client/src/variants/Chaturanga.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export const VariantRules = class ChaturangaRules extends ChessRules {
   4   static get HasFlags() {
   5     return false;
   6   }
   7
   8   static get HasEnpassant() {
   9     return false;
  10   }
  11
  12   static get ElephantSteps() {
  13     return [
  14       [-2, -2],
  15       [-2, 2],
  16       [2, -2],
  17       [2, 2]
  18     ];
  19   }
  20
  21   static GenRandInitFen() {
  22     return ChessRules.GenRandInitFen().replace("w 1111 -", "w");
  23   }
  24
  25   getPotentialPawnMoves([x, y]) {
  26     const color = this.turn;
  27     let moves = [];
  28     const [sizeX, sizeY] = [V.size.x, V.size.y];
  29     const shiftX = color == "w" ? -1 : 1;
  30     const startRank = color == "w" ? sizeX - 2 : 1;
  31     const lastRank = color == "w" ? 0 : sizeX - 1;
  32     // Promotion in minister (queen) only:
  33     const finalPiece = x + shiftX == lastRank ? V.QUEEN : V.PAWN;
  34
  35     if (this.board[x + shiftX][y] == V.EMPTY) {
  36       // One square forward
  37       moves.push(
  38         this.getBasicMove([x, y], [x + shiftX, y], {
  39           c: color,
  40           p: finalPiece
  41         })
  42       );
  43     }
  44     // Captures
  45     for (let shiftY of [-1, 1]) {
  46       if (
  47         y + shiftY >= 0 &&
  48         y + shiftY < sizeY &&
  49         this.board[x + shiftX][y + shiftY] != V.EMPTY &&
  50         this.canTake([x, y], [x + shiftX, y + shiftY])
  51       ) {
  52         moves.push(
  53           this.getBasicMove([x, y], [x + shiftX, y + shiftY], {
  54             c: color,
  55             p: finalPiece
  56           })
  57         );
  58       }
  59     }
  60
  61     return moves;
  62   }
  63
  64   getPotentialBishopMoves(sq) {
  65     let moves = this.getSlideNJumpMoves(sq, V.ElephantSteps, "oneStep");
  66     // Complete with "repositioning moves": like a queen, without capture
  67     let repositioningMoves = this.getSlideNJumpMoves(
  68       sq,
  69       V.steps[V.BISHOP],
  70       "oneStep"
  71     ).filter(m => m.vanish.length == 1);
  72     return moves.concat(repositioningMoves);
  73   }
  74
  75   getPotentialQueenMoves(sq) {
  76     return this.getSlideNJumpMoves(
  77       sq,
  78       V.steps[V.BISHOP],
  79       "oneStep"
  80     );
  81   }
  82
  83   getPotentialKingMoves(sq) {
  84     return this.getSlideNJumpMoves(
  85       sq,
  86       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
  87       "oneStep"
  88     );
  89   }
  90
  91   isAttackedByBishop(sq, colors) {
  92     return this.isAttackedBySlideNJump(
  93       sq,
  94       colors,
  95       V.BISHOP,
  96       V.ElephantSteps,
  97       "oneStep"
  98     );
  99   }
 100
 101   isAttackedByQueen(sq, colors) {
 102     return this.isAttackedBySlideNJump(
 103       sq,
 104       colors,
 105       V.QUEEN,
 106       V.steps[V.BISHOP],
 107       "oneStep"
 108     );
 109   }
 110
 111   static get VALUES() {
 112     return {
 113       p: 1,
 114       r: 5,
 115       n: 3,
 116       b: 2.5,
 117       q: 2,
 118       k: 1000
 119     };
 120   }
 121 };