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