client/src/variants/Cannibal.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class CannibalRules extends ChessRules {
   4   // Trim all non-capturing moves
   5   static KeepCaptures(moves) {
   6     return moves.filter(m => m.vanish.length == 2 && m.appear.length == 1);
   7   }
   8
   9     // Stop at the first capture found (if any)
  10   atLeastOneCapture() {
  11     const color = this.turn;
  12     const oppCol = V.GetOppCol(color);
  13     for (let i = 0; i < V.size.x; i++) {
  14       for (let j = 0; j < V.size.y; j++) {
  15         if (
  16           this.board[i][j] != V.EMPTY &&
  17           this.getColor(i, j) != oppCol &&
  18           this.filterValid(this.getPotentialMovesFrom([i, j])).some(m =>
  19             // Warning: discard castle moves
  20             m.vanish.length == 2 && m.appear.length == 1)
  21         ) {
  22           return true;
  23         }
  24       }
  25     }
  26     return false;
  27   }
  28
  29   getPotentialMovesFrom([x, y]) {
  30     let moves = super.getPotentialMovesFrom([x, y]);
  31     // Transform capturers, except for the king
  32     moves.forEach(m => {
  33       if (
  34         m.appear[0].p != V.KING &&
  35         m.vanish.length == 2 &&
  36         m.appear.length == 1 &&
  37         m.vanish[0].p != m.vanish[1].p
  38       ) {
  39         m.appear[0].p = m.vanish[1].p;
  40       }
  41     });
  42     return moves;
  43   }
  44
  45   getPossibleMovesFrom(sq) {
  46     let moves = this.filterValid(this.getPotentialMovesFrom(sq));
  47     const captureMoves = V.KeepCaptures(moves);
  48     if (captureMoves.length > 0) return captureMoves;
  49     if (this.atLeastOneCapture()) return [];
  50     return moves;
  51   }
  52
  53   getAllValidMoves() {
  54     const moves = super.getAllValidMoves();
  55     if (moves.some(m => m.vanish.length == 2)) return V.KeepCaptures(moves);
  56     return moves;
  57   }
  58
  59   static get SEARCH_DEPTH() {
  60     return 4;
  61   }
  62 };