variants/Circular/class.js

   1 import ChessRules from "/base_rules.js";
   2 import {FenUtil} from "/utils/setupPieces.js";
   3
   4 export default class CircularRules extends ChessRules {
   5
   6   get hasCastle() {
   7     return false;
   8   }
   9   get hasEnpassant() {
  10     return false;
  11   }
  12
  13   // Everypawn is going up!
  14   getPawnShift(color) {
  15     return -1;
  16   }
  17   isPawnInitRank(x, color) {
  18     return (color == 'w' && x == 6) || (color == 'b' && x == 2);
  19   }
  20
  21   get flippedBoard() {
  22     return false;
  23   }
  24
  25   // Circular board:
  26   getX(x) {
  27     let res = x % this.size.x;
  28     if (res < 0)
  29       res += this.size.x;
  30     return res;
  31   }
  32
  33   // TODO: rewrite in more elegant way
  34   getFlagsFen() {
  35     let flags = "";
  36     for (let c of ["w", "b"]) {
  37       for (let i = 0; i < 8; i++)
  38         flags += this.pawnFlags[c][i] ? "1" : "0";
  39     }
  40     return flags;
  41   }
  42
  43   setFlags(fenflags) {
  44     this.pawnFlags = {
  45       w: [...Array(8)], //pawns can move 2 squares?
  46       b: [...Array(8)]
  47     };
  48     for (let c of ["w", "b"]) {
  49       for (let i = 0; i < 8; i++)
  50         this.pawnFlags[c][i] = fenflags.charAt((c == "w" ? 0 : 8) + i) == "1";
  51     }
  52   }
  53
  54   genRandInitBaseFen() {
  55     let setupOpts = {
  56       randomness: this.options["randomness"],
  57       diffCol: ['b']
  58     };
  59     const s = FenUtil.setupPieces(
  60       ['r', 'n', 'b', 'q', 'k', 'b', 'n', 'r'], setupOpts);
  61     return {
  62       fen: "8/8/pppppppp/" + s.b.join("") + "/8/8/PPPPPPPP/" +
  63            s.w.join("").toUpperCase(),
  64       o: {flags: "11111111"}
  65     };
  66   }
  67
  68   filterValid(moves) {
  69     const filteredMoves = super.filterValid(moves);
  70     // If at least one full move made, everything is allowed:
  71     if (this.movesCount >= 2)
  72       return filteredMoves;
  73     // Else, forbid checks:
  74     const oppCol = C.GetOppTurn(this.turn);
  75     const oppKingPos = this.searchKingPos(oppCol);
  76     return filteredMoves.filter(m => {
  77       this.playOnBoard(m);
  78       const res = !this.underCheck(oppKingPos, [this.turn]);
  79       this.undoOnBoard(m);
  80       return res;
  81     });
  82   }
  83
  84   prePlay(move) {
  85     if (move.appear.length > 0 && move.vanish.length > 0) {
  86       super.prePlay(move);
  87       if (
  88         [2, 6].includes(move.start.x) &&
  89         move.vanish[0].p == 'p' &&
  90         Math.abs(move.end.x - move.start.x) == 2
  91       ) {
  92         // This move turns off a 2-squares pawn flag
  93         this.pawnFlags[move.start.x == 6 ? "w" : "b"][move.start.y] = false;
  94       }
  95     }
  96   }
  97
  98 };