| 1 | import { ChessRules } from "@/base_rules"; |
| 2 | import { randInt } from "@/utils/alea"; |
| 3 | |
| 4 | export class TakenmakeRules extends ChessRules { |
| 5 | |
| 6 | setOtherVariables(fen) { |
| 7 | super.setOtherVariables(fen); |
| 8 | // Stack of "last move" only for intermediate captures |
| 9 | this.lastMoveEnd = [null]; |
| 10 | } |
| 11 | |
| 12 | getPotentialMovesFrom([x, y], asA) { |
| 13 | const L = this.lastMoveEnd.length; |
| 14 | if (!asA && !!this.lastMoveEnd[L-1]) { |
| 15 | asA = this.lastMoveEnd[L-1].p; |
| 16 | if (x != this.lastMoveEnd[L-1].x || y != this.lastMoveEnd[L-1].y) |
| 17 | // A capture was played: wrong square |
| 18 | return []; |
| 19 | } |
| 20 | let moves = []; |
| 21 | const piece = this.getPiece(x, y); |
| 22 | switch (asA || piece) { |
| 23 | case V.PAWN: |
| 24 | if (!asA || piece == V.PAWN) |
| 25 | moves = super.getPotentialPawnMoves([x, y]); |
| 26 | else { |
| 27 | // Special case: we don't want promotion, since just moving like |
| 28 | // a pawn, but I'm in fact not a pawn :) |
| 29 | const shiftX = (this.turn == 'w' ? -1 : 1); |
| 30 | if (this.board[x + shiftX][y] == V.EMPTY) |
| 31 | moves = [this.getBasicMove([x, y], [x + shiftX, y])]; |
| 32 | } |
| 33 | break; |
| 34 | case V.ROOK: |
| 35 | moves = this.getPotentialRookMoves([x, y]); |
| 36 | break; |
| 37 | case V.KNIGHT: |
| 38 | moves = this.getPotentialKnightMoves([x, y]); |
| 39 | break; |
| 40 | case V.BISHOP: |
| 41 | moves = this.getPotentialBishopMoves([x, y]); |
| 42 | break; |
| 43 | case V.KING: |
| 44 | moves = this.getPotentialKingMoves([x, y]); |
| 45 | break; |
| 46 | case V.QUEEN: |
| 47 | moves = this.getPotentialQueenMoves([x, y]); |
| 48 | break; |
| 49 | } |
| 50 | // Post-process: if capture, |
| 51 | // can a move "as-capturer" be achieved with the same piece? |
| 52 | if (!asA) { |
| 53 | const color = this.turn; |
| 54 | return moves.filter(m => { |
| 55 | if (m.vanish.length == 2 && m.appear.length == 1) { |
| 56 | this.play(m); |
| 57 | let moveOk = true; |
| 58 | const makeMoves = |
| 59 | this.getPotentialMovesFrom([m.end.x, m.end.y], m.vanish[1].p); |
| 60 | if ( |
| 61 | makeMoves.every(mm => { |
| 62 | // Cannot castle after a capturing move |
| 63 | // (with the capturing piece): |
| 64 | if (mm.vanish.length == 2) return true; |
| 65 | this.play(mm); |
| 66 | const res = this.underCheck(color); |
| 67 | this.undo(mm); |
| 68 | return res; |
| 69 | }) |
| 70 | ) { |
| 71 | moveOk = false; |
| 72 | } |
| 73 | this.undo(m); |
| 74 | return moveOk; |
| 75 | } |
| 76 | return true; |
| 77 | }); |
| 78 | } |
| 79 | // Moving "as a": filter out captures (no castles here) |
| 80 | return moves.filter(m => m.vanish.length == 1); |
| 81 | } |
| 82 | |
| 83 | getPossibleMovesFrom(sq) { |
| 84 | const L = this.lastMoveEnd.length; |
| 85 | let asA = undefined; |
| 86 | if (!!this.lastMoveEnd[L-1]) { |
| 87 | if ( |
| 88 | sq[0] != this.lastMoveEnd[L-1].x || |
| 89 | sq[1] != this.lastMoveEnd[L-1].y |
| 90 | ) { |
| 91 | return []; |
| 92 | } |
| 93 | asA = this.lastMoveEnd[L-1].p; |
| 94 | } |
| 95 | return this.filterValid(this.getPotentialMovesFrom(sq, asA)); |
| 96 | } |
| 97 | |
| 98 | filterValid(moves) { |
| 99 | let noCaptureMoves = []; |
| 100 | let captureMoves = []; |
| 101 | moves.forEach(m => { |
| 102 | if (m.vanish.length == 1 || m.appear.length == 2) noCaptureMoves.push(m); |
| 103 | else captureMoves.push(m); |
| 104 | }); |
| 105 | // Capturing moves were already checked in getPotentialMovesFrom() |
| 106 | return super.filterValid(noCaptureMoves).concat(captureMoves); |
| 107 | } |
| 108 | |
| 109 | play(move) { |
| 110 | move.flags = JSON.stringify(this.aggregateFlags()); |
| 111 | this.epSquares.push(this.getEpSquare(move)); |
| 112 | V.PlayOnBoard(this.board, move); |
| 113 | if (move.vanish.length == 1 || move.appear.length == 2) { |
| 114 | // Not a capture: change turn |
| 115 | this.turn = V.GetOppCol(this.turn); |
| 116 | this.movesCount++; |
| 117 | this.lastMoveEnd.push(null); |
| 118 | } |
| 119 | else { |
| 120 | this.lastMoveEnd.push( |
| 121 | Object.assign({}, move.end, { p: move.vanish[1].p }) |
| 122 | ); |
| 123 | } |
| 124 | this.postPlay(move); |
| 125 | } |
| 126 | |
| 127 | postPlay(move) { |
| 128 | const c = move.vanish[0].c; |
| 129 | const piece = move.vanish[0].p; |
| 130 | if (piece == V.KING && move.appear.length > 0) { |
| 131 | this.kingPos[c][0] = move.appear[0].x; |
| 132 | this.kingPos[c][1] = move.appear[0].y; |
| 133 | } |
| 134 | super.updateCastleFlags(move, piece, c); |
| 135 | } |
| 136 | |
| 137 | undo(move) { |
| 138 | this.disaggregateFlags(JSON.parse(move.flags)); |
| 139 | this.epSquares.pop(); |
| 140 | this.lastMoveEnd.pop(); |
| 141 | V.UndoOnBoard(this.board, move); |
| 142 | if (move.vanish.length == 1 || move.appear.length == 2) { |
| 143 | this.turn = V.GetOppCol(this.turn); |
| 144 | this.movesCount--; |
| 145 | } |
| 146 | super.postUndo(move); |
| 147 | } |
| 148 | |
| 149 | getComputerMove() { |
| 150 | let moves = this.getAllValidMoves(); |
| 151 | if (moves.length == 0) return null; |
| 152 | // Custom "search" at depth 1 (for now. TODO?) |
| 153 | const maxeval = V.INFINITY; |
| 154 | const color = this.turn; |
| 155 | moves.forEach(m => { |
| 156 | this.play(m); |
| 157 | m.eval = (color == "w" ? -1 : 1) * maxeval; |
| 158 | if (m.vanish.length == 2 && m.appear.length == 1) { |
| 159 | const moves2 = this.getPossibleMovesFrom([m.end.x, m.end.y]); |
| 160 | m.next = moves2[0]; |
| 161 | moves2.forEach(m2 => { |
| 162 | this.play(m2); |
| 163 | const score = this.getCurrentScore(); |
| 164 | let mvEval = 0; |
| 165 | if (score != "1/2") { |
| 166 | if (score != "*") mvEval = (score == "1-0" ? 1 : -1) * maxeval; |
| 167 | else mvEval = this.evalPosition(); |
| 168 | } |
| 169 | if ( |
| 170 | (color == 'w' && mvEval > m.eval) || |
| 171 | (color == 'b' && mvEval < m.eval) |
| 172 | ) { |
| 173 | m.eval = mvEval; |
| 174 | m.next = m2; |
| 175 | } |
| 176 | this.undo(m2); |
| 177 | }); |
| 178 | } |
| 179 | else { |
| 180 | const score = this.getCurrentScore(); |
| 181 | if (score != "1/2") { |
| 182 | if (score != "*") m.eval = (score == "1-0" ? 1 : -1) * maxeval; |
| 183 | else m.eval = this.evalPosition(); |
| 184 | } |
| 185 | } |
| 186 | this.undo(m); |
| 187 | }); |
| 188 | moves.sort((a, b) => { |
| 189 | return (color == "w" ? 1 : -1) * (b.eval - a.eval); |
| 190 | }); |
| 191 | let candidates = [0]; |
| 192 | for (let i = 1; i < moves.length && moves[i].eval == moves[0].eval; i++) |
| 193 | candidates.push(i); |
| 194 | const mIdx = candidates[randInt(candidates.length)]; |
| 195 | if (!moves[mIdx].next) return moves[mIdx]; |
| 196 | const move2 = moves[mIdx].next; |
| 197 | delete moves[mIdx]["next"]; |
| 198 | return [moves[mIdx], move2]; |
| 199 | } |
| 200 | |
| 201 | }; |