client/src/variants/Losers.js

   1 import { ChessRules } from "@/base_rules";
   2 import { ArrayFun } from "@/utils/array";
   3 import { randInt } from "@/utils/alea";
   4
   5 export class LosersRules extends ChessRules {
   6
   7   // Trim all non-capturing moves
   8   static KeepCaptures(moves) {
   9     return moves.filter(m => m.vanish.length == 2 && m.appear.length == 1);
  10   }
  11
  12   // Stop at the first capture found (if any)
  13   atLeastOneCapture() {
  14     const color = this.turn;
  15     for (let i = 0; i < V.size.x; i++) {
  16       for (let j = 0; j < V.size.y; j++) {
  17         if (
  18           this.board[i][j] != V.EMPTY &&
  19           this.getColor(i, j) == color &&
  20           this.getPotentialMovesFrom([i, j]).some(m => {
  21             return (
  22               // Warning: discard castle moves
  23               m.vanish.length == 2 && m.appear.length == 1 &&
  24               this.filterValid([m]).length == 1
  25             );
  26           })
  27         ) {
  28           return true;
  29         }
  30       }
  31     }
  32     return false;
  33   }
  34
  35   getPossibleMovesFrom(sq) {
  36     let moves = this.filterValid(this.getPotentialMovesFrom(sq));
  37     const captureMoves = V.KeepCaptures(moves);
  38     if (captureMoves.length > 0) return captureMoves;
  39     if (this.atLeastOneCapture()) return [];
  40     return moves;
  41   }
  42
  43   getAllValidMoves() {
  44     const moves = super.getAllValidMoves();
  45     if (moves.some(m => m.vanish.length == 2 && m.appear.length == 1))
  46       return V.KeepCaptures(moves);
  47     return moves;
  48   }
  49
  50   getCurrentScore() {
  51     // If only my king remains, I win
  52     const color = this.turn;
  53     let onlyKing = true;
  54     outerLoop: for (let i=0; i<V.size.x; i++) {
  55       for (let j=0; j<V.size.y; j++) {
  56         if (
  57           this.board[i][j] != V.EMPTY &&
  58           this.getColor(i,j) == color &&
  59           this.getPiece(i,j) != V.KING
  60         ) {
  61           onlyKing = false;
  62           break outerLoop;
  63         }
  64       }
  65     }
  66     if (onlyKing) return color == "w" ? "1-0" : "0-1";
  67     if (this.atLeastOneMove()) return "*";
  68     // No valid move: the side who cannot move (or is checkmated) wins
  69     return this.turn == "w" ? "1-0" : "0-1";
  70   }
  71
  72   evalPosition() {
  73     // Less material is better (more subtle in fact but...)
  74     return -super.evalPosition();
  75   }
  76
  77 };