utils/setupPieces.js

   1 import {Random} from "/utils/alea.js";
   2
   3 export const FenUtil = {
   4
   5   // arg o (constraints): "between" with p1 and p2.
   6   //                      "flags", "diffCol": array of pieceType
   7   setupRow: function(arr, o) {
   8     let res = JSON.parse(JSON.stringify(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.randomness >= 1) {
  19       if (o.diffCol) {
  20         o.diffCol.forEach(p => {
  21           // Pieces of type p on different colors:
  22           const firstP = res.indexOf(p),
  23                 lastP = res.lastIndexOf(p);
  24           if ((firstP - lastP) % 2 != 0) {
  25             const choice1 = Random.randBool() ? firstP : lastP;
  26             let choice2;
  27             do {
  28               choice2 = Random.randInt(arr.length);
  29             }
  30             while (
  31               choice2 == choice1 ||
  32               o.diffCol.includes(choice2) ||
  33               (choice2 - choice1) % 2 != 0
  34             );
  35             res[choice1] = res[choice2];
  36             res[choice2] = p;
  37           }
  38         });
  39       }
  40       if (o.between) {
  41         // Locate p1. If appearing first, exchange with first p2.
  42         // If appearing last, exchange with last p2.
  43         const p1 = res.indexOf(o.between["p1"]);
  44         const firstP2 = res.indexOf(o.between["p2"]),
  45               lastP2 = res.lastIndexOf(o.between["p2"]);
  46         if (p1 < firstP2 || p1 > lastP2) {
  47           res[p1] = o.between["p2"];
  48           if (p1 < firstP2)
  49             res[firstP2] = o.between["p1"];
  50           else //p1 > lastP2
  51             res[lastP2] = o.between["p1"];
  52         }
  53       }
  54     }
  55     return {fen: res, flags: flags};
  56   },
  57
  58   setupPieces: function(arr, o) {
  59     const row1 = FenUtil.setupRow(arr, o);
  60     const row2 = o.randomness == 2 ? FenUtil.setupRow(arr, o) : row1;
  61     return {
  62       w: row1.fen,
  63       b: row2.fen,
  64       flags: row1.flags + row2.flags
  65     };
  66   }
  67
  68 };