client/src/variants/Knightrelay.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export const VariantRules = class KnightrelayRules extends ChessRules {
   4   getPotentialMovesFrom([x, y]) {
   5     let moves = super.getPotentialMovesFrom([x, y]);
   6
   7     // Expand possible moves if guarded by a knight:
   8     if (this.getPiece(x,y) != V.KNIGHT) {
   9       const color = this.turn;
  10       let guardedByKnight = false;
  11       for (const step of V.steps[V.KNIGHT]) {
  12         if (
  13           V.OnBoard(x+step[0],y+step[1]) &&
  14           this.getPiece(x+step[0],y+step[1]) == V.KNIGHT &&
  15           this.getColor(x+step[0],y+step[1]) == color
  16         ) {
  17           guardedByKnight = true;
  18           break;
  19         }
  20       }
  21       if (guardedByKnight) {
  22         for (const step of V.steps[V.KNIGHT]) {
  23           if (
  24             V.OnBoard(x+step[0],y+step[1]) &&
  25             this.getColor(x+step[0],y+step[1]) != color
  26           ) {
  27             moves.push(this.getBasicMove([x,y], [x+step[0],y+step[1]]));
  28           }
  29         }
  30       }
  31     }
  32
  33     return moves;
  34   }
  35
  36   isAttacked(sq, colors) {
  37     if (super.isAttacked(sq, colors))
  38       return true;
  39
  40     // Check if a (non-knight) piece at knight distance
  41     // is guarded by a knight (and thus attacking)
  42     const x = sq[0],
  43           y = sq[1];
  44     for (const step of V.steps[V.KNIGHT]) {
  45       if (
  46         V.OnBoard(x+step[0],y+step[1]) &&
  47         colors.includes(this.getColor(x+step[0],y+step[1])) &&
  48         this.getPiece(x+step[0],y+step[1]) != V.KNIGHT
  49       ) {
  50         for (const step2 of V.steps[V.KNIGHT]) {
  51           const xx = x+step[0]+step2[0],
  52                 yy = y+step[1]+step2[1];
  53           if (
  54             V.OnBoard(xx,yy) &&
  55             colors.includes(this.getColor(xx,yy)) &&
  56             this.getPiece(xx,yy) == V.KNIGHT
  57           ) {
  58             return true;
  59           }
  60         }
  61       }
  62     }
  63
  64     return false;
  65   }
  66
  67   getNotation(move) {
  68     if (move.appear.length == 2 && move.appear[0].p == V.KING)
  69       // Castle
  70       return move.end.y < move.start.y ? "0-0-0" : "0-0";
  71
  72     // Translate final and initial square
  73     const initSquare = V.CoordsToSquare(move.start);
  74     const finalSquare = V.CoordsToSquare(move.end);
  75     const piece = this.getPiece(move.start.x, move.start.y);
  76
  77     // Since pieces and pawns could move like knight, indicate start and end squares
  78     let notation =
  79       piece.toUpperCase() +
  80       initSquare +
  81       (move.vanish.length > move.appear.length ? "x" : "") +
  82       finalSquare
  83
  84     if (
  85       piece == V.PAWN &&
  86       move.appear.length > 0 &&
  87       move.appear[0].p != V.PAWN
  88     ) {
  89       // Promotion
  90       notation += "=" + move.appear[0].p.toUpperCase();
  91     }
  92
  93     return notation;
  94   }
  95 };