client/src/variants/Kingsmaker.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class KingsmakerRules extends ChessRules {
   4
   5   static IsGoodPosition(position) {
   6     if (position.length == 0) return false;
   7     const rows = position.split("/");
   8     if (rows.length != V.size.x) return false;
   9     let kings = { "k": 0, "K": 0 };
  10     for (let row of rows) {
  11       let sumElts = 0;
  12       for (let i = 0; i < row.length; i++) {
  13         if (['K','k'].includes(row[i])) kings[row[i]]++;
  14         if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
  15         else {
  16           const num = parseInt(row[i], 10);
  17           if (isNaN(num) || num <= 0) return false;
  18           sumElts += num;
  19         }
  20       }
  21       if (sumElts != V.size.y) return false;
  22     }
  23     // At least one king per color.
  24     if (Object.values(kings).some(v => v == 0)) return false;
  25     return true;
  26   }
  27
  28   scanKings() {}
  29
  30   getPotentialMovesFrom([x, y]) {
  31     const moves = super.getPotentialMovesFrom([x, y]);
  32     if (this.getPiece(x, y) != V.PAWN) return moves;
  33     const c = this.getColor(x, y);
  34     const oppCol = V.GetOppCol(c);
  35     const forward = (c == 'w' ? -1 : 1);
  36     const lastRanks = (c == 'w' ? [0, 1] : [7, 6]);
  37     let newKingMoves = [];
  38     if (lastRanks.includes(x + forward)) {
  39       // Manually add promotion into enemy king:
  40       const trials = [
  41         { step: [forward, 0] },
  42         { step: [forward, 1], capture: true },
  43         { step: [forward, -1], capture: true }
  44       ];
  45       for (let s of trials) {
  46         const [i, j] = [x + s.step[0], y + s.step[1]];
  47         if (
  48           V.OnBoard(i, j) &&
  49           (
  50             (!s.capture && this.board[i][j] == V.EMPTY) ||
  51             (
  52               s.capture &&
  53               this.board[i][j] != V.EMPTY &&
  54               this.getColor(i, j) == oppCol
  55             )
  56           )
  57         ) {
  58           newKingMoves.push(
  59             super.getBasicMove([x, y], [i, j], { c: oppCol, p: V.KING })
  60           );
  61         }
  62       }
  63     }
  64     return moves.concat(newKingMoves);
  65   }
  66
  67   underCheck(color) {
  68     // First at first check found (if any)
  69     const oppCol = V.GetOppCol(color);
  70     for (let i=0; i<8; i++) {
  71       for (let j=0; j<8; j++) {
  72         if (
  73           this.board[i][j] != V.EMPTY &&
  74           this.getPiece(i, j) == V.KING &&
  75           this.getColor(i, j) == color
  76         ) {
  77           if (super.isAttacked([i, j], oppCol)) return true;
  78         }
  79       }
  80     }
  81     return false;
  82   }
  83
  84   getCheckSquares() {
  85     const color = this.turn;
  86     const oppCol = V.GetOppCol(color);
  87     let res = [];
  88     // Scan all kings
  89     for (let i=0; i<8; i++) {
  90       for (let j=0; j<8; j++) {
  91         if (
  92           this.board[i][j] != V.EMPTY &&
  93           this.getPiece(i, j) == V.KING &&
  94           this.getColor(i, j) == color
  95         ) {
  96           if (super.isAttacked([i, j], oppCol)) res.push([i, j]);
  97         }
  98       }
  99     }
 100     return res;
 101   }
 102
 103   postPlay(move) {
 104     this.updateCastleFlags(move, move.vanish[0].p);
 105   }
 106
 107   postUndo() {}
 108
 109   static get VALUES() {
 110     // Assign -5 to the king, so that the bot sometimes promote into king
 111     return Object.assign({}, ChessRules.VALUES, { k: -5 });
 112   }
 113
 114 };