client/src/variants/Upsidedown.js

   1 import { ChessRules } from "@/base_rules";
   2 import { randInt } from "@/utils/alea";
   3 import { ArrayFun } from "@/utils/array";
   4
   5 export const VariantRules = class UpsidedownRules extends ChessRules {
   6   static get HasFlags() {
   7     return false;
   8   }
   9
  10   static get HasEnpassant() {
  11     return false;
  12   }
  13
  14   getPotentialKingMoves(sq) {
  15     // No castle
  16     return this.getSlideNJumpMoves(
  17       sq,
  18       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
  19       "oneStep"
  20     );
  21   }
  22
  23   static GenRandInitFen(randomness) {
  24     if (randomness == 0)
  25       return "RNBQKBNR/PPPPPPPP/8/8/8/8/pppppppp/rnbqkbnr w 0";
  26
  27     let pieces = { w: new Array(8), b: new Array(8) };
  28     for (let c of ["w", "b"]) {
  29       if (c == 'b' && randomness == 1) {
  30         pieces['b'] = pieces['w'];
  31         break;
  32       }
  33
  34       let positions = ArrayFun.range(8);
  35
  36       let randIndex = randInt(8);
  37       const kingPos = positions[randIndex];
  38       positions.splice(randIndex, 1);
  39
  40       // At least a knight must be next to the king:
  41       let knight1Pos = undefined;
  42       if (kingPos == 0) knight1Pos = 1;
  43       else if (kingPos == V.size.y - 1) knight1Pos = V.size.y - 2;
  44       else knight1Pos = kingPos + (Math.random() < 0.5 ? 1 : -1);
  45       // Search for knight1Pos index in positions and remove it
  46       const knight1Index = positions.indexOf(knight1Pos);
  47       positions.splice(knight1Index, 1);
  48
  49       // King+knight1 are on two consecutive squares: one light, one dark
  50       randIndex = 2 * randInt(3);
  51       const bishop1Pos = positions[randIndex];
  52       let randIndex_tmp = 2 * randInt(3) + 1;
  53       const bishop2Pos = positions[randIndex_tmp];
  54       positions.splice(Math.max(randIndex, randIndex_tmp), 1);
  55       positions.splice(Math.min(randIndex, randIndex_tmp), 1);
  56
  57       randIndex = randInt(4);
  58       const knight2Pos = positions[randIndex];
  59       positions.splice(randIndex, 1);
  60
  61       randIndex = randInt(3);
  62       const queenPos = positions[randIndex];
  63       positions.splice(randIndex, 1);
  64
  65       const rook1Pos = positions[0];
  66       const rook2Pos = positions[1];
  67
  68       pieces[c][rook1Pos] = "r";
  69       pieces[c][knight1Pos] = "n";
  70       pieces[c][bishop1Pos] = "b";
  71       pieces[c][queenPos] = "q";
  72       pieces[c][kingPos] = "k";
  73       pieces[c][bishop2Pos] = "b";
  74       pieces[c][knight2Pos] = "n";
  75       pieces[c][rook2Pos] = "r";
  76     }
  77     return (
  78       pieces["w"].join("").toUpperCase() +
  79       "/PPPPPPPP/8/8/8/8/pppppppp/" +
  80       pieces["b"].join("") +
  81       " w 0"
  82     ); //no castle, no en-passant
  83   }
  84
  85   static get SEARCH_DEPTH() {
  86     return 2;
  87   }
  88 };