937b5741eb5e27ecaff450ad70d8723df8573d02
[vchess.git] / client / src / variants / Checkered.js
1 import { ChessRules, Move, PiPo } from "@/base_rules";
2
3 export const VariantRules = class CheckeredRules extends ChessRules {
4 static board2fen(b) {
5 const checkered_codes = {
6 p: "s",
7 q: "t",
8 r: "u",
9 b: "c",
10 n: "o"
11 };
12 if (b[0] == "c") return checkered_codes[b[1]];
13 return ChessRules.board2fen(b);
14 }
15
16 static fen2board(f) {
17 // Tolerate upper-case versions of checkered pieces (why not?)
18 const checkered_pieces = {
19 s: "p",
20 S: "p",
21 t: "q",
22 T: "q",
23 u: "r",
24 U: "r",
25 c: "b",
26 C: "b",
27 o: "n",
28 O: "n"
29 };
30 if (Object.keys(checkered_pieces).includes(f))
31 return "c" + checkered_pieces[f];
32 return ChessRules.fen2board(f);
33 }
34
35 static get PIECES() {
36 return ChessRules.PIECES.concat(["s", "t", "u", "c", "o"]);
37 }
38
39 getPpath(b) {
40 return (b[0] == "c" ? "Checkered/" : "") + b;
41 }
42
43 setOtherVariables(fen) {
44 super.setOtherVariables(fen);
45 // Local stack of non-capturing checkered moves:
46 this.cmoves = [];
47 const cmove = V.ParseFen(fen).cmove;
48 if (cmove == "-") this.cmoves.push(null);
49 else {
50 this.cmoves.push({
51 start: ChessRules.SquareToCoords(cmove.substr(0, 2)),
52 end: ChessRules.SquareToCoords(cmove.substr(2))
53 });
54 }
55 }
56
57 static IsGoodFen(fen) {
58 if (!ChessRules.IsGoodFen(fen)) return false;
59 const fenParts = fen.split(" ");
60 if (fenParts.length != 6) return false;
61 if (fenParts[5] != "-" && !fenParts[5].match(/^([a-h][1-8]){2}$/))
62 return false;
63 return true;
64 }
65
66 static IsGoodFlags(flags) {
67 // 4 for castle + 16 for pawns
68 return !!flags.match(/^[a-z]{4,4}[01]{16,16}$/);
69 }
70
71 setFlags(fenflags) {
72 super.setFlags(fenflags); //castleFlags
73 this.pawnFlags = {
74 w: [...Array(8).fill(true)], //pawns can move 2 squares?
75 b: [...Array(8).fill(true)]
76 };
77 const flags = fenflags.substr(4); //skip first 4 letters, for castle
78 for (let c of ["w", "b"]) {
79 for (let i = 0; i < 8; i++)
80 this.pawnFlags[c][i] = flags.charAt((c == "w" ? 0 : 8) + i) == "1";
81 }
82 }
83
84 aggregateFlags() {
85 return [this.castleFlags, this.pawnFlags];
86 }
87
88 disaggregateFlags(flags) {
89 this.castleFlags = flags[0];
90 this.pawnFlags = flags[1];
91 }
92
93 getEpSquare(moveOrSquare) {
94 if (typeof moveOrSquare !== "object" || moveOrSquare.appear[0].c != 'c')
95 return super.getEpSquare(moveOrSquare);
96 // Checkered move: no en-passant
97 return undefined;
98 }
99
100 getCmove(move) {
101 if (move.appear[0].c == "c" && move.vanish.length == 1)
102 return { start: move.start, end: move.end };
103 return null;
104 }
105
106 canTake([x1, y1], [x2, y2]) {
107 const color1 = this.getColor(x1, y1);
108 const color2 = this.getColor(x2, y2);
109 // Checkered aren't captured
110 return (
111 color1 != color2 &&
112 color2 != "c" &&
113 (color1 != "c" || color2 != this.turn)
114 );
115 }
116
117 // Post-processing: apply "checkerization" of standard moves
118 getPotentialMovesFrom([x, y]) {
119 let standardMoves = super.getPotentialMovesFrom([x, y]);
120 const lastRank = this.turn == "w" ? 0 : 7;
121 // King has to be treated differently (for castles)
122 if (this.getPiece(x, y) == V.KING) return standardMoves;
123 let moves = [];
124 standardMoves.forEach(m => {
125 if (m.vanish[0].p == V.PAWN) {
126 if (
127 Math.abs(m.end.x - m.start.x) == 2 &&
128 !this.pawnFlags[this.turn][m.start.y]
129 )
130 return; //skip forbidden 2-squares jumps
131 if (
132 this.board[m.end.x][m.end.y] == V.EMPTY &&
133 m.vanish.length == 2 &&
134 this.getColor(m.start.x, m.start.y) == "c"
135 ) {
136 return; //checkered pawns cannot take en-passant
137 }
138 }
139 if (m.vanish.length == 1) moves.push(m);
140 // No capture
141 else {
142 // A capture occured (m.vanish.length == 2)
143 m.appear[0].c = "c";
144 moves.push(m);
145 if (
146 m.appear[0].p != m.vanish[1].p && //avoid promotions (already treated):
147 (m.vanish[0].p != V.PAWN || m.end.x != lastRank)
148 ) {
149 // Add transformation into captured piece
150 let m2 = JSON.parse(JSON.stringify(m));
151 m2.appear[0].p = m.vanish[1].p;
152 moves.push(m2);
153 }
154 }
155 });
156 return moves;
157 }
158
159 getPotentialPawnMoves([x, y]) {
160 const color = this.turn;
161 let moves = [];
162 const [sizeX, sizeY] = [V.size.x, V.size.y];
163 const shiftX = color == "w" ? -1 : 1;
164 const startRank = color == "w" ? sizeX - 2 : 1;
165 const lastRank = color == "w" ? 0 : sizeX - 1;
166 const pawnColor = this.getColor(x, y); //can be checkered
167
168 const finalPieces =
169 x + shiftX == lastRank
170 ? [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN]
171 : [V.PAWN];
172 if (this.board[x + shiftX][y] == V.EMPTY) {
173 // One square forward
174 for (let piece of finalPieces) {
175 moves.push(
176 this.getBasicMove([x, y], [x + shiftX, y], {
177 c: pawnColor,
178 p: piece
179 })
180 );
181 }
182 if (
183 x == startRank &&
184 this.board[x + 2 * shiftX][y] == V.EMPTY
185 ) {
186 // Two squares jump
187 moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
188 }
189 }
190 // Captures
191 for (let shiftY of [-1, 1]) {
192 if (
193 y + shiftY >= 0 &&
194 y + shiftY < sizeY &&
195 this.board[x + shiftX][y + shiftY] != V.EMPTY &&
196 this.canTake([x, y], [x + shiftX, y + shiftY])
197 ) {
198 for (let piece of finalPieces) {
199 moves.push(
200 this.getBasicMove([x, y], [x + shiftX, y + shiftY], {
201 c: pawnColor,
202 p: piece
203 })
204 );
205 }
206 }
207 }
208
209 // En passant
210 const Lep = this.epSquares.length;
211 const epSquare = this.epSquares[Lep - 1]; //always at least one element
212 if (
213 !!epSquare &&
214 epSquare.x == x + shiftX &&
215 Math.abs(epSquare.y - y) == 1
216 ) {
217 let enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
218 enpassantMove.vanish.push({
219 x: x,
220 y: epSquare.y,
221 p: "p",
222 c: this.getColor(x, epSquare.y)
223 });
224 moves.push(enpassantMove);
225 }
226
227 return moves;
228 }
229
230 // Same as in base_rules but with an array given to isAttacked:
231 getCastleMoves([x, y]) {
232 const c = this.getColor(x, y);
233 if (x != (c == "w" ? V.size.x - 1 : 0) || y != this.INIT_COL_KING[c])
234 return []; //x isn't first rank, or king has moved (shortcut)
235
236 // Castling ?
237 const oppCol = V.GetOppCol(c);
238 let moves = [];
239 let i = 0;
240 // King, then rook:
241 const finalSquares = [
242 [2, 3],
243 [V.size.y - 2, V.size.y - 3]
244 ];
245 castlingCheck: for (
246 let castleSide = 0;
247 castleSide < 2;
248 castleSide++ //large, then small
249 ) {
250 if (this.castleFlags[c][castleSide] >= V.size.y) continue;
251 // If this code is reached, rooks and king are on initial position
252
253 // Nothing on the path of the king ? (and no checks)
254 const finDist = finalSquares[castleSide][0] - y;
255 let step = finDist / Math.max(1, Math.abs(finDist));
256 i = y;
257 do {
258 if (
259 this.isAttacked([x, i], [oppCol]) ||
260 (this.board[x][i] != V.EMPTY &&
261 // NOTE: next check is enough, because of chessboard constraints
262 (this.getColor(x, i) != c ||
263 ![V.KING, V.ROOK].includes(this.getPiece(x, i))))
264 ) {
265 continue castlingCheck;
266 }
267 i += step;
268 } while (i != finalSquares[castleSide][0]);
269
270 // Nothing on the path to the rook?
271 step = castleSide == 0 ? -1 : 1;
272 const rookPos = this.castleFlags[c][castleSide];
273 for (i = y + step; i != rookPos; i += step) {
274 if (this.board[x][i] != V.EMPTY) continue castlingCheck;
275 }
276
277 // Nothing on final squares, except maybe king and castling rook?
278 for (i = 0; i < 2; i++) {
279 if (
280 this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
281 this.getPiece(x, finalSquares[castleSide][i]) != V.KING &&
282 finalSquares[castleSide][i] != rookPos
283 ) {
284 continue castlingCheck;
285 }
286 }
287
288 // If this code is reached, castle is valid
289 moves.push(
290 new Move({
291 appear: [
292 new PiPo({ x: x, y: finalSquares[castleSide][0], p: V.KING, c: c }),
293 new PiPo({ x: x, y: finalSquares[castleSide][1], p: V.ROOK, c: c })
294 ],
295 vanish: [
296 new PiPo({ x: x, y: y, p: V.KING, c: c }),
297 new PiPo({ x: x, y: rookPos, p: V.ROOK, c: c })
298 ],
299 end:
300 Math.abs(y - rookPos) <= 2
301 ? { x: x, y: rookPos }
302 : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) }
303 })
304 );
305 }
306
307 return moves;
308 }
309
310 canIplay(side, [x, y]) {
311 return side == this.turn && [side, "c"].includes(this.getColor(x, y));
312 }
313
314 // Does m2 un-do m1 ? (to disallow undoing checkered moves)
315 oppositeMoves(m1, m2) {
316 return (
317 m1 &&
318 m2.appear[0].c == "c" &&
319 m2.appear.length == 1 &&
320 m2.vanish.length == 1 &&
321 m1.start.x == m2.end.x &&
322 m1.end.x == m2.start.x &&
323 m1.start.y == m2.end.y &&
324 m1.end.y == m2.start.y
325 );
326 }
327
328 filterValid(moves) {
329 if (moves.length == 0) return [];
330 const color = this.turn;
331 const L = this.cmoves.length; //at least 1: init from FEN
332 return moves.filter(m => {
333 if (this.oppositeMoves(this.cmoves[L - 1], m)) return false;
334 this.play(m);
335 const res = !this.underCheck(color);
336 this.undo(m);
337 return res;
338 });
339 }
340
341 getAllValidMoves() {
342 const oppCol = V.GetOppCol(this.turn);
343 let potentialMoves = [];
344 for (let i = 0; i < V.size.x; i++) {
345 for (let j = 0; j < V.size.y; j++) {
346 // NOTE: just testing == color isn't enough because of checkred pieces
347 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) != oppCol) {
348 Array.prototype.push.apply(
349 potentialMoves,
350 this.getPotentialMovesFrom([i, j])
351 );
352 }
353 }
354 }
355 return this.filterValid(potentialMoves);
356 }
357
358 atLeastOneMove() {
359 const oppCol = V.GetOppCol(this.turn);
360 for (let i = 0; i < V.size.x; i++) {
361 for (let j = 0; j < V.size.y; j++) {
362 // NOTE: just testing == color isn't enough because of checkered pieces
363 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) != oppCol) {
364 const moves = this.getPotentialMovesFrom([i, j]);
365 if (moves.length > 0) {
366 for (let k = 0; k < moves.length; k++) {
367 if (this.filterValid([moves[k]]).length > 0) return true;
368 }
369 }
370 }
371 }
372 }
373 return false;
374 }
375
376 // colors: array, generally 'w' and 'c' or 'b' and 'c'
377 isAttacked(sq, colors) {
378 return (
379 this.isAttackedByPawn(sq, colors) ||
380 this.isAttackedByRook(sq, colors) ||
381 this.isAttackedByKnight(sq, colors) ||
382 this.isAttackedByBishop(sq, colors) ||
383 this.isAttackedByQueen(sq, colors) ||
384 this.isAttackedByKing(sq, colors)
385 );
386 }
387
388 isAttackedByPawn([x, y], colors) {
389 for (let c of colors) {
390 const color = (c == "c" ? this.turn : c);
391 let pawnShift = color == "w" ? 1 : -1;
392 if (x + pawnShift >= 0 && x + pawnShift < 8) {
393 for (let i of [-1, 1]) {
394 if (
395 y + i >= 0 &&
396 y + i < 8 &&
397 this.getPiece(x + pawnShift, y + i) == V.PAWN &&
398 this.getColor(x + pawnShift, y + i) == c
399 ) {
400 return true;
401 }
402 }
403 }
404 }
405 return false;
406 }
407
408 isAttackedBySlideNJump([x, y], colors, piece, steps, oneStep) {
409 for (let step of steps) {
410 let rx = x + step[0],
411 ry = y + step[1];
412 while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
413 rx += step[0];
414 ry += step[1];
415 }
416 if (
417 V.OnBoard(rx, ry) &&
418 this.getPiece(rx, ry) === piece &&
419 colors.includes(this.getColor(rx, ry))
420 ) {
421 return true;
422 }
423 }
424 return false;
425 }
426
427 isAttackedByRook(sq, colors) {
428 return this.isAttackedBySlideNJump(sq, colors, V.ROOK, V.steps[V.ROOK]);
429 }
430
431 isAttackedByKnight(sq, colors) {
432 return this.isAttackedBySlideNJump(
433 sq,
434 colors,
435 V.KNIGHT,
436 V.steps[V.KNIGHT],
437 "oneStep"
438 );
439 }
440
441 isAttackedByBishop(sq, colors) {
442 return this.isAttackedBySlideNJump(sq, colors, V.BISHOP, V.steps[V.BISHOP]);
443 }
444
445 isAttackedByQueen(sq, colors) {
446 return this.isAttackedBySlideNJump(
447 sq,
448 colors,
449 V.QUEEN,
450 V.steps[V.ROOK].concat(V.steps[V.BISHOP])
451 );
452 }
453
454 isAttackedByKing(sq, colors) {
455 return this.isAttackedBySlideNJump(
456 sq,
457 colors,
458 V.KING,
459 V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
460 "oneStep"
461 );
462 }
463
464 underCheck(color) {
465 return this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"]);
466 }
467
468 getCheckSquares(color) {
469 // Artifically change turn, for checkered pawns
470 this.turn = V.GetOppCol(color);
471 const kingAttacked = this.isAttacked(this.kingPos[color], [
472 V.GetOppCol(color),
473 "c"
474 ]);
475 let res = kingAttacked
476 ? [JSON.parse(JSON.stringify(this.kingPos[color]))] //need to duplicate!
477 : [];
478 this.turn = color;
479 return res;
480 }
481
482 postPlay(move) {
483 super.postPlay(move);
484 // Does this move turn off a 2-squares pawn flag?
485 if ([1, 6].includes(move.start.x) && move.vanish[0].p == V.PAWN)
486 this.pawnFlags[move.start.x == 6 ? "w" : "b"][move.start.y] = false;
487 this.cmoves.push(this.getCmove(move));
488 }
489
490 postUndo(move) {
491 super.postUndo(move);
492 this.cmoves.pop();
493 }
494
495 getCurrentScore() {
496 if (this.atLeastOneMove())
497 // game not over
498 return "*";
499
500 const color = this.turn;
501 // Artifically change turn, for checkered pawns
502 this.turn = V.GetOppCol(this.turn);
503 const res = this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"])
504 ? color == "w"
505 ? "0-1"
506 : "1-0"
507 : "1/2";
508 this.turn = V.GetOppCol(this.turn);
509 return res;
510 }
511
512 evalPosition() {
513 let evaluation = 0;
514 // Just count material for now, considering checkered neutral (...)
515 for (let i = 0; i < V.size.x; i++) {
516 for (let j = 0; j < V.size.y; j++) {
517 if (this.board[i][j] != V.EMPTY) {
518 const sqColor = this.getColor(i, j);
519 if (["w","b"].includes(sqColor)) {
520 const sign = sqColor == "w" ? 1 : -1;
521 evaluation += sign * V.VALUES[this.getPiece(i, j)];
522 }
523 }
524 }
525 }
526 return evaluation;
527 }
528
529 static GenRandInitFen(randomness) {
530 // Add 16 pawns flags + empty cmove:
531 return ChessRules.GenRandInitFen(randomness)
532 .slice(0, -2) + "1111111111111111 - -";
533 }
534
535 static ParseFen(fen) {
536 return Object.assign({}, ChessRules.ParseFen(fen), {
537 cmove: fen.split(" ")[5]
538 });
539 }
540
541 getFen() {
542 const L = this.cmoves.length;
543 const cmoveFen = !this.cmoves[L - 1]
544 ? "-"
545 : ChessRules.CoordsToSquare(this.cmoves[L - 1].start) +
546 ChessRules.CoordsToSquare(this.cmoves[L - 1].end);
547 return super.getFen() + " " + cmoveFen;
548 }
549
550 getFlagsFen() {
551 let fen = super.getFlagsFen();
552 // Add pawns flags
553 for (let c of ["w", "b"]) {
554 for (let i = 0; i < 8; i++) fen += this.pawnFlags[c][i] ? "1" : "0";
555 }
556 return fen;
557 }
558
559 static get SEARCH_DEPTH() {
560 return 2;
561 }
562
563 getNotation(move) {
564 if (move.appear.length == 2) {
565 // Castle
566 if (move.end.y < move.start.y) return "0-0-0";
567 return "0-0";
568 }
569
570 // Translate final square
571 const finalSquare = V.CoordsToSquare(move.end);
572
573 const piece = this.getPiece(move.start.x, move.start.y);
574 if (piece == V.PAWN) {
575 // Pawn move
576 let notation = "";
577 if (move.vanish.length > 1) {
578 // Capture
579 const startColumn = V.CoordToColumn(move.start.y);
580 notation =
581 startColumn +
582 "x" +
583 finalSquare +
584 "=" +
585 move.appear[0].p.toUpperCase();
586 } //no capture
587 else {
588 notation = finalSquare;
589 if (move.appear.length > 0 && piece != move.appear[0].p)
590 //promotion
591 notation += "=" + move.appear[0].p.toUpperCase();
592 }
593 return notation;
594 }
595 // Piece movement
596 return (
597 piece.toUpperCase() +
598 (move.vanish.length > 1 ? "x" : "") +
599 finalSquare +
600 (move.vanish.length > 1 ? "=" + move.appear[0].p.toUpperCase() : "")
601 );
602 }
603 };