client/src/variants/Zen.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class ZenRules extends ChessRules {
   4   // NOTE: enPassant, if enabled, would need to redefine carefully getEpSquare
   5   static get HasEnpassant() {
   6     return false;
   7   }
   8
   9   // TODO(?): some duplicated code in 2 next functions
  10   getSlideNJumpMoves([x, y], steps, oneStep) {
  11     let moves = [];
  12     outerLoop: for (let loop = 0; loop < steps.length; loop++) {
  13       const step = steps[loop];
  14       let i = x + step[0];
  15       let j = y + step[1];
  16       while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
  17         moves.push(this.getBasicMove([x, y], [i, j]));
  18         if (oneStep) continue outerLoop;
  19         i += step[0];
  20         j += step[1];
  21       }
  22       // No capture check: handled elsewhere (next method)
  23     }
  24     return moves;
  25   }
  26
  27   // follow steps from x,y until something is met.
  28   // if met piece is opponent and same movement (asA): eat it!
  29   findCaptures_aux([x, y], asA) {
  30     const color = this.getColor(x, y);
  31     let moves = [];
  32     const steps =
  33       asA != V.PAWN
  34         ? asA == V.QUEEN
  35           ? V.steps[V.ROOK].concat(V.steps[V.BISHOP])
  36           : V.steps[asA]
  37         : color == "w"
  38           ? [
  39             [-1, -1],
  40             [-1, 1]
  41           ]
  42           : [
  43             [1, -1],
  44             [1, 1]
  45           ];
  46     const oneStep = [V.KNIGHT,V.PAWN].includes(asA); //we don't capture king
  47     const lastRank = color == "w" ? 0 : V.size.x - 1;
  48     const promotionPieces = [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN];
  49     outerLoop: for (let loop = 0; loop < steps.length; loop++) {
  50       const step = steps[loop];
  51       let i = x + step[0];
  52       let j = y + step[1];
  53       while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
  54         if (oneStep) continue outerLoop;
  55         i += step[0];
  56         j += step[1];
  57       }
  58       if (
  59         V.OnBoard(i, j) &&
  60         this.getColor(i, j) == V.GetOppCol(color) &&
  61         this.getPiece(i, j) == asA
  62       ) {
  63         // eat!
  64         if (this.getPiece(x, y) == V.PAWN && i == lastRank) {
  65           // Special case of promotion:
  66           promotionPieces.forEach(p => {
  67             moves.push(this.getBasicMove([x, y], [i, j], { c: color, p: p }));
  68           });
  69         } else {
  70           // All other cases
  71           moves.push(this.getBasicMove([x, y], [i, j]));
  72         }
  73       }
  74     }
  75     return moves;
  76   }
  77
  78   // Find possible captures from a square: look in every direction!
  79   findCaptures(sq) {
  80     let moves = [];
  81
  82     Array.prototype.push.apply(moves, this.findCaptures_aux(sq, V.PAWN));
  83     Array.prototype.push.apply(moves, this.findCaptures_aux(sq, V.ROOK));
  84     Array.prototype.push.apply(moves, this.findCaptures_aux(sq, V.KNIGHT));
  85     Array.prototype.push.apply(moves, this.findCaptures_aux(sq, V.BISHOP));
  86     Array.prototype.push.apply(moves, this.findCaptures_aux(sq, V.QUEEN));
  87
  88     return moves;
  89   }
  90
  91   canTake(sq1, sq2) {
  92     return false; //captures handled separately
  93   }
  94
  95   getPotentialPawnMoves([x, y]) {
  96     let moves = super.getPotentialPawnMoves([x, y]);
  97     // Add "zen" captures
  98     Array.prototype.push.apply(moves, this.findCaptures([x, y]));
  99     return moves;
 100   }
 101
 102   getPotentialRookMoves(sq) {
 103     let noCaptures = this.getSlideNJumpMoves(sq, V.steps[V.ROOK]);
 104     let captures = this.findCaptures(sq);
 105     return noCaptures.concat(captures);
 106   }
 107
 108   getPotentialKnightMoves(sq) {
 109     let noCaptures = this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep");
 110     let captures = this.findCaptures(sq);
 111     return noCaptures.concat(captures);
 112   }
 113
 114   getPotentialBishopMoves(sq) {
 115     let noCaptures = this.getSlideNJumpMoves(sq, V.steps[V.BISHOP]);
 116     let captures = this.findCaptures(sq);
 117     return noCaptures.concat(captures);
 118   }
 119
 120   getPotentialQueenMoves(sq) {
 121     let noCaptures = this.getSlideNJumpMoves(
 122       sq,
 123       V.steps[V.ROOK].concat(V.steps[V.BISHOP])
 124     );
 125     let captures = this.findCaptures(sq);
 126     return noCaptures.concat(captures);
 127   }
 128
 129   getPotentialKingMoves(sq) {
 130     // Initialize with normal moves
 131     let noCaptures = this.getSlideNJumpMoves(
 132       sq,
 133       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
 134       "oneStep"
 135     );
 136     let captures = this.findCaptures(sq);
 137     return noCaptures.concat(captures).concat(this.getCastleMoves(sq));
 138   }
 139
 140   getNotation(move) {
 141     // Recognize special moves first
 142     if (move.appear.length == 2) {
 143       // castle
 144       if (move.end.y < move.start.y) return "0-0-0";
 145       return "0-0";
 146     }
 147
 148     // Translate initial square (because pieces may fly unusually!)
 149     const initialSquare = V.CoordsToSquare(move.start);
 150
 151     // Translate final square
 152     const finalSquare = V.CoordsToSquare(move.end);
 153
 154     let notation = "";
 155     const piece = this.getPiece(move.start.x, move.start.y);
 156     if (piece == V.PAWN) {
 157       // pawn move (TODO: enPassant indication)
 158       if (move.vanish.length > 1) {
 159         // capture
 160         notation = initialSquare + "x" + finalSquare;
 161       } //no capture
 162       else notation = finalSquare;
 163       if (piece != move.appear[0].p)
 164         //promotion
 165         notation += "=" + move.appear[0].p.toUpperCase();
 166     } else {
 167       // Piece movement
 168       notation = piece.toUpperCase();
 169       if (move.vanish.length > 1) notation += initialSquare + "x";
 170       notation += finalSquare;
 171     }
 172     return notation;
 173   }
 174
 175   static get VALUES() {
 176     return {
 177       p: 1,
 178       r: 3,
 179       n: 2,
 180       b: 2,
 181       q: 5,
 182       k: 1000
 183     };
 184   }
 185 };