| 1 | import { ChessRules, PiPo, Move } from "@/base_rules"; |
| 2 | |
| 3 | export class EnpassantRules extends ChessRules { |
| 4 | static IsGoodEnpassant(enpassant) { |
| 5 | if (enpassant != "-") { |
| 6 | const squares = enpassant.split(","); |
| 7 | if (squares.length > 2) return false; |
| 8 | for (let sq of squares) { |
| 9 | const ep = V.SquareToCoords(sq); |
| 10 | if (isNaN(ep.x) || !V.OnBoard(ep)) return false; |
| 11 | } |
| 12 | } |
| 13 | return true; |
| 14 | } |
| 15 | |
| 16 | getPpath(b) { |
| 17 | return (b[1] == V.KNIGHT ? "Enpassant/" : "") + b; |
| 18 | } |
| 19 | |
| 20 | getEpSquare(moveOrSquare) { |
| 21 | if (!moveOrSquare) return undefined; |
| 22 | if (typeof moveOrSquare === "string") { |
| 23 | const square = moveOrSquare; |
| 24 | if (square == "-") return undefined; |
| 25 | // Expand init + dest squares into a full path: |
| 26 | const init = V.SquareToCoords(square.substr(0, 2)); |
| 27 | let newPath = [init]; |
| 28 | if (square.length == 2) return newPath; |
| 29 | const dest = V.SquareToCoords(square.substr(2)); |
| 30 | const delta = ['x', 'y'].map(i => Math.abs(dest[i] - init[i])); |
| 31 | // Check if it's a knight(rider) movement: |
| 32 | let step = [0, 0]; |
| 33 | if (delta[0] > 0 && delta[1] > 0 && delta[0] != delta[1]) { |
| 34 | // Knightrider |
| 35 | const minShift = Math.min(delta[0], delta[1]); |
| 36 | step[0] = (dest.x - init.x) / minShift; |
| 37 | step[1] = (dest.y - init.y) / minShift; |
| 38 | } else { |
| 39 | // "Sliders" |
| 40 | step = ['x', 'y'].map((i, idx) => { |
| 41 | return (dest[i] - init[i]) / delta[idx] || 0 |
| 42 | }); |
| 43 | } |
| 44 | let x = init.x + step[0], |
| 45 | y = init.y + step[1]; |
| 46 | while (x != dest.x || y != dest.y) { |
| 47 | newPath.push({ x: x, y: y }); |
| 48 | x += step[0]; |
| 49 | y += step[1]; |
| 50 | } |
| 51 | newPath.push(dest); |
| 52 | return newPath; |
| 53 | } |
| 54 | // Argument is a move: all intermediate squares are en-passant candidates, |
| 55 | // except if the moving piece is a king. |
| 56 | const move = moveOrSquare; |
| 57 | const piece = move.appear[0].p; |
| 58 | if (piece == V.KING || |
| 59 | ( |
| 60 | Math.abs(move.end.x-move.start.x) <= 1 && |
| 61 | Math.abs(move.end.y-move.start.y) <= 1 |
| 62 | ) |
| 63 | ) { |
| 64 | return undefined; |
| 65 | } |
| 66 | const delta = [move.end.x-move.start.x, move.end.y-move.start.y]; |
| 67 | let step = undefined; |
| 68 | if (piece == V.KNIGHT) { |
| 69 | const divisor = Math.min(Math.abs(delta[0]), Math.abs(delta[1])); |
| 70 | step = [delta[0]/divisor || 0, delta[1]/divisor || 0]; |
| 71 | } else { |
| 72 | step = [ |
| 73 | delta[0]/Math.abs(delta[0]) || 0, |
| 74 | delta[1]/Math.abs(delta[1]) || 0 |
| 75 | ]; |
| 76 | } |
| 77 | let res = []; |
| 78 | for ( |
| 79 | let [x,y] = [move.start.x+step[0],move.start.y+step[1]]; |
| 80 | x != move.end.x || y != move.end.y; |
| 81 | x += step[0], y += step[1] |
| 82 | ) { |
| 83 | res.push({ x: x, y: y }); |
| 84 | } |
| 85 | // Add final square to know which piece is taken en passant: |
| 86 | res.push(move.end); |
| 87 | return res; |
| 88 | } |
| 89 | |
| 90 | getEnpassantFen() { |
| 91 | const L = this.epSquares.length; |
| 92 | if (!this.epSquares[L - 1]) return "-"; //no en-passant |
| 93 | const epsq = this.epSquares[L - 1]; |
| 94 | if (epsq.length <= 2) return epsq.map(V.CoordsToSquare).join(""); |
| 95 | // Condensate path: just need initial and final squares: |
| 96 | return V.CoordsToSquare(epsq[0]) + V.CoordsToSquare(epsq[epsq.length - 1]); |
| 97 | } |
| 98 | |
| 99 | getPotentialMovesFrom([x, y]) { |
| 100 | let moves = super.getPotentialMovesFrom([x,y]); |
| 101 | // Add en-passant captures from this square: |
| 102 | const L = this.epSquares.length; |
| 103 | if (!this.epSquares[L - 1]) return moves; |
| 104 | const squares = this.epSquares[L - 1]; |
| 105 | const S = squares.length; |
| 106 | // Object describing the removed opponent's piece: |
| 107 | const pipoV = new PiPo({ |
| 108 | x: squares[S-1].x, |
| 109 | y: squares[S-1].y, |
| 110 | c: V.GetOppCol(this.turn), |
| 111 | p: this.getPiece(squares[S-1].x, squares[S-1].y) |
| 112 | }); |
| 113 | // Check if existing non-capturing moves could also capture en passant |
| 114 | moves.forEach(m => { |
| 115 | if ( |
| 116 | m.appear[0].p != V.PAWN && //special pawn case is handled elsewhere |
| 117 | m.vanish.length <= 1 && |
| 118 | [...Array(S-1).keys()].some(i => { |
| 119 | return m.end.x == squares[i].x && m.end.y == squares[i].y; |
| 120 | }) |
| 121 | ) { |
| 122 | m.vanish.push(pipoV); |
| 123 | } |
| 124 | }); |
| 125 | // Special case of the king knight's movement: |
| 126 | if (this.getPiece(x, y) == V.KING) { |
| 127 | V.steps[V.KNIGHT].forEach(step => { |
| 128 | const endX = x + step[0]; |
| 129 | const endY = y + step[1]; |
| 130 | if ( |
| 131 | V.OnBoard(endX, endY) && |
| 132 | [...Array(S-1).keys()].some(i => { |
| 133 | return endX == squares[i].x && endY == squares[i].y; |
| 134 | }) |
| 135 | ) { |
| 136 | let enpassantMove = this.getBasicMove([x, y], [endX, endY]); |
| 137 | enpassantMove.vanish.push(pipoV); |
| 138 | moves.push(enpassantMove); |
| 139 | } |
| 140 | }); |
| 141 | } |
| 142 | return moves; |
| 143 | } |
| 144 | |
| 145 | getEnpassantCaptures([x, y], shiftX) { |
| 146 | const Lep = this.epSquares.length; |
| 147 | const squares = this.epSquares[Lep - 1]; |
| 148 | let moves = []; |
| 149 | if (!!squares) { |
| 150 | const S = squares.length; |
| 151 | const taken = squares[S-1]; |
| 152 | const pipoV = new PiPo({ |
| 153 | x: taken.x, |
| 154 | y: taken.y, |
| 155 | p: this.getPiece(taken.x, taken.y), |
| 156 | c: this.getColor(taken.x, taken.y) |
| 157 | }); |
| 158 | [...Array(S-1).keys()].forEach(i => { |
| 159 | const sq = squares[i]; |
| 160 | if (sq.x == x + shiftX && Math.abs(sq.y - y) == 1) { |
| 161 | let enpassantMove = this.getBasicMove([x, y], [sq.x, sq.y]); |
| 162 | enpassantMove.vanish.push(pipoV); |
| 163 | moves.push(enpassantMove); |
| 164 | } |
| 165 | }); |
| 166 | } |
| 167 | return moves; |
| 168 | } |
| 169 | |
| 170 | // Remove the "onestep" condition: knight promote to knightrider: |
| 171 | getPotentialKnightMoves(sq) { |
| 172 | return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT]); |
| 173 | } |
| 174 | |
| 175 | filterValid(moves) { |
| 176 | const filteredMoves = super.filterValid(moves); |
| 177 | // If at least one full move made, everything is allowed: |
| 178 | if (this.movesCount >= 2) |
| 179 | return filteredMoves; |
| 180 | // Else, forbid captures: |
| 181 | return filteredMoves.filter(m => m.vanish.length == 1); |
| 182 | } |
| 183 | |
| 184 | isAttackedByKnight(sq, color) { |
| 185 | return this.isAttackedBySlideNJump( |
| 186 | sq, |
| 187 | color, |
| 188 | V.KNIGHT, |
| 189 | V.steps[V.KNIGHT] |
| 190 | ); |
| 191 | } |
| 192 | |
| 193 | static get SEARCH_DEPTH() { |
| 194 | return 2; |
| 195 | } |
| 196 | |
| 197 | static get VALUES() { |
| 198 | return { |
| 199 | p: 1, |
| 200 | r: 5, |
| 201 | n: 4, |
| 202 | b: 3, |
| 203 | q: 9, |
| 204 | k: 1000 |
| 205 | }; |
| 206 | } |
| 207 | }; |