client/src/variants/Rampage.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class RampageRules extends ChessRules {
   4
   5   // Sum white pieces attacking a square, and remove black pieces count.
   6   sumAttacks([x, y]) {
   7     const getSign = (color) => {
   8       return (color == 'w' ? 1 : -1);
   9     };
  10     let res = 0;
  11     // Knights:
  12     V.steps[V.KNIGHT].forEach(s => {
  13       const [i, j] = [x + s[0], y + s[1]];
  14       if (V.OnBoard(i, j) && this.getPiece(i, j) == V.KNIGHT)
  15         res += getSign(this.getColor(i, j));
  16     });
  17     // Kings:
  18     V.steps[V.ROOK].concat(V.steps[V.BISHOP]).forEach(s => {
  19       const [i, j] = [x + s[0], y + s[1]];
  20       if (V.OnBoard(i, j) && this.getPiece(i, j) == V.KING)
  21         res += getSign(this.getColor(i, j));
  22     });
  23     // Pawns:
  24     for (let c of ['w', 'b']) {
  25       for (let shift of [-1, 1]) {
  26         const sign = getSign(c);
  27         const [i, j] = [x + sign, y + shift];
  28         if (
  29           V.OnBoard(i, j) &&
  30           this.getPiece(i, j) == V.PAWN &&
  31           this.getColor(i, j) == c
  32         ) {
  33           res += sign;
  34         }
  35       }
  36     }
  37     // Other pieces (sliders):
  38     V.steps[V.ROOK].concat(V.steps[V.BISHOP]).forEach(s => {
  39       let [i, j] = [x + s[0], y + s[1]];
  40       let compatible = [V.QUEEN];
  41       compatible.push(s[0] == 0 || s[1] == 0 ? V.ROOK : V.BISHOP);
  42       let firstCol = undefined;
  43       while (V.OnBoard(i, j)) {
  44         if (this.board[i][j] != V.EMPTY) {
  45           if (!(compatible.includes(this.getPiece(i, j)))) break;
  46           const colIJ = this.getColor(i, j);
  47           if (!firstCol) firstCol = colIJ;
  48           if (colIJ == firstCol) res += getSign(colIJ);
  49           else break;
  50         }
  51         i += s[0];
  52         j += s[1];
  53       }
  54     });
  55     return res;
  56   }
  57
  58   getPotentialMovesFrom([x, y]) {
  59     let moves = super.getPotentialMovesFrom([x, y]);
  60     const color = this.turn;
  61     if (this.getPiece(x, y) == V.KING && this.underCheck(color))
  62       // The king under check can only move as usual
  63       return moves;
  64     // Remember current final squares to not add moves twice:
  65     const destinations = {};
  66     const lastRank = (color == 'w' ? 0 : 7);
  67     const piece = this.getPiece(x, y);
  68     moves.forEach(m => destinations[m.end.x + "_" + m.end.y] = true);
  69     for (let i=0; i<8; i++) {
  70       for (let j=0; j<8; j++) {
  71         if (this.board[i][j] == V.EMPTY && !destinations[i + "_" + j]) {
  72           const sa = this.sumAttacks([i, j]);
  73           if (
  74             ((color == 'w' && sa > 0) || (color == 'b' && sa < 0)) &&
  75             (piece != V.PAWN || i != lastRank)
  76           ) {
  77             moves.push(this.getBasicMove([x, y], [i, j]));
  78           }
  79         }
  80       }
  81     }
  82     return moves;
  83   }
  84
  85   static get SEARCH_DEPTH() {
  86     return 1;
  87   }
  88
  89 };