client/src/variants/Rampage.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class RampageRules extends ChessRules {
   4   // Sum white pieces attacking a square, and remove black pieces count.
   5   sumAttacks([x, y]) {
   6     const getSign = (color) => {
   7       return (color == 'w' ? 1 : -1);
   8     };
   9     let res = 0;
  10     // Knights:
  11     V.steps[V.KNIGHT].forEach(s => {
  12       const [i, j] = [x + s[0], y + s[1]];
  13       if (V.OnBoard(i, j) && this.getPiece(i, j) == V.KNIGHT)
  14         res += getSign(this.getColor(i, j));
  15     });
  16     // Kings:
  17     V.steps[V.ROOK].concat(V.steps[V.BISHOP]).forEach(s => {
  18       const [i, j] = [x + s[0], y + s[1]];
  19       if (V.OnBoard(i, j) && this.getPiece(i, j) == V.KING)
  20         res += getSign(this.getColor(i, j));
  21     });
  22     // Pawns:
  23     for (let c of ['w', 'b']) {
  24       for (let shift of [-1, 1]) {
  25         const sign = getSign(c);
  26         const [i, j] = [x + sign, y + shift];
  27         if (
  28           V.OnBoard(i, j) &&
  29           this.getPiece(i, j) == V.PAWN &&
  30           this.getColor(i, j) == c
  31         ) {
  32           res += sign;
  33         }
  34       }
  35     }
  36     // Other pieces (sliders):
  37     V.steps[V.ROOK].concat(V.steps[V.BISHOP]).forEach(s => {
  38       let [i, j] = [x + s[0], y + s[1]];
  39       let compatible = [V.QUEEN];
  40       compatible.push(s[0] == 0 || s[1] == 0 ? V.ROOK : V.BISHOP);
  41       let firstCol = undefined;
  42       while (V.OnBoard(i, j)) {
  43         if (this.board[i][j] != V.EMPTY) {
  44           if (!(compatible.includes(this.getPiece(i, j)))) break;
  45           const colIJ = this.getColor(i, j);
  46           if (!firstCol) firstCol = colIJ;
  47           if (colIJ == firstCol) res += getSign(colIJ);
  48           else break;
  49         }
  50         i += s[0];
  51         j += s[1];
  52       }
  53     });
  54     return res;
  55   }
  56
  57   getPotentialMovesFrom([x, y]) {
  58     let moves = super.getPotentialMovesFrom([x, y]);
  59     const color = this.turn;
  60     if (this.getPiece(x, y) == V.KING && this.underCheck(color))
  61       // The king under check can only move as usual
  62       return moves;
  63     // Remember current final squares to not add moves twice:
  64     const destinations = {};
  65     const lastRank = (color == 'w' ? 0 : 7);
  66     const piece = this.getPiece(x, y);
  67     moves.forEach(m => destinations[m.end.x + "_" + m.end.y] = true);
  68     for (let i=0; i<8; i++) {
  69       for (let j=0; j<8; j++) {
  70         if (this.board[i][j] == V.EMPTY && !destinations[i + "_" + j]) {
  71           const sa = this.sumAttacks([i, j]);
  72           if (
  73             ((color == 'w' && sa > 0) || (color == 'b' && sa < 0)) &&
  74             (piece != V.PAWN || i != lastRank)
  75           ) {
  76             moves.push(this.getBasicMove([x, y], [i, j]));
  77           }
  78         }
  79       }
  80     }
  81     return moves;
  82   }
  83
  84   static get SEARCH_DEPTH() {
  85     return 1;
  86   }
  87 };