client/src/variants/Twokings.js

   1 import { ChessRules } from "@/base_rules";
   2 import { CoregalRules } from "@/variants/Coregal";
   3
   4 export class TwokingsRules extends CoregalRules {
   5   static get PawnSpecs() {
   6     return Object.assign(
   7       {},
   8       ChessRules.PawnSpecs,
   9       { promotions: ChessRules.PawnSpecs.promotions.concat([V.KING]) }
  10     );
  11   }
  12
  13   static IsGoodPosition(position) {
  14     if (position.length == 0) return false;
  15     const rows = position.split("/");
  16     if (rows.length != V.size.x) return false;
  17     let kings = { "w": 0, "b": 0 };
  18     for (let row of rows) {
  19       let sumElts = 0;
  20       for (let i = 0; i < row.length; i++) {
  21         if (['K','k'].includes(row[i])) kings[row[i]]++;
  22         if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
  23         else {
  24           const num = parseInt(row[i], 10);
  25           if (isNaN(num)) return false;
  26           sumElts += num;
  27         }
  28       }
  29       if (sumElts != V.size.y) return false;
  30     }
  31     // Two kings (at least) per side should be present:
  32     if (Object.values(kings).some(v => v < 2)) return false;
  33     return true;
  34   }
  35
  36   // Not scanning king positions. In this variant, scan the board everytime.
  37   scanKings() {}
  38
  39   getCheckSquares() {
  40     const color = this.turn;
  41     let squares = [];
  42     const oppCol = V.GetOppCol(color);
  43     for (let i=0; i<V.size.x; i++) {
  44       for (let j=0; j<V.size.y; j++) {
  45         if (
  46           this.getColor(i, j) == color &&
  47           this.getPiece(i, j) == V.KING &&
  48           this.isAttacked([i, j], oppCol)
  49         ) {
  50           squares.push([i, j]);
  51         }
  52       }
  53     }
  54     return squares;
  55   }
  56
  57   static GenRandInitFen(randomness) {
  58     if (randomness == 0)
  59       return "rnqkkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNQKKBNR w 0 adehadeh -";
  60
  61     const replaceBishop = (fen, first, ch1, ch2) => {
  62       // Remove and re-add final part:
  63       const suffix = fen.substr(-15);
  64       fen = fen.slice(0, -15);
  65       if (first) fen = fen.replace(ch1, ch2);
  66       else {
  67         fen =
  68           fen.split("").reverse().join("")
  69           .replace(ch1, ch2)
  70           .split("").reverse().join("")
  71       }
  72       return fen + suffix;
  73     };
  74
  75     const sameIndexReplace = (fen) => {
  76       const first = (Math.random() < 0.5);
  77       return replaceBishop(
  78         replaceBishop(fen, first, 'B', 'Q'),
  79         first,
  80         'b',
  81         'q'
  82       );
  83     };
  84
  85     const fen =
  86       CoregalRules.GenRandInitFen(randomness)
  87       .replace("q", "k").replace("Q", "K");
  88     // Now replace a bishop by the queen,
  89     // so that bishops are of different colors:
  90     if (randomness == 1) return sameIndexReplace(fen);
  91     const wOdd = fen.indexOf('B') % 2;
  92     const bOdd = fen.indexOf('b') % 2;
  93     // Since there are 7 slashes, different oddities means symmetric
  94     if (wOdd != bOdd) return sameIndexReplace(fen);
  95     const wFirst = (Math.random() < 0.5);
  96     return replaceBishop(
  97       replaceBishop(fen, wFirst, 'B', 'Q'),
  98       !wFirst,
  99       'b',
 100       'q'
 101     );
 102   }
 103
 104   underCheck(color) {
 105     const oppCol = V.GetOppCol(color);
 106     for (let i=0; i<V.size.x; i++) {
 107       for (let j=0; j<V.size.y; j++) {
 108         if (
 109           this.getColor(i, j) == color &&
 110           this.getPiece(i, j) == V.KING &&
 111           this.isAttacked([i, j], oppCol)
 112         ) {
 113           return true;
 114         }
 115       }
 116     }
 117     return false;
 118   }
 119
 120   postPlay(move) {
 121     const piece = move.vanish[0].p;
 122     super.updateCastleFlags(move, piece, "twoKings");
 123   }
 124
 125   postUndo() {}
 126 };