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
   6   static get PawnSpecs() {
   7     return Object.assign(
   8       {},
   9       ChessRules.PawnSpecs,
  10       { promotions: ChessRules.PawnSpecs.promotions.concat([V.KING]) }
  11     );
  12   }
  13
  14   static IsGoodPosition(position) {
  15     if (position.length == 0) return false;
  16     const rows = position.split("/");
  17     if (rows.length != V.size.x) return false;
  18     let kings = { 'K': 0, 'k': 0 };
  19     for (let row of rows) {
  20       let sumElts = 0;
  21       for (let i = 0; i < row.length; i++) {
  22         if (['K','k'].includes(row[i])) kings[row[i]]++;
  23         if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
  24         else {
  25           const num = parseInt(row[i], 10);
  26           if (isNaN(num)) return false;
  27           sumElts += num;
  28         }
  29       }
  30       if (sumElts != V.size.y) return false;
  31     }
  32     // Two kings (at least) per side should be present:
  33     if (Object.values(kings).some(v => v < 2)) return false;
  34     return true;
  35   }
  36
  37   // Not scanning king positions. In this variant, scan the board everytime.
  38   scanKings() {}
  39
  40   getCheckSquares() {
  41     const color = this.turn;
  42     let squares = [];
  43     const oppCol = V.GetOppCol(color);
  44     for (let i=0; i<V.size.x; i++) {
  45       for (let j=0; j<V.size.y; j++) {
  46         if (
  47           this.getColor(i, j) == color &&
  48           this.getPiece(i, j) == V.KING &&
  49           this.isAttacked([i, j], oppCol)
  50         ) {
  51           squares.push([i, j]);
  52         }
  53       }
  54     }
  55     return squares;
  56   }
  57
  58   static GenRandInitFen(randomness) {
  59     if (randomness == 0)
  60       return "rnqkkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNQKKBNR w 0 adehadeh -";
  61
  62     const replaceBishop = (fen, first, ch1, ch2) => {
  63       // Remove and re-add final part:
  64       const suffix = fen.substr(-15);
  65       fen = fen.slice(0, -15);
  66       if (first) fen = fen.replace(ch1, ch2);
  67       else {
  68         fen =
  69           fen.split("").reverse().join("")
  70           .replace(ch1, ch2)
  71           .split("").reverse().join("")
  72       }
  73       return fen + suffix;
  74     };
  75
  76     const sameIndexReplace = (fen) => {
  77       const first = (Math.random() < 0.5);
  78       return replaceBishop(
  79         replaceBishop(fen, first, 'B', 'Q'),
  80         first,
  81         'b',
  82         'q'
  83       );
  84     };
  85
  86     const fen =
  87       CoregalRules.GenRandInitFen(randomness)
  88       .replace("q", "k").replace("Q", "K");
  89     // Now replace a bishop by the queen,
  90     // so that bishops are of different colors:
  91     if (randomness == 1) return sameIndexReplace(fen);
  92     const wOdd = fen.indexOf('B') % 2;
  93     const bOdd = fen.indexOf('b') % 2;
  94     // Since there are 7 slashes, different oddities means symmetric
  95     if (wOdd != bOdd) return sameIndexReplace(fen);
  96     const wFirst = (Math.random() < 0.5);
  97     return replaceBishop(
  98       replaceBishop(fen, wFirst, 'B', 'Q'),
  99       !wFirst,
 100       'b',
 101       'q'
 102     );
 103   }
 104
 105   getPotentialQueenMoves(sq) {
 106     return this.getSlideNJumpMoves(sq,
 107       V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
 108   }
 109
 110   underCheck(color) {
 111     const oppCol = V.GetOppCol(color);
 112     for (let i=0; i<V.size.x; i++) {
 113       for (let j=0; j<V.size.y; j++) {
 114         if (
 115           this.getColor(i, j) == color &&
 116           this.getPiece(i, j) == V.KING &&
 117           this.isAttacked([i, j], oppCol)
 118         ) {
 119           return true;
 120         }
 121       }
 122     }
 123     return false;
 124   }
 125
 126   postPlay(move) {
 127     const piece = move.vanish[0].p;
 128     super.updateCastleFlags(move, piece, "twoKings");
 129   }
 130
 131   postUndo() {}
 132
 133 };