Flip knights for variants with knightriders (waiting for a better image)
[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
BA
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
BA
69 epMove.vanish.push({
70 x: x,
71 y: sq.y,
6808d7a1 72 p: "p",
dac39588
BA
73 c: oppCol
74 });
75 moves.push(epMove);
76 }
77 }
78 }
dac39588
BA
79 return moves;
80 }
6e62b1c7 81
34bfe151 82 isAttacked() {
bc0b9205 83 // Goal is king capture => no checks
b406466b
BA
84 return false;
85 }
86
87 filterValid(moves) {
bc0b9205
BA
88 return moves;
89 }
90
91 getCheckSquares() {
92 return [];
93 }
94
95 getCurrentScore() {
96 const color = this.turn;
97 if (this.kingPos[color][0] < 0) return (color == 'w' ? "0-1" : "1-0");
98 return "*";
b406466b
BA
99 }
100
6808d7a1 101 play(move) {
dac39588 102 move.flags = JSON.stringify(this.aggregateFlags());
dac39588
BA
103 V.PlayOnBoard(this.board, move);
104 const epSq = this.getEpSquare(move);
b406466b
BA
105 if (this.subTurn == 2) {
106 let lastEpsq = this.epSquares[this.epSquares.length - 1];
107 lastEpsq.push(epSq);
dac39588 108 this.turn = V.GetOppCol(this.turn);
b406466b
BA
109 }
110 else {
dac39588 111 this.epSquares.push([epSq]);
9842aca2 112 this.movesCount++;
964eda04
BA
113 if (
114 this.movesCount == 1 ||
115 // King is captured at subTurn 1?
116 (move.vanish.length == 2 && move.vanish[1].p == V.KING)
117 ) {
118 this.turn = "b";
119 }
dac39588 120 }
b406466b 121 if (this.movesCount > 1) this.subTurn = 3 - this.subTurn;
3a2a7b5f
BA
122 this.postPlay(move);
123 }
124
125 postPlay(move) {
b406466b 126 const c = move.vanish[0].c;
3a2a7b5f
BA
127 const piece = move.vanish[0].p;
128 const firstRank = c == "w" ? V.size.x - 1 : 0;
129
737a5daf 130 if (piece == V.KING) {
bc0b9205 131 this.kingPos[c] = [move.appear[0].x, move.appear[0].y];
0d5335de 132 this.castleFlags[c] = [V.size.y, V.size.y];
3a2a7b5f
BA
133 return;
134 }
135 const oppCol = V.GetOppCol(c);
964eda04 136 if (move.vanish.length == 2 && move.vanish[1].p == V.KING) {
bc0b9205
BA
137 // Opponent's king is captured, game over
138 this.kingPos[oppCol] = [-1, -1];
964eda04
BA
139 move.captureKing = true; //for undo
140 }
3a2a7b5f
BA
141 const oppFirstRank = V.size.x - 1 - firstRank;
142 if (
143 move.start.x == firstRank && //our rook moves?
144 this.castleFlags[c].includes(move.start.y)
145 ) {
146 const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
147 this.castleFlags[c][flagIdx] = V.size.y;
bc0b9205 148 }
737a5daf 149 if (
3a2a7b5f
BA
150 move.end.x == oppFirstRank && //we took opponent rook?
151 this.castleFlags[oppCol].includes(move.end.y)
152 ) {
153 const flagIdx = (move.end.y == this.castleFlags[oppCol][0] ? 0 : 1);
154 this.castleFlags[oppCol][flagIdx] = V.size.y;
155 }
dac39588 156 }
6e62b1c7 157
6808d7a1 158 undo(move) {
dac39588
BA
159 this.disaggregateFlags(JSON.parse(move.flags));
160 V.UndoOnBoard(this.board, move);
964eda04 161 if (this.subTurn == 2 || this.movesCount == 1 || !!move.captureKing) {
dac39588 162 this.epSquares.pop();
9842aca2 163 this.movesCount--;
b406466b
BA
164 if (this.movesCount == 0) this.turn = "w";
165 }
166 else {
6808d7a1 167 let lastEpsq = this.epSquares[this.epSquares.length - 1];
dac39588 168 lastEpsq.pop();
b406466b 169 this.turn = V.GetOppCol(this.turn);
dac39588 170 }
b406466b 171 if (this.movesCount > 0) this.subTurn = 3 - this.subTurn;
bc0b9205 172 this.postUndo(move);
dac39588 173 }
6e62b1c7 174
bc0b9205
BA
175 postUndo(move) {
176 if (move.vanish.length == 2 && move.vanish[1].p == V.KING)
177 // Opponent's king was captured
178 this.kingPos[move.vanish[1].c] = [move.vanish[1].x, move.vanish[1].y];
179 super.postUndo(move);
dac39588 180 }
0596f5e7 181
bc0b9205 182 // No alpha-beta here, just adapted min-max at depth 2(+1)
6808d7a1 183 getComputerMove() {
bc0b9205 184 const maxeval = V.INFINITY;
dac39588 185 const color = this.turn;
bc0b9205
BA
186 const oppCol = V.GetOppCol(this.turn);
187
188 // Search best (half) move for opponent turn
189 const getBestMoveEval = () => {
190 let score = this.getCurrentScore();
191 if (score != "*") return maxeval * (score == "1-0" ? 1 : -1);
192 let moves = this.getAllValidMoves();
193 let res = oppCol == "w" ? -maxeval : maxeval;
194 for (let m of moves) {
195 this.play(m);
196 score = this.getCurrentScore();
197 if (score != "*") {
198 // King captured
199 this.undo(m);
200 return maxeval * (score == "1-0" ? 1 : -1);
201 }
202 const evalPos = this.evalPosition();
203 res = oppCol == "w" ? Math.max(res, evalPos) : Math.min(res, evalPos);
204 this.undo(m);
205 }
206 return res;
207 };
208
5d75c82c
BA
209 const moves11 = this.getAllValidMoves();
210 if (this.movesCount == 0)
211 // First white move at random:
212 return moves11[randInt(moves11.length)];
737a5daf
BA
213 let doubleMove = null;
214 let bestEval = Number.POSITIVE_INFINITY * (color == 'w' ? -1 : 1);
5d75c82c 215 // Rank moves using a min-max at depth 2
6808d7a1 216 for (let i = 0; i < moves11.length; i++) {
dac39588 217 this.play(moves11[i]);
5d75c82c 218 const moves12 = this.getAllValidMoves();
b406466b
BA
219 for (let j = 0; j < moves12.length; j++) {
220 this.play(moves12[j]);
737a5daf
BA
221 // Small fluctuations to uniformize play a little
222 const evalM = getBestMoveEval() + 0.05 - Math.random() / 10
223 if (
224 (color == 'w' && evalM > bestEval) ||
225 (color == 'b' && evalM < bestEval)
226 ) {
227 doubleMove = [moves11[i], moves12[j]];
228 bestEval = evalM;
229 }
b406466b 230 this.undo(moves12[j]);
dac39588
BA
231 }
232 this.undo(moves11[i]);
233 }
737a5daf
BA
234 // TODO: not always the best move played (why ???)
235 return doubleMove;
dac39588 236 }
6808d7a1 237};