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92342261 BA |
1 | // (Orthodox) Chess rules are defined in ChessRules class. |
2 | // Variants generally inherit from it, and modify some parts. | |
3 | ||
e2732923 | 4 | import { ArrayFun } from "@/utils/array"; |
0c3fe8a6 | 5 | import { randInt, shuffle } from "@/utils/alea"; |
e2732923 | 6 | |
910d631b | 7 | // class "PiPo": Piece + Position |
6808d7a1 | 8 | export const PiPo = class PiPo { |
1c9f093d | 9 | // o: {piece[p], color[c], posX[x], posY[y]} |
6808d7a1 | 10 | constructor(o) { |
1c9f093d BA |
11 | this.p = o.p; |
12 | this.c = o.c; | |
13 | this.x = o.x; | |
14 | this.y = o.y; | |
15 | } | |
6808d7a1 | 16 | }; |
1d184b4c | 17 | |
6808d7a1 | 18 | export const Move = class Move { |
1c9f093d BA |
19 | // o: {appear, vanish, [start,] [end,]} |
20 | // appear,vanish = arrays of PiPo | |
21 | // start,end = coordinates to apply to trigger move visually (think castle) | |
6808d7a1 | 22 | constructor(o) { |
1c9f093d BA |
23 | this.appear = o.appear; |
24 | this.vanish = o.vanish; | |
6808d7a1 BA |
25 | this.start = o.start ? o.start : { x: o.vanish[0].x, y: o.vanish[0].y }; |
26 | this.end = o.end ? o.end : { x: o.appear[0].x, y: o.appear[0].y }; | |
1c9f093d | 27 | } |
6808d7a1 | 28 | }; |
1d184b4c BA |
29 | |
30 | // NOTE: x coords = top to bottom; y = left to right (from white player perspective) | |
6808d7a1 | 31 | export const ChessRules = class ChessRules { |
1c9f093d BA |
32 | ////////////// |
33 | // MISC UTILS | |
34 | ||
20620465 | 35 | // Some variants don't have flags: |
6808d7a1 BA |
36 | static get HasFlags() { |
37 | return true; | |
20620465 | 38 | } |
1c9f093d | 39 | |
3a2a7b5f BA |
40 | // Or castle |
41 | static get HasCastle() { | |
42 | return V.HasFlags; | |
43 | } | |
44 | ||
20620465 | 45 | // Some variants don't have en-passant |
6808d7a1 BA |
46 | static get HasEnpassant() { |
47 | return true; | |
20620465 BA |
48 | } |
49 | ||
50 | // Some variants cannot have analyse mode | |
8477e53d | 51 | static get CanAnalyze() { |
20620465 BA |
52 | return true; |
53 | } | |
933fd1f9 BA |
54 | // Patch: issues with javascript OOP, objects can't access static fields. |
55 | get canAnalyze() { | |
56 | return V.CanAnalyze; | |
57 | } | |
20620465 BA |
58 | |
59 | // Some variants show incomplete information, | |
60 | // and thus show only a partial moves list or no list at all. | |
61 | static get ShowMoves() { | |
62 | return "all"; | |
63 | } | |
933fd1f9 BA |
64 | get showMoves() { |
65 | return V.ShowMoves; | |
66 | } | |
1c9f093d | 67 | |
71ef1664 BA |
68 | // Some variants always show the same orientation |
69 | static get CanFlip() { | |
70 | return true; | |
71 | } | |
72 | get canFlip() { | |
73 | return V.CanFlip; | |
74 | } | |
75 | ||
14edde72 BA |
76 | static get IMAGE_EXTENSION() { |
77 | // All pieces should be in the SVG format | |
78 | return ".svg"; | |
79 | } | |
80 | ||
1c9f093d | 81 | // Turn "wb" into "B" (for FEN) |
6808d7a1 BA |
82 | static board2fen(b) { |
83 | return b[0] == "w" ? b[1].toUpperCase() : b[1]; | |
1c9f093d BA |
84 | } |
85 | ||
86 | // Turn "p" into "bp" (for board) | |
6808d7a1 BA |
87 | static fen2board(f) { |
88 | return f.charCodeAt() <= 90 ? "w" + f.toLowerCase() : "b" + f; | |
1c9f093d BA |
89 | } |
90 | ||
89021f18 | 91 | // Check if FEN describe a board situation correctly |
6808d7a1 | 92 | static IsGoodFen(fen) { |
1c9f093d BA |
93 | const fenParsed = V.ParseFen(fen); |
94 | // 1) Check position | |
6808d7a1 | 95 | if (!V.IsGoodPosition(fenParsed.position)) return false; |
1c9f093d | 96 | // 2) Check turn |
6808d7a1 | 97 | if (!fenParsed.turn || !V.IsGoodTurn(fenParsed.turn)) return false; |
1c9f093d BA |
98 | // 3) Check moves count |
99 | if (!fenParsed.movesCount || !(parseInt(fenParsed.movesCount) >= 0)) | |
100 | return false; | |
101 | // 4) Check flags | |
102 | if (V.HasFlags && (!fenParsed.flags || !V.IsGoodFlags(fenParsed.flags))) | |
103 | return false; | |
104 | // 5) Check enpassant | |
6808d7a1 BA |
105 | if ( |
106 | V.HasEnpassant && | |
107 | (!fenParsed.enpassant || !V.IsGoodEnpassant(fenParsed.enpassant)) | |
108 | ) { | |
1c9f093d BA |
109 | return false; |
110 | } | |
111 | return true; | |
112 | } | |
113 | ||
114 | // Is position part of the FEN a priori correct? | |
6808d7a1 BA |
115 | static IsGoodPosition(position) { |
116 | if (position.length == 0) return false; | |
1c9f093d | 117 | const rows = position.split("/"); |
6808d7a1 | 118 | if (rows.length != V.size.x) return false; |
d7c00f6a | 119 | let kings = {}; |
6808d7a1 | 120 | for (let row of rows) { |
1c9f093d | 121 | let sumElts = 0; |
6808d7a1 | 122 | for (let i = 0; i < row.length; i++) { |
d7c00f6a BA |
123 | if (['K','k'].includes(row[i])) |
124 | kings[row[i]] = true; | |
6808d7a1 BA |
125 | if (V.PIECES.includes(row[i].toLowerCase())) sumElts++; |
126 | else { | |
1c9f093d | 127 | const num = parseInt(row[i]); |
6808d7a1 | 128 | if (isNaN(num)) return false; |
1c9f093d BA |
129 | sumElts += num; |
130 | } | |
131 | } | |
6808d7a1 | 132 | if (sumElts != V.size.y) return false; |
1c9f093d | 133 | } |
d7c00f6a BA |
134 | // Both kings should be on board: |
135 | if (Object.keys(kings).length != 2) | |
136 | return false; | |
1c9f093d BA |
137 | return true; |
138 | } | |
139 | ||
140 | // For FEN checking | |
6808d7a1 BA |
141 | static IsGoodTurn(turn) { |
142 | return ["w", "b"].includes(turn); | |
1c9f093d BA |
143 | } |
144 | ||
145 | // For FEN checking | |
6808d7a1 | 146 | static IsGoodFlags(flags) { |
3a2a7b5f BA |
147 | // NOTE: a little too permissive to work with more variants |
148 | return !!flags.match(/^[a-z]{4,4}$/); | |
1c9f093d BA |
149 | } |
150 | ||
6808d7a1 BA |
151 | static IsGoodEnpassant(enpassant) { |
152 | if (enpassant != "-") { | |
153 | const ep = V.SquareToCoords(enpassant); | |
154 | if (isNaN(ep.x) || !V.OnBoard(ep)) return false; | |
1c9f093d BA |
155 | } |
156 | return true; | |
157 | } | |
158 | ||
159 | // 3 --> d (column number to letter) | |
6808d7a1 | 160 | static CoordToColumn(colnum) { |
1c9f093d BA |
161 | return String.fromCharCode(97 + colnum); |
162 | } | |
163 | ||
164 | // d --> 3 (column letter to number) | |
6808d7a1 | 165 | static ColumnToCoord(column) { |
1c9f093d BA |
166 | return column.charCodeAt(0) - 97; |
167 | } | |
168 | ||
169 | // a4 --> {x:3,y:0} | |
6808d7a1 | 170 | static SquareToCoords(sq) { |
1c9f093d BA |
171 | return { |
172 | // NOTE: column is always one char => max 26 columns | |
173 | // row is counted from black side => subtraction | |
174 | x: V.size.x - parseInt(sq.substr(1)), | |
175 | y: sq[0].charCodeAt() - 97 | |
176 | }; | |
177 | } | |
178 | ||
179 | // {x:0,y:4} --> e8 | |
6808d7a1 | 180 | static CoordsToSquare(coords) { |
1c9f093d BA |
181 | return V.CoordToColumn(coords.y) + (V.size.x - coords.x); |
182 | } | |
183 | ||
241bf8f2 BA |
184 | // Path to pieces |
185 | getPpath(b) { | |
186 | return b; //usual pieces in pieces/ folder | |
187 | } | |
188 | ||
3a2a7b5f BA |
189 | // Path to promotion pieces (usually the same) |
190 | getPPpath(b) { | |
191 | return this.getPpath(b); | |
192 | } | |
193 | ||
1c9f093d | 194 | // Aggregates flags into one object |
6808d7a1 | 195 | aggregateFlags() { |
1c9f093d BA |
196 | return this.castleFlags; |
197 | } | |
198 | ||
199 | // Reverse operation | |
6808d7a1 | 200 | disaggregateFlags(flags) { |
1c9f093d BA |
201 | this.castleFlags = flags; |
202 | } | |
203 | ||
204 | // En-passant square, if any | |
6808d7a1 BA |
205 | getEpSquare(moveOrSquare) { |
206 | if (!moveOrSquare) return undefined; | |
207 | if (typeof moveOrSquare === "string") { | |
1c9f093d | 208 | const square = moveOrSquare; |
6808d7a1 | 209 | if (square == "-") return undefined; |
1c9f093d BA |
210 | return V.SquareToCoords(square); |
211 | } | |
212 | // Argument is a move: | |
213 | const move = moveOrSquare; | |
1c5bfdf2 BA |
214 | const s = move.start, |
215 | e = move.end; | |
6808d7a1 | 216 | if ( |
1c5bfdf2 BA |
217 | Math.abs(s.x - e.x) == 2 && |
218 | s.y == e.y && | |
e727fe31 | 219 | move.appear[0].p == V.PAWN |
6808d7a1 | 220 | ) { |
1c9f093d | 221 | return { |
1c5bfdf2 BA |
222 | x: (s.x + e.x) / 2, |
223 | y: s.y | |
1c9f093d BA |
224 | }; |
225 | } | |
226 | return undefined; //default | |
227 | } | |
228 | ||
229 | // Can thing on square1 take thing on square2 | |
6808d7a1 BA |
230 | canTake([x1, y1], [x2, y2]) { |
231 | return this.getColor(x1, y1) !== this.getColor(x2, y2); | |
1c9f093d BA |
232 | } |
233 | ||
234 | // Is (x,y) on the chessboard? | |
6808d7a1 BA |
235 | static OnBoard(x, y) { |
236 | return x >= 0 && x < V.size.x && y >= 0 && y < V.size.y; | |
1c9f093d BA |
237 | } |
238 | ||
239 | // Used in interface: 'side' arg == player color | |
6808d7a1 BA |
240 | canIplay(side, [x, y]) { |
241 | return this.turn == side && this.getColor(x, y) == side; | |
1c9f093d BA |
242 | } |
243 | ||
244 | // On which squares is color under check ? (for interface) | |
6808d7a1 | 245 | getCheckSquares(color) { |
b0a0468a BA |
246 | return ( |
247 | this.underCheck(color) | |
248 | ? [JSON.parse(JSON.stringify(this.kingPos[color]))] //need to duplicate! | |
249 | : [] | |
250 | ); | |
1c9f093d BA |
251 | } |
252 | ||
253 | ///////////// | |
254 | // FEN UTILS | |
255 | ||
7ba4a5bc BA |
256 | // Setup the initial random (asymmetric) position |
257 | static GenRandInitFen(randomness) { | |
7ba4a5bc BA |
258 | if (randomness == 0) |
259 | // Deterministic: | |
3a2a7b5f | 260 | return "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w 0 ahah -"; |
7ba4a5bc | 261 | |
6808d7a1 | 262 | let pieces = { w: new Array(8), b: new Array(8) }; |
3a2a7b5f | 263 | let flags = ""; |
7ba4a5bc | 264 | // Shuffle pieces on first (and last rank if randomness == 2) |
6808d7a1 | 265 | for (let c of ["w", "b"]) { |
7ba4a5bc BA |
266 | if (c == 'b' && randomness == 1) { |
267 | pieces['b'] = pieces['w']; | |
3a2a7b5f | 268 | flags += flags; |
7ba4a5bc BA |
269 | break; |
270 | } | |
271 | ||
1c9f093d BA |
272 | let positions = ArrayFun.range(8); |
273 | ||
274 | // Get random squares for bishops | |
656b1878 | 275 | let randIndex = 2 * randInt(4); |
1c9f093d BA |
276 | const bishop1Pos = positions[randIndex]; |
277 | // The second bishop must be on a square of different color | |
656b1878 | 278 | let randIndex_tmp = 2 * randInt(4) + 1; |
1c9f093d BA |
279 | const bishop2Pos = positions[randIndex_tmp]; |
280 | // Remove chosen squares | |
6808d7a1 BA |
281 | positions.splice(Math.max(randIndex, randIndex_tmp), 1); |
282 | positions.splice(Math.min(randIndex, randIndex_tmp), 1); | |
1c9f093d BA |
283 | |
284 | // Get random squares for knights | |
656b1878 | 285 | randIndex = randInt(6); |
1c9f093d BA |
286 | const knight1Pos = positions[randIndex]; |
287 | positions.splice(randIndex, 1); | |
656b1878 | 288 | randIndex = randInt(5); |
1c9f093d BA |
289 | const knight2Pos = positions[randIndex]; |
290 | positions.splice(randIndex, 1); | |
291 | ||
292 | // Get random square for queen | |
656b1878 | 293 | randIndex = randInt(4); |
1c9f093d BA |
294 | const queenPos = positions[randIndex]; |
295 | positions.splice(randIndex, 1); | |
296 | ||
297 | // Rooks and king positions are now fixed, | |
298 | // because of the ordering rook-king-rook | |
299 | const rook1Pos = positions[0]; | |
300 | const kingPos = positions[1]; | |
301 | const rook2Pos = positions[2]; | |
302 | ||
303 | // Finally put the shuffled pieces in the board array | |
6808d7a1 BA |
304 | pieces[c][rook1Pos] = "r"; |
305 | pieces[c][knight1Pos] = "n"; | |
306 | pieces[c][bishop1Pos] = "b"; | |
307 | pieces[c][queenPos] = "q"; | |
308 | pieces[c][kingPos] = "k"; | |
309 | pieces[c][bishop2Pos] = "b"; | |
310 | pieces[c][knight2Pos] = "n"; | |
311 | pieces[c][rook2Pos] = "r"; | |
3a2a7b5f | 312 | flags += V.CoordToColumn(rook1Pos) + V.CoordToColumn(rook2Pos); |
1c9f093d | 313 | } |
e3e2cc44 | 314 | // Add turn + flags + enpassant |
6808d7a1 BA |
315 | return ( |
316 | pieces["b"].join("") + | |
1c9f093d BA |
317 | "/pppppppp/8/8/8/8/PPPPPPPP/" + |
318 | pieces["w"].join("").toUpperCase() + | |
3a2a7b5f | 319 | " w 0 " + flags + " -" |
e3e2cc44 | 320 | ); |
1c9f093d BA |
321 | } |
322 | ||
323 | // "Parse" FEN: just return untransformed string data | |
6808d7a1 | 324 | static ParseFen(fen) { |
1c9f093d | 325 | const fenParts = fen.split(" "); |
6808d7a1 | 326 | let res = { |
1c9f093d BA |
327 | position: fenParts[0], |
328 | turn: fenParts[1], | |
6808d7a1 | 329 | movesCount: fenParts[2] |
1c9f093d BA |
330 | }; |
331 | let nextIdx = 3; | |
6808d7a1 BA |
332 | if (V.HasFlags) Object.assign(res, { flags: fenParts[nextIdx++] }); |
333 | if (V.HasEnpassant) Object.assign(res, { enpassant: fenParts[nextIdx] }); | |
1c9f093d BA |
334 | return res; |
335 | } | |
336 | ||
337 | // Return current fen (game state) | |
6808d7a1 BA |
338 | getFen() { |
339 | return ( | |
f9c36b2d BA |
340 | this.getBaseFen() + " " + |
341 | this.getTurnFen() + " " + | |
6808d7a1 BA |
342 | this.movesCount + |
343 | (V.HasFlags ? " " + this.getFlagsFen() : "") + | |
344 | (V.HasEnpassant ? " " + this.getEnpassantFen() : "") | |
345 | ); | |
1c9f093d BA |
346 | } |
347 | ||
f9c36b2d BA |
348 | getFenForRepeat() { |
349 | // Omit movesCount, only variable allowed to differ | |
350 | return ( | |
351 | this.getBaseFen() + "_" + | |
352 | this.getTurnFen() + | |
353 | (V.HasFlags ? "_" + this.getFlagsFen() : "") + | |
354 | (V.HasEnpassant ? "_" + this.getEnpassantFen() : "") | |
355 | ); | |
356 | } | |
357 | ||
1c9f093d | 358 | // Position part of the FEN string |
6808d7a1 | 359 | getBaseFen() { |
1c9f093d | 360 | let position = ""; |
6808d7a1 | 361 | for (let i = 0; i < V.size.x; i++) { |
1c9f093d | 362 | let emptyCount = 0; |
6808d7a1 BA |
363 | for (let j = 0; j < V.size.y; j++) { |
364 | if (this.board[i][j] == V.EMPTY) emptyCount++; | |
365 | else { | |
366 | if (emptyCount > 0) { | |
1c9f093d BA |
367 | // Add empty squares in-between |
368 | position += emptyCount; | |
369 | emptyCount = 0; | |
370 | } | |
371 | position += V.board2fen(this.board[i][j]); | |
372 | } | |
373 | } | |
6808d7a1 | 374 | if (emptyCount > 0) { |
1c9f093d BA |
375 | // "Flush remainder" |
376 | position += emptyCount; | |
377 | } | |
6808d7a1 | 378 | if (i < V.size.x - 1) position += "/"; //separate rows |
1c9f093d BA |
379 | } |
380 | return position; | |
381 | } | |
382 | ||
6808d7a1 | 383 | getTurnFen() { |
1c9f093d BA |
384 | return this.turn; |
385 | } | |
386 | ||
387 | // Flags part of the FEN string | |
6808d7a1 | 388 | getFlagsFen() { |
1c9f093d | 389 | let flags = ""; |
3a2a7b5f BA |
390 | // Castling flags |
391 | for (let c of ["w", "b"]) | |
392 | flags += this.castleFlags[c].map(V.CoordToColumn).join(""); | |
1c9f093d BA |
393 | return flags; |
394 | } | |
395 | ||
396 | // Enpassant part of the FEN string | |
6808d7a1 | 397 | getEnpassantFen() { |
1c9f093d | 398 | const L = this.epSquares.length; |
6808d7a1 BA |
399 | if (!this.epSquares[L - 1]) return "-"; //no en-passant |
400 | return V.CoordsToSquare(this.epSquares[L - 1]); | |
1c9f093d BA |
401 | } |
402 | ||
403 | // Turn position fen into double array ["wb","wp","bk",...] | |
6808d7a1 | 404 | static GetBoard(position) { |
1c9f093d BA |
405 | const rows = position.split("/"); |
406 | let board = ArrayFun.init(V.size.x, V.size.y, ""); | |
6808d7a1 | 407 | for (let i = 0; i < rows.length; i++) { |
1c9f093d | 408 | let j = 0; |
6808d7a1 | 409 | for (let indexInRow = 0; indexInRow < rows[i].length; indexInRow++) { |
1c9f093d BA |
410 | const character = rows[i][indexInRow]; |
411 | const num = parseInt(character); | |
a13cbc0f | 412 | // If num is a number, just shift j: |
6808d7a1 | 413 | if (!isNaN(num)) j += num; |
a13cbc0f | 414 | // Else: something at position i,j |
6808d7a1 | 415 | else board[i][j++] = V.fen2board(character); |
1c9f093d BA |
416 | } |
417 | } | |
418 | return board; | |
419 | } | |
420 | ||
421 | // Extract (relevant) flags from fen | |
6808d7a1 | 422 | setFlags(fenflags) { |
1c9f093d | 423 | // white a-castle, h-castle, black a-castle, h-castle |
6808d7a1 | 424 | this.castleFlags = { w: [true, true], b: [true, true] }; |
3a2a7b5f BA |
425 | for (let i = 0; i < 4; i++) { |
426 | this.castleFlags[i < 2 ? "w" : "b"][i % 2] = | |
427 | V.ColumnToCoord(fenflags.charAt(i)); | |
428 | } | |
1c9f093d BA |
429 | } |
430 | ||
431 | ////////////////// | |
432 | // INITIALIZATION | |
433 | ||
37cdcbf3 | 434 | // Fen string fully describes the game state |
b627d118 BA |
435 | constructor(fen) { |
436 | if (!fen) | |
437 | // In printDiagram() fen isn't supply because only getPpath() is used | |
438 | // TODO: find a better solution! | |
439 | return; | |
1c9f093d BA |
440 | const fenParsed = V.ParseFen(fen); |
441 | this.board = V.GetBoard(fenParsed.position); | |
442 | this.turn = fenParsed.turn[0]; //[0] to work with MarseilleRules | |
443 | this.movesCount = parseInt(fenParsed.movesCount); | |
444 | this.setOtherVariables(fen); | |
445 | } | |
446 | ||
3a2a7b5f BA |
447 | // Scan board for kings positions |
448 | scanKings(fen) { | |
6808d7a1 | 449 | this.INIT_COL_KING = { w: -1, b: -1 }; |
6808d7a1 | 450 | this.kingPos = { w: [-1, -1], b: [-1, -1] }; //squares of white and black king |
1c9f093d | 451 | const fenRows = V.ParseFen(fen).position.split("/"); |
90e814b6 | 452 | const startRow = { 'w': V.size.x - 1, 'b': 0 }; |
6808d7a1 | 453 | for (let i = 0; i < fenRows.length; i++) { |
1c9f093d | 454 | let k = 0; //column index on board |
6808d7a1 BA |
455 | for (let j = 0; j < fenRows[i].length; j++) { |
456 | switch (fenRows[i].charAt(j)) { | |
457 | case "k": | |
458 | this.kingPos["b"] = [i, k]; | |
459 | this.INIT_COL_KING["b"] = k; | |
1c9f093d | 460 | break; |
6808d7a1 BA |
461 | case "K": |
462 | this.kingPos["w"] = [i, k]; | |
463 | this.INIT_COL_KING["w"] = k; | |
1c9f093d | 464 | break; |
6808d7a1 | 465 | default: { |
1c9f093d | 466 | const num = parseInt(fenRows[i].charAt(j)); |
6808d7a1 BA |
467 | if (!isNaN(num)) k += num - 1; |
468 | } | |
1c9f093d BA |
469 | } |
470 | k++; | |
471 | } | |
472 | } | |
473 | } | |
474 | ||
475 | // Some additional variables from FEN (variant dependant) | |
6808d7a1 | 476 | setOtherVariables(fen) { |
1c9f093d BA |
477 | // Set flags and enpassant: |
478 | const parsedFen = V.ParseFen(fen); | |
6808d7a1 BA |
479 | if (V.HasFlags) this.setFlags(parsedFen.flags); |
480 | if (V.HasEnpassant) { | |
481 | const epSq = | |
482 | parsedFen.enpassant != "-" | |
9bd6786b | 483 | ? this.getEpSquare(parsedFen.enpassant) |
6808d7a1 BA |
484 | : undefined; |
485 | this.epSquares = [epSq]; | |
1c9f093d | 486 | } |
3a2a7b5f BA |
487 | // Search for kings positions: |
488 | this.scanKings(fen); | |
1c9f093d BA |
489 | } |
490 | ||
491 | ///////////////////// | |
492 | // GETTERS & SETTERS | |
493 | ||
6808d7a1 BA |
494 | static get size() { |
495 | return { x: 8, y: 8 }; | |
1c9f093d BA |
496 | } |
497 | ||
0ba6420d | 498 | // Color of thing on square (i,j). 'undefined' if square is empty |
6808d7a1 | 499 | getColor(i, j) { |
1c9f093d BA |
500 | return this.board[i][j].charAt(0); |
501 | } | |
502 | ||
503 | // Piece type on square (i,j). 'undefined' if square is empty | |
6808d7a1 | 504 | getPiece(i, j) { |
1c9f093d BA |
505 | return this.board[i][j].charAt(1); |
506 | } | |
507 | ||
508 | // Get opponent color | |
6808d7a1 BA |
509 | static GetOppCol(color) { |
510 | return color == "w" ? "b" : "w"; | |
1c9f093d BA |
511 | } |
512 | ||
1c9f093d | 513 | // Pieces codes (for a clearer code) |
6808d7a1 BA |
514 | static get PAWN() { |
515 | return "p"; | |
516 | } | |
517 | static get ROOK() { | |
518 | return "r"; | |
519 | } | |
520 | static get KNIGHT() { | |
521 | return "n"; | |
522 | } | |
523 | static get BISHOP() { | |
524 | return "b"; | |
525 | } | |
526 | static get QUEEN() { | |
527 | return "q"; | |
528 | } | |
529 | static get KING() { | |
530 | return "k"; | |
531 | } | |
1c9f093d BA |
532 | |
533 | // For FEN checking: | |
6808d7a1 BA |
534 | static get PIECES() { |
535 | return [V.PAWN, V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN, V.KING]; | |
1c9f093d BA |
536 | } |
537 | ||
538 | // Empty square | |
6808d7a1 BA |
539 | static get EMPTY() { |
540 | return ""; | |
541 | } | |
1c9f093d BA |
542 | |
543 | // Some pieces movements | |
6808d7a1 | 544 | static get steps() { |
1c9f093d | 545 | return { |
6808d7a1 BA |
546 | r: [ |
547 | [-1, 0], | |
548 | [1, 0], | |
549 | [0, -1], | |
550 | [0, 1] | |
551 | ], | |
552 | n: [ | |
553 | [-1, -2], | |
554 | [-1, 2], | |
555 | [1, -2], | |
556 | [1, 2], | |
557 | [-2, -1], | |
558 | [-2, 1], | |
559 | [2, -1], | |
560 | [2, 1] | |
561 | ], | |
562 | b: [ | |
563 | [-1, -1], | |
564 | [-1, 1], | |
565 | [1, -1], | |
566 | [1, 1] | |
567 | ] | |
1c9f093d BA |
568 | }; |
569 | } | |
570 | ||
571 | //////////////////// | |
572 | // MOVES GENERATION | |
573 | ||
0ba6420d | 574 | // All possible moves from selected square |
6808d7a1 BA |
575 | getPotentialMovesFrom([x, y]) { |
576 | switch (this.getPiece(x, y)) { | |
1c9f093d | 577 | case V.PAWN: |
6808d7a1 | 578 | return this.getPotentialPawnMoves([x, y]); |
1c9f093d | 579 | case V.ROOK: |
6808d7a1 | 580 | return this.getPotentialRookMoves([x, y]); |
1c9f093d | 581 | case V.KNIGHT: |
6808d7a1 | 582 | return this.getPotentialKnightMoves([x, y]); |
1c9f093d | 583 | case V.BISHOP: |
6808d7a1 | 584 | return this.getPotentialBishopMoves([x, y]); |
1c9f093d | 585 | case V.QUEEN: |
6808d7a1 | 586 | return this.getPotentialQueenMoves([x, y]); |
1c9f093d | 587 | case V.KING: |
6808d7a1 | 588 | return this.getPotentialKingMoves([x, y]); |
1c9f093d | 589 | } |
6808d7a1 | 590 | return []; //never reached |
1c9f093d BA |
591 | } |
592 | ||
593 | // Build a regular move from its initial and destination squares. | |
594 | // tr: transformation | |
6808d7a1 | 595 | getBasicMove([sx, sy], [ex, ey], tr) { |
1c9f093d BA |
596 | let mv = new Move({ |
597 | appear: [ | |
598 | new PiPo({ | |
599 | x: ex, | |
600 | y: ey, | |
6808d7a1 BA |
601 | c: tr ? tr.c : this.getColor(sx, sy), |
602 | p: tr ? tr.p : this.getPiece(sx, sy) | |
1c9f093d BA |
603 | }) |
604 | ], | |
605 | vanish: [ | |
606 | new PiPo({ | |
607 | x: sx, | |
608 | y: sy, | |
6808d7a1 BA |
609 | c: this.getColor(sx, sy), |
610 | p: this.getPiece(sx, sy) | |
1c9f093d BA |
611 | }) |
612 | ] | |
613 | }); | |
614 | ||
615 | // The opponent piece disappears if we take it | |
6808d7a1 | 616 | if (this.board[ex][ey] != V.EMPTY) { |
1c9f093d BA |
617 | mv.vanish.push( |
618 | new PiPo({ | |
619 | x: ex, | |
620 | y: ey, | |
6808d7a1 BA |
621 | c: this.getColor(ex, ey), |
622 | p: this.getPiece(ex, ey) | |
1c9f093d BA |
623 | }) |
624 | ); | |
625 | } | |
1c5bfdf2 | 626 | |
1c9f093d BA |
627 | return mv; |
628 | } | |
629 | ||
630 | // Generic method to find possible moves of non-pawn pieces: | |
631 | // "sliding or jumping" | |
6808d7a1 | 632 | getSlideNJumpMoves([x, y], steps, oneStep) { |
1c9f093d | 633 | let moves = []; |
6808d7a1 | 634 | outerLoop: for (let step of steps) { |
1c9f093d BA |
635 | let i = x + step[0]; |
636 | let j = y + step[1]; | |
6808d7a1 BA |
637 | while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
638 | moves.push(this.getBasicMove([x, y], [i, j])); | |
d1be8046 | 639 | if (oneStep) continue outerLoop; |
1c9f093d BA |
640 | i += step[0]; |
641 | j += step[1]; | |
642 | } | |
6808d7a1 BA |
643 | if (V.OnBoard(i, j) && this.canTake([x, y], [i, j])) |
644 | moves.push(this.getBasicMove([x, y], [i, j])); | |
1c9f093d BA |
645 | } |
646 | return moves; | |
647 | } | |
648 | ||
649 | // What are the pawn moves from square x,y ? | |
6808d7a1 | 650 | getPotentialPawnMoves([x, y]) { |
1c9f093d BA |
651 | const color = this.turn; |
652 | let moves = []; | |
6808d7a1 BA |
653 | const [sizeX, sizeY] = [V.size.x, V.size.y]; |
654 | const shiftX = color == "w" ? -1 : 1; | |
655 | const firstRank = color == "w" ? sizeX - 1 : 0; | |
656 | const startRank = color == "w" ? sizeX - 2 : 1; | |
657 | const lastRank = color == "w" ? 0 : sizeX - 1; | |
1c9f093d BA |
658 | |
659 | // NOTE: next condition is generally true (no pawn on last rank) | |
6808d7a1 BA |
660 | if (x + shiftX >= 0 && x + shiftX < sizeX) { |
661 | const finalPieces = | |
662 | x + shiftX == lastRank | |
663 | ? [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN] | |
664 | : [V.PAWN]; | |
6808d7a1 | 665 | if (this.board[x + shiftX][y] == V.EMPTY) { |
71ef1664 | 666 | // One square forward |
6808d7a1 BA |
667 | for (let piece of finalPieces) { |
668 | moves.push( | |
669 | this.getBasicMove([x, y], [x + shiftX, y], { | |
e727fe31 | 670 | c: color, |
6808d7a1 BA |
671 | p: piece |
672 | }) | |
673 | ); | |
1c9f093d BA |
674 | } |
675 | // Next condition because pawns on 1st rank can generally jump | |
6808d7a1 BA |
676 | if ( |
677 | [startRank, firstRank].includes(x) && | |
678 | this.board[x + 2 * shiftX][y] == V.EMPTY | |
679 | ) { | |
1c9f093d | 680 | // Two squares jump |
6808d7a1 | 681 | moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y])); |
1c9f093d BA |
682 | } |
683 | } | |
684 | // Captures | |
6808d7a1 BA |
685 | for (let shiftY of [-1, 1]) { |
686 | if ( | |
687 | y + shiftY >= 0 && | |
688 | y + shiftY < sizeY && | |
689 | this.board[x + shiftX][y + shiftY] != V.EMPTY && | |
690 | this.canTake([x, y], [x + shiftX, y + shiftY]) | |
691 | ) { | |
692 | for (let piece of finalPieces) { | |
693 | moves.push( | |
694 | this.getBasicMove([x, y], [x + shiftX, y + shiftY], { | |
e727fe31 | 695 | c: color, |
6808d7a1 BA |
696 | p: piece |
697 | }) | |
698 | ); | |
1c9f093d BA |
699 | } |
700 | } | |
701 | } | |
702 | } | |
703 | ||
6808d7a1 | 704 | if (V.HasEnpassant) { |
1c9f093d BA |
705 | // En passant |
706 | const Lep = this.epSquares.length; | |
6808d7a1 BA |
707 | const epSquare = this.epSquares[Lep - 1]; //always at least one element |
708 | if ( | |
709 | !!epSquare && | |
710 | epSquare.x == x + shiftX && | |
711 | Math.abs(epSquare.y - y) == 1 | |
712 | ) { | |
713 | let enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]); | |
1c9f093d BA |
714 | enpassantMove.vanish.push({ |
715 | x: x, | |
716 | y: epSquare.y, | |
6808d7a1 BA |
717 | p: "p", |
718 | c: this.getColor(x, epSquare.y) | |
1c9f093d BA |
719 | }); |
720 | moves.push(enpassantMove); | |
721 | } | |
722 | } | |
723 | ||
724 | return moves; | |
725 | } | |
726 | ||
727 | // What are the rook moves from square x,y ? | |
6808d7a1 | 728 | getPotentialRookMoves(sq) { |
1c9f093d BA |
729 | return this.getSlideNJumpMoves(sq, V.steps[V.ROOK]); |
730 | } | |
731 | ||
732 | // What are the knight moves from square x,y ? | |
6808d7a1 | 733 | getPotentialKnightMoves(sq) { |
1c9f093d BA |
734 | return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep"); |
735 | } | |
736 | ||
737 | // What are the bishop moves from square x,y ? | |
6808d7a1 | 738 | getPotentialBishopMoves(sq) { |
1c9f093d BA |
739 | return this.getSlideNJumpMoves(sq, V.steps[V.BISHOP]); |
740 | } | |
741 | ||
742 | // What are the queen moves from square x,y ? | |
6808d7a1 BA |
743 | getPotentialQueenMoves(sq) { |
744 | return this.getSlideNJumpMoves( | |
745 | sq, | |
746 | V.steps[V.ROOK].concat(V.steps[V.BISHOP]) | |
747 | ); | |
1c9f093d BA |
748 | } |
749 | ||
750 | // What are the king moves from square x,y ? | |
6808d7a1 | 751 | getPotentialKingMoves(sq) { |
1c9f093d | 752 | // Initialize with normal moves |
3a2a7b5f | 753 | const moves = this.getSlideNJumpMoves( |
6808d7a1 BA |
754 | sq, |
755 | V.steps[V.ROOK].concat(V.steps[V.BISHOP]), | |
756 | "oneStep" | |
757 | ); | |
1c9f093d BA |
758 | return moves.concat(this.getCastleMoves(sq)); |
759 | } | |
760 | ||
6808d7a1 BA |
761 | getCastleMoves([x, y]) { |
762 | const c = this.getColor(x, y); | |
763 | if (x != (c == "w" ? V.size.x - 1 : 0) || y != this.INIT_COL_KING[c]) | |
1c9f093d BA |
764 | return []; //x isn't first rank, or king has moved (shortcut) |
765 | ||
766 | // Castling ? | |
767 | const oppCol = V.GetOppCol(c); | |
768 | let moves = []; | |
769 | let i = 0; | |
9bd6786b | 770 | // King, then rook: |
6808d7a1 BA |
771 | const finalSquares = [ |
772 | [2, 3], | |
773 | [V.size.y - 2, V.size.y - 3] | |
9bd6786b | 774 | ]; |
6808d7a1 BA |
775 | castlingCheck: for ( |
776 | let castleSide = 0; | |
777 | castleSide < 2; | |
778 | castleSide++ //large, then small | |
779 | ) { | |
3a2a7b5f | 780 | if (this.castleFlags[c][castleSide] >= V.size.y) continue; |
1c9f093d BA |
781 | // If this code is reached, rooks and king are on initial position |
782 | ||
2beba6db BA |
783 | // Nothing on the path of the king ? (and no checks) |
784 | const finDist = finalSquares[castleSide][0] - y; | |
785 | let step = finDist / Math.max(1, Math.abs(finDist)); | |
786 | i = y; | |
6808d7a1 BA |
787 | do { |
788 | if ( | |
789 | this.isAttacked([x, i], [oppCol]) || | |
790 | (this.board[x][i] != V.EMPTY && | |
791 | // NOTE: next check is enough, because of chessboard constraints | |
792 | (this.getColor(x, i) != c || | |
793 | ![V.KING, V.ROOK].includes(this.getPiece(x, i)))) | |
794 | ) { | |
1c9f093d BA |
795 | continue castlingCheck; |
796 | } | |
2beba6db | 797 | i += step; |
6808d7a1 | 798 | } while (i != finalSquares[castleSide][0]); |
1c9f093d BA |
799 | |
800 | // Nothing on the path to the rook? | |
6808d7a1 | 801 | step = castleSide == 0 ? -1 : 1; |
3a2a7b5f BA |
802 | const rookPos = this.castleFlags[c][castleSide]; |
803 | for (i = y + step; i != rookPos; i += step) { | |
6808d7a1 | 804 | if (this.board[x][i] != V.EMPTY) continue castlingCheck; |
1c9f093d | 805 | } |
1c9f093d BA |
806 | |
807 | // Nothing on final squares, except maybe king and castling rook? | |
6808d7a1 BA |
808 | for (i = 0; i < 2; i++) { |
809 | if ( | |
810 | this.board[x][finalSquares[castleSide][i]] != V.EMPTY && | |
811 | this.getPiece(x, finalSquares[castleSide][i]) != V.KING && | |
812 | finalSquares[castleSide][i] != rookPos | |
813 | ) { | |
1c9f093d BA |
814 | continue castlingCheck; |
815 | } | |
816 | } | |
817 | ||
818 | // If this code is reached, castle is valid | |
6808d7a1 BA |
819 | moves.push( |
820 | new Move({ | |
821 | appear: [ | |
822 | new PiPo({ x: x, y: finalSquares[castleSide][0], p: V.KING, c: c }), | |
823 | new PiPo({ x: x, y: finalSquares[castleSide][1], p: V.ROOK, c: c }) | |
824 | ], | |
825 | vanish: [ | |
826 | new PiPo({ x: x, y: y, p: V.KING, c: c }), | |
827 | new PiPo({ x: x, y: rookPos, p: V.ROOK, c: c }) | |
828 | ], | |
829 | end: | |
830 | Math.abs(y - rookPos) <= 2 | |
831 | ? { x: x, y: rookPos } | |
832 | : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) } | |
833 | }) | |
834 | ); | |
1c9f093d BA |
835 | } |
836 | ||
837 | return moves; | |
838 | } | |
839 | ||
840 | //////////////////// | |
841 | // MOVES VALIDATION | |
842 | ||
843 | // For the interface: possible moves for the current turn from square sq | |
6808d7a1 BA |
844 | getPossibleMovesFrom(sq) { |
845 | return this.filterValid(this.getPotentialMovesFrom(sq)); | |
1c9f093d BA |
846 | } |
847 | ||
848 | // TODO: promotions (into R,B,N,Q) should be filtered only once | |
6808d7a1 BA |
849 | filterValid(moves) { |
850 | if (moves.length == 0) return []; | |
1c9f093d BA |
851 | const color = this.turn; |
852 | return moves.filter(m => { | |
853 | this.play(m); | |
854 | const res = !this.underCheck(color); | |
855 | this.undo(m); | |
856 | return res; | |
857 | }); | |
858 | } | |
859 | ||
860 | // Search for all valid moves considering current turn | |
861 | // (for engine and game end) | |
6808d7a1 | 862 | getAllValidMoves() { |
1c9f093d | 863 | const color = this.turn; |
1c9f093d | 864 | let potentialMoves = []; |
6808d7a1 BA |
865 | for (let i = 0; i < V.size.x; i++) { |
866 | for (let j = 0; j < V.size.y; j++) { | |
d1be8046 | 867 | if (this.getColor(i, j) == color) { |
6808d7a1 BA |
868 | Array.prototype.push.apply( |
869 | potentialMoves, | |
870 | this.getPotentialMovesFrom([i, j]) | |
871 | ); | |
1c9f093d BA |
872 | } |
873 | } | |
874 | } | |
875 | return this.filterValid(potentialMoves); | |
876 | } | |
877 | ||
878 | // Stop at the first move found | |
6808d7a1 | 879 | atLeastOneMove() { |
1c9f093d | 880 | const color = this.turn; |
6808d7a1 BA |
881 | for (let i = 0; i < V.size.x; i++) { |
882 | for (let j = 0; j < V.size.y; j++) { | |
d1be8046 | 883 | if (this.getColor(i, j) == color) { |
6808d7a1 BA |
884 | const moves = this.getPotentialMovesFrom([i, j]); |
885 | if (moves.length > 0) { | |
886 | for (let k = 0; k < moves.length; k++) { | |
887 | if (this.filterValid([moves[k]]).length > 0) return true; | |
1c9f093d BA |
888 | } |
889 | } | |
890 | } | |
891 | } | |
892 | } | |
893 | return false; | |
894 | } | |
895 | ||
896 | // Check if pieces of color in 'colors' are attacking (king) on square x,y | |
6808d7a1 BA |
897 | isAttacked(sq, colors) { |
898 | return ( | |
899 | this.isAttackedByPawn(sq, colors) || | |
900 | this.isAttackedByRook(sq, colors) || | |
901 | this.isAttackedByKnight(sq, colors) || | |
902 | this.isAttackedByBishop(sq, colors) || | |
903 | this.isAttackedByQueen(sq, colors) || | |
904 | this.isAttackedByKing(sq, colors) | |
905 | ); | |
1c9f093d BA |
906 | } |
907 | ||
d1be8046 BA |
908 | // Generic method for non-pawn pieces ("sliding or jumping"): |
909 | // is x,y attacked by a piece of color in array 'colors' ? | |
910 | isAttackedBySlideNJump([x, y], colors, piece, steps, oneStep) { | |
911 | for (let step of steps) { | |
912 | let rx = x + step[0], | |
913 | ry = y + step[1]; | |
914 | while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) { | |
915 | rx += step[0]; | |
916 | ry += step[1]; | |
917 | } | |
918 | if ( | |
919 | V.OnBoard(rx, ry) && | |
920 | this.getPiece(rx, ry) === piece && | |
921 | colors.includes(this.getColor(rx, ry)) | |
922 | ) { | |
923 | return true; | |
924 | } | |
925 | } | |
926 | return false; | |
927 | } | |
928 | ||
1c9f093d | 929 | // Is square x,y attacked by 'colors' pawns ? |
6808d7a1 BA |
930 | isAttackedByPawn([x, y], colors) { |
931 | for (let c of colors) { | |
d1be8046 | 932 | const pawnShift = c == "w" ? 1 : -1; |
6808d7a1 BA |
933 | if (x + pawnShift >= 0 && x + pawnShift < V.size.x) { |
934 | for (let i of [-1, 1]) { | |
935 | if ( | |
936 | y + i >= 0 && | |
937 | y + i < V.size.y && | |
938 | this.getPiece(x + pawnShift, y + i) == V.PAWN && | |
939 | this.getColor(x + pawnShift, y + i) == c | |
940 | ) { | |
1c9f093d BA |
941 | return true; |
942 | } | |
943 | } | |
944 | } | |
945 | } | |
946 | return false; | |
947 | } | |
948 | ||
949 | // Is square x,y attacked by 'colors' rooks ? | |
6808d7a1 | 950 | isAttackedByRook(sq, colors) { |
1c9f093d BA |
951 | return this.isAttackedBySlideNJump(sq, colors, V.ROOK, V.steps[V.ROOK]); |
952 | } | |
953 | ||
954 | // Is square x,y attacked by 'colors' knights ? | |
6808d7a1 BA |
955 | isAttackedByKnight(sq, colors) { |
956 | return this.isAttackedBySlideNJump( | |
957 | sq, | |
958 | colors, | |
959 | V.KNIGHT, | |
960 | V.steps[V.KNIGHT], | |
961 | "oneStep" | |
962 | ); | |
1c9f093d BA |
963 | } |
964 | ||
965 | // Is square x,y attacked by 'colors' bishops ? | |
6808d7a1 | 966 | isAttackedByBishop(sq, colors) { |
1c9f093d BA |
967 | return this.isAttackedBySlideNJump(sq, colors, V.BISHOP, V.steps[V.BISHOP]); |
968 | } | |
969 | ||
970 | // Is square x,y attacked by 'colors' queens ? | |
6808d7a1 BA |
971 | isAttackedByQueen(sq, colors) { |
972 | return this.isAttackedBySlideNJump( | |
973 | sq, | |
974 | colors, | |
975 | V.QUEEN, | |
976 | V.steps[V.ROOK].concat(V.steps[V.BISHOP]) | |
977 | ); | |
1c9f093d BA |
978 | } |
979 | ||
980 | // Is square x,y attacked by 'colors' king(s) ? | |
6808d7a1 BA |
981 | isAttackedByKing(sq, colors) { |
982 | return this.isAttackedBySlideNJump( | |
983 | sq, | |
984 | colors, | |
985 | V.KING, | |
986 | V.steps[V.ROOK].concat(V.steps[V.BISHOP]), | |
987 | "oneStep" | |
988 | ); | |
1c9f093d BA |
989 | } |
990 | ||
1c9f093d | 991 | // Is color under check after his move ? |
6808d7a1 | 992 | underCheck(color) { |
1c9f093d BA |
993 | return this.isAttacked(this.kingPos[color], [V.GetOppCol(color)]); |
994 | } | |
995 | ||
996 | ///////////////// | |
997 | // MOVES PLAYING | |
998 | ||
999 | // Apply a move on board | |
6808d7a1 BA |
1000 | static PlayOnBoard(board, move) { |
1001 | for (let psq of move.vanish) board[psq.x][psq.y] = V.EMPTY; | |
1002 | for (let psq of move.appear) board[psq.x][psq.y] = psq.c + psq.p; | |
1c9f093d BA |
1003 | } |
1004 | // Un-apply the played move | |
6808d7a1 BA |
1005 | static UndoOnBoard(board, move) { |
1006 | for (let psq of move.appear) board[psq.x][psq.y] = V.EMPTY; | |
1007 | for (let psq of move.vanish) board[psq.x][psq.y] = psq.c + psq.p; | |
1c9f093d BA |
1008 | } |
1009 | ||
3a2a7b5f BA |
1010 | prePlay() {} |
1011 | ||
1012 | play(move) { | |
1013 | // DEBUG: | |
1014 | // if (!this.states) this.states = []; | |
1015 | // const stateFen = this.getBaseFen() + this.getTurnFen();// + this.getFlagsFen(); | |
1016 | // this.states.push(stateFen); | |
1017 | ||
1018 | this.prePlay(move); | |
1019 | if (V.HasFlags) move.flags = JSON.stringify(this.aggregateFlags()); //save flags (for undo) | |
1020 | if (V.HasEnpassant) this.epSquares.push(this.getEpSquare(move)); | |
1021 | V.PlayOnBoard(this.board, move); | |
1022 | this.turn = V.GetOppCol(this.turn); | |
1023 | this.movesCount++; | |
1024 | this.postPlay(move); | |
1025 | } | |
1026 | ||
1c9f093d | 1027 | // After move is played, update variables + flags |
3a2a7b5f BA |
1028 | postPlay(move) { |
1029 | const c = V.GetOppCol(this.turn); | |
1c9f093d | 1030 | let piece = undefined; |
3a2a7b5f | 1031 | if (move.vanish.length >= 1) |
1c9f093d BA |
1032 | // Usual case, something is moved |
1033 | piece = move.vanish[0].p; | |
3a2a7b5f | 1034 | else |
1c9f093d BA |
1035 | // Crazyhouse-like variants |
1036 | piece = move.appear[0].p; | |
6808d7a1 | 1037 | const firstRank = c == "w" ? V.size.x - 1 : 0; |
1c9f093d BA |
1038 | |
1039 | // Update king position + flags | |
6808d7a1 | 1040 | if (piece == V.KING && move.appear.length > 0) { |
1c9f093d BA |
1041 | this.kingPos[c][0] = move.appear[0].x; |
1042 | this.kingPos[c][1] = move.appear[0].y; | |
3a2a7b5f | 1043 | if (V.HasCastle) this.castleFlags[c] = [V.size.y, V.size.y]; |
1c9f093d BA |
1044 | return; |
1045 | } | |
3a2a7b5f | 1046 | if (V.HasCastle) { |
1c9f093d BA |
1047 | // Update castling flags if rooks are moved |
1048 | const oppCol = V.GetOppCol(c); | |
6808d7a1 BA |
1049 | const oppFirstRank = V.size.x - 1 - firstRank; |
1050 | if ( | |
1051 | move.start.x == firstRank && //our rook moves? | |
3a2a7b5f | 1052 | this.castleFlags[c].includes(move.start.y) |
6808d7a1 | 1053 | ) { |
3a2a7b5f BA |
1054 | const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1); |
1055 | this.castleFlags[c][flagIdx] = V.size.y; | |
6808d7a1 BA |
1056 | } else if ( |
1057 | move.end.x == oppFirstRank && //we took opponent rook? | |
3a2a7b5f | 1058 | this.castleFlags[oppCol].includes(move.end.y) |
6808d7a1 | 1059 | ) { |
3a2a7b5f BA |
1060 | const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1); |
1061 | this.castleFlags[oppCol][flagIdx] = V.size.y; | |
1c9f093d BA |
1062 | } |
1063 | } | |
1064 | } | |
1065 | ||
3a2a7b5f | 1066 | preUndo() {} |
1c9f093d | 1067 | |
6808d7a1 | 1068 | undo(move) { |
3a2a7b5f | 1069 | this.preUndo(move); |
6808d7a1 BA |
1070 | if (V.HasEnpassant) this.epSquares.pop(); |
1071 | if (V.HasFlags) this.disaggregateFlags(JSON.parse(move.flags)); | |
1c9f093d BA |
1072 | V.UndoOnBoard(this.board, move); |
1073 | this.turn = V.GetOppCol(this.turn); | |
1074 | this.movesCount--; | |
3a2a7b5f | 1075 | this.postUndo(move); |
1c9f093d BA |
1076 | |
1077 | // DEBUG: | |
6b7b2cf7 | 1078 | // const stateFen = this.getBaseFen() + this.getTurnFen();// + this.getFlagsFen(); |
9bd6786b BA |
1079 | // if (stateFen != this.states[this.states.length-1]) debugger; |
1080 | // this.states.pop(); | |
1c9f093d BA |
1081 | } |
1082 | ||
3a2a7b5f BA |
1083 | // After move is undo-ed *and flags resetted*, un-update other variables |
1084 | // TODO: more symmetry, by storing flags increment in move (?!) | |
1085 | postUndo(move) { | |
1086 | // (Potentially) Reset king position | |
1087 | const c = this.getColor(move.start.x, move.start.y); | |
1088 | if (this.getPiece(move.start.x, move.start.y) == V.KING) | |
1089 | this.kingPos[c] = [move.start.x, move.start.y]; | |
1090 | } | |
1091 | ||
1c9f093d BA |
1092 | /////////////// |
1093 | // END OF GAME | |
1094 | ||
1095 | // What is the score ? (Interesting if game is over) | |
6808d7a1 BA |
1096 | getCurrentScore() { |
1097 | if (this.atLeastOneMove()) | |
1c9f093d BA |
1098 | return "*"; |
1099 | ||
1100 | // Game over | |
1101 | const color = this.turn; | |
1102 | // No valid move: stalemate or checkmate? | |
1103 | if (!this.isAttacked(this.kingPos[color], [V.GetOppCol(color)])) | |
1104 | return "1/2"; | |
1105 | // OK, checkmate | |
6808d7a1 | 1106 | return color == "w" ? "0-1" : "1-0"; |
1c9f093d BA |
1107 | } |
1108 | ||
1109 | /////////////// | |
1110 | // ENGINE PLAY | |
1111 | ||
1112 | // Pieces values | |
6808d7a1 | 1113 | static get VALUES() { |
1c9f093d | 1114 | return { |
6808d7a1 BA |
1115 | p: 1, |
1116 | r: 5, | |
1117 | n: 3, | |
1118 | b: 3, | |
1119 | q: 9, | |
1120 | k: 1000 | |
1c9f093d BA |
1121 | }; |
1122 | } | |
1123 | ||
1124 | // "Checkmate" (unreachable eval) | |
6808d7a1 BA |
1125 | static get INFINITY() { |
1126 | return 9999; | |
1127 | } | |
1c9f093d BA |
1128 | |
1129 | // At this value or above, the game is over | |
6808d7a1 BA |
1130 | static get THRESHOLD_MATE() { |
1131 | return V.INFINITY; | |
1132 | } | |
1c9f093d BA |
1133 | |
1134 | // Search depth: 2 for high branching factor, 4 for small (Loser chess, eg.) | |
6808d7a1 BA |
1135 | static get SEARCH_DEPTH() { |
1136 | return 3; | |
1137 | } | |
1c9f093d | 1138 | |
6808d7a1 | 1139 | getComputerMove() { |
1c9f093d BA |
1140 | const maxeval = V.INFINITY; |
1141 | const color = this.turn; | |
a97bdbda | 1142 | let moves1 = this.getAllValidMoves(); |
c322a844 | 1143 | |
6808d7a1 | 1144 | if (moves1.length == 0) |
e71161fb | 1145 | // TODO: this situation should not happen |
41cb9b94 | 1146 | return null; |
1c9f093d | 1147 | |
b83a675a | 1148 | // Rank moves using a min-max at depth 2 (if search_depth >= 2!) |
6808d7a1 | 1149 | for (let i = 0; i < moves1.length; i++) { |
afbf3ca7 BA |
1150 | this.play(moves1[i]); |
1151 | const score1 = this.getCurrentScore(); | |
1152 | if (score1 != "*") { | |
1153 | moves1[i].eval = | |
1154 | score1 == "1/2" | |
1155 | ? 0 | |
1156 | : (score1 == "1-0" ? 1 : -1) * maxeval; | |
1157 | } | |
1158 | if (V.SEARCH_DEPTH == 1 || score1 != "*") { | |
1159 | if (!moves1[i].eval) moves1[i].eval = this.evalPosition(); | |
1160 | this.undo(moves1[i]); | |
b83a675a BA |
1161 | continue; |
1162 | } | |
1c9f093d | 1163 | // Initial self evaluation is very low: "I'm checkmated" |
6808d7a1 | 1164 | moves1[i].eval = (color == "w" ? -1 : 1) * maxeval; |
afbf3ca7 BA |
1165 | // Initial enemy evaluation is very low too, for him |
1166 | let eval2 = (color == "w" ? 1 : -1) * maxeval; | |
1167 | // Second half-move: | |
1168 | let moves2 = this.getAllValidMoves(); | |
1169 | for (let j = 0; j < moves2.length; j++) { | |
1170 | this.play(moves2[j]); | |
1171 | const score2 = this.getCurrentScore(); | |
1172 | let evalPos = 0; //1/2 value | |
1173 | switch (score2) { | |
1174 | case "*": | |
1175 | evalPos = this.evalPosition(); | |
1176 | break; | |
1177 | case "1-0": | |
1178 | evalPos = maxeval; | |
1179 | break; | |
1180 | case "0-1": | |
1181 | evalPos = -maxeval; | |
1182 | break; | |
1c9f093d | 1183 | } |
afbf3ca7 BA |
1184 | if ( |
1185 | (color == "w" && evalPos < eval2) || | |
1186 | (color == "b" && evalPos > eval2) | |
1187 | ) { | |
1188 | eval2 = evalPos; | |
1189 | } | |
1190 | this.undo(moves2[j]); | |
1191 | } | |
6808d7a1 BA |
1192 | if ( |
1193 | (color == "w" && eval2 > moves1[i].eval) || | |
1194 | (color == "b" && eval2 < moves1[i].eval) | |
1195 | ) { | |
1c9f093d BA |
1196 | moves1[i].eval = eval2; |
1197 | } | |
1198 | this.undo(moves1[i]); | |
1199 | } | |
6808d7a1 BA |
1200 | moves1.sort((a, b) => { |
1201 | return (color == "w" ? 1 : -1) * (b.eval - a.eval); | |
1202 | }); | |
a97bdbda | 1203 | // console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; })); |
1c9f093d | 1204 | |
1c9f093d | 1205 | // Skip depth 3+ if we found a checkmate (or if we are checkmated in 1...) |
6808d7a1 | 1206 | if (V.SEARCH_DEPTH >= 3 && Math.abs(moves1[0].eval) < V.THRESHOLD_MATE) { |
6808d7a1 | 1207 | for (let i = 0; i < moves1.length; i++) { |
1c9f093d BA |
1208 | this.play(moves1[i]); |
1209 | // 0.1 * oldEval : heuristic to avoid some bad moves (not all...) | |
6808d7a1 BA |
1210 | moves1[i].eval = |
1211 | 0.1 * moves1[i].eval + | |
1212 | this.alphabeta(V.SEARCH_DEPTH - 1, -maxeval, maxeval); | |
1c9f093d BA |
1213 | this.undo(moves1[i]); |
1214 | } | |
6808d7a1 BA |
1215 | moves1.sort((a, b) => { |
1216 | return (color == "w" ? 1 : -1) * (b.eval - a.eval); | |
1217 | }); | |
b83a675a | 1218 | } |
1c9f093d | 1219 | |
b83a675a | 1220 | let candidates = [0]; |
6808d7a1 | 1221 | for (let j = 1; j < moves1.length && moves1[j].eval == moves1[0].eval; j++) |
1c9f093d | 1222 | candidates.push(j); |
656b1878 | 1223 | return moves1[candidates[randInt(candidates.length)]]; |
1c9f093d BA |
1224 | } |
1225 | ||
6808d7a1 | 1226 | alphabeta(depth, alpha, beta) { |
1c9f093d BA |
1227 | const maxeval = V.INFINITY; |
1228 | const color = this.turn; | |
1229 | const score = this.getCurrentScore(); | |
1230 | if (score != "*") | |
6808d7a1 BA |
1231 | return score == "1/2" ? 0 : (score == "1-0" ? 1 : -1) * maxeval; |
1232 | if (depth == 0) return this.evalPosition(); | |
a97bdbda | 1233 | const moves = this.getAllValidMoves(); |
6808d7a1 BA |
1234 | let v = color == "w" ? -maxeval : maxeval; |
1235 | if (color == "w") { | |
1236 | for (let i = 0; i < moves.length; i++) { | |
1c9f093d | 1237 | this.play(moves[i]); |
6808d7a1 | 1238 | v = Math.max(v, this.alphabeta(depth - 1, alpha, beta)); |
1c9f093d BA |
1239 | this.undo(moves[i]); |
1240 | alpha = Math.max(alpha, v); | |
6808d7a1 | 1241 | if (alpha >= beta) break; //beta cutoff |
1c9f093d | 1242 | } |
1c5bfdf2 | 1243 | } |
6808d7a1 | 1244 | else { |
1c5bfdf2 | 1245 | // color=="b" |
6808d7a1 | 1246 | for (let i = 0; i < moves.length; i++) { |
1c9f093d | 1247 | this.play(moves[i]); |
6808d7a1 | 1248 | v = Math.min(v, this.alphabeta(depth - 1, alpha, beta)); |
1c9f093d BA |
1249 | this.undo(moves[i]); |
1250 | beta = Math.min(beta, v); | |
6808d7a1 | 1251 | if (alpha >= beta) break; //alpha cutoff |
1c9f093d BA |
1252 | } |
1253 | } | |
1254 | return v; | |
1255 | } | |
1256 | ||
6808d7a1 | 1257 | evalPosition() { |
1c9f093d BA |
1258 | let evaluation = 0; |
1259 | // Just count material for now | |
6808d7a1 BA |
1260 | for (let i = 0; i < V.size.x; i++) { |
1261 | for (let j = 0; j < V.size.y; j++) { | |
1262 | if (this.board[i][j] != V.EMPTY) { | |
1263 | const sign = this.getColor(i, j) == "w" ? 1 : -1; | |
1264 | evaluation += sign * V.VALUES[this.getPiece(i, j)]; | |
1c9f093d BA |
1265 | } |
1266 | } | |
1267 | } | |
1268 | return evaluation; | |
1269 | } | |
1270 | ||
1271 | ///////////////////////// | |
1272 | // MOVES + GAME NOTATION | |
1273 | ///////////////////////// | |
1274 | ||
1275 | // Context: just before move is played, turn hasn't changed | |
1276 | // TODO: un-ambiguous notation (switch on piece type, check directions...) | |
6808d7a1 BA |
1277 | getNotation(move) { |
1278 | if (move.appear.length == 2 && move.appear[0].p == V.KING) | |
1cd3e362 | 1279 | // Castle |
6808d7a1 | 1280 | return move.end.y < move.start.y ? "0-0-0" : "0-0"; |
1c9f093d BA |
1281 | |
1282 | // Translate final square | |
1283 | const finalSquare = V.CoordsToSquare(move.end); | |
1284 | ||
1285 | const piece = this.getPiece(move.start.x, move.start.y); | |
6808d7a1 | 1286 | if (piece == V.PAWN) { |
1c9f093d BA |
1287 | // Pawn move |
1288 | let notation = ""; | |
6808d7a1 | 1289 | if (move.vanish.length > move.appear.length) { |
1c9f093d BA |
1290 | // Capture |
1291 | const startColumn = V.CoordToColumn(move.start.y); | |
1292 | notation = startColumn + "x" + finalSquare; | |
78d64531 | 1293 | } |
6808d7a1 BA |
1294 | else notation = finalSquare; |
1295 | if (move.appear.length > 0 && move.appear[0].p != V.PAWN) | |
78d64531 | 1296 | // Promotion |
1c9f093d BA |
1297 | notation += "=" + move.appear[0].p.toUpperCase(); |
1298 | return notation; | |
1299 | } | |
6808d7a1 BA |
1300 | // Piece movement |
1301 | return ( | |
1302 | piece.toUpperCase() + | |
1303 | (move.vanish.length > move.appear.length ? "x" : "") + | |
1304 | finalSquare | |
1305 | ); | |
1306 | } | |
1307 | }; |