Generalize pawn movements: cleaner and smaller code
[vchess.git] / client / src / variants / Checkered.js
CommitLineData
68e19a44 1import { ChessRules, Move, PiPo } from "@/base_rules";
0c3fe8a6 2
32f6285e 3export class CheckeredRules extends ChessRules {
6808d7a1 4 static board2fen(b) {
dac39588 5 const checkered_codes = {
6808d7a1
BA
6 p: "s",
7 q: "t",
8 r: "u",
9 b: "c",
10 n: "o"
dac39588 11 };
6808d7a1 12 if (b[0] == "c") return checkered_codes[b[1]];
dac39588
BA
13 return ChessRules.board2fen(b);
14 }
15
6808d7a1 16 static fen2board(f) {
dac39588
BA
17 // Tolerate upper-case versions of checkered pieces (why not?)
18 const checkered_pieces = {
6808d7a1
BA
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"
dac39588
BA
29 };
30 if (Object.keys(checkered_pieces).includes(f))
6808d7a1 31 return "c" + checkered_pieces[f];
dac39588
BA
32 return ChessRules.fen2board(f);
33 }
34
6808d7a1
BA
35 static get PIECES() {
36 return ChessRules.PIECES.concat(["s", "t", "u", "c", "o"]);
dac39588 37 }
7931e479 38
241bf8f2 39 getPpath(b) {
d1be8046 40 return (b[0] == "c" ? "Checkered/" : "") + b;
241bf8f2
BA
41 }
42
6808d7a1 43 setOtherVariables(fen) {
03cff0f7
BA
44 super.setOtherVariables(fen);
45 // Local stack of non-capturing checkered moves:
46 this.cmoves = [];
3a2a7b5f 47 const cmove = V.ParseFen(fen).cmove;
6808d7a1
BA
48 if (cmove == "-") this.cmoves.push(null);
49 else {
03cff0f7 50 this.cmoves.push({
6808d7a1
BA
51 start: ChessRules.SquareToCoords(cmove.substr(0, 2)),
52 end: ChessRules.SquareToCoords(cmove.substr(2))
03cff0f7
BA
53 });
54 }
55 }
56
6808d7a1
BA
57 static IsGoodFen(fen) {
58 if (!ChessRules.IsGoodFen(fen)) return false;
03cff0f7 59 const fenParts = fen.split(" ");
6808d7a1 60 if (fenParts.length != 6) return false;
03cff0f7
BA
61 if (fenParts[5] != "-" && !fenParts[5].match(/^([a-h][1-8]){2}$/))
62 return false;
63 return true;
64 }
65
6808d7a1 66 static IsGoodFlags(flags) {
dac39588 67 // 4 for castle + 16 for pawns
3a2a7b5f 68 return !!flags.match(/^[a-z]{4,4}[01]{16,16}$/);
dac39588
BA
69 }
70
6808d7a1 71 setFlags(fenflags) {
dac39588 72 super.setFlags(fenflags); //castleFlags
6808d7a1
BA
73 this.pawnFlags = {
74 w: [...Array(8).fill(true)], //pawns can move 2 squares?
75 b: [...Array(8).fill(true)]
dac39588 76 };
3a2a7b5f 77 const flags = fenflags.substr(4); //skip first 4 letters, for castle
6808d7a1
BA
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";
dac39588
BA
81 }
82 }
83
6808d7a1 84 aggregateFlags() {
dac39588
BA
85 return [this.castleFlags, this.pawnFlags];
86 }
87
6808d7a1 88 disaggregateFlags(flags) {
dac39588
BA
89 this.castleFlags = flags[0];
90 this.pawnFlags = flags[1];
91 }
1d184b4c 92
e727fe31 93 getEpSquare(moveOrSquare) {
bbf66837 94 if (typeof moveOrSquare !== "object" || moveOrSquare.appear[0].c != 'c')
e727fe31
BA
95 return super.getEpSquare(moveOrSquare);
96 // Checkered move: no en-passant
97 return undefined;
98 }
99
6808d7a1
BA
100 getCmove(move) {
101 if (move.appear[0].c == "c" && move.vanish.length == 1)
102 return { start: move.start, end: move.end };
03cff0f7
BA
103 return null;
104 }
105
6808d7a1
BA
106 canTake([x1, y1], [x2, y2]) {
107 const color1 = this.getColor(x1, y1);
108 const color2 = this.getColor(x2, y2);
dac39588 109 // Checkered aren't captured
6808d7a1
BA
110 return (
111 color1 != color2 &&
112 color2 != "c" &&
113 (color1 != "c" || color2 != this.turn)
114 );
dac39588
BA
115 }
116
117 // Post-processing: apply "checkerization" of standard moves
6808d7a1
BA
118 getPotentialMovesFrom([x, y]) {
119 let standardMoves = super.getPotentialMovesFrom([x, y]);
dac39588 120 const lastRank = this.turn == "w" ? 0 : 7;
32f6285e 121 // King is treated differently: it never turn checkered
71ef1664 122 if (this.getPiece(x, y) == V.KING) return standardMoves;
dac39588
BA
123 let moves = [];
124 standardMoves.forEach(m => {
6808d7a1
BA
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]
32f6285e 129 ) {
dac39588 130 return; //skip forbidden 2-squares jumps
32f6285e 131 }
6808d7a1
BA
132 if (
133 this.board[m.end.x][m.end.y] == V.EMPTY &&
134 m.vanish.length == 2 &&
135 this.getColor(m.start.x, m.start.y) == "c"
136 ) {
dac39588
BA
137 return; //checkered pawns cannot take en-passant
138 }
139 }
32f6285e
BA
140 if (m.vanish.length == 1)
141 // No capture
142 moves.push(m);
6808d7a1 143 else {
dac39588
BA
144 // A capture occured (m.vanish.length == 2)
145 m.appear[0].c = "c";
146 moves.push(m);
6808d7a1 147 if (
32f6285e
BA
148 // Avoid promotions (already treated):
149 m.appear[0].p != m.vanish[1].p &&
6808d7a1
BA
150 (m.vanish[0].p != V.PAWN || m.end.x != lastRank)
151 ) {
dac39588
BA
152 // Add transformation into captured piece
153 let m2 = JSON.parse(JSON.stringify(m));
154 m2.appear[0].p = m.vanish[1].p;
155 moves.push(m2);
156 }
157 }
158 });
159 return moves;
160 }
161
e727fe31 162 getPotentialPawnMoves([x, y]) {
32f6285e
BA
163 let moves = super.getPotentialPawnMoves([x, y]);
164 // Post-process: set right color for checkered moves
165 if (this.getColor(x, y) == 'c')
166 moves.forEach(m => {
167 m.appear[0].c = 'c'; //may be done twice if capture
168 m.vanish[0].c = 'c';
e727fe31 169 });
68e19a44
BA
170 return moves;
171 }
172
6808d7a1
BA
173 canIplay(side, [x, y]) {
174 return side == this.turn && [side, "c"].includes(this.getColor(x, y));
dac39588
BA
175 }
176
177 // Does m2 un-do m1 ? (to disallow undoing checkered moves)
6808d7a1
BA
178 oppositeMoves(m1, m2) {
179 return (
241bf8f2 180 m1 &&
6808d7a1
BA
181 m2.appear[0].c == "c" &&
182 m2.appear.length == 1 &&
183 m2.vanish.length == 1 &&
184 m1.start.x == m2.end.x &&
185 m1.end.x == m2.start.x &&
186 m1.start.y == m2.end.y &&
187 m1.end.y == m2.start.y
188 );
dac39588
BA
189 }
190
6808d7a1
BA
191 filterValid(moves) {
192 if (moves.length == 0) return [];
dac39588 193 const color = this.turn;
241bf8f2 194 const L = this.cmoves.length; //at least 1: init from FEN
dac39588 195 return moves.filter(m => {
6808d7a1 196 if (this.oppositeMoves(this.cmoves[L - 1], m)) return false;
dac39588
BA
197 this.play(m);
198 const res = !this.underCheck(color);
199 this.undo(m);
200 return res;
201 });
202 }
203
d1be8046
BA
204 getAllValidMoves() {
205 const oppCol = V.GetOppCol(this.turn);
206 let potentialMoves = [];
207 for (let i = 0; i < V.size.x; i++) {
208 for (let j = 0; j < V.size.y; j++) {
209 // NOTE: just testing == color isn't enough because of checkred pieces
210 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) != oppCol) {
211 Array.prototype.push.apply(
212 potentialMoves,
213 this.getPotentialMovesFrom([i, j])
214 );
215 }
216 }
217 }
218 return this.filterValid(potentialMoves);
219 }
220
221 atLeastOneMove() {
222 const oppCol = V.GetOppCol(this.turn);
223 for (let i = 0; i < V.size.x; i++) {
224 for (let j = 0; j < V.size.y; j++) {
b83a675a 225 // NOTE: just testing == color isn't enough because of checkered pieces
d1be8046
BA
226 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) != oppCol) {
227 const moves = this.getPotentialMovesFrom([i, j]);
228 if (moves.length > 0) {
229 for (let k = 0; k < moves.length; k++) {
230 if (this.filterValid([moves[k]]).length > 0) return true;
231 }
232 }
233 }
234 }
235 }
236 return false;
237 }
238
68e19a44
BA
239 // colors: array, generally 'w' and 'c' or 'b' and 'c'
240 isAttacked(sq, colors) {
32f6285e 241 if (!Array.isArray(colors)) colors = [colors];
68e19a44
BA
242 return (
243 this.isAttackedByPawn(sq, colors) ||
244 this.isAttackedByRook(sq, colors) ||
245 this.isAttackedByKnight(sq, colors) ||
246 this.isAttackedByBishop(sq, colors) ||
247 this.isAttackedByQueen(sq, colors) ||
248 this.isAttackedByKing(sq, colors)
249 );
250 }
251
6808d7a1
BA
252 isAttackedByPawn([x, y], colors) {
253 for (let c of colors) {
68e19a44 254 const color = (c == "c" ? this.turn : c);
6808d7a1
BA
255 let pawnShift = color == "w" ? 1 : -1;
256 if (x + pawnShift >= 0 && x + pawnShift < 8) {
257 for (let i of [-1, 1]) {
258 if (
259 y + i >= 0 &&
260 y + i < 8 &&
261 this.getPiece(x + pawnShift, y + i) == V.PAWN &&
262 this.getColor(x + pawnShift, y + i) == c
263 ) {
dac39588
BA
264 return true;
265 }
266 }
267 }
268 }
269 return false;
270 }
271
68e19a44
BA
272 isAttackedBySlideNJump([x, y], colors, piece, steps, oneStep) {
273 for (let step of steps) {
274 let rx = x + step[0],
275 ry = y + step[1];
276 while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
277 rx += step[0];
278 ry += step[1];
279 }
280 if (
281 V.OnBoard(rx, ry) &&
282 this.getPiece(rx, ry) === piece &&
283 colors.includes(this.getColor(rx, ry))
284 ) {
285 return true;
286 }
287 }
288 return false;
289 }
290
291 isAttackedByRook(sq, colors) {
292 return this.isAttackedBySlideNJump(sq, colors, V.ROOK, V.steps[V.ROOK]);
293 }
294
295 isAttackedByKnight(sq, colors) {
296 return this.isAttackedBySlideNJump(
297 sq,
298 colors,
299 V.KNIGHT,
300 V.steps[V.KNIGHT],
301 "oneStep"
302 );
303 }
304
305 isAttackedByBishop(sq, colors) {
306 return this.isAttackedBySlideNJump(sq, colors, V.BISHOP, V.steps[V.BISHOP]);
307 }
308
309 isAttackedByQueen(sq, colors) {
310 return this.isAttackedBySlideNJump(
311 sq,
312 colors,
313 V.QUEEN,
314 V.steps[V.ROOK].concat(V.steps[V.BISHOP])
315 );
316 }
317
318 isAttackedByKing(sq, colors) {
319 return this.isAttackedBySlideNJump(
320 sq,
321 colors,
322 V.KING,
323 V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
324 "oneStep"
325 );
326 }
327
6808d7a1
BA
328 underCheck(color) {
329 return this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"]);
dac39588
BA
330 }
331
6808d7a1 332 getCheckSquares(color) {
dac39588
BA
333 // Artifically change turn, for checkered pawns
334 this.turn = V.GetOppCol(color);
6808d7a1
BA
335 const kingAttacked = this.isAttacked(this.kingPos[color], [
336 V.GetOppCol(color),
337 "c"
338 ]);
dac39588
BA
339 let res = kingAttacked
340 ? [JSON.parse(JSON.stringify(this.kingPos[color]))] //need to duplicate!
341 : [];
342 this.turn = color;
343 return res;
344 }
345
3a2a7b5f
BA
346 postPlay(move) {
347 super.postPlay(move);
dac39588 348 // Does this move turn off a 2-squares pawn flag?
3a2a7b5f 349 if ([1, 6].includes(move.start.x) && move.vanish[0].p == V.PAWN)
6808d7a1 350 this.pawnFlags[move.start.x == 6 ? "w" : "b"][move.start.y] = false;
3a2a7b5f
BA
351 this.cmoves.push(this.getCmove(move));
352 }
353
354 postUndo(move) {
355 super.postUndo(move);
356 this.cmoves.pop();
dac39588
BA
357 }
358
6808d7a1
BA
359 getCurrentScore() {
360 if (this.atLeastOneMove())
361 // game not over
0c3fe8a6
BA
362 return "*";
363
364 const color = this.turn;
dac39588
BA
365 // Artifically change turn, for checkered pawns
366 this.turn = V.GetOppCol(this.turn);
6808d7a1
BA
367 const res = this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"])
368 ? color == "w"
369 ? "0-1"
370 : "1-0"
dac39588
BA
371 : "1/2";
372 this.turn = V.GetOppCol(this.turn);
373 return res;
374 }
375
6808d7a1 376 evalPosition() {
dac39588 377 let evaluation = 0;
d1be8046 378 // Just count material for now, considering checkered neutral (...)
6808d7a1
BA
379 for (let i = 0; i < V.size.x; i++) {
380 for (let j = 0; j < V.size.y; j++) {
381 if (this.board[i][j] != V.EMPTY) {
382 const sqColor = this.getColor(i, j);
d1be8046
BA
383 if (["w","b"].includes(sqColor)) {
384 const sign = sqColor == "w" ? 1 : -1;
385 evaluation += sign * V.VALUES[this.getPiece(i, j)];
386 }
dac39588
BA
387 }
388 }
389 }
390 return evaluation;
391 }
392
7ba4a5bc 393 static GenRandInitFen(randomness) {
3a2a7b5f 394 // Add 16 pawns flags + empty cmove:
7ba4a5bc 395 return ChessRules.GenRandInitFen(randomness)
3a2a7b5f 396 .slice(0, -2) + "1111111111111111 - -";
dac39588 397 }
1d184b4c 398
6808d7a1
BA
399 static ParseFen(fen) {
400 return Object.assign({}, ChessRules.ParseFen(fen), {
401 cmove: fen.split(" ")[5]
402 });
03cff0f7
BA
403 }
404
6808d7a1 405 getFen() {
03cff0f7 406 const L = this.cmoves.length;
6808d7a1 407 const cmoveFen = !this.cmoves[L - 1]
03cff0f7 408 ? "-"
6808d7a1
BA
409 : ChessRules.CoordsToSquare(this.cmoves[L - 1].start) +
410 ChessRules.CoordsToSquare(this.cmoves[L - 1].end);
03cff0f7
BA
411 return super.getFen() + " " + cmoveFen;
412 }
413
6808d7a1 414 getFlagsFen() {
dac39588
BA
415 let fen = super.getFlagsFen();
416 // Add pawns flags
6808d7a1
BA
417 for (let c of ["w", "b"]) {
418 for (let i = 0; i < 8; i++) fen += this.pawnFlags[c][i] ? "1" : "0";
dac39588
BA
419 }
420 return fen;
421 }
1d184b4c 422
b83a675a
BA
423 static get SEARCH_DEPTH() {
424 return 2;
425 }
426
6808d7a1
BA
427 getNotation(move) {
428 if (move.appear.length == 2) {
dac39588 429 // Castle
6808d7a1
BA
430 if (move.end.y < move.start.y) return "0-0-0";
431 return "0-0";
dac39588
BA
432 }
433
434 // Translate final square
435 const finalSquare = V.CoordsToSquare(move.end);
436
437 const piece = this.getPiece(move.start.x, move.start.y);
6808d7a1 438 if (piece == V.PAWN) {
dac39588
BA
439 // Pawn move
440 let notation = "";
6808d7a1 441 if (move.vanish.length > 1) {
dac39588
BA
442 // Capture
443 const startColumn = V.CoordToColumn(move.start.y);
6808d7a1
BA
444 notation =
445 startColumn +
446 "x" +
447 finalSquare +
448 "=" +
449 move.appear[0].p.toUpperCase();
450 } //no capture
451 else {
dac39588 452 notation = finalSquare;
6808d7a1
BA
453 if (move.appear.length > 0 && piece != move.appear[0].p)
454 //promotion
dac39588
BA
455 notation += "=" + move.appear[0].p.toUpperCase();
456 }
457 return notation;
458 }
6808d7a1
BA
459 // Piece movement
460 return (
461 piece.toUpperCase() +
462 (move.vanish.length > 1 ? "x" : "") +
463 finalSquare +
464 (move.vanish.length > 1 ? "=" + move.appear[0].p.toUpperCase() : "")
465 );
dac39588 466 }
6808d7a1 467};