0549139877e5ad5ebb1ed6bc54b318febb4ce212
[vchess.git] / client / src / base_rules.js
1 // (Orthodox) Chess rules are defined in ChessRules class.
2 // Variants generally inherit from it, and modify some parts.
3
4 import { ArrayFun } from "@/utils/array";
5 import { randInt, shuffle } from "@/utils/alea";
6
7 // class "PiPo": Piece + Position
8 export const PiPo = class PiPo {
9 // o: {piece[p], color[c], posX[x], posY[y]}
10 constructor(o) {
11 this.p = o.p;
12 this.c = o.c;
13 this.x = o.x;
14 this.y = o.y;
15 }
16 };
17
18 export const Move = class Move {
19 // o: {appear, vanish, [start,] [end,]}
20 // appear,vanish = arrays of PiPo
21 // start,end = coordinates to apply to trigger move visually (think castle)
22 constructor(o) {
23 this.appear = o.appear;
24 this.vanish = o.vanish;
25 this.start = o.start || { x: o.vanish[0].x, y: o.vanish[0].y };
26 this.end = o.end || { x: o.appear[0].x, y: o.appear[0].y };
27 }
28 };
29
30 // NOTE: x coords = top to bottom; y = left to right
31 // (from white player perspective)
32 export const ChessRules = class ChessRules {
33
34 //////////////
35 // MISC UTILS
36
37 // Some variants don't have flags:
38 static get HasFlags() {
39 return true;
40 }
41
42 // Or castle
43 static get HasCastle() {
44 return V.HasFlags;
45 }
46
47 // Pawns specifications
48 static get PawnSpecs() {
49 return {
50 directions: { 'w': -1, 'b': 1 },
51 initShift: { w: 1, b: 1 },
52 twoSquares: true,
53 threeSquares: false,
54 promotions: [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN],
55 canCapture: true,
56 captureBackward: false,
57 bidirectional: false
58 };
59 }
60
61 // En-passant captures need a stack of squares:
62 static get HasEnpassant() {
63 return true;
64 }
65
66 // Some variants cannot have analyse mode
67 static get CanAnalyze() {
68 return true;
69 }
70 // Patch: issues with javascript OOP, objects can't access static fields.
71 get canAnalyze() {
72 return V.CanAnalyze;
73 }
74
75 // Some variants show incomplete information,
76 // and thus show only a partial moves list or no list at all.
77 static get ShowMoves() {
78 return "all";
79 }
80 get showMoves() {
81 return V.ShowMoves;
82 }
83
84 // Sometimes moves must remain hidden until game ends
85 static get SomeHiddenMoves() {
86 return false;
87 }
88 get someHiddenMoves() {
89 return V.SomeHiddenMoves;
90 }
91
92 // Generally true, unless the variant includes random effects
93 static get CorrConfirm() {
94 return true;
95 }
96
97 // Used for Monochrome variant (TODO: harmonize: !canFlip ==> showFirstTurn)
98 get showFirstTurn() {
99 return false;
100 }
101
102 // Some variants always show the same orientation
103 static get CanFlip() {
104 return true;
105 }
106 get canFlip() {
107 return V.CanFlip;
108 }
109
110 // For (generally old) variants without checkered board
111 static get Monochrome() {
112 return false;
113 }
114
115 // Some games are drawn unusually (bottom right corner is black)
116 static get DarkBottomRight() {
117 return false;
118 }
119
120 // Some variants require lines drawing
121 static get Lines() {
122 if (V.Monochrome) {
123 let lines = [];
124 // Draw all inter-squares lines
125 for (let i = 0; i <= V.size.x; i++)
126 lines.push([[i, 0], [i, V.size.y]]);
127 for (let j = 0; j <= V.size.y; j++)
128 lines.push([[0, j], [V.size.x, j]]);
129 return lines;
130 }
131 return null;
132 }
133
134 // In some variants, the player who repeat a position loses
135 static get LoseOnRepetition() {
136 return false;
137 }
138
139 // At some stages, some games could wait clicks only:
140 onlyClick() {
141 return false;
142 }
143
144 // Some variants use click infos:
145 doClick() {
146 return null;
147 }
148
149 // Some variants may need to highlight squares on hover (Hamilton, Weiqi...)
150 hoverHighlight() {
151 return false;
152 }
153
154 static get IMAGE_EXTENSION() {
155 // All pieces should be in the SVG format
156 return ".svg";
157 }
158
159 // Turn "wb" into "B" (for FEN)
160 static board2fen(b) {
161 return b[0] == "w" ? b[1].toUpperCase() : b[1];
162 }
163
164 // Turn "p" into "bp" (for board)
165 static fen2board(f) {
166 return f.charCodeAt(0) <= 90 ? "w" + f.toLowerCase() : "b" + f;
167 }
168
169 // Check if FEN describes a board situation correctly
170 static IsGoodFen(fen) {
171 const fenParsed = V.ParseFen(fen);
172 // 1) Check position
173 if (!V.IsGoodPosition(fenParsed.position)) return false;
174 // 2) Check turn
175 if (!fenParsed.turn || !V.IsGoodTurn(fenParsed.turn)) return false;
176 // 3) Check moves count
177 if (!fenParsed.movesCount || !(parseInt(fenParsed.movesCount, 10) >= 0))
178 return false;
179 // 4) Check flags
180 if (V.HasFlags && (!fenParsed.flags || !V.IsGoodFlags(fenParsed.flags)))
181 return false;
182 // 5) Check enpassant
183 if (
184 V.HasEnpassant &&
185 (!fenParsed.enpassant || !V.IsGoodEnpassant(fenParsed.enpassant))
186 ) {
187 return false;
188 }
189 return true;
190 }
191
192 // Is position part of the FEN a priori correct?
193 static IsGoodPosition(position) {
194 if (position.length == 0) return false;
195 const rows = position.split("/");
196 if (rows.length != V.size.x) return false;
197 let kings = { "k": 0, "K": 0 };
198 for (let row of rows) {
199 let sumElts = 0;
200 for (let i = 0; i < row.length; i++) {
201 if (['K','k'].includes(row[i])) kings[row[i]]++;
202 if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
203 else {
204 const num = parseInt(row[i], 10);
205 if (isNaN(num) || num <= 0) return false;
206 sumElts += num;
207 }
208 }
209 if (sumElts != V.size.y) return false;
210 }
211 // Both kings should be on board. Exactly one per color.
212 if (Object.values(kings).some(v => v != 1)) return false;
213 return true;
214 }
215
216 // For FEN checking
217 static IsGoodTurn(turn) {
218 return ["w", "b"].includes(turn);
219 }
220
221 // For FEN checking
222 static IsGoodFlags(flags) {
223 // NOTE: a little too permissive to work with more variants
224 return !!flags.match(/^[a-z]{4,4}$/);
225 }
226
227 // NOTE: not with regexp to adapt to different board sizes. (TODO?)
228 static IsGoodEnpassant(enpassant) {
229 if (enpassant != "-") {
230 const ep = V.SquareToCoords(enpassant);
231 if (isNaN(ep.x) || !V.OnBoard(ep)) return false;
232 }
233 return true;
234 }
235
236 // 3 --> d (column number to letter)
237 static CoordToColumn(colnum) {
238 return String.fromCharCode(97 + colnum);
239 }
240
241 // d --> 3 (column letter to number)
242 static ColumnToCoord(column) {
243 return column.charCodeAt(0) - 97;
244 }
245
246 // a4 --> {x:3,y:0}
247 static SquareToCoords(sq) {
248 return {
249 // NOTE: column is always one char => max 26 columns
250 // row is counted from black side => subtraction
251 x: V.size.x - parseInt(sq.substr(1), 10),
252 y: sq[0].charCodeAt() - 97
253 };
254 }
255
256 // {x:0,y:4} --> e8
257 static CoordsToSquare(coords) {
258 return V.CoordToColumn(coords.y) + (V.size.x - coords.x);
259 }
260
261 // Path to pieces (standard ones in pieces/ folder)
262 getPpath(b) {
263 return b;
264 }
265
266 // Path to promotion pieces (usually the same)
267 getPPpath(m) {
268 return this.getPpath(m.appear[0].c + m.appear[0].p);
269 }
270
271 // Aggregates flags into one object
272 aggregateFlags() {
273 return this.castleFlags;
274 }
275
276 // Reverse operation
277 disaggregateFlags(flags) {
278 this.castleFlags = flags;
279 }
280
281 // En-passant square, if any
282 getEpSquare(moveOrSquare) {
283 if (!moveOrSquare) return undefined; //TODO: necessary line?!
284 if (typeof moveOrSquare === "string") {
285 const square = moveOrSquare;
286 if (square == "-") return undefined;
287 return V.SquareToCoords(square);
288 }
289 // Argument is a move:
290 const move = moveOrSquare;
291 const s = move.start,
292 e = move.end;
293 if (
294 s.y == e.y &&
295 Math.abs(s.x - e.x) == 2 &&
296 // Next conditions for variants like Atomic or Rifle, Recycle...
297 (move.appear.length > 0 && move.appear[0].p == V.PAWN) &&
298 (move.vanish.length > 0 && move.vanish[0].p == V.PAWN)
299 ) {
300 return {
301 x: (s.x + e.x) / 2,
302 y: s.y
303 };
304 }
305 return undefined; //default
306 }
307
308 // Can thing on square1 take thing on square2
309 canTake([x1, y1], [x2, y2]) {
310 return this.getColor(x1, y1) !== this.getColor(x2, y2);
311 }
312
313 // Is (x,y) on the chessboard?
314 static OnBoard(x, y) {
315 return x >= 0 && x < V.size.x && y >= 0 && y < V.size.y;
316 }
317
318 // Used in interface: 'side' arg == player color
319 canIplay(side, [x, y]) {
320 return this.turn == side && this.getColor(x, y) == side;
321 }
322
323 // On which squares is color under check ? (for interface)
324 getCheckSquares() {
325 const color = this.turn;
326 return (
327 this.underCheck(color)
328 // kingPos must be duplicated, because it may change:
329 ? [JSON.parse(JSON.stringify(this.kingPos[color]))]
330 : []
331 );
332 }
333
334 /////////////
335 // FEN UTILS
336
337 // Setup the initial random (asymmetric) position
338 static GenRandInitFen(randomness) {
339 if (randomness == 0)
340 // Deterministic:
341 return "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w 0 ahah -";
342
343 let pieces = { w: new Array(8), b: new Array(8) };
344 let flags = "";
345 // Shuffle pieces on first (and last rank if randomness == 2)
346 for (let c of ["w", "b"]) {
347 if (c == 'b' && randomness == 1) {
348 pieces['b'] = pieces['w'];
349 flags += flags;
350 break;
351 }
352
353 let positions = ArrayFun.range(8);
354
355 // Get random squares for bishops
356 let randIndex = 2 * randInt(4);
357 const bishop1Pos = positions[randIndex];
358 // The second bishop must be on a square of different color
359 let randIndex_tmp = 2 * randInt(4) + 1;
360 const bishop2Pos = positions[randIndex_tmp];
361 // Remove chosen squares
362 positions.splice(Math.max(randIndex, randIndex_tmp), 1);
363 positions.splice(Math.min(randIndex, randIndex_tmp), 1);
364
365 // Get random squares for knights
366 randIndex = randInt(6);
367 const knight1Pos = positions[randIndex];
368 positions.splice(randIndex, 1);
369 randIndex = randInt(5);
370 const knight2Pos = positions[randIndex];
371 positions.splice(randIndex, 1);
372
373 // Get random square for queen
374 randIndex = randInt(4);
375 const queenPos = positions[randIndex];
376 positions.splice(randIndex, 1);
377
378 // Rooks and king positions are now fixed,
379 // because of the ordering rook-king-rook
380 const rook1Pos = positions[0];
381 const kingPos = positions[1];
382 const rook2Pos = positions[2];
383
384 // Finally put the shuffled pieces in the board array
385 pieces[c][rook1Pos] = "r";
386 pieces[c][knight1Pos] = "n";
387 pieces[c][bishop1Pos] = "b";
388 pieces[c][queenPos] = "q";
389 pieces[c][kingPos] = "k";
390 pieces[c][bishop2Pos] = "b";
391 pieces[c][knight2Pos] = "n";
392 pieces[c][rook2Pos] = "r";
393 flags += V.CoordToColumn(rook1Pos) + V.CoordToColumn(rook2Pos);
394 }
395 // Add turn + flags + enpassant
396 return (
397 pieces["b"].join("") +
398 "/pppppppp/8/8/8/8/PPPPPPPP/" +
399 pieces["w"].join("").toUpperCase() +
400 " w 0 " + flags + " -"
401 );
402 }
403
404 // "Parse" FEN: just return untransformed string data
405 static ParseFen(fen) {
406 const fenParts = fen.split(" ");
407 let res = {
408 position: fenParts[0],
409 turn: fenParts[1],
410 movesCount: fenParts[2]
411 };
412 let nextIdx = 3;
413 if (V.HasFlags) Object.assign(res, { flags: fenParts[nextIdx++] });
414 if (V.HasEnpassant) Object.assign(res, { enpassant: fenParts[nextIdx] });
415 return res;
416 }
417
418 // Return current fen (game state)
419 getFen() {
420 return (
421 this.getBaseFen() + " " +
422 this.getTurnFen() + " " +
423 this.movesCount +
424 (V.HasFlags ? " " + this.getFlagsFen() : "") +
425 (V.HasEnpassant ? " " + this.getEnpassantFen() : "")
426 );
427 }
428
429 getFenForRepeat() {
430 // Omit movesCount, only variable allowed to differ
431 return (
432 this.getBaseFen() + "_" +
433 this.getTurnFen() +
434 (V.HasFlags ? "_" + this.getFlagsFen() : "") +
435 (V.HasEnpassant ? "_" + this.getEnpassantFen() : "")
436 );
437 }
438
439 // Position part of the FEN string
440 getBaseFen() {
441 const format = (count) => {
442 // if more than 9 consecutive free spaces, break the integer,
443 // otherwise FEN parsing will fail.
444 if (count <= 9) return count;
445 // Currently only boards of size up to 11 or 12:
446 return "9" + (count - 9);
447 };
448 let position = "";
449 for (let i = 0; i < V.size.x; i++) {
450 let emptyCount = 0;
451 for (let j = 0; j < V.size.y; j++) {
452 if (this.board[i][j] == V.EMPTY) emptyCount++;
453 else {
454 if (emptyCount > 0) {
455 // Add empty squares in-between
456 position += format(emptyCount);
457 emptyCount = 0;
458 }
459 position += V.board2fen(this.board[i][j]);
460 }
461 }
462 if (emptyCount > 0) {
463 // "Flush remainder"
464 position += format(emptyCount);
465 }
466 if (i < V.size.x - 1) position += "/"; //separate rows
467 }
468 return position;
469 }
470
471 getTurnFen() {
472 return this.turn;
473 }
474
475 // Flags part of the FEN string
476 getFlagsFen() {
477 let flags = "";
478 // Castling flags
479 for (let c of ["w", "b"])
480 flags += this.castleFlags[c].map(V.CoordToColumn).join("");
481 return flags;
482 }
483
484 // Enpassant part of the FEN string
485 getEnpassantFen() {
486 const L = this.epSquares.length;
487 if (!this.epSquares[L - 1]) return "-"; //no en-passant
488 return V.CoordsToSquare(this.epSquares[L - 1]);
489 }
490
491 // Turn position fen into double array ["wb","wp","bk",...]
492 static GetBoard(position) {
493 const rows = position.split("/");
494 let board = ArrayFun.init(V.size.x, V.size.y, "");
495 for (let i = 0; i < rows.length; i++) {
496 let j = 0;
497 for (let indexInRow = 0; indexInRow < rows[i].length; indexInRow++) {
498 const character = rows[i][indexInRow];
499 const num = parseInt(character, 10);
500 // If num is a number, just shift j:
501 if (!isNaN(num)) j += num;
502 // Else: something at position i,j
503 else board[i][j++] = V.fen2board(character);
504 }
505 }
506 return board;
507 }
508
509 // Extract (relevant) flags from fen
510 setFlags(fenflags) {
511 // white a-castle, h-castle, black a-castle, h-castle
512 this.castleFlags = { w: [-1, -1], b: [-1, -1] };
513 for (let i = 0; i < 4; i++) {
514 this.castleFlags[i < 2 ? "w" : "b"][i % 2] =
515 V.ColumnToCoord(fenflags.charAt(i));
516 }
517 }
518
519 //////////////////
520 // INITIALIZATION
521
522 // Fen string fully describes the game state
523 constructor(fen) {
524 if (!fen)
525 // In printDiagram() fen isn't supply because only getPpath() is used
526 // TODO: find a better solution!
527 return;
528 const fenParsed = V.ParseFen(fen);
529 this.board = V.GetBoard(fenParsed.position);
530 this.turn = fenParsed.turn;
531 this.movesCount = parseInt(fenParsed.movesCount, 10);
532 this.setOtherVariables(fen);
533 }
534
535 // Scan board for kings positions
536 // TODO: should be done from board, no need for the complete FEN
537 scanKings(fen) {
538 // Squares of white and black king:
539 this.kingPos = { w: [-1, -1], b: [-1, -1] };
540 const fenRows = V.ParseFen(fen).position.split("/");
541 for (let i = 0; i < fenRows.length; i++) {
542 let k = 0; //column index on board
543 for (let j = 0; j < fenRows[i].length; j++) {
544 switch (fenRows[i].charAt(j)) {
545 case "k":
546 this.kingPos["b"] = [i, k];
547 break;
548 case "K":
549 this.kingPos["w"] = [i, k];
550 break;
551 default: {
552 const num = parseInt(fenRows[i].charAt(j), 10);
553 if (!isNaN(num)) k += num - 1;
554 }
555 }
556 k++;
557 }
558 }
559 }
560
561 // Some additional variables from FEN (variant dependant)
562 setOtherVariables(fen) {
563 // Set flags and enpassant:
564 const parsedFen = V.ParseFen(fen);
565 if (V.HasFlags) this.setFlags(parsedFen.flags);
566 if (V.HasEnpassant) {
567 const epSq =
568 parsedFen.enpassant != "-"
569 ? this.getEpSquare(parsedFen.enpassant)
570 : undefined;
571 this.epSquares = [epSq];
572 }
573 // Search for kings positions:
574 this.scanKings(fen);
575 }
576
577 /////////////////////
578 // GETTERS & SETTERS
579
580 static get size() {
581 return { x: 8, y: 8 };
582 }
583
584 // Color of thing on square (i,j). 'undefined' if square is empty
585 getColor(i, j) {
586 return this.board[i][j].charAt(0);
587 }
588
589 // Piece type on square (i,j). 'undefined' if square is empty
590 getPiece(i, j) {
591 return this.board[i][j].charAt(1);
592 }
593
594 // Get opponent color
595 static GetOppCol(color) {
596 return color == "w" ? "b" : "w";
597 }
598
599 // Pieces codes (for a clearer code)
600 static get PAWN() {
601 return "p";
602 }
603 static get ROOK() {
604 return "r";
605 }
606 static get KNIGHT() {
607 return "n";
608 }
609 static get BISHOP() {
610 return "b";
611 }
612 static get QUEEN() {
613 return "q";
614 }
615 static get KING() {
616 return "k";
617 }
618
619 // For FEN checking:
620 static get PIECES() {
621 return [V.PAWN, V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN, V.KING];
622 }
623
624 // Empty square
625 static get EMPTY() {
626 return "";
627 }
628
629 // Some pieces movements
630 static get steps() {
631 return {
632 r: [
633 [-1, 0],
634 [1, 0],
635 [0, -1],
636 [0, 1]
637 ],
638 n: [
639 [-1, -2],
640 [-1, 2],
641 [1, -2],
642 [1, 2],
643 [-2, -1],
644 [-2, 1],
645 [2, -1],
646 [2, 1]
647 ],
648 b: [
649 [-1, -1],
650 [-1, 1],
651 [1, -1],
652 [1, 1]
653 ]
654 };
655 }
656
657 ////////////////////
658 // MOVES GENERATION
659
660 // All possible moves from selected square
661 getPotentialMovesFrom(sq) {
662 switch (this.getPiece(sq[0], sq[1])) {
663 case V.PAWN: return this.getPotentialPawnMoves(sq);
664 case V.ROOK: return this.getPotentialRookMoves(sq);
665 case V.KNIGHT: return this.getPotentialKnightMoves(sq);
666 case V.BISHOP: return this.getPotentialBishopMoves(sq);
667 case V.QUEEN: return this.getPotentialQueenMoves(sq);
668 case V.KING: return this.getPotentialKingMoves(sq);
669 }
670 return []; //never reached (but some variants may use it: Bario...)
671 }
672
673 // Build a regular move from its initial and destination squares.
674 // tr: transformation
675 getBasicMove([sx, sy], [ex, ey], tr) {
676 const initColor = this.getColor(sx, sy);
677 const initPiece = this.board[sx][sy].charAt(1);
678 let mv = new Move({
679 appear: [
680 new PiPo({
681 x: ex,
682 y: ey,
683 c: !!tr ? tr.c : initColor,
684 p: !!tr ? tr.p : initPiece
685 })
686 ],
687 vanish: [
688 new PiPo({
689 x: sx,
690 y: sy,
691 c: initColor,
692 p: initPiece
693 })
694 ]
695 });
696
697 // The opponent piece disappears if we take it
698 if (this.board[ex][ey] != V.EMPTY) {
699 mv.vanish.push(
700 new PiPo({
701 x: ex,
702 y: ey,
703 c: this.getColor(ex, ey),
704 p: this.board[ex][ey].charAt(1)
705 })
706 );
707 }
708
709 return mv;
710 }
711
712 // Generic method to find possible moves of non-pawn pieces:
713 // "sliding or jumping"
714 getSlideNJumpMoves([x, y], steps, oneStep) {
715 let moves = [];
716 outerLoop: for (let step of steps) {
717 let i = x + step[0];
718 let j = y + step[1];
719 while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
720 moves.push(this.getBasicMove([x, y], [i, j]));
721 if (!!oneStep) continue outerLoop;
722 i += step[0];
723 j += step[1];
724 }
725 if (V.OnBoard(i, j) && this.canTake([x, y], [i, j]))
726 moves.push(this.getBasicMove([x, y], [i, j]));
727 }
728 return moves;
729 }
730
731 // Special case of en-passant captures: treated separately
732 getEnpassantCaptures([x, y], shiftX) {
733 const Lep = this.epSquares.length;
734 const epSquare = this.epSquares[Lep - 1]; //always at least one element
735 let enpassantMove = null;
736 if (
737 !!epSquare &&
738 epSquare.x == x + shiftX &&
739 Math.abs(epSquare.y - y) == 1
740 ) {
741 enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
742 enpassantMove.vanish.push({
743 x: x,
744 y: epSquare.y,
745 p: this.board[x][epSquare.y].charAt(1),
746 c: this.getColor(x, epSquare.y)
747 });
748 }
749 return !!enpassantMove ? [enpassantMove] : [];
750 }
751
752 // Consider all potential promotions:
753 addPawnMoves([x1, y1], [x2, y2], moves, promotions) {
754 let finalPieces = [V.PAWN];
755 const color = this.turn; //this.getColor(x1, y1);
756 const lastRank = (color == "w" ? 0 : V.size.x - 1);
757 if (x2 == lastRank) {
758 // promotions arg: special override for Hiddenqueen variant
759 if (!!promotions) finalPieces = promotions;
760 else if (!!V.PawnSpecs.promotions) finalPieces = V.PawnSpecs.promotions;
761 }
762 let tr = null;
763 for (let piece of finalPieces) {
764 tr = (piece != V.PAWN ? { c: color, p: piece } : null);
765 moves.push(this.getBasicMove([x1, y1], [x2, y2], tr));
766 }
767 }
768
769 // What are the pawn moves from square x,y ?
770 getPotentialPawnMoves([x, y], promotions) {
771 const color = this.turn; //this.getColor(x, y);
772 const [sizeX, sizeY] = [V.size.x, V.size.y];
773 const pawnShiftX = V.PawnSpecs.directions[color];
774 const firstRank = (color == "w" ? sizeX - 1 : 0);
775 const forward = (color == 'w' ? -1 : 1);
776
777 // Pawn movements in shiftX direction:
778 const getPawnMoves = (shiftX) => {
779 let moves = [];
780 // NOTE: next condition is generally true (no pawn on last rank)
781 if (x + shiftX >= 0 && x + shiftX < sizeX) {
782 if (this.board[x + shiftX][y] == V.EMPTY) {
783 // One square forward (or backward)
784 this.addPawnMoves([x, y], [x + shiftX, y], moves, promotions);
785 // Next condition because pawns on 1st rank can generally jump
786 if (
787 V.PawnSpecs.twoSquares &&
788 (
789 (color == 'w' && x >= V.size.x - 1 - V.PawnSpecs.initShift['w'])
790 ||
791 (color == 'b' && x <= V.PawnSpecs.initShift['b'])
792 )
793 ) {
794 if (
795 shiftX == forward &&
796 this.board[x + 2 * shiftX][y] == V.EMPTY
797 ) {
798 // Two squares jump
799 moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
800 if (
801 V.PawnSpecs.threeSquares &&
802 this.board[x + 3 * shiftX][y] == V.EMPTY
803 ) {
804 // Three squares jump
805 moves.push(this.getBasicMove([x, y], [x + 3 * shiftX, y]));
806 }
807 }
808 }
809 }
810 // Captures
811 if (V.PawnSpecs.canCapture) {
812 for (let shiftY of [-1, 1]) {
813 if (y + shiftY >= 0 && y + shiftY < sizeY) {
814 if (
815 this.board[x + shiftX][y + shiftY] != V.EMPTY &&
816 this.canTake([x, y], [x + shiftX, y + shiftY])
817 ) {
818 this.addPawnMoves(
819 [x, y], [x + shiftX, y + shiftY],
820 moves, promotions
821 );
822 }
823 if (
824 V.PawnSpecs.captureBackward && shiftX == forward &&
825 x - shiftX >= 0 && x - shiftX < V.size.x &&
826 this.board[x - shiftX][y + shiftY] != V.EMPTY &&
827 this.canTake([x, y], [x - shiftX, y + shiftY])
828 ) {
829 this.addPawnMoves(
830 [x, y], [x - shiftX, y + shiftY],
831 moves, promotions
832 );
833 }
834 }
835 }
836 }
837 }
838 return moves;
839 }
840
841 let pMoves = getPawnMoves(pawnShiftX);
842 if (V.PawnSpecs.bidirectional)
843 pMoves = pMoves.concat(getPawnMoves(-pawnShiftX));
844
845 if (V.HasEnpassant) {
846 // NOTE: backward en-passant captures are not considered
847 // because no rules define them (for now).
848 Array.prototype.push.apply(
849 pMoves,
850 this.getEnpassantCaptures([x, y], pawnShiftX)
851 );
852 }
853
854 return pMoves;
855 }
856
857 // What are the rook moves from square x,y ?
858 getPotentialRookMoves(sq) {
859 return this.getSlideNJumpMoves(sq, V.steps[V.ROOK]);
860 }
861
862 // What are the knight moves from square x,y ?
863 getPotentialKnightMoves(sq) {
864 return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep");
865 }
866
867 // What are the bishop moves from square x,y ?
868 getPotentialBishopMoves(sq) {
869 return this.getSlideNJumpMoves(sq, V.steps[V.BISHOP]);
870 }
871
872 // What are the queen moves from square x,y ?
873 getPotentialQueenMoves(sq) {
874 return this.getSlideNJumpMoves(
875 sq,
876 V.steps[V.ROOK].concat(V.steps[V.BISHOP])
877 );
878 }
879
880 // What are the king moves from square x,y ?
881 getPotentialKingMoves(sq) {
882 // Initialize with normal moves
883 let moves = this.getSlideNJumpMoves(
884 sq,
885 V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
886 "oneStep"
887 );
888 if (V.HasCastle && this.castleFlags[this.turn].some(v => v < V.size.y))
889 moves = moves.concat(this.getCastleMoves(sq));
890 return moves;
891 }
892
893 // "castleInCheck" arg to let some variants castle under check
894 getCastleMoves([x, y], finalSquares, castleInCheck, castleWith) {
895 const c = this.getColor(x, y);
896
897 // Castling ?
898 const oppCol = V.GetOppCol(c);
899 let moves = [];
900 // King, then rook:
901 finalSquares = finalSquares || [ [2, 3], [V.size.y - 2, V.size.y - 3] ];
902 const castlingKing = this.board[x][y].charAt(1);
903 castlingCheck: for (
904 let castleSide = 0;
905 castleSide < 2;
906 castleSide++ //large, then small
907 ) {
908 if (this.castleFlags[c][castleSide] >= V.size.y) continue;
909 // If this code is reached, rook and king are on initial position
910
911 // NOTE: in some variants this is not a rook
912 const rookPos = this.castleFlags[c][castleSide];
913 const castlingPiece = this.board[x][rookPos].charAt(1);
914 if (
915 this.board[x][rookPos] == V.EMPTY ||
916 this.getColor(x, rookPos) != c ||
917 (!!castleWith && !castleWith.includes(castlingPiece))
918 ) {
919 // Rook is not here, or changed color (see Benedict)
920 continue;
921 }
922
923 // Nothing on the path of the king ? (and no checks)
924 const finDist = finalSquares[castleSide][0] - y;
925 let step = finDist / Math.max(1, Math.abs(finDist));
926 let i = y;
927 do {
928 if (
929 (!castleInCheck && this.isAttacked([x, i], oppCol)) ||
930 (
931 this.board[x][i] != V.EMPTY &&
932 // NOTE: next check is enough, because of chessboard constraints
933 (this.getColor(x, i) != c || ![y, rookPos].includes(i))
934 )
935 ) {
936 continue castlingCheck;
937 }
938 i += step;
939 } while (i != finalSquares[castleSide][0]);
940
941 // Nothing on the path to the rook?
942 step = castleSide == 0 ? -1 : 1;
943 for (i = y + step; i != rookPos; i += step) {
944 if (this.board[x][i] != V.EMPTY) continue castlingCheck;
945 }
946
947 // Nothing on final squares, except maybe king and castling rook?
948 for (i = 0; i < 2; i++) {
949 if (
950 finalSquares[castleSide][i] != rookPos &&
951 this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
952 (
953 finalSquares[castleSide][i] != y ||
954 this.getColor(x, finalSquares[castleSide][i]) != c
955 )
956 ) {
957 continue castlingCheck;
958 }
959 }
960
961 // If this code is reached, castle is valid
962 moves.push(
963 new Move({
964 appear: [
965 new PiPo({
966 x: x,
967 y: finalSquares[castleSide][0],
968 p: castlingKing,
969 c: c
970 }),
971 new PiPo({
972 x: x,
973 y: finalSquares[castleSide][1],
974 p: castlingPiece,
975 c: c
976 })
977 ],
978 vanish: [
979 // King might be initially disguised (Titan...)
980 new PiPo({ x: x, y: y, p: castlingKing, c: c }),
981 new PiPo({ x: x, y: rookPos, p: castlingPiece, c: c })
982 ],
983 end:
984 Math.abs(y - rookPos) <= 2
985 ? { x: x, y: rookPos }
986 : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) }
987 })
988 );
989 }
990
991 return moves;
992 }
993
994 ////////////////////
995 // MOVES VALIDATION
996
997 // For the interface: possible moves for the current turn from square sq
998 getPossibleMovesFrom(sq) {
999 return this.filterValid(this.getPotentialMovesFrom(sq));
1000 }
1001
1002 // TODO: promotions (into R,B,N,Q) should be filtered only once
1003 filterValid(moves) {
1004 if (moves.length == 0) return [];
1005 const color = this.turn;
1006 return moves.filter(m => {
1007 this.play(m);
1008 const res = !this.underCheck(color);
1009 this.undo(m);
1010 return res;
1011 });
1012 }
1013
1014 getAllPotentialMoves() {
1015 const color = this.turn;
1016 let potentialMoves = [];
1017 for (let i = 0; i < V.size.x; i++) {
1018 for (let j = 0; j < V.size.y; j++) {
1019 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == color) {
1020 Array.prototype.push.apply(
1021 potentialMoves,
1022 this.getPotentialMovesFrom([i, j])
1023 );
1024 }
1025 }
1026 }
1027 return potentialMoves;
1028 }
1029
1030 // Search for all valid moves considering current turn
1031 // (for engine and game end)
1032 getAllValidMoves() {
1033 return this.filterValid(this.getAllPotentialMoves());
1034 }
1035
1036 // Stop at the first move found
1037 // TODO: not really, it explores all moves from a square (one is enough).
1038 atLeastOneMove() {
1039 const color = this.turn;
1040 for (let i = 0; i < V.size.x; i++) {
1041 for (let j = 0; j < V.size.y; j++) {
1042 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == color) {
1043 const moves = this.getPotentialMovesFrom([i, j]);
1044 if (moves.length > 0) {
1045 for (let k = 0; k < moves.length; k++)
1046 if (this.filterValid([moves[k]]).length > 0) return true;
1047 }
1048 }
1049 }
1050 }
1051 return false;
1052 }
1053
1054 // Check if pieces of given color are attacking (king) on square x,y
1055 isAttacked(sq, color) {
1056 return (
1057 this.isAttackedByPawn(sq, color) ||
1058 this.isAttackedByRook(sq, color) ||
1059 this.isAttackedByKnight(sq, color) ||
1060 this.isAttackedByBishop(sq, color) ||
1061 this.isAttackedByQueen(sq, color) ||
1062 this.isAttackedByKing(sq, color)
1063 );
1064 }
1065
1066 // Generic method for non-pawn pieces ("sliding or jumping"):
1067 // is x,y attacked by a piece of given color ?
1068 isAttackedBySlideNJump([x, y], color, piece, steps, oneStep) {
1069 for (let step of steps) {
1070 let rx = x + step[0],
1071 ry = y + step[1];
1072 while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
1073 rx += step[0];
1074 ry += step[1];
1075 }
1076 if (
1077 V.OnBoard(rx, ry) &&
1078 this.board[rx][ry] != V.EMPTY &&
1079 this.getPiece(rx, ry) == piece &&
1080 this.getColor(rx, ry) == color
1081 ) {
1082 return true;
1083 }
1084 }
1085 return false;
1086 }
1087
1088 // Is square x,y attacked by 'color' pawns ?
1089 isAttackedByPawn(sq, color) {
1090 const pawnShift = (color == "w" ? 1 : -1);
1091 return this.isAttackedBySlideNJump(
1092 sq,
1093 color,
1094 V.PAWN,
1095 [[pawnShift, 1], [pawnShift, -1]],
1096 "oneStep"
1097 );
1098 }
1099
1100 // Is square x,y attacked by 'color' rooks ?
1101 isAttackedByRook(sq, color) {
1102 return this.isAttackedBySlideNJump(sq, color, V.ROOK, V.steps[V.ROOK]);
1103 }
1104
1105 // Is square x,y attacked by 'color' knights ?
1106 isAttackedByKnight(sq, color) {
1107 return this.isAttackedBySlideNJump(
1108 sq,
1109 color,
1110 V.KNIGHT,
1111 V.steps[V.KNIGHT],
1112 "oneStep"
1113 );
1114 }
1115
1116 // Is square x,y attacked by 'color' bishops ?
1117 isAttackedByBishop(sq, color) {
1118 return this.isAttackedBySlideNJump(sq, color, V.BISHOP, V.steps[V.BISHOP]);
1119 }
1120
1121 // Is square x,y attacked by 'color' queens ?
1122 isAttackedByQueen(sq, color) {
1123 return this.isAttackedBySlideNJump(
1124 sq,
1125 color,
1126 V.QUEEN,
1127 V.steps[V.ROOK].concat(V.steps[V.BISHOP])
1128 );
1129 }
1130
1131 // Is square x,y attacked by 'color' king(s) ?
1132 isAttackedByKing(sq, color) {
1133 return this.isAttackedBySlideNJump(
1134 sq,
1135 color,
1136 V.KING,
1137 V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
1138 "oneStep"
1139 );
1140 }
1141
1142 // Is color under check after his move ?
1143 underCheck(color) {
1144 return this.isAttacked(this.kingPos[color], V.GetOppCol(color));
1145 }
1146
1147 /////////////////
1148 // MOVES PLAYING
1149
1150 // Apply a move on board
1151 static PlayOnBoard(board, move) {
1152 for (let psq of move.vanish) board[psq.x][psq.y] = V.EMPTY;
1153 for (let psq of move.appear) board[psq.x][psq.y] = psq.c + psq.p;
1154 }
1155 // Un-apply the played move
1156 static UndoOnBoard(board, move) {
1157 for (let psq of move.appear) board[psq.x][psq.y] = V.EMPTY;
1158 for (let psq of move.vanish) board[psq.x][psq.y] = psq.c + psq.p;
1159 }
1160
1161 prePlay() {}
1162
1163 play(move) {
1164 // DEBUG:
1165 // if (!this.states) this.states = [];
1166 // const stateFen = this.getFen() + JSON.stringify(this.kingPos);
1167 // this.states.push(stateFen);
1168
1169 this.prePlay(move);
1170 // Save flags (for undo)
1171 if (V.HasFlags) move.flags = JSON.stringify(this.aggregateFlags());
1172 if (V.HasEnpassant) this.epSquares.push(this.getEpSquare(move));
1173 V.PlayOnBoard(this.board, move);
1174 this.turn = V.GetOppCol(this.turn);
1175 this.movesCount++;
1176 this.postPlay(move);
1177 }
1178
1179 updateCastleFlags(move, piece, color) {
1180 // TODO: check flags. If already off, no need to always re-evaluate
1181 const c = color || V.GetOppCol(this.turn);
1182 const firstRank = (c == "w" ? V.size.x - 1 : 0);
1183 // Update castling flags if rooks are moved
1184 const oppCol = this.turn;
1185 const oppFirstRank = V.size.x - 1 - firstRank;
1186 if (piece == V.KING && move.appear.length > 0)
1187 this.castleFlags[c] = [V.size.y, V.size.y];
1188 else if (
1189 move.start.x == firstRank && //our rook moves?
1190 this.castleFlags[c].includes(move.start.y)
1191 ) {
1192 const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
1193 this.castleFlags[c][flagIdx] = V.size.y;
1194 }
1195 // NOTE: not "else if" because a rook could take an opposing rook
1196 if (
1197 move.end.x == oppFirstRank && //we took opponent rook?
1198 this.castleFlags[oppCol].includes(move.end.y)
1199 ) {
1200 const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
1201 this.castleFlags[oppCol][flagIdx] = V.size.y;
1202 }
1203 }
1204
1205 // After move is played, update variables + flags
1206 postPlay(move) {
1207 const c = V.GetOppCol(this.turn);
1208 let piece = undefined;
1209 if (move.vanish.length >= 1)
1210 // Usual case, something is moved
1211 piece = move.vanish[0].p;
1212 else
1213 // Crazyhouse-like variants
1214 piece = move.appear[0].p;
1215
1216 // Update king position + flags
1217 if (piece == V.KING && move.appear.length > 0)
1218 this.kingPos[c] = [move.appear[0].x, move.appear[0].y];
1219 if (V.HasCastle) this.updateCastleFlags(move, piece);
1220 }
1221
1222 preUndo() {}
1223
1224 undo(move) {
1225 this.preUndo(move);
1226 if (V.HasEnpassant) this.epSquares.pop();
1227 if (V.HasFlags) this.disaggregateFlags(JSON.parse(move.flags));
1228 V.UndoOnBoard(this.board, move);
1229 this.turn = V.GetOppCol(this.turn);
1230 this.movesCount--;
1231 this.postUndo(move);
1232
1233 // DEBUG:
1234 // const stateFen = this.getFen() + JSON.stringify(this.kingPos);
1235 // if (stateFen != this.states[this.states.length-1]) debugger;
1236 // this.states.pop();
1237 }
1238
1239 // After move is undo-ed *and flags resetted*, un-update other variables
1240 // TODO: more symmetry, by storing flags increment in move (?!)
1241 postUndo(move) {
1242 // (Potentially) Reset king position
1243 const c = this.getColor(move.start.x, move.start.y);
1244 if (this.getPiece(move.start.x, move.start.y) == V.KING)
1245 this.kingPos[c] = [move.start.x, move.start.y];
1246 }
1247
1248 ///////////////
1249 // END OF GAME
1250
1251 // What is the score ? (Interesting if game is over)
1252 getCurrentScore() {
1253 if (this.atLeastOneMove()) return "*";
1254 // Game over
1255 const color = this.turn;
1256 // No valid move: stalemate or checkmate?
1257 if (!this.underCheck(color)) return "1/2";
1258 // OK, checkmate
1259 return (color == "w" ? "0-1" : "1-0");
1260 }
1261
1262 ///////////////
1263 // ENGINE PLAY
1264
1265 // Pieces values
1266 static get VALUES() {
1267 return {
1268 p: 1,
1269 r: 5,
1270 n: 3,
1271 b: 3,
1272 q: 9,
1273 k: 1000
1274 };
1275 }
1276
1277 // "Checkmate" (unreachable eval)
1278 static get INFINITY() {
1279 return 9999;
1280 }
1281
1282 // At this value or above, the game is over
1283 static get THRESHOLD_MATE() {
1284 return V.INFINITY;
1285 }
1286
1287 // Search depth: 1,2 for e.g. higher branching factor, 4 for smaller
1288 static get SEARCH_DEPTH() {
1289 return 3;
1290 }
1291
1292 // 'movesList' arg for some variants to provide a custom list
1293 getComputerMove(movesList) {
1294 const maxeval = V.INFINITY;
1295 const color = this.turn;
1296 let moves1 = movesList || this.getAllValidMoves();
1297
1298 if (moves1.length == 0)
1299 // TODO: this situation should not happen
1300 return null;
1301
1302 // Rank moves using a min-max at depth 2 (if search_depth >= 2!)
1303 for (let i = 0; i < moves1.length; i++) {
1304 this.play(moves1[i]);
1305 const score1 = this.getCurrentScore();
1306 if (score1 != "*") {
1307 moves1[i].eval =
1308 score1 == "1/2"
1309 ? 0
1310 : (score1 == "1-0" ? 1 : -1) * maxeval;
1311 }
1312 if (V.SEARCH_DEPTH == 1 || score1 != "*") {
1313 if (!moves1[i].eval) moves1[i].eval = this.evalPosition();
1314 this.undo(moves1[i]);
1315 continue;
1316 }
1317 // Initial self evaluation is very low: "I'm checkmated"
1318 moves1[i].eval = (color == "w" ? -1 : 1) * maxeval;
1319 // Initial enemy evaluation is very low too, for him
1320 let eval2 = (color == "w" ? 1 : -1) * maxeval;
1321 // Second half-move:
1322 let moves2 = this.getAllValidMoves();
1323 for (let j = 0; j < moves2.length; j++) {
1324 this.play(moves2[j]);
1325 const score2 = this.getCurrentScore();
1326 let evalPos = 0; //1/2 value
1327 switch (score2) {
1328 case "*":
1329 evalPos = this.evalPosition();
1330 break;
1331 case "1-0":
1332 evalPos = maxeval;
1333 break;
1334 case "0-1":
1335 evalPos = -maxeval;
1336 break;
1337 }
1338 if (
1339 (color == "w" && evalPos < eval2) ||
1340 (color == "b" && evalPos > eval2)
1341 ) {
1342 eval2 = evalPos;
1343 }
1344 this.undo(moves2[j]);
1345 }
1346 if (
1347 (color == "w" && eval2 > moves1[i].eval) ||
1348 (color == "b" && eval2 < moves1[i].eval)
1349 ) {
1350 moves1[i].eval = eval2;
1351 }
1352 this.undo(moves1[i]);
1353 }
1354 moves1.sort((a, b) => {
1355 return (color == "w" ? 1 : -1) * (b.eval - a.eval);
1356 });
1357 // console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
1358
1359 // Skip depth 3+ if we found a checkmate (or if we are checkmated in 1...)
1360 if (V.SEARCH_DEPTH >= 3 && Math.abs(moves1[0].eval) < V.THRESHOLD_MATE) {
1361 for (let i = 0; i < moves1.length; i++) {
1362 this.play(moves1[i]);
1363 // 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
1364 moves1[i].eval =
1365 0.1 * moves1[i].eval +
1366 this.alphabeta(V.SEARCH_DEPTH - 1, -maxeval, maxeval);
1367 this.undo(moves1[i]);
1368 }
1369 moves1.sort((a, b) => {
1370 return (color == "w" ? 1 : -1) * (b.eval - a.eval);
1371 });
1372 }
1373
1374 let candidates = [0];
1375 for (let i = 1; i < moves1.length && moves1[i].eval == moves1[0].eval; i++)
1376 candidates.push(i);
1377 return moves1[candidates[randInt(candidates.length)]];
1378 }
1379
1380 alphabeta(depth, alpha, beta) {
1381 const maxeval = V.INFINITY;
1382 const color = this.turn;
1383 const score = this.getCurrentScore();
1384 if (score != "*")
1385 return score == "1/2" ? 0 : (score == "1-0" ? 1 : -1) * maxeval;
1386 if (depth == 0) return this.evalPosition();
1387 const moves = this.getAllValidMoves();
1388 let v = color == "w" ? -maxeval : maxeval;
1389 if (color == "w") {
1390 for (let i = 0; i < moves.length; i++) {
1391 this.play(moves[i]);
1392 v = Math.max(v, this.alphabeta(depth - 1, alpha, beta));
1393 this.undo(moves[i]);
1394 alpha = Math.max(alpha, v);
1395 if (alpha >= beta) break; //beta cutoff
1396 }
1397 }
1398 else {
1399 // color=="b"
1400 for (let i = 0; i < moves.length; i++) {
1401 this.play(moves[i]);
1402 v = Math.min(v, this.alphabeta(depth - 1, alpha, beta));
1403 this.undo(moves[i]);
1404 beta = Math.min(beta, v);
1405 if (alpha >= beta) break; //alpha cutoff
1406 }
1407 }
1408 return v;
1409 }
1410
1411 evalPosition() {
1412 let evaluation = 0;
1413 // Just count material for now
1414 for (let i = 0; i < V.size.x; i++) {
1415 for (let j = 0; j < V.size.y; j++) {
1416 if (this.board[i][j] != V.EMPTY) {
1417 const sign = this.getColor(i, j) == "w" ? 1 : -1;
1418 evaluation += sign * V.VALUES[this.getPiece(i, j)];
1419 }
1420 }
1421 }
1422 return evaluation;
1423 }
1424
1425 /////////////////////////
1426 // MOVES + GAME NOTATION
1427 /////////////////////////
1428
1429 // Context: just before move is played, turn hasn't changed
1430 // TODO: un-ambiguous notation (switch on piece type, check directions...)
1431 getNotation(move) {
1432 if (move.appear.length == 2 && move.appear[0].p == V.KING)
1433 // Castle
1434 return move.end.y < move.start.y ? "0-0-0" : "0-0";
1435
1436 // Translate final square
1437 const finalSquare = V.CoordsToSquare(move.end);
1438
1439 const piece = this.getPiece(move.start.x, move.start.y);
1440 if (piece == V.PAWN) {
1441 // Pawn move
1442 let notation = "";
1443 if (move.vanish.length > move.appear.length) {
1444 // Capture
1445 const startColumn = V.CoordToColumn(move.start.y);
1446 notation = startColumn + "x" + finalSquare;
1447 }
1448 else notation = finalSquare;
1449 if (move.appear.length > 0 && move.appear[0].p != V.PAWN)
1450 // Promotion
1451 notation += "=" + move.appear[0].p.toUpperCase();
1452 return notation;
1453 }
1454 // Piece movement
1455 return (
1456 piece.toUpperCase() +
1457 (move.vanish.length > move.appear.length ? "x" : "") +
1458 finalSquare
1459 );
1460 }
1461
1462 static GetUnambiguousNotation(move) {
1463 // Machine-readable format with all the informations about the move
1464 return (
1465 (!!move.start && V.OnBoard(move.start.x, move.start.y)
1466 ? V.CoordsToSquare(move.start)
1467 : "-"
1468 ) + "." +
1469 (!!move.end && V.OnBoard(move.end.x, move.end.y)
1470 ? V.CoordsToSquare(move.end)
1471 : "-"
1472 ) + " " +
1473 (!!move.appear && move.appear.length > 0
1474 ? move.appear.map(a =>
1475 a.c + a.p + V.CoordsToSquare({ x: a.x, y: a.y })).join(".")
1476 : "-"
1477 ) + "/" +
1478 (!!move.vanish && move.vanish.length > 0
1479 ? move.vanish.map(a =>
1480 a.c + a.p + V.CoordsToSquare({ x: a.x, y: a.y })).join(".")
1481 : "-"
1482 )
1483 );
1484 }
1485
1486 };