client/src/variants/Bicolour.js

   1 import { ChessRules } from "@/base_rules";
   2 import { randInt } from "@/utils/alea";
   3 import { ArrayFun } from "@/utils/array";
   4
   5 export class BicolourRules extends ChessRules {
   6   static get HasFlags() {
   7     return false;
   8   }
   9
  10   canTake([x1, y1], [x2, y2]) {
  11     return (
  12       this.getPiece(x1, y1) == V.KING || super.canTake([x1, y1], [x2, y2])
  13     );
  14   }
  15
  16   static GenRandInitFen(randomness) {
  17     if (randomness == 0)
  18       return "rqbnkbnr/pppppppp/8/8/8/8/PPPPPPPP/RQBNKBNR w 0 -";
  19
  20     // Place pieces at random but the king cannot be next to a rook or queen.
  21     // => One bishop and one knight should surround the king.
  22     let pieces = { w: new Array(8), b: new Array(8) };
  23     let flags = "";
  24     for (let c of ["w", "b"]) {
  25       if (c == 'b' && randomness == 1) {
  26         pieces['b'] = pieces['w'];
  27         break;
  28       }
  29
  30       let positions = ArrayFun.range(8);
  31
  32       const kingPos = randInt(8);
  33       let toRemove = [kingPos];
  34       let knight1Pos = undefined;
  35       let bishop1Pos = undefined;
  36       if (kingPos == 0) {
  37         if (Math.random() < 0.5) knight1Pos = 1;
  38         else bishop1Pos = 1;
  39         toRemove.push(1);
  40       }
  41       else if (kingPos == V.size.y - 1) {
  42         if (Math.random() < 0.5) knight1Pos = V.size.y - 2;
  43         else bishop1Pos = V.size.y - 2;
  44         toRemove.push(V.size.y - 2);
  45       }
  46       else {
  47         knight1Pos = kingPos + (Math.random() < 0.5 ? 1 : -1);
  48         bishop1Pos = kingPos + (knight1Pos < kingPos ? 1 : -1);
  49         toRemove.push(knight1Pos, bishop1Pos);
  50       }
  51       const firstPieces = [kingPos, knight1Pos, bishop1Pos]
  52         .filter(elt => elt !== undefined);
  53       firstPieces
  54         .sort((a, b) => b - a)
  55         .forEach(elt => positions.splice(elt, 1));
  56
  57       let randIndex = undefined;
  58       if (bishop1Pos === undefined) {
  59         const posWithIdx = positions.map((e,i) => { return { e: e, i: i }; });
  60         let availableSquares = posWithIdx.filter(p => p.e % 2 == 0);
  61         randIndex = randInt(availableSquares.length);
  62         bishop1Pos = availableSquares[randIndex].e;
  63         positions.splice(availableSquares[randIndex].i, 1);
  64       }
  65       const posWithIdx = positions.map((e,i) => { return { e: e, i: i }; });
  66       const rem1B = bishop1Pos % 2;
  67       let availableSquares = posWithIdx.filter(p => p.e % 2 == 1 - rem1B);
  68       randIndex = randInt(availableSquares.length);
  69       const bishop2Pos = availableSquares[randIndex].e;
  70       positions.splice(availableSquares[randIndex].i, 1);
  71
  72       if (knight1Pos === undefined) {
  73         randIndex = randInt(5);
  74         knight1Pos = positions[randIndex];
  75         positions.splice(randIndex, 1);
  76       }
  77       randIndex = randInt(4);
  78       const knight2Pos = positions[randIndex];
  79       positions.splice(randIndex, 1);
  80
  81       randIndex = randInt(3);
  82       const queenPos = positions[randIndex];
  83       positions.splice(randIndex, 1);
  84
  85       const rook1Pos = positions[0];
  86       const rook2Pos = positions[1];
  87
  88       pieces[c][rook1Pos] = "r";
  89       pieces[c][knight1Pos] = "n";
  90       pieces[c][bishop1Pos] = "b";
  91       pieces[c][queenPos] = "q";
  92       pieces[c][kingPos] = "k";
  93       pieces[c][bishop2Pos] = "b";
  94       pieces[c][knight2Pos] = "n";
  95       pieces[c][rook2Pos] = "r";
  96     }
  97     return (
  98       pieces["b"].join("") +
  99       "/pppppppp/8/8/8/8/PPPPPPPP/" +
 100       pieces["w"].join("").toUpperCase() +
 101       " w 0 -"
 102     );
 103   }
 104
 105   underCheck(color) {
 106     return (
 107       this.isAttacked(this.kingPos[color], 'w') ||
 108       this.isAttacked(this.kingPos[color], 'b')
 109     );
 110   }
 111 };