0e089f38048f36b4eab74212e335da00f53f7bc0
[vchess.git] / client / src / variants / Checkered.js
1 import { ChessRules } 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 canIplay(side, [x, y]) {
231 return side == this.turn && [side, "c"].includes(this.getColor(x, y));
232 }
233
234 // Does m2 un-do m1 ? (to disallow undoing checkered moves)
235 oppositeMoves(m1, m2) {
236 return (
237 m1 &&
238 m2.appear[0].c == "c" &&
239 m2.appear.length == 1 &&
240 m2.vanish.length == 1 &&
241 m1.start.x == m2.end.x &&
242 m1.end.x == m2.start.x &&
243 m1.start.y == m2.end.y &&
244 m1.end.y == m2.start.y
245 );
246 }
247
248 filterValid(moves) {
249 if (moves.length == 0) return [];
250 const color = this.turn;
251 const L = this.cmoves.length; //at least 1: init from FEN
252 return moves.filter(m => {
253 if (this.oppositeMoves(this.cmoves[L - 1], m)) return false;
254 this.play(m);
255 const res = !this.underCheck(color);
256 this.undo(m);
257 return res;
258 });
259 }
260
261 getAllValidMoves() {
262 const oppCol = V.GetOppCol(this.turn);
263 let potentialMoves = [];
264 for (let i = 0; i < V.size.x; i++) {
265 for (let j = 0; j < V.size.y; j++) {
266 // NOTE: just testing == color isn't enough because of checkred pieces
267 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) != oppCol) {
268 Array.prototype.push.apply(
269 potentialMoves,
270 this.getPotentialMovesFrom([i, j])
271 );
272 }
273 }
274 }
275 return this.filterValid(potentialMoves);
276 }
277
278 atLeastOneMove() {
279 const oppCol = V.GetOppCol(this.turn);
280 for (let i = 0; i < V.size.x; i++) {
281 for (let j = 0; j < V.size.y; j++) {
282 // NOTE: just testing == color isn't enough because of checkered pieces
283 if (this.board[i][j] != V.EMPTY && this.getColor(i, j) != oppCol) {
284 const moves = this.getPotentialMovesFrom([i, j]);
285 if (moves.length > 0) {
286 for (let k = 0; k < moves.length; k++) {
287 if (this.filterValid([moves[k]]).length > 0) return true;
288 }
289 }
290 }
291 }
292 }
293 return false;
294 }
295
296 isAttackedByPawn([x, y], colors) {
297 for (let c of colors) {
298 const color = c == "c" ? this.turn : c;
299 let pawnShift = color == "w" ? 1 : -1;
300 if (x + pawnShift >= 0 && x + pawnShift < 8) {
301 for (let i of [-1, 1]) {
302 if (
303 y + i >= 0 &&
304 y + i < 8 &&
305 this.getPiece(x + pawnShift, y + i) == V.PAWN &&
306 this.getColor(x + pawnShift, y + i) == c
307 ) {
308 return true;
309 }
310 }
311 }
312 }
313 return false;
314 }
315
316 underCheck(color) {
317 return this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"]);
318 }
319
320 getCheckSquares(color) {
321 // Artifically change turn, for checkered pawns
322 this.turn = V.GetOppCol(color);
323 const kingAttacked = this.isAttacked(this.kingPos[color], [
324 V.GetOppCol(color),
325 "c"
326 ]);
327 let res = kingAttacked
328 ? [JSON.parse(JSON.stringify(this.kingPos[color]))] //need to duplicate!
329 : [];
330 this.turn = color;
331 return res;
332 }
333
334 postPlay(move) {
335 super.postPlay(move);
336 // Does this move turn off a 2-squares pawn flag?
337 if ([1, 6].includes(move.start.x) && move.vanish[0].p == V.PAWN)
338 this.pawnFlags[move.start.x == 6 ? "w" : "b"][move.start.y] = false;
339 this.cmoves.push(this.getCmove(move));
340 }
341
342 postUndo(move) {
343 super.postUndo(move);
344 this.cmoves.pop();
345 }
346
347 getCurrentScore() {
348 if (this.atLeastOneMove())
349 // game not over
350 return "*";
351
352 const color = this.turn;
353 // Artifically change turn, for checkered pawns
354 this.turn = V.GetOppCol(this.turn);
355 const res = this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"])
356 ? color == "w"
357 ? "0-1"
358 : "1-0"
359 : "1/2";
360 this.turn = V.GetOppCol(this.turn);
361 return res;
362 }
363
364 evalPosition() {
365 let evaluation = 0;
366 // Just count material for now, considering checkered neutral (...)
367 for (let i = 0; i < V.size.x; i++) {
368 for (let j = 0; j < V.size.y; j++) {
369 if (this.board[i][j] != V.EMPTY) {
370 const sqColor = this.getColor(i, j);
371 if (["w","b"].includes(sqColor)) {
372 const sign = sqColor == "w" ? 1 : -1;
373 evaluation += sign * V.VALUES[this.getPiece(i, j)];
374 }
375 }
376 }
377 }
378 return evaluation;
379 }
380
381 static GenRandInitFen(randomness) {
382 // Add 16 pawns flags + empty cmove:
383 return ChessRules.GenRandInitFen(randomness)
384 .slice(0, -2) + "1111111111111111 - -";
385 }
386
387 static ParseFen(fen) {
388 return Object.assign({}, ChessRules.ParseFen(fen), {
389 cmove: fen.split(" ")[5]
390 });
391 }
392
393 getFen() {
394 const L = this.cmoves.length;
395 const cmoveFen = !this.cmoves[L - 1]
396 ? "-"
397 : ChessRules.CoordsToSquare(this.cmoves[L - 1].start) +
398 ChessRules.CoordsToSquare(this.cmoves[L - 1].end);
399 return super.getFen() + " " + cmoveFen;
400 }
401
402 getFlagsFen() {
403 let fen = super.getFlagsFen();
404 // Add pawns flags
405 for (let c of ["w", "b"]) {
406 for (let i = 0; i < 8; i++) fen += this.pawnFlags[c][i] ? "1" : "0";
407 }
408 return fen;
409 }
410
411 static get SEARCH_DEPTH() {
412 return 2;
413 }
414
415 getNotation(move) {
416 if (move.appear.length == 2) {
417 // Castle
418 if (move.end.y < move.start.y) return "0-0-0";
419 return "0-0";
420 }
421
422 // Translate final square
423 const finalSquare = V.CoordsToSquare(move.end);
424
425 const piece = this.getPiece(move.start.x, move.start.y);
426 if (piece == V.PAWN) {
427 // Pawn move
428 let notation = "";
429 if (move.vanish.length > 1) {
430 // Capture
431 const startColumn = V.CoordToColumn(move.start.y);
432 notation =
433 startColumn +
434 "x" +
435 finalSquare +
436 "=" +
437 move.appear[0].p.toUpperCase();
438 } //no capture
439 else {
440 notation = finalSquare;
441 if (move.appear.length > 0 && piece != move.appear[0].p)
442 //promotion
443 notation += "=" + move.appear[0].p.toUpperCase();
444 }
445 return notation;
446 }
447 // Piece movement
448 return (
449 piece.toUpperCase() +
450 (move.vanish.length > 1 ? "x" : "") +
451 finalSquare +
452 (move.vanish.length > 1 ? "=" + move.appear[0].p.toUpperCase() : "")
453 );
454 }
455 };