utils/setupPieces.js

   1 import {Random} from "/utils/alea.js";
   2
   3 export class Fenutil = {
   4
   5   // arg o (constraints): "between" with p1 and p2.
   6   //                      "flags", "diffCol": array of pieceType
   7   setupRow(arr, o) {
   8     let res = arr;
   9     if (o.randomness >= 1)
  10       res = Random.shuffle(arr);
  11     let flags = "";
  12     if (o.flags) {
  13       res.forEach((p, i) => {
  14         if (o.flags.includes(p))
  15           flags += i;
  16       });
  17     }
  18     if (o.between) {
  19       // Locate p1. If appearing first, exchange with first p2.
  20       // If appearing last, exchange with last p2.
  21       res.findIndex(p => p == o.between["p1"])
  22     }
  23
  24     return {fen: res, flags: flags};
  25   }
  26
  27   setupPieces(arr, o) {
  28     if (o.randomness == 0)
  29
  30
  31     return {
  32       row1:
  33
  34
  35
  36   }
  37 };
  38
  39 let fen, flags = "0707";
  40     if (!this.options.randomness)
  41       // Deterministic:
  42       fen = "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR";
  43
  44     else {
  45       // Randomize
  46       let pieces = {w: new Array(8), b: new Array(8)};
  47       flags = "";
  48       // Shuffle pieces on first (and last rank if randomness == 2)
  49       for (let c of ["w", "b"]) {
  50         if (c == 'b' && this.options.randomness == 1) {
  51           pieces['b'] = pieces['w'];
  52           flags += flags;
  53           break;
  54         }
  55         let positions = ArrayFun.range(8);
  56         // Get random squares for bishops
  57         let randIndex = 2 * Random.randInt(4);
  58         const bishop1Pos = positions[randIndex];
  59         // The second bishop must be on a square of different color
  60         let randIndex_tmp = 2 * Random.randInt(4) + 1;
  61         const bishop2Pos = positions[randIndex_tmp];
  62         // Remove chosen squares
  63         positions.splice(Math.max(randIndex, randIndex_tmp), 1);
  64         positions.splice(Math.min(randIndex, randIndex_tmp), 1);
  65         // Get random squares for knights
  66         randIndex = Random.randInt(6);
  67         const knight1Pos = positions[randIndex];
  68         positions.splice(randIndex, 1);
  69         randIndex = Random.randInt(5);
  70         const knight2Pos = positions[randIndex];
  71         positions.splice(randIndex, 1);
  72         // Get random square for queen
  73         randIndex = Random.randInt(4);
  74         const queenPos = positions[randIndex];
  75         positions.splice(randIndex, 1);
  76         // Rooks and king positions are now fixed,
  77         // because of the ordering rook-king-rook
  78         const rook1Pos = positions[0];
  79         const kingPos = positions[1];
  80         const rook2Pos = positions[2];
  81         // Finally put the shuffled pieces in the board array
  82         pieces[c][rook1Pos] = "r";
  83         pieces[c][knight1Pos] = "n";
  84         pieces[c][bishop1Pos] = "b";
  85         pieces[c][queenPos] = "q";
  86         pieces[c][kingPos] = "k";
  87         pieces[c][bishop2Pos] = "b";
  88         pieces[c][knight2Pos] = "n";
  89         pieces[c][rook2Pos] = "r";
  90         flags += rook1Pos.toString() + rook2Pos.toString();
  91       }
  92       fen = (
  93         pieces["b"].join("") +
  94         "/pppppppp/8/8/8/8/PPPPPPPP/" +
  95         pieces["w"].join("").toUpperCase()
  96       );
  97     }
  98     return { fen: fen, o: {flags: flags} };