Lighter color for diagonal lines on board
[vchess.git] / client / src / variants / Doublemove2.js
CommitLineData
829f6574 1import { ChessRules } from "@/base_rules";
5fde3a01 2import { randInt } from "@/utils/alea";
829f6574 3
b406466b 4export class Doublemove2Rules extends ChessRules {
6808d7a1 5 static IsGoodEnpassant(enpassant) {
e71161fb
BA
6 const squares = enpassant.split(",");
7 if (squares.length > 2) return false;
8 for (let sq of squares) {
9 if (sq != "-") {
dac39588 10 const ep = V.SquareToCoords(sq);
6808d7a1 11 if (isNaN(ep.x) || !V.OnBoard(ep)) return false;
dac39588
BA
12 }
13 }
14 return true;
15 }
6e62b1c7 16
dac39588 17 // There may be 2 enPassant squares (if 2 pawns jump 2 squares in same turn)
6808d7a1 18 getEnpassantFen() {
e71161fb
BA
19 return this.epSquares[this.epSquares.length - 1].map(
20 epsq => epsq === undefined
21 ? "-" //no en-passant
22 : V.CoordsToSquare(epsq)
23 ).join(",");
dac39588 24 }
6e62b1c7 25
6808d7a1 26 setOtherVariables(fen) {
dac39588
BA
27 const parsedFen = V.ParseFen(fen);
28 this.setFlags(parsedFen.flags);
e71161fb
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29 this.epSquares = [parsedFen.enpassant.split(",").map(sq => {
30 if (sq != "-") return V.SquareToCoords(sq);
31 return undefined;
32 })];
3a2a7b5f 33 this.scanKings(fen);
dac39588
BA
34 // Extract subTurn from turn indicator: "w" (first move), or
35 // "w1" or "w2" white subturn 1 or 2, and same for black
af34341d
BA
36 this.turn = parsedFen.turn;
37 this.subTurn = 1;
dac39588 38 }
6e62b1c7 39
32f6285e 40 getEnpassantCaptures([x, y], shiftX) {
dac39588 41 let moves = [];
dac39588
BA
42 // En passant: always OK if subturn 1,
43 // OK on subturn 2 only if enPassant was played at subturn 1
44 // (and if there are two e.p. squares available).
45 const Lep = this.epSquares.length;
6808d7a1 46 const epSquares = this.epSquares[Lep - 1]; //always at least one element
dac39588
BA
47 let epSqs = [];
48 epSquares.forEach(sq => {
6808d7a1 49 if (sq) epSqs.push(sq);
dac39588 50 });
6808d7a1 51 if (epSqs.length == 0) return moves;
32f6285e 52 const oppCol = V.GetOppCol(this.getColor(x, y));
6808d7a1
BA
53 for (let sq of epSqs) {
54 if (
55 this.subTurn == 1 ||
56 (epSqs.length == 2 &&
57 // Was this en-passant capture already played at subturn 1 ?
58 // (Or maybe the opponent filled the en-passant square with a piece)
59 this.board[epSqs[0].x][epSqs[0].y] != V.EMPTY)
60 ) {
61 if (
62 sq.x == x + shiftX &&
63 Math.abs(sq.y - y) == 1 &&
dac39588 64 // Add condition "enemy pawn must be present"
6808d7a1
BA
65 this.getPiece(x, sq.y) == V.PAWN &&
66 this.getColor(x, sq.y) == oppCol
67 ) {
68 let epMove = this.getBasicMove([x, y], [sq.x, sq.y]);
dac39588
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69 epMove.vanish.push({
70 x: x,
71 y: sq.y,
6808d7a1 72 p: "p",
dac39588
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73 c: oppCol
74 });
75 moves.push(epMove);
76 }
77 }
78 }
dac39588
BA
79 return moves;
80 }
6e62b1c7 81
b406466b
BA
82 isAttacked(sq, color, castling) {
83 const singleMoveAttack = super.isAttacked(sq, color);
84 if (singleMoveAttack) return true;
85 if (!!castling) {
86 if (this.subTurn == 1)
87 // Castling at move 1 could be done into check
88 return false;
89 return singleMoveAttack;
90 }
91 // Double-move allowed:
92 const curTurn = this.turn;
93 this.turn = color;
94 const moves1 = super.getAllPotentialMoves();
95 this.turn = curTurn;
96 for (let move of moves1) {
97 this.play(move);
98 const res = super.isAttacked(sq, color);
99 this.undo(move);
100 if (res) return res;
101 }
102 return false;
103 }
104
105 filterValid(moves) {
106 if (this.subTurn == 1) {
107 return moves.filter(m1 => {
108 this.play(m1);
109 // NOTE: no recursion because next call will see subTurn == 2
110 const res = super.atLeastOneMove();
111 this.undo(m1);
112 return res;
113 });
114 }
115 return super.filterValid(moves);
116 }
117
6808d7a1 118 play(move) {
dac39588 119 move.flags = JSON.stringify(this.aggregateFlags());
dac39588
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120 V.PlayOnBoard(this.board, move);
121 const epSq = this.getEpSquare(move);
b406466b
BA
122 if (this.subTurn == 2) {
123 let lastEpsq = this.epSquares[this.epSquares.length - 1];
124 lastEpsq.push(epSq);
dac39588 125 this.turn = V.GetOppCol(this.turn);
b406466b
BA
126 }
127 else {
dac39588 128 this.epSquares.push([epSq]);
9842aca2 129 this.movesCount++;
b406466b 130 if (this.movesCount == 1) this.turn = "b";
dac39588 131 }
b406466b 132 if (this.movesCount > 1) this.subTurn = 3 - this.subTurn;
3a2a7b5f
BA
133 this.postPlay(move);
134 }
135
136 postPlay(move) {
b406466b 137 const c = move.vanish[0].c;
3a2a7b5f
BA
138 const piece = move.vanish[0].p;
139 const firstRank = c == "w" ? V.size.x - 1 : 0;
140
141 if (piece == V.KING && move.appear.length > 0) {
142 this.kingPos[c][0] = move.appear[0].x;
143 this.kingPos[c][1] = move.appear[0].y;
0d5335de 144 this.castleFlags[c] = [V.size.y, V.size.y];
3a2a7b5f
BA
145 return;
146 }
147 const oppCol = V.GetOppCol(c);
148 const oppFirstRank = V.size.x - 1 - firstRank;
149 if (
150 move.start.x == firstRank && //our rook moves?
151 this.castleFlags[c].includes(move.start.y)
152 ) {
153 const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
154 this.castleFlags[c][flagIdx] = V.size.y;
155 } else if (
156 move.end.x == oppFirstRank && //we took opponent rook?
157 this.castleFlags[oppCol].includes(move.end.y)
158 ) {
159 const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
160 this.castleFlags[oppCol][flagIdx] = V.size.y;
161 }
dac39588 162 }
6e62b1c7 163
6808d7a1 164 undo(move) {
dac39588
BA
165 this.disaggregateFlags(JSON.parse(move.flags));
166 V.UndoOnBoard(this.board, move);
b406466b 167 if (this.subTurn == 2 || this.movesCount == 1) {
dac39588 168 this.epSquares.pop();
9842aca2 169 this.movesCount--;
b406466b
BA
170 if (this.movesCount == 0) this.turn = "w";
171 }
172 else {
6808d7a1 173 let lastEpsq = this.epSquares[this.epSquares.length - 1];
dac39588 174 lastEpsq.pop();
b406466b 175 this.turn = V.GetOppCol(this.turn);
dac39588 176 }
b406466b 177 if (this.movesCount > 0) this.subTurn = 3 - this.subTurn;
3a2a7b5f 178 super.postUndo(move);
dac39588 179 }
6e62b1c7 180
6808d7a1 181 static get VALUES() {
dac39588 182 return {
6808d7a1
BA
183 p: 1,
184 r: 5,
185 n: 3,
186 b: 3,
187 q: 7, //slightly less than in orthodox game
188 k: 1000
dac39588
BA
189 };
190 }
0596f5e7 191
dac39588 192 // No alpha-beta here, just adapted min-max at depth 2(+1)
6808d7a1 193 getComputerMove() {
dac39588
BA
194 const maxeval = V.INFINITY;
195 const color = this.turn;
196 const oppCol = V.GetOppCol(this.turn);
51882959 197
dac39588
BA
198 // Search best (half) move for opponent turn
199 const getBestMoveEval = () => {
dac39588 200 let score = this.getCurrentScore();
6808d7a1
BA
201 if (score != "*") {
202 if (score == "1/2") return 0;
dac39588
BA
203 return maxeval * (score == "1-0" ? 1 : -1);
204 }
205 let moves = this.getAllValidMoves();
6808d7a1
BA
206 let res = oppCol == "w" ? -maxeval : maxeval;
207 for (let m of moves) {
dac39588
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208 this.play(m);
209 score = this.getCurrentScore();
b406466b 210 // Now turn is oppCol,2
6808d7a1 211 if (score != "*") {
dac39588 212 if (score == "1/2")
6808d7a1
BA
213 res = oppCol == "w" ? Math.max(res, 0) : Math.min(res, 0);
214 else {
b406466b 215 // King captured
dac39588
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216 this.undo(m);
217 return maxeval * (score == "1-0" ? 1 : -1);
218 }
219 }
220 const evalPos = this.evalPosition();
6808d7a1 221 res = oppCol == "w" ? Math.max(res, evalPos) : Math.min(res, evalPos);
dac39588
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222 this.undo(m);
223 }
224 return res;
225 };
6e62b1c7 226
dac39588
BA
227 let moves11 = this.getAllValidMoves();
228 let doubleMoves = [];
b406466b 229 // Rank moves using a min-max at depth 2(+1)
6808d7a1 230 for (let i = 0; i < moves11.length; i++) {
dac39588 231 this.play(moves11[i]);
b406466b
BA
232 let moves12 = this.getAllValidMoves();
233 for (let j = 0; j < moves12.length; j++) {
234 this.play(moves12[j]);
235 doubleMoves.push({
236 moves: [moves11[i], moves12[j]],
237 eval: getBestMoveEval()
238 });
239 this.undo(moves12[j]);
dac39588
BA
240 }
241 this.undo(moves11[i]);
242 }
6e62b1c7 243
6808d7a1
BA
244 doubleMoves.sort((a, b) => {
245 return (color == "w" ? 1 : -1) * (b.eval - a.eval);
246 });
dac39588 247 let candidates = [0]; //indices of candidates moves
6808d7a1
BA
248 for (
249 let i = 1;
250 i < doubleMoves.length && doubleMoves[i].eval == doubleMoves[0].eval;
251 i++
252 ) {
dac39588
BA
253 candidates.push(i);
254 }
b406466b 255 return doubleMoves[randInt(candidates.length)].moves;
dac39588 256 }
6808d7a1 257};