808             this.g_pieces[i][j].style.transform =
 809               `translate(${ip - newX}px,${jp - newY}px)`;
 810           }
 811         }
 812       }
 813     }
 814     if (this.hasReserve)
 815       this.rescaleReserve(newR);
 816   }
 817
 818   rescaleReserve(r) {
 819     for (let c of ['w','b']) {
 820       if (!this.reserve[c])
 821         continue;
 822       const nbR = this.getNbReservePieces(c);
 823       if (nbR == 0)
 824         continue;
 825       // Resize container first
 826       const sqResSize = this.getReserveSquareSize(r.width, nbR);
 827       const vShift = (c == this.playerColor ? r.height + 5 : -sqResSize - 5);
 828       const [i0, j0] = [r.x, r.y + vShift];
 829       let rcontainer = document.getElementById("reserves_" + c);
 830       rcontainer.style.left = i0 + "px";
 831       rcontainer.style.top = j0 + "px";
 832       rcontainer.style.width = (nbR * sqResSize + 1) + "px";
 833       rcontainer.style.height = sqResSize + "px";
 834       // And then reserve cells:
 835       const rpieceWidth = this.getReserveSquareSize(r.width, nbR);
 836       Object.keys(this.reserve[c]).forEach(p => {
 837         if (this.reserve[c][p] == 0)
 838           return;
 839         let r_cell = document.getElementById(this.coordsToId({x: c, y: p}));
 840         r_cell.style.width = sqResSize + "px";
 841         r_cell.style.height = sqResSize + "px";
 842       });
 843     }
 844   }
 845
 846   // Return the absolute pixel coordinates given current position.
 847   // Our coordinate system differs from CSS one (x <--> y).
 848   // We return here the CSS coordinates (more useful).
 849   getPixelPosition(i, j, r) {
 850     if (i < 0 || j < 0)
 851       return [0, 0]; //piece vanishes
 852     let x, y;
 853     if (typeof i == "string") {
 854       // Reserves: need to know the rank of piece
 855       const nbR = this.getNbReservePieces(i);
 856       const rsqSize = this.getReserveSquareSize(r.width, nbR);
 857       x = this.getRankInReserve(i, j) * rsqSize;
 858       y = (this.playerColor == i ? y = r.height + 5 : - 5 - rsqSize);
 859     }
 860     else {
 861       const sqSize = r.width / this.size.y;
 862       const flipped = (this.playerColor == 'b');
 863       x = (flipped ? this.size.y - 1 - j : j) * sqSize;
 864       y = (flipped ? this.size.x - 1 - i : i) * sqSize;
 865     }
 866     return [r.x + x, r.y + y];
 867   }
 868
 869   initMouseEvents() {
 870     let container = document.getElementById(this.containerId);
 871     let chessboard = container.querySelector(".chessboard");
 872
 873     const getOffset = e => {
 874       if (e.clientX)
 875         // Mouse
 876         return {x: e.clientX, y: e.clientY};
 877       let touchLocation = null;
 878       if (e.targetTouches && e.targetTouches.length >= 1)
 879         // Touch screen, dragstart
 880         touchLocation = e.targetTouches[0];
 881       else if (e.changedTouches && e.changedTouches.length >= 1)
 882         // Touch screen, dragend
 883         touchLocation = e.changedTouches[0];
 884       if (touchLocation)
 885         return {x: touchLocation.clientX, y: touchLocation.clientY};
 886       return {x: 0, y: 0}; //shouldn't reach here =)
 887     }
 888
 889     const centerOnCursor = (piece, e) => {
 890       const centerShift = this.getPieceWidth(r.width) / 2;
 891       const offset = getOffset(e);
 892       piece.style.left = (offset.x - centerShift) + "px";
 893       piece.style.top = (offset.y - centerShift) + "px";
 894     }
 895
 896     let start = null,
 897         r = null,
 898         startPiece, curPiece = null,
 899         pieceWidth;
 900     const mousedown = (e) => {
 901       // Disable zoom on smartphones:
 902       if (e.touches && e.touches.length > 1)
 903         e.preventDefault();
 904       r = chessboard.getBoundingClientRect();
 905       pieceWidth = this.getPieceWidth(r.width);
 906       const cd = this.idToCoords(e.target.id);
 907       if (cd) {
 908         const move = this.doClick(cd);
 909         if (move)
 910           this.buildMoveStack(move, r);
 911         else if (!this.clickOnly) {
 912           const [x, y] = Object.values(cd);
 913           if (typeof x != "number")
 914             startPiece = this.r_pieces[x][y];
 915           else
 916             startPiece = this.g_pieces[x][y];
 917           if (startPiece && this.canIplay(x, y)) {
 918             e.preventDefault();
 919             start = cd;
 920             curPiece = startPiece.cloneNode();
 921             curPiece.style.transform = "none";
 922             curPiece.style.zIndex = 5;
 923             curPiece.style.width = pieceWidth + "px";
 924             curPiece.style.height = pieceWidth + "px";
 925             centerOnCursor(curPiece, e);
 926             container.appendChild(curPiece);
 927             startPiece.style.opacity = "0.4";
 928             chessboard.style.cursor = "none";
 929           }
 930         }
 931       }
 932     };
 933
 934     const mousemove = (e) => {
 935       if (start) {
 936         e.preventDefault();
 937         centerOnCursor(curPiece, e);
 938       }
 939       else if (e.changedTouches && e.changedTouches.length >= 1)
 940         // Attempt to prevent horizontal swipe...
 941         e.preventDefault();
 942     };
 943
 944     const mouseup = (e) => {
 945       if (!start)
 946         return;
 947       const [x, y] = [start.x, start.y];
 948       start = null;
 949       e.preventDefault();
 950       chessboard.style.cursor = "pointer";
 951       startPiece.style.opacity = "1";
 952       const offset = getOffset(e);
 953       const landingElt = document.elementFromPoint(offset.x, offset.y);
 954       const cd =
 955         (landingElt ? this.idToCoords(landingElt.id) : undefined);
 956       if (cd) {
 957         // NOTE: clearly suboptimal, but much easier, and not a big deal.
 958         const potentialMoves = this.getPotentialMovesFrom([x, y])
 959           .filter(m => m.end.x == cd.x && m.end.y == cd.y);
 960         const moves = this.filterValid(potentialMoves);
 961         if (moves.length >= 2)
 962           this.showChoices(moves, r);
 963         else if (moves.length == 1)
 964           this.buildMoveStack(moves[0], r);
 965       }
 966       curPiece.remove();
 967     };
 968
 969     if ('onmousedown' in window) {
 970       document.addEventListener("mousedown", mousedown);
 971       document.addEventListener("mousemove", mousemove);
 972       document.addEventListener("mouseup", mouseup);
 973       document.addEventListener("wheel",
 974         (e) => this.rescale(e.deltaY < 0 ? "up" : "down"));
 975     }
 976     if ('ontouchstart' in window) {
 977       // https://stackoverflow.com/a/42509310/12660887
 978       document.addEventListener("touchstart", mousedown, {passive: false});
 979       document.addEventListener("touchmove", mousemove, {passive: false});
 980       document.addEventListener("touchend", mouseup, {passive: false});
 981     }
 982     // TODO: onpointerdown/move/up ? See reveal.js /controllers/touch.js
 983   }
 984
 985   showChoices(moves, r) {
 986     let container = document.getElementById(this.containerId);
 987     let chessboard = container.querySelector(".chessboard");
 988     let choices = document.createElement("div");
 989     choices.id = "choices";
 990     if (!r)
 991       r = chessboard.getBoundingClientRect();
 992     choices.style.width = r.width + "px";
 993     choices.style.height = r.height + "px";
 994     choices.style.left = r.x + "px";
 995     choices.style.top = r.y + "px";
 996     chessboard.style.opacity = "0.5";
 997     container.appendChild(choices);
 998     const squareWidth = r.width / this.size.y;
 999     const firstUpLeft = (r.width - (moves.length * squareWidth)) / 2;
1000     const firstUpTop = (r.height - squareWidth) / 2;
1001     const color = moves[0].appear[0].c;
1002     const callback = (m) => {
1003       chessboard.style.opacity = "1";
1004       container.removeChild(choices);
1005       this.buildMoveStack(m, r);
1006     }
1007     for (let i=0; i < moves.length; i++) {
1008       let choice = document.createElement("div");
1009       choice.classList.add("choice");
1010       choice.style.width = squareWidth + "px";
1011       choice.style.height = squareWidth + "px";
1012       choice.style.left = (firstUpLeft + i * squareWidth) + "px";
1013       choice.style.top = firstUpTop + "px";
1014       choice.style.backgroundColor = "lightyellow";
1015       choice.onclick = () => callback(moves[i]);
1016       const piece = document.createElement("piece");
1017       const cdisp = moves[i].choice || moves[i].appear[0].p;
1018       C.AddClass_es(piece,
1019         this.pieces(color, moves[i].end.x, moves[i].end.y)[cdisp]["class"]);
1020       piece.classList.add(C.GetColorClass(color));
1021       piece.style.width = "100%";
1022       piece.style.height = "100%";
1023       choice.appendChild(piece);
1024       choices.appendChild(choice);
1025     }
1026   }
1027
1028   ////////////////
1029   // DARK METHODS
1030
1031   updateEnlightened() {
1032     this.oldEnlightened = this.enlightened;
1033     this.enlightened = ArrayFun.init(this.size.x, this.size.y, false);
1034     // Add pieces positions + all squares reachable by moves (includes Zen):
1035     for (let x=0; x<this.size.x; x++) {
1036       for (let y=0; y<this.size.y; y++) {
1037         if (this.board[x][y] != "" && this.getColor(x, y) == this.playerColor)
1038         {
1039           this.enlightened[x][y] = true;
1040           this.getPotentialMovesFrom([x, y]).forEach(m => {
1041             this.enlightened[m.end.x][m.end.y] = true;
1042           });
1043         }
1044       }
1045     }
1046     if (this.epSquare)
1047       this.enlightEnpassant();
1048   }
1049
1050   // Include square of the en-passant capturing square:
1051   enlightEnpassant() {
1052     // NOTE: shortcut, pawn has only one attack type, doesn't depend on square
1053     const steps = this.pieces(this.playerColor)["p"].attack[0].steps;
1054     for (let step of steps) {
1055       const x = this.epSquare.x - step[0],
1056             y = this.getY(this.epSquare.y - step[1]);
1057       if (
1058         this.onBoard(x, y) &&
1059         this.getColor(x, y) == this.playerColor &&
1060         this.getPieceType(x, y) == "p"
1061       ) {
1062         this.enlightened[x][this.epSquare.y] = true;
1063         break;
1064       }
1065     }
1066   }
1067
1068   // Apply diff this.enlightened --> oldEnlightened on board
1069   graphUpdateEnlightened() {
1070     let chessboard =
1071       document.getElementById(this.containerId).querySelector(".chessboard");
1072     const r = chessboard.getBoundingClientRect();
1073     const pieceWidth = this.getPieceWidth(r.width);
1074     for (let x=0; x<this.size.x; x++) {
1075       for (let y=0; y<this.size.y; y++) {
1076         if (!this.enlightened[x][y] && this.oldEnlightened[x][y]) {
1077           let elt = document.getElementById(this.coordsToId({x: x, y: y}));
1078           elt.classList.add("in-shadow");
1079           if (this.g_pieces[x][y])
1080             this.g_pieces[x][y].classList.add("hidden");
1081         }
1082         else if (this.enlightened[x][y] && !this.oldEnlightened[x][y]) {
1083           let elt = document.getElementById(this.coordsToId({x: x, y: y}));
1084           elt.classList.remove("in-shadow");
1085           if (this.g_pieces[x][y])
1086             this.g_pieces[x][y].classList.remove("hidden");
1087         }
1088       }
1089     }
1090   }
1091
1092   //////////////
1093   // BASIC UTILS
1094
1095   get size() {
1096     return {
1097       x: 8,
1098       y: 8,
1099       ratio: 1 //for rectangular board = y / x (optional, 1 = default)
1100     };
1101   }
1102
1103   // Color of thing on square (i,j). '' if square is empty
1104   getColor(i, j) {
1105     if (typeof i == "string")
1106       return i; //reserves
1107     return this.board[i][j].charAt(0);
1108   }
1109
1110   static GetColorClass(c) {
1111     if (c == 'w')
1112       return "white";
1113     if (c == 'b')
1114       return "black";
1115     return "other-color"; //unidentified color
1116   }
1117
1118   // Piece on i,j. '' if square is empty
1119   getPiece(i, j) {
1120     if (typeof j == "string")
1121       return j; //reserves
1122     return this.board[i][j].charAt(1);
1123   }
1124
1125   // Piece type on square (i,j)
1126   getPieceType(x, y, p) {
1127     if (!p)
1128       p = this.getPiece(x, y);
1129     return this.pieces()[p].moveas || p;
1130   }
1131
1132   isKing(x, y, p) {
1133     if (!p)
1134       p = this.getPiece(x, y);
1135     if (!this.options["cannibal"])
1136       return p == 'k';
1137     return !!C.CannibalKings[p];
1138   }
1139
1140   // Get opponent color
1141   static GetOppCol(color) {
1142     return (color == "w" ? "b" : "w");
1143   }
1144
1145   // Is (x,y) on the chessboard?
1146   onBoard(x, y) {
1147     return (x >= 0 && x < this.size.x &&
1148             y >= 0 && y < this.size.y);
1149   }
1150
1151   // Am I allowed to move thing at square x,y ?
1152   canIplay(x, y) {
1153     return (this.playerColor == this.turn && this.getColor(x, y) == this.turn);
1154   }
1155
1156   ////////////////////////
1157   // PIECES SPECIFICATIONS
1158
1159   pieces(color, x, y) {
1160     const pawnShift = (color == "w" ? -1 : 1);
1161     // NOTE: jump 2 squares from first rank (pawns can be here sometimes)
1162     const initRank = ((color == 'w' && x >= 6) || (color == 'b' && x <= 1));
1163     return {
1164       'p': {
1165         "class": "pawn",
1166         moves: [
1167           {
1168             steps: [[pawnShift, 0]],
1169             range: (initRank ? 2 : 1)
1170           }
1171         ],
1172         attack: [
1173           {
1174             steps: [[pawnShift, 1], [pawnShift, -1]],
1175             range: 1
1176           }
1177         ]
1178       },
1179       'r': {
1180         "class": "rook",
1181         moves: [
1182           {steps: [[0, 1], [0, -1], [1, 0], [-1, 0]]}
1183         ]
1184       },
1185       'n': {
1186         "class": "knight",
1187         moves: [
1188           {
1189             steps: [
1190               [1, 2], [1, -2], [-1, 2], [-1, -2],
1191               [2, 1], [-2, 1], [2, -1], [-2, -1]
1192             ],
1193             range: 1
1194           }
1195         ]
1196       },
1197       'b': {
1198         "class": "bishop",
1199         moves: [
1200           {steps: [[1, 1], [1, -1], [-1, 1], [-1, -1]]}
1201         ]
1202       },
1203       'q': {
1204         "class": "queen",
1205         moves: [
1206           {
1207             steps: [
1208               [0, 1], [0, -1], [1, 0], [-1, 0],
1209               [1, 1], [1, -1], [-1, 1], [-1, -1]
1210             ]
1211           }
1212         ]
1213       },
1214       'k': {
1215         "class": "king",
1216         moves: [
1217           {
1218             steps: [
1219               [0, 1], [0, -1], [1, 0], [-1, 0],
1220               [1, 1], [1, -1], [-1, 1], [-1, -1]
1221             ],
1222             range: 1
1223           }
1224         ]
1225       },
1226       // Cannibal kings:
1227       '!': {"class": "king-pawn", moveas: "p"},
1228       '#': {"class": "king-rook", moveas: "r"},
1229       '$': {"class": "king-knight", moveas: "n"},
1230       '%': {"class": "king-bishop", moveas: "b"},
1231       '*': {"class": "king-queen", moveas: "q"}
1232     };
1233   }
1234
1235   // NOTE: using special symbols to not interfere with variants' pieces codes
1236   static get CannibalKings() {
1237     return {
1238       "!": "p",
1239       "#": "r",
1240       "$": "n",
1241       "%": "b",
1242       "*": "q",
1243       "k": "k"
1244     };
1245   }
1246
1247   static get CannibalKingCode() {
1248     return {
1249       "p": "!",
1250       "r": "#",
1251       "n": "$",
1252       "b": "%",
1253       "q": "*",
1254       "k": "k"
1255     };
1256   }
1257
1258   //////////////////////////
1259   // MOVES GENERATION UTILS
1260
1261   // For Cylinder: get Y coordinate
1262   getY(y) {
1263     if (!this.options["cylinder"])
1264       return y;
1265     let res = y % this.size.y;
1266     if (res < 0)
1267       res += this.size.y;
1268     return res;
1269   }
1270
1271   getSegments(curSeg, segStart, segEnd) {
1272     if (curSeg.length == 0)
1273       return undefined;
1274     let segments = JSON.parse(JSON.stringify(curSeg)); //not altering
1275     segments.push([[segStart[0], segStart[1]], [segEnd[0], segEnd[1]]]);
1276     return segments;
1277   }
1278
1279   getStepSpec(color, x, y, piece) {
1280     return this.pieces(color, x, y)[piece || this.getPieceType(x, y)];
1281   }
1282
1283   // Can thing on square1 capture thing on square2?
1284   canTake([x1, y1], [x2, y2]) {
1285     return this.getColor(x1, y1) !== this.getColor(x2, y2);
1286   }
1287
1288   canStepOver(i, j, p) {
1289     // In some variants, objects on boards don't stop movement (Chakart)
1290     return this.board[i][j] == "";
1291   }
1292
1293   canDrop([c, p], [i, j]) {
1294     return (
1295       this.board[i][j] == "" &&
1296       (!this.enlightened || this.enlightened[i][j]) &&
1297       (
1298         p != "p" ||
1299         (c == 'w' && i < this.size.x - 1) ||
1300         (c == 'b' && i > 0)
1301       )
1302     );
1303   }
1304
1305   // For Madrasi:
1306   // (redefined in Baroque etc, where Madrasi condition doesn't make sense)
1307   isImmobilized([x, y]) {
1308     if (!this.options["madrasi"])
1309       return false;
1310     const color = this.getColor(x, y);
1311     const oppCol = C.GetOppCol(color);
1312     const piece = this.getPieceType(x, y);
1313     const stepSpec = this.getStepSpec(color, x, y, piece);
1314     const attacks = stepSpec.attack || stepSpec.moves;
1315     for (let a of attacks) {
1316       outerLoop: for (let step of a.steps) {
1317         let [i, j] = [x + step[0], y + step[1]];
1318         let stepCounter = 1;
1319         while (this.onBoard(i, j) && this.board[i][j] == "") {
1320           if (a.range <= stepCounter++)
1321             continue outerLoop;
1322           i += step[0];
1323           j = this.getY(j + step[1]);
1324         }
1325         if (
1326           this.onBoard(i, j) &&
1327           this.getColor(i, j) == oppCol &&
1328           this.getPieceType(i, j) == piece
1329         ) {
1330           return true;
1331         }
1332       }
1333     }
1334     return false;
1335   }
1336
1337   // Stop at the first capture found
1338   atLeastOneCapture(color) {
1339     const oppCol = C.GetOppCol(color);
1340     const allowed = (sq1, sq2) => {
1341       return (
1342         // NOTE: canTake is reversed for Zen.
1343         // Generally ok because of the symmetry. TODO?
1344         this.canTake(sq1, sq2) &&
1345         this.filterValid(
1346           [this.getBasicMove(sq1, sq2)]).length >= 1
1347       );
1348     };
1349     for (let i=0; i<this.size.x; i++) {
1350       for (let j=0; j<this.size.y; j++) {
1351         if (this.getColor(i, j) == color) {
1352           if (
1353             (
1354               !this.options["zen"] &&
1355               this.findDestSquares(
1356                 [i, j],
1357                 {
1358                   attackOnly: true,
1359                   one: true,
1360                   segments: this.options["cylinder"]
1361                 },
1362                 allowed
1363               )
1364             )
1365             ||
1366             (
1367               (
1368                 this.options["zen"] &&
1369                 this.findCapturesOn(
1370                   [i, j],
1371                   {
1372                     one: true,
1373                     segments: this.options["cylinder"]
1374                   },
1375                   allowed
1376                 )
1377               )
1378             )
1379           ) {
1380             return true;
1381           }
1382         }
1383       }
1384     }
1385     return false;
1386   }
1387
1388   compatibleStep([x1, y1], [x2, y2], step, range) {
1389     const epsilon = 1e-7; //arbitrary small value
1390     let shifts = [0];
1391     if (this.options["cylinder"])
1392       Array.prototype.push.apply(shifts, [-this.size.y, this.size.y]);
1393     for (let sh of shifts) {
1394       const rx = (x2 - x1) / step[0],
1395             ry = (y2 + sh - y1) / step[1];
1396       if (
1397         // Zero step but non-zero interval => impossible
1398         (!Number.isFinite(rx) && !Number.isNaN(rx)) ||
1399         (!Number.isFinite(ry) && !Number.isNaN(ry)) ||
1400         // Negative number of step (impossible)
1401         (rx < 0 || ry < 0) ||
1402         // Not the same number of steps in both directions:
1403         (!Number.isNaN(rx) && !Number.isNaN(ry) && Math.abs(rx - ry) > epsilon)
1404       ) {
1405         continue;
1406       }
1407       let distance = (Number.isNaN(rx) ? ry : rx);
1408       if (Math.abs(distance - Math.round(distance)) > epsilon)
1409         continue;
1410       distance = Math.round(distance); //in case of (numerical...)
1411       if (!range || range >= distance)
1412         return true;
1413     }
1414     return false;
1415   }
1416
1417   ////////////////////
1418   // MOVES GENERATION
1419
1420   getDropMovesFrom([c, p]) {
1421     // NOTE: by design, this.reserve[c][p] >= 1 on user click
1422     // (but not necessarily otherwise: atLeastOneMove() etc)
1423     if (this.reserve[c][p] == 0)
1424       return [];
1425     let moves = [];
1426     for (let i=0; i<this.size.x; i++) {
1427       for (let j=0; j<this.size.y; j++) {
1428         if (this.canDrop([c, p], [i, j])) {
1429           let mv = new Move({
1430             start: {x: c, y: p},
1431             end: {x: i, y: j},
1432             appear: [new PiPo({x: i, y: j, c: c, p: p})],
1433             vanish: []
1434           });
1435           if (this.board[i][j] != "") {
1436             mv.vanish.push(new PiPo({
1437               x: i,
1438               y: j,
1439               c: this.getColor(i, j),
1440               p: this.getPiece(i, j)
1441             }));
1442           }
1443           moves.push(mv);
1444         }
1445       }
1446     }
1447     return moves;
1448   }
1449
1450   // All possible moves from selected square
1451   getPotentialMovesFrom([x, y], color) {
1452     if (this.subTurnTeleport == 2)
1453       return [];
1454     if (typeof x == "string")
1455       return this.getDropMovesFrom([x, y]);
1456     if (this.isImmobilized([x, y]))
1457       return [];
1458     const piece = this.getPieceType(x, y);
1459     let moves = this.getPotentialMovesOf(piece, [x, y]);
1460     if (piece == "p" && this.hasEnpassant && this.epSquare)
1461       Array.prototype.push.apply(moves, this.getEnpassantCaptures([x, y]));
1462     if (
1463       piece == "k" && this.hasCastle &&
1464       this.castleFlags[color || this.turn].some(v => v < this.size.y)
1465     ) {
1466       Array.prototype.push.apply(moves, this.getCastleMoves([x, y]));
1467     }
1468     return this.postProcessPotentialMoves(moves);
1469   }
1470
1471   postProcessPotentialMoves(moves) {
1472     if (moves.length == 0)
1473       return [];
1474     const color = this.getColor(moves[0].start.x, moves[0].start.y);
1475     const oppCol = C.GetOppCol(color);
1476
1477     if (this.options["capture"] && this.atLeastOneCapture(color))
1478       moves = this.capturePostProcess(moves, oppCol);
1479
1480     if (this.options["atomic"])
1481       this.atomicPostProcess(moves, color, oppCol);
1482
1483     if (
1484       moves.length > 0 &&
1485       this.getPieceType(moves[0].start.x, moves[0].start.y) == "p"
1486     ) {
1487       this.pawnPostProcess(moves, color, oppCol);
1488     }
1489
1490     if (this.options["cannibal"] && this.options["rifle"])
1491       // In this case a rifle-capture from last rank may promote a pawn
1492       this.riflePromotePostProcess(moves, color);
1493
1494     return moves;
1495   }
1496
1497   capturePostProcess(moves, oppCol) {
1498     // Filter out non-capturing moves (not using m.vanish because of
1499     // self captures of Recycle and Teleport).
1500     return moves.filter(m => {
1501       return (
1502         this.board[m.end.x][m.end.y] != "" &&
1503         this.getColor(m.end.x, m.end.y) == oppCol
1504       );
1505     });
1506   }
1507
1508   atomicPostProcess(moves, color, oppCol) {
1509     moves.forEach(m => {
1510       if (
1511         this.board[m.end.x][m.end.y] != "" &&
1512         this.getColor(m.end.x, m.end.y) == oppCol
1513       ) {
1514         // Explosion!
1515         let steps = [
1516           [-1, -1],
1517           [-1, 0],
1518           [-1, 1],
1519           [0, -1],
1520           [0, 1],
1521           [1, -1],
1522           [1, 0],
1523           [1, 1]
1524         ];
1525         let mNext = new Move({
1526           start: m.end,
1527           end: m.end,
1528           appear: [],
1529           vanish: []
1530         });
1531         for (let step of steps) {
1532           let x = m.end.x + step[0];
1533           let y = this.getY(m.end.y + step[1]);
1534           if (
1535             this.onBoard(x, y) &&
1536             this.board[x][y] != "" &&
1537             (x != m.start.x || y != m.start.y) &&
1538             this.getPieceType(x, y) != "p"
1539           ) {
1540             mNext.vanish.push(
1541               new PiPo({
1542                 p: this.getPiece(x, y),
1543                 c: this.getColor(x, y),
1544                 x: x,
1545                 y: y
1546               })
1547             );
1548           }
1549         }
1550         if (!this.options["rifle"]) {
1551           // The moving piece also vanish
1552           mNext.vanish.unshift(
1553             new PiPo({
1554               x: m.end.x,
1555               y: m.end.y,
1556               c: color,
1557               p: this.getPiece(m.start.x, m.start.y)
1558             })
1559           );
1560         }
1561         m.next = mNext;
1562       }
1563     });
1564   }
1565
1566   pawnPostProcess(moves, color, oppCol) {
1567     let moreMoves = [];
1568     const lastRank = (color == "w" ? 0 : this.size.x - 1);
1569     const initPiece = this.getPiece(moves[0].start.x, moves[0].start.y);
1570     moves.forEach(m => {
1571       const [x1, y1] = [m.start.x, m.start.y];
1572       const [x2, y2] = [m.end.x, m.end.y];
1573       const promotionOk = (
1574         x2 == lastRank &&
1575         (!this.options["rifle"] || this.board[x2][y2] == "")
1576       );
1577       if (!promotionOk)
1578         return; //nothing to do
1579       if (this.options["pawnfall"]) {
1580         m.appear.shift();
1581         return;
1582       }
1583       let finalPieces = ["p"];
1584       if (
1585         this.options["cannibal"] &&
1586         this.board[x2][y2] != "" &&
1587         this.getColor(x2, y2) == oppCol
1588       ) {
1589         finalPieces = [this.getPieceType(x2, y2)];
1590       }
1591       else
1592         finalPieces = this.pawnPromotions;
1593       m.appear[0].p = finalPieces[0];
1594       if (initPiece == "!") //cannibal king-pawn
1595         m.appear[0].p = C.CannibalKingCode[finalPieces[0]];
1596       for (let i=1; i<finalPieces.length; i++) {
1597         const piece = finalPieces[i];
1598         const tr = {
1599           c: color,
1600           p: (initPiece != "!" ? piece : C.CannibalKingCode[piece])
1601         };
1602         let newMove = this.getBasicMove([x1, y1], [x2, y2], tr);
1603         moreMoves.push(newMove);
1604       }
1605     });
1606     Array.prototype.push.apply(moves, moreMoves);
1607   }
1608
1609   riflePromotePostProcess(moves, color) {
1610     const lastRank = (color == "w" ? 0 : this.size.x - 1);
1611     let newMoves = [];
1612     moves.forEach(m => {
1613       if (
1614         m.start.x == lastRank &&
1615         m.appear.length >= 1 &&
1616         m.appear[0].p == "p" &&
1617         m.appear[0].x == m.start.x &&
1618         m.appear[0].y == m.start.y
1619       ) {
1620         m.appear[0].p = this.pawnPromotions[0];
1621         for (let i=1; i<this.pawnPromotions.length; i++) {
1622           let newMv = JSON.parse(JSON.stringify(m));
1623           newMv.appear[0].p = this.pawnSpecs.promotions[i];
1624           newMoves.push(newMv);
1625         }
1626       }
1627     });
1628     Array.prototype.push.apply(moves, newMoves);
1629   }
1630
1631   // Generic method to find possible moves of "sliding or jumping" pieces
1632   getPotentialMovesOf(piece, [x, y]) {
1633     const color = this.getColor(x, y);
1634     const stepSpec = this.getStepSpec(color, x, y, piece);
1635     let squares = [];
1636     if (stepSpec.attack) {
1637       squares = this.findDestSquares(
1638         [x, y],
1639         {
1640           attackOnly: true,
1641           segments: this.options["cylinder"],
1642           stepSpec: stepSpec
1643         },
1644         ([i1, j1], [i2, j2]) => {
1645           return (
1646             (!this.options["zen"] || this.isKing(i2, j2)) &&
1647             this.canTake([i1, j1], [i2, j2])
1648           );
1649         }
1650       );
1651     }
1652     const noSpecials = this.findDestSquares(
1653       [x, y],
1654       {
1655         moveOnly: !!stepSpec.attack || this.options["zen"],
1656         segments: this.options["cylinder"],
1657         stepSpec: stepSpec
1658       }
1659     );
1660     Array.prototype.push.apply(squares, noSpecials);
1661     if (this.options["zen"]) {
1662       let zenCaptures = this.findCapturesOn(
1663         [x, y],
1664         {}, //byCol: default is ok
1665         ([i1, j1], [i2, j2]) =>
1666           !this.isKing(i1, j1) && this.canTake([i2, j2], [i1, j1])
1667       );
1668       // Technical step: segments (if any) are reversed
1669       if (this.options["cylinder"]) {
1670         zenCaptures.forEach(z => {
1671           z.segments = z.segments.reverse().map(s => s.reverse())
1672         });
1673       }
1674       Array.prototype.push.apply(squares, zenCaptures);
1675     }
1676     if (
1677       this.options["recycle"] ||
1678       (this.options["teleport"] && this.subTurnTeleport == 1)
1679     ) {
1680       const selfCaptures = this.findDestSquares(
1681         [x, y],
1682         {
1683           attackOnly: true,
1684           segments: this.options["cylinder"],
1685           stepSpec: stepSpec
1686         },
1687         ([i1, j1], [i2, j2]) =>
1688           this.getColor(i2, j2) == color && !this.isKing(i2, j2)
1689       );
1690       Array.prototype.push.apply(squares, selfCaptures);
1691     }
1692     return squares.map(s => {
1693       let mv = this.getBasicMove([x, y], s.sq);
1694       if (this.options["cylinder"] && s.segments.length >= 2)
1695         mv.segments = s.segments;
1696       return mv;
1697     });
1698   }
1699
1700   findDestSquares([x, y], o, allowed) {
1701     if (!allowed)
1702       allowed = (sq1, sq2) => this.canTake(sq1, sq2);
1703     const apparentPiece = this.getPiece(x, y); //how it looks
1704     let res = [];
1705     // Next 3 for Cylinder mode: (unused if !o.segments)
1706     let explored = {};
1707     let segments = [];
1708     let segStart = [];
1709     const addSquare = ([i, j]) => {
1710       let elt = {sq: [i, j]};
1711       if (o.segments)
1712         elt.segments = this.getSegments(segments, segStart, end);
1713       res.push(elt);
1714     };
1715     const exploreSteps = (stepArray) => {
1716       for (let s of stepArray) {
1717         outerLoop: for (let step of s.steps) {
1718           if (o.segments) {
1719             segments = [];
1720             segStart = [x, y];
1721           }
1722           let [i, j] = [x, y];
1723           let stepCounter = 0;
1724           while (
1725             this.onBoard(i, j) &&
1726             ((i == x && j == y) || this.canStepOver(i, j, apparentPiece))
1727           ) {
1728             if (!explored[i + "." + j] && (i != x || j != y)) {
1729               explored[i + "." + j] = true;
1730               if (
1731                 !o.captureTarget ||
1732                 (o.captureTarget[0] == i && o.captureTarget[1] == j)
1733               ) {
1734                 if (o.one && !o.attackOnly)
1735                   return true;
1736                 if (!o.attackOnly)
1737                   addSquare(!o.captureTarget ? [i, j] : [x, y]);
1738                 if (o.captureTarget)
1739                   return res[0];
1740               }
1741             }
1742             if (s.range <= stepCounter++)
1743               continue outerLoop;
1744             const oldIJ = [i, j];
1745             i += step[0];
1746             j = this.getY(j + step[1]);
1747             if (o.segments && Math.abs(j - oldIJ[1]) > 1) {
1748               // Boundary between segments (cylinder mode)
1749               segments.push([[segStart[0], segStart[1]], oldIJ]);
1750               segStart = [i, j];
1751             }
1752           }
1753           if (!this.onBoard(i, j))
1754             continue;
1755           const pieceIJ = this.getPieceType(i, j);
1756           if (!explored[i + "." + j]) {
1757             explored[i + "." + j] = true;
1758             if (allowed([x, y], [i, j])) {
1759               if (o.one && !o.moveOnly)
1760                 return true;
1761               if (!o.moveOnly)
1762                 addSquare(!o.captureTarget ? [i, j] : [x, y]);
1763               if (
1764                 o.captureTarget &&
1765                 o.captureTarget[0] == i && o.captureTarget[1] == j
1766               ) {
1767                 return res[0];
1768               }
1769             }
1770           }
1771         }
1772       }
1773       return undefined; //default, but let's explicit it
1774     };
1775     if (o.captureTarget)
1776       return exploreSteps(o.captureSteps)
1777     else {
1778       const stepSpec =
1779         o.stepSpec || this.getStepSpec(this.getColor(x, y), x, y);
1780       let outOne = false;
1781       if (!o.attackOnly || !stepSpec.attack)
1782         outOne = exploreSteps(stepSpec.moves);
1783       if (!outOne && !o.moveOnly && !!stepSpec.attack) {
1784         o.attackOnly = true; //ok because o is always a temporary object
1785         outOne = exploreSteps(stepSpec.attack);
1786       }
1787       return (o.one ? outOne : res);
1788     }
1789   }
1790
1791   // Search for enemy (or not) pieces attacking [x, y]
1792   findCapturesOn([x, y], o, allowed) {
1793     if (!o.byCol)
1794       o.byCol = [C.GetOppCol(this.getColor(x, y) || this.turn)];
1795     let res = [];
1796     for (let i=0; i<this.size.x; i++) {
1797       for (let j=0; j<this.size.y; j++) {
1798         const colIJ = this.getColor(i, j);
1799         if (
1800           this.board[i][j] != "" &&
1801           o.byCol.includes(colIJ) &&
1802           !this.isImmobilized([i, j])
1803         ) {
1804           const apparentPiece = this.getPiece(i, j);
1805           // Quick check: does this potential attacker target x,y ?
1806           if (this.canStepOver(x, y, apparentPiece))
1807             continue;
1808           const stepSpec = this.getStepSpec(colIJ, i, j);
1809           const attacks = stepSpec.attack || stepSpec.moves;
1810           for (let a of attacks) {
1811             for (let s of a.steps) {
1812               // Quick check: if step isn't compatible, don't even try
1813               if (!this.compatibleStep([i, j], [x, y], s, a.range))
1814                 continue;
1815               // Finally verify that nothing stand in-between
1816               const out = this.findDestSquares(
1817                 [i, j],
1818                 {
1819                   captureTarget: [x, y],
1820                   captureSteps: [{steps: [s], range: a.range}],
1821                   segments: o.segments,
1822                   attackOnly: true,
1823                   one: false //one and captureTarget are mutually exclusive
1824                 },
1825                 allowed
1826               );
1827               if (out) {
1828                 if (o.one)
1829                   return true;
1830                 res.push(out);
1831               }
1832             }
1833           }
1834         }
1835       }
1836     }
1837     return (o.one ? false : res);
1838   }
1839
1840   // Build a regular move from its initial and destination squares.
1841   // tr: transformation
1842   getBasicMove([sx, sy], [ex, ey], tr) {
1843     const initColor = this.getColor(sx, sy);
1844     const initPiece = this.getPiece(sx, sy);
1845     const destColor = (this.board[ex][ey] != "" ? this.getColor(ex, ey) : "");
1846     let mv = new Move({
1847       appear: [],
1848       vanish: [],
1849       start: {x: sx, y: sy},
1850       end: {x: ex, y: ey}
1851     });
1852     if (
1853       !this.options["rifle"] ||
1854       this.board[ex][ey] == "" ||
1855       destColor == initColor //Recycle, Teleport
1856     ) {
1857       mv.appear = [
1858         new PiPo({
1859           x: ex,
1860           y: ey,
1861           c: !!tr ? tr.c : initColor,
1862           p: !!tr ? tr.p : initPiece
1863         })
1864       ];
1865       mv.vanish = [
1866         new PiPo({
1867           x: sx,
1868           y: sy,
1869           c: initColor,
1870           p: initPiece
1871         })
1872       ];
1873     }
1874     if (this.board[ex][ey] != "") {
1875       mv.vanish.push(
1876         new PiPo({
1877           x: ex,
1878           y: ey,
1879           c: this.getColor(ex, ey),
1880           p: this.getPiece(ex, ey)
1881         })
1882       );
1883       if (this.options["cannibal"] && destColor != initColor) {
1884         const lastIdx = mv.vanish.length - 1; //think "Rifle+Cannibal"
1885         let trPiece = mv.vanish[lastIdx].p;
1886         if (this.isKing(sx, sy))
1887           trPiece = C.CannibalKingCode[trPiece];
1888         if (mv.appear.length >= 1)
1889           mv.appear[0].p = trPiece;
1890         else if (this.options["rifle"]) {
1891           mv.appear.unshift(
1892             new PiPo({
1893               x: sx,
1894               y: sy,
1895               c: initColor,
1896               p: trPiece
1897             })
1898           );
1899           mv.vanish.unshift(
1900             new PiPo({
1901               x: sx,
1902               y: sy,
1903               c: initColor,
1904               p: initPiece
1905             })
1906           );
1907         }
1908       }
1909     }
1910     return mv;
1911   }
1912
1913   // En-passant square, if any
1914   getEpSquare(moveOrSquare) {
1915     if (typeof moveOrSquare === "string") {
1916       const square = moveOrSquare;
1917       if (square == "-")
1918         return undefined;
1919       return C.SquareToCoords(square);
1920     }
1921     // Argument is a move:
1922     const move = moveOrSquare;
1923     const s = move.start,
1924           e = move.end;
1925     if (
1926       s.y == e.y &&
1927       Math.abs(s.x - e.x) == 2 &&
1928       // Next conditions for variants like Atomic or Rifle, Recycle...
1929       (
1930         move.appear.length > 0 &&
1931         this.getPieceType(0, 0, move.appear[0].p) == 'p'
1932       )
1933       &&
1934       (
1935         move.vanish.length > 0 &&
1936         this.getPieceType(0, 0, move.vanish[0].p) == 'p'
1937       )
1938     ) {
1939       return {
1940         x: (s.x + e.x) / 2,
1941         y: s.y
1942       };
1943     }
1944     return undefined; //default
1945   }
1946
1947   // Special case of en-passant captures: treated separately
1948   getEnpassantCaptures([x, y]) {
1949     const color = this.getColor(x, y);
1950     const shiftX = (color == 'w' ? -1 : 1);
1951     const oppCol = C.GetOppCol(color);
1952     if (
1953       this.epSquare &&
1954       this.epSquare.x == x + shiftX &&
1955       Math.abs(this.getY(this.epSquare.y - y)) == 1 &&
1956       // Doublemove (and Progressive?) guards:
1957       this.board[this.epSquare.x][this.epSquare.y] == "" &&
1958       this.getColor(x, this.epSquare.y) == oppCol
1959     ) {
1960       const [epx, epy] = [this.epSquare.x, this.epSquare.y];
1961       this.board[epx][epy] = oppCol + 'p';
1962       let enpassantMove = this.getBasicMove([x, y], [epx, epy]);
1963       this.board[epx][epy] = "";
1964       const lastIdx = enpassantMove.vanish.length - 1; //think Rifle
1965       enpassantMove.vanish[lastIdx].x = x;
1966       return [enpassantMove];
1967     }
1968     return [];
1969   }
1970
1971   getCastleMoves([x, y], finalSquares, castleWith) {
1972     const c = this.getColor(x, y);
1973
1974     // Castling ?
1975     const oppCol = C.GetOppCol(c);
1976     let moves = [];
1977     // King, then rook:
1978     finalSquares =
1979       finalSquares || [ [2, 3], [this.size.y - 2, this.size.y - 3] ];
1980     const castlingKing = this.getPiece(x, y);
1981     castlingCheck: for (
1982       let castleSide = 0;
1983       castleSide < 2;
1984       castleSide++ //large, then small
1985     ) {
1986       if (this.castleFlags[c][castleSide] >= this.size.y)
1987         continue;
1988       // If this code is reached, rook and king are on initial position
1989
1990       // NOTE: in some variants this is not a rook
1991       const rookPos = this.castleFlags[c][castleSide];
1992       const castlingPiece = this.getPiece(x, rookPos);
1993       if (
1994         this.board[x][rookPos] == "" ||
1995         this.getColor(x, rookPos) != c ||
1996         (castleWith && !castleWith.includes(castlingPiece))
1997       ) {
1998         // Rook is not here, or changed color (see Benedict)
1999         continue;
2000       }
2001       // Nothing on the path of the king ? (and no checks)
2002       const finDist = finalSquares[castleSide][0] - y;
2003       let step = finDist / Math.max(1, Math.abs(finDist));
2004       let i = y;
2005       do {
2006         if (
2007           // NOTE: next weird test because underCheck() verification
2008           // will be executed in filterValid() later.
2009           (
2010             i != finalSquares[castleSide][0] &&
2011             this.underCheck([x, i], oppCol)
2012           )
2013           ||
2014           (
2015             this.board[x][i] != "" &&
2016             // NOTE: next check is enough, because of chessboard constraints
2017             (this.getColor(x, i) != c || ![rookPos, y].includes(i))
2018           )
2019         ) {
2020           continue castlingCheck;
2021         }
2022         i += step;
2023       } while (i != finalSquares[castleSide][0]);
2024       // Nothing on the path to the rook?
2025       step = (castleSide == 0 ? -1 : 1);
2026       for (i = y + step; i != rookPos; i += step) {
2027         if (this.board[x][i] != "")
2028           continue castlingCheck;
2029       }
2030
2031       // Nothing on final squares, except maybe king and castling rook?
2032       for (i = 0; i < 2; i++) {
2033         if (
2034           finalSquares[castleSide][i] != rookPos &&
2035           this.board[x][finalSquares[castleSide][i]] != "" &&
2036           (
2037             finalSquares[castleSide][i] != y ||
2038             this.getColor(x, finalSquares[castleSide][i]) != c
2039           )
2040         ) {
2041           continue castlingCheck;
2042         }
2043       }
2044
2045       // If this code is reached, castle is potentially valid
2046       moves.push(
2047         new Move({
2048           appear: [
2049             new PiPo({
2050               x: x,
2051               y: finalSquares[castleSide][0],
2052               p: castlingKing,
2053               c: c
2054             }),
2055             new PiPo({
2056               x: x,
2057               y: finalSquares[castleSide][1],
2058               p: castlingPiece,
2059               c: c
2060             })
2061           ],
2062           vanish: [
2063             // King might be initially disguised (Titan...)
2064             new PiPo({ x: x, y: y, p: castlingKing, c: c }),
2065             new PiPo({ x: x, y: rookPos, p: castlingPiece, c: c })
2066           ],
2067           end:
2068             Math.abs(y - rookPos) <= 2
2069               ? {x: x, y: rookPos}
2070               : {x: x, y: y + 2 * (castleSide == 0 ? -1 : 1)}
2071         })
2072       );
2073     }
2074
2075     return moves;
2076   }
2077
2078   ////////////////////
2079   // MOVES VALIDATION
2080
2081   // Is piece (or square) at given position attacked by "oppCol" ?
2082   underAttack([x, y], oppCol) {
2083     // An empty square is considered as king,
2084     // since it's used only in getCastleMoves (TODO?)
2085     const king = this.board[x][y] == "" || this.isKing(x, y);
2086     return (
2087       (
2088         (!this.options["zen"] || king) &&
2089         this.findCapturesOn(
2090           [x, y],
2091           {
2092             byCol: [oppCol],
2093             segments: this.options["cylinder"],
2094             one: true
2095           }
2096         )
2097       )
2098       ||
2099       (
2100         (!!this.options["zen"] && !king) &&
2101         this.findDestSquares(
2102           [x, y],
2103           {
2104             attackOnly: true,
2105             segments: this.options["cylinder"],
2106             one: true
2107           },
2108           ([i1, j1], [i2, j2]) => this.getColor(i2, j2) == oppCol
2109         )
2110       )
2111     );
2112   }
2113
2114   underCheck([x, y], oppCol) {
2115     if (this.options["taking"] || this.options["dark"])
2116       return false;
2117     return this.underAttack([x, y], oppCol);
2118   }
2119
2120   // Stop at first king found (TODO: multi-kings)
2121   searchKingPos(color) {
2122     for (let i=0; i < this.size.x; i++) {
2123       for (let j=0; j < this.size.y; j++) {
2124         if (this.getColor(i, j) == color && this.isKing(i, j))
2125           return [i, j];
2126       }
2127     }
2128     return [-1, -1]; //king not found
2129   }
2130
2131   // 'color' arg because some variants (e.g. Refusal) check opponent moves
2132   filterValid(moves, color) {
2133     if (!color)
2134       color = this.turn;
2135     const oppCol = C.GetOppCol(color);
2136     const kingPos = this.searchKingPos(color);
2137     let filtered = {}; //avoid re-checking similar moves (promotions...)
2138     return moves.filter(m => {
2139       const key = m.start.x + m.start.y + '.' + m.end.x + m.end.y;
2140       if (!filtered[key]) {
2141         this.playOnBoard(m);
2142         let square = kingPos,
2143             res = true; //a priori valid
2144         if (m.vanish.some(v => this.isKing(0, 0, v.p) && v.c == color)) {
2145           // Search king in appear array:
2146           const newKingIdx =
2147             m.appear.findIndex(a => this.isKing(0, 0, a.p) && a.c == color);
2148           if (newKingIdx >= 0)
2149             square = [m.appear[newKingIdx].x, m.appear[newKingIdx].y];
2150           else
2151             res = false;
2152         }
2153         res &&= !this.underCheck(square, oppCol);
2154         this.undoOnBoard(m);
2155         filtered[key] = res;
2156         return res;
2157       }
2158       return filtered[key];
2159     });
2160   }
2161
2162   /////////////////
2163   // MOVES PLAYING
2164
2165   // Apply a move on board
2166   playOnBoard(move) {
2167     for (let psq of move.vanish)
2168       this.board[psq.x][psq.y] = "";
2169     for (let psq of move.appear)
2170       this.board[psq.x][psq.y] = psq.c + psq.p;
2171   }
2172   // Un-apply the played move
2173   undoOnBoard(move) {
2174     for (let psq of move.appear)
2175       this.board[psq.x][psq.y] = "";
2176     for (let psq of move.vanish)
2177       this.board[psq.x][psq.y] = psq.c + psq.p;
2178   }
2179
2180   updateCastleFlags(move) {
2181     // Update castling flags if start or arrive from/at rook/king locations
2182     move.appear.concat(move.vanish).forEach(psq => {
2183       if (this.isKing(0, 0, psq.p))
2184         this.castleFlags[psq.c] = [this.size.y, this.size.y];
2185       // NOTE: not "else if" because king can capture enemy rook...
2186       let c = "";
2187       if (psq.x == 0)
2188         c = "b";
2189       else if (psq.x == this.size.x - 1)
2190         c = "w";
2191       if (c != "") {
2192         const fidx = this.castleFlags[c].findIndex(f => f == psq.y);
2193         if (fidx >= 0)
2194           this.castleFlags[c][fidx] = this.size.y;
2195       }
2196     });
2197   }
2198
2199   prePlay(move) {
2200     if (
2201       this.hasCastle &&
2202       // If flags already off, no need to re-check:
2203       Object.values(this.castleFlags).some(cvals =>
2204         cvals.some(val => val < this.size.y))
2205     ) {
2206       this.updateCastleFlags(move);
2207     }
2208     if (this.options["crazyhouse"]) {
2209       move.vanish.forEach(v => {
2210         const square = C.CoordsToSquare({x: v.x, y: v.y});
2211         if (this.ispawn[square])
2212           delete this.ispawn[square];
2213       });
2214       if (move.appear.length > 0 && move.vanish.length > 0) {
2215         // Assumption: something is moving
2216         const initSquare = C.CoordsToSquare(move.start);
2217         const destSquare = C.CoordsToSquare(move.end);
2218         if (
2219           this.ispawn[initSquare] ||
2220           (move.vanish[0].p == 'p' && move.appear[0].p != 'p')
2221         ) {
2222           this.ispawn[destSquare] = true;
2223         }
2224         else if (
2225           this.ispawn[destSquare] &&
2226           this.getColor(move.end.x, move.end.y) != move.vanish[0].c
2227         ) {
2228           move.vanish[1].p = 'p';
2229           delete this.ispawn[destSquare];
2230         }
2231       }
2232     }
2233     const minSize = Math.min(move.appear.length, move.vanish.length);
2234     if (
2235       this.hasReserve &&
2236       // Warning; atomic pawn removal isn't a capture
2237       (!this.options["atomic"] || !this.rempawn || this.movesCount >= 1)
2238     ) {
2239       const color = this.turn;
2240       for (let i=minSize; i<move.appear.length; i++) {
2241         // Something appears = dropped on board (some exceptions, Chakart...)
2242         if (move.appear[i].c == color) {
2243           const piece = move.appear[i].p;
2244           this.updateReserve(color, piece, this.reserve[color][piece] - 1);
2245         }
2246       }
2247       for (let i=minSize; i<move.vanish.length; i++) {
2248         // Something vanish: add to reserve except if recycle & opponent
2249         if (
2250           this.options["crazyhouse"] ||
2251           (this.options["recycle"] && move.vanish[i].c == color)
2252         ) {
2253           const piece = move.vanish[i].p;
2254           this.updateReserve(color, piece, this.reserve[color][piece] + 1);
2255         }
2256       }
2257     }
2258   }
2259
2260   play(move) {
2261     this.prePlay(move);
2262     if (this.hasEnpassant)
2263       this.epSquare = this.getEpSquare(move);
2264     this.playOnBoard(move);
2265     this.postPlay(move);
2266   }
2267
2268   postPlay(move) {
2269     const color = this.turn;
2270     if (this.options["dark"])
2271       this.updateEnlightened();
2272     if (this.options["teleport"]) {
2273       if (
2274         this.subTurnTeleport == 1 &&
2275         move.vanish.length > move.appear.length &&
2276         move.vanish[1].c == color
2277       ) {
2278         const v = move.vanish[move.vanish.length - 1];
2279         this.captured = {x: v.x, y: v.y, c: v.c, p: v.p};
2280         this.subTurnTeleport = 2;
2281         return;
2282       }
2283       this.subTurnTeleport = 1;
2284       this.captured = null;
2285     }
2286     if (this.isLastMove(move)) {
2287       this.turn = C.GetOppCol(color);
2288       this.movesCount++;
2289       this.subTurn = 1;
2290     }
2291     else if (!move.next)
2292       this.subTurn++;
2293   }
2294
2295   isLastMove(move) {
2296     if (move.next)
2297       return false;
2298     const color = this.turn;
2299     const oppKingPos = this.searchKingPos(C.GetOppCol(color));
2300     if (oppKingPos[0] < 0 || this.underCheck(oppKingPos, color))
2301       return true;
2302     return (
2303       (
2304         !this.options["balance"] ||
2305         ![1, 2].includes(this.movesCount) ||
2306         this.subTurn == 2
2307       )
2308       &&
2309       (
2310         !this.options["doublemove"] ||
2311         this.movesCount == 0 ||
2312         this.subTurn == 2
2313       )
2314       &&
2315       (
2316         !this.options["progressive"] ||
2317         this.subTurn == this.movesCount + 1
2318       )
2319     );
2320   }
2321
2322   // "Stop at the first move found"
2323   atLeastOneMove(color) {
2324     for (let i = 0; i < this.size.x; i++) {
2325       for (let j = 0; j < this.size.y; j++) {
2326         if (this.board[i][j] != "" && this.getColor(i, j) == color) {
2327           // NOTE: in fact searching for all potential moves from i,j.
2328           //       I don't believe this is an issue, for now at least.
2329           const moves = this.getPotentialMovesFrom([i, j]);
2330           if (moves.some(m => this.filterValid([m]).length >= 1))
2331             return true;
2332         }
2333       }
2334     }
2335     if (this.hasReserve && this.reserve[color]) {
2336       for (let p of Object.keys(this.reserve[color])) {
2337         const moves = this.getDropMovesFrom([color, p]);
2338         if (moves.some(m => this.filterValid([m]).length >= 1))
2339           return true;
2340       }
2341     }
2342     return false;
2343   }
2344
2345   // What is the score ? (Interesting if game is over)
2346   getCurrentScore(move) {
2347     const color = this.turn;
2348     const oppCol = C.GetOppCol(color);
2349     const kingPos = [this.searchKingPos(color), this.searchKingPos(oppCol)];
2350     if (kingPos[0][0] < 0 && kingPos[1][0] < 0)
2351       return "1/2";
2352     if (kingPos[0][0] < 0)
2353       return (color == "w" ? "0-1" : "1-0");
2354     if (kingPos[1][0] < 0)
2355       return (color == "w" ? "1-0" : "0-1");
2356     if (this.atLeastOneMove(color))
2357       return "*";
2358     // No valid move: stalemate or checkmate?
2359     if (!this.underCheck(kingPos[0], oppCol))
2360       return "1/2";
2361     // OK, checkmate
2362     return (color == "w" ? "0-1" : "1-0");
2363   }
2364
2365   playVisual(move, r) {
2366     move.vanish.forEach(v => {
2367       this.g_pieces[v.x][v.y].remove();
2368       this.g_pieces[v.x][v.y] = null;
2369     });
2370     let chessboard =
2371       document.getElementById(this.containerId).querySelector(".chessboard");
2372     if (!r)
2373       r = chessboard.getBoundingClientRect();
2374     const pieceWidth = this.getPieceWidth(r.width);
2375     move.appear.forEach(a => {
2376       this.g_pieces[a.x][a.y] = document.createElement("piece");
2377       C.AddClass_es(this.g_pieces[a.x][a.y],
2378                     this.pieces(a.c, a.x, a.y)[a.p]["class"]);
2379       this.g_pieces[a.x][a.y].classList.add(C.GetColorClass(a.c));
2380       this.g_pieces[a.x][a.y].style.width = pieceWidth + "px";
2381       this.g_pieces[a.x][a.y].style.height = pieceWidth + "px";
2382       const [ip, jp] = this.getPixelPosition(a.x, a.y, r);
2383       // Translate coordinates to use chessboard as reference:
2384       this.g_pieces[a.x][a.y].style.transform =
2385         `translate(${ip - r.x}px,${jp - r.y}px)`;
2386       if (this.enlightened && !this.enlightened[a.x][a.y])
2387         this.g_pieces[a.x][a.y].classList.add("hidden");
2388       chessboard.appendChild(this.g_pieces[a.x][a.y]);
2389     });
2390     if (this.options["dark"])
2391       this.graphUpdateEnlightened();
2392   }
2393
2394   // TODO: send stack receive stack, or allow incremental? (good/bad points)
2395   buildMoveStack(move, r) {
2396     this.moveStack.push(move);
2397     this.computeNextMove(move);
2398     this.play(move);
2399     const newTurn = this.turn;
2400     if (this.moveStack.length == 1)
2401       this.playVisual(move, r);
2402     if (move.next) {
2403       this.gameState = {
2404         fen: this.getFen(),
2405         board: JSON.parse(JSON.stringify(this.board)) //easier
2406       };
2407       this.buildMoveStack(move.next, r);
2408     }
2409     else {
2410       if (this.moveStack.length == 1) {
2411         // Usual case (one normal move)
2412         this.afterPlay(this.moveStack, newTurn, {send: true, res: true});
2413         this.moveStack = []
2414       }
2415       else {
2416         this.afterPlay(this.moveStack, newTurn, {send: true, res: false});
2417         this.re_initFromFen(this.gameState.fen, this.gameState.board);
2418         this.playReceivedMove(this.moveStack.slice(1), () => {
2419           this.afterPlay(this.moveStack, newTurn, {send: false, res: true});
2420           this.moveStack = []
2421         });
2422       }
2423     }
2424   }
2425
2426   // Implemented in variants using (automatic) moveStack
2427   computeNextMove(move) {}
2428
2429   animateMoving(start, end, drag, segments, cb) {
2430     let initPiece = this.getDomPiece(start.x, start.y);
2431     // NOTE: cloning often not required, but light enough, and simpler
2432     let movingPiece = initPiece.cloneNode();
2433     initPiece.style.opacity = "0";
2434     let container =
2435       document.getElementById(this.containerId)
2436     const r = container.querySelector(".chessboard").getBoundingClientRect();
2437     if (typeof start.x == "string") {
2438       // Need to bound width/height (was 100% for reserve pieces)
2439       const pieceWidth = this.getPieceWidth(r.width);
2440       movingPiece.style.width = pieceWidth + "px";
2441       movingPiece.style.height = pieceWidth + "px";
2442     }
2443     const maxDist = this.getMaxDistance(r);
2444     const apparentColor = this.getColor(start.x, start.y);
2445     const pieces = this.pieces(apparentColor, start.x, start.y);
2446     if (drag) {
2447       const startCode = this.getPiece(start.x, start.y);
2448       C.RemoveClass_es(movingPiece, pieces[startCode]["class"]);
2449       C.AddClass_es(movingPiece, pieces[drag.p]["class"]);
2450       if (apparentColor != drag.c) {
2451         movingPiece.classList.remove(C.GetColorClass(apparentColor));
2452         movingPiece.classList.add(C.GetColorClass(drag.c));
2453       }
2454     }
2455     container.appendChild(movingPiece);
2456     const animateSegment = (index, cb) => {
2457       // NOTE: move.drag could be generalized per-segment (usage?)
2458       const [i1, j1] = segments[index][0];
2459       const [i2, j2] = segments[index][1];
2460       const dep = this.getPixelPosition(i1, j1, r);
2461       const arr = this.getPixelPosition(i2, j2, r);
2462       movingPiece.style.transitionDuration = "0s";
2463       movingPiece.style.transform = `translate(${dep[0]}px, ${dep[1]}px)`;
2464       const distance =
2465         Math.sqrt((arr[0] - dep[0]) ** 2 + (arr[1] - dep[1]) ** 2);
2466       const duration = 0.2 + (distance / maxDist) * 0.3;
2467       // TODO: unclear why we need this new delay below:
2468       setTimeout(() => {
2469         movingPiece.style.transitionDuration = duration + "s";
2470         // movingPiece is child of container: no need to adjust coordinates
2471         movingPiece.style.transform = `translate(${arr[0]}px, ${arr[1]}px)`;
2472         setTimeout(cb, duration * 1000);
2473       }, 50);
2474     };
2475     let index = 0;
2476     const animateSegmentCallback = () => {
2477       if (index < segments.length)
2478         animateSegment(index++, animateSegmentCallback);
2479       else {
2480         movingPiece.remove();
2481         initPiece.style.opacity = "1";
2482         cb();
2483       }
2484     };
2485     animateSegmentCallback();
2486   }
2487
2488   // Input array of objects with at least fields x,y (e.g. PiPo)
2489   animateFading(arr, cb) {
2490     const animLength = 350; //TODO: 350ms? More? Less?
2491     arr.forEach(v => {
2492       let fadingPiece = this.getDomPiece(v.x, v.y);
2493       fadingPiece.style.transitionDuration = (animLength / 1000) + "s";
2494       fadingPiece.style.opacity = "0";
2495     });
2496     setTimeout(cb, animLength);
2497   }
2498
2499   animate(move, callback) {
2500     if (this.noAnimate || move.noAnimate) {
2501       callback();
2502       return;
2503     }
2504     let segments = move.segments;
2505     if (!segments)
2506       segments = [ [[move.start.x, move.start.y], [move.end.x, move.end.y]] ];
2507     let targetObj = new TargetObj(callback);
2508     if (move.start.x != move.end.x || move.start.y != move.end.y) {
2509       targetObj.target++;
2510       this.animateMoving(move.start, move.end, move.drag, segments,
2511                          () => targetObj.increment());
2512     }
2513     if (move.vanish.length > move.appear.length) {
2514       const arr = move.vanish.slice(move.appear.length)
2515         // Ignore disappearing pieces hidden by some appearing ones:
2516         .filter(v => move.appear.every(a => a.x != v.x || a.y != v.y));
2517       if (arr.length > 0) {
2518         targetObj.target++;
2519         this.animateFading(arr, () => targetObj.increment());
2520       }
2521     }
2522     targetObj.target +=
2523       this.customAnimate(move, segments, () => targetObj.increment());
2524     if (targetObj.target == 0)
2525       callback();
2526   }
2527
2528   // Potential other animations (e.g. for Suction variant)
2529   customAnimate(move, segments, cb) {
2530     return 0; //nb of targets
2531   }
2532
2533   playReceivedMove(moves, callback) {
2534     const launchAnimation = () => {
2535       const r = container.querySelector(".chessboard").getBoundingClientRect();
2536       const animateRec = i => {
2537         this.animate(moves[i], () => {
2538           this.play(moves[i]);
2539           this.playVisual(moves[i], r);
2540           if (i < moves.length - 1)
2541             setTimeout(() => animateRec(i+1), 300);
2542           else
2543             callback();
2544         });
2545       };
2546       animateRec(0);
2547     };
2548     // Delay if user wasn't focused:
2549     const checkDisplayThenAnimate = (delay) => {
2550       if (container.style.display == "none") {
2551         alert("New move! Let's go back to game...");
2552         document.getElementById("gameInfos").style.display = "none";
2553         container.style.display = "block";
2554         setTimeout(launchAnimation, 700);
2555       }
2556       else
2557         setTimeout(launchAnimation, delay || 0);
2558     };
2559     let container = document.getElementById(this.containerId);
2560     if (document.hidden) {
2561       document.onvisibilitychange = () => {
2562         document.onvisibilitychange = undefined;
2563         checkDisplayThenAnimate(700);
2564       };
2565     }
2566     else
2567       checkDisplayThenAnimate();
2568   }
2569
2570 };