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