client/src/variants/Suction.js

   1 import { ChessRules, PiPo, Move } from "@/base_rules";
   2
   3 export class SuctionRules extends ChessRules {
   4   static get HasFlags() {
   5     return false;
   6   }
   7
   8   setOtherVariables(fen) {
   9     super.setOtherVariables(fen);
  10     // Local stack of "captures"
  11     this.cmoves = [];
  12     const cmove = V.ParseFen(fen).cmove;
  13     if (cmove == "-") this.cmoves.push(null);
  14     else {
  15       this.cmoves.push({
  16         start: ChessRules.SquareToCoords(cmove.substr(0, 2)),
  17         end: ChessRules.SquareToCoords(cmove.substr(2))
  18       });
  19     }
  20   }
  21
  22   static ParseFen(fen) {
  23     return Object.assign(
  24       ChessRules.ParseFen(fen),
  25       { cmove: fen.split(" ")[4] }
  26     );
  27   }
  28
  29   static IsGoodFen(fen) {
  30     if (!ChessRules.IsGoodFen(fen)) return false;
  31     const fenParts = fen.split(" ");
  32     if (fenParts.length != 6) return false;
  33     if (fenParts[5] != "-" && !fenParts[5].match(/^([a-h][1-8]){2}$/))
  34       return false;
  35     return true;
  36   }
  37
  38   getCmove(move) {
  39     if (move.vanish.length == 2)
  40       return { start: move.start, end: move.end };
  41     return null;
  42   }
  43
  44   getBasicMove([sx, sy], [ex, ey]) {
  45     const startColor = this.getColor(sx, sy);
  46     const startPiece = this.getPiece(sx, sy);
  47     let mv = new Move({
  48       appear: [
  49         new PiPo({
  50           x: ex,
  51           y: ey,
  52           c: startColor,
  53           p: startPiece
  54         })
  55       ],
  56       vanish: [
  57         new PiPo({
  58           x: sx,
  59           y: sy,
  60           c: startColor,
  61           p: startPiece
  62         })
  63       ]
  64     });
  65
  66     if (this.board[ex][ey] != V.EMPTY) {
  67       const endColor = this.getColor(ex, ey);
  68       const endPiece = this.getPiece(ex, ey);
  69       mv.vanish.push(
  70         new PiPo({
  71           x: ex,
  72           y: ey,
  73           c: endColor,
  74           p: endPiece
  75         })
  76       );
  77       mv.appear.push(
  78         new PiPo({
  79           x: sx,
  80           y: sy,
  81           c: endColor,
  82           p: endPiece
  83         })
  84       );
  85     }
  86     return mv;
  87   }
  88
  89   getEnpassantCaptures([x, y], shiftX) {
  90     let moves = [];
  91     const Lep = this.epSquares.length;
  92     const epSquare = this.epSquares[Lep - 1]; //always at least one element
  93     if (
  94       !!epSquare &&
  95       epSquare.x == x + shiftX &&
  96       Math.abs(epSquare.y - y) == 1
  97     ) {
  98       let enpassantMove = this.getBasicMove([x, y], [epSquare.x, epSquare.y]);
  99       const oppCol = V.GetOppCol(color);
 100       enpassantMove.vanish.push({
 101         x: x,
 102         y: epSquare.y,
 103         p: "p",
 104         c: oppCol
 105       });
 106       enpassantMove.appear.push({
 107         x: x,
 108         y: y,
 109         p: "p",
 110         c: oppCol
 111       });
 112       moves.push(enpassantMove);
 113     }
 114     return moves;
 115   }
 116
 117   getPotentialKingMoves() {
 118     return [];
 119   }
 120
 121   // Does m2 un-do m1 ? (to disallow undoing captures)
 122   oppositeMoves(m1, m2) {
 123     return (
 124       m1 &&
 125       m2.vanish.length == 2 &&
 126       m1.start.x == m2.start.x &&
 127       m1.end.x == m2.end.x &&
 128       m1.start.y == m2.start.y &&
 129       m1.end.y == m2.end.y
 130     );
 131   }
 132
 133   filterValid(moves) {
 134     if (moves.length == 0) return [];
 135     const color = this.turn;
 136     return moves.filter(m => {
 137       const L = this.cmoves.length; //at least 1: init from FEN
 138       return !this.oppositeMoves(this.cmoves[L - 1], m);
 139     });
 140   }
 141
 142   static GenRandInitFen(randomness) {
 143     // Add empty cmove:
 144     return ChessRules.GenRandInitFen(randomness).slice(0, -6) + "- -";
 145   }
 146
 147   getFen() {
 148     const L = this.cmoves.length;
 149     const cmoveFen = !this.cmoves[L - 1]
 150       ? "-"
 151       : ChessRules.CoordsToSquare(this.cmoves[L - 1].start) +
 152         ChessRules.CoordsToSquare(this.cmoves[L - 1].end);
 153     return super.getFen() + " " + cmoveFen;
 154   }
 155
 156   postPlay(move) {
 157     super.postPlay(move);
 158     if (move.vanish.length == 2) {
 159       // Was opponent king swapped?
 160       if (move.vanish[1].p == V.KING)
 161         this.kingPos[this.turn] = [move.appear[1].x, move.appear[1].y];
 162     }
 163     this.cmoves.push(this.getCmove(move));
 164   }
 165
 166   postUndo(move) {
 167     super.postUndo(move);
 168     if (move.appear.length == 2) {
 169       if (move.appear[1].p == V.KING)
 170         this.kingPos[move.vanish[1].c] = [move.vanish[1].x, move.vanish[1].y];
 171     }
 172     this.cmoves.pop();
 173   }
 174
 175   atLeastOneMove() {
 176     return true;
 177   }
 178
 179   getCheckSquares() {
 180     return [];
 181   }
 182
 183   getCurrentScore() {
 184     const color = this.turn;
 185     const kp = this.kingPos[color];
 186     if (color == "w" && kp[0] == 0) return "0-1";
 187     if (color == "b" && kp[0] == V.size.x - 1) return "1-0";
 188     // King is not on the opposite edge: game not over
 189     return "*";
 190   }
 191
 192   evalPosition() {
 193     // Very simple criterion for now: kings position
 194     return this.kingPos["w"][0] + this.kingPos["b"][0];
 195   }
 196
 197   getNotation(move) {
 198     // Translate final square
 199     const finalSquare = V.CoordsToSquare(move.end);
 200
 201     const piece = this.getPiece(move.start.x, move.start.y);
 202     if (piece == V.PAWN) {
 203       // Pawn move
 204       let notation = "";
 205       if (move.vanish.length == 2) {
 206         // Capture
 207         const startColumn = V.CoordToColumn(move.start.y);
 208         notation = startColumn + "x" + finalSquare;
 209       }
 210       else notation = finalSquare;
 211       return notation;
 212     }
 213     // Piece movement
 214     return (
 215       piece.toUpperCase() +
 216       (move.vanish.length == 2 ? "x" : "") +
 217       finalSquare
 218     );
 219   }
 220 };