client/src/variants/Extinction.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export const VariantRules = class ExtinctionRules extends ChessRules {
   4   static IsGoodPosition(position) {
   5     if (!ChessRules.IsGoodPosition(position))
   6       return false;
   7     // Also check that each piece type is present
   8     const rows = position.split("/");
   9     let pieces = {};
  10     for (let row of rows) {
  11       for (let i = 0; i < row.length; i++) {
  12         if (isNaN(parseInt(row[i])) && !pieces[row[i]])
  13           pieces[row[i]] = true;
  14       }
  15     }
  16     if (Object.keys(pieces).length != 12)
  17       return false;
  18     return true;
  19   }
  20
  21   setOtherVariables(fen) {
  22     super.setOtherVariables(fen);
  23     const pos = V.ParseFen(fen).position;
  24     // NOTE: no need for safety "|| []", because each piece type must be present
  25     // (otherwise game is already over!)
  26     this.material = {
  27       w: {
  28         [V.KING]: pos.match(/K/g).length,
  29         [V.QUEEN]: pos.match(/Q/g).length,
  30         [V.ROOK]: pos.match(/R/g).length,
  31         [V.KNIGHT]: pos.match(/N/g).length,
  32         [V.BISHOP]: pos.match(/B/g).length,
  33         [V.PAWN]: pos.match(/P/g).length
  34       },
  35       b: {
  36         [V.KING]: pos.match(/k/g).length,
  37         [V.QUEEN]: pos.match(/q/g).length,
  38         [V.ROOK]: pos.match(/r/g).length,
  39         [V.KNIGHT]: pos.match(/n/g).length,
  40         [V.BISHOP]: pos.match(/b/g).length,
  41         [V.PAWN]: pos.match(/p/g).length
  42       }
  43     };
  44   }
  45
  46   getPotentialPawnMoves([x, y]) {
  47     let moves = super.getPotentialPawnMoves([x, y]);
  48     // Add potential promotions into king
  49     const color = this.turn;
  50     const shift = color == "w" ? -1 : 1;
  51     const lastRank = color == "w" ? 0 : V.size.x - 1;
  52
  53     if (x + shift == lastRank) {
  54       // Normal move
  55       if (this.board[x + shift][y] == V.EMPTY)
  56         moves.push(
  57           this.getBasicMove([x, y], [x + shift, y], { c: color, p: V.KING })
  58         );
  59       // Captures
  60       if (
  61         y > 0 &&
  62         this.board[x + shift][y - 1] != V.EMPTY &&
  63         this.canTake([x, y], [x + shift, y - 1])
  64       ) {
  65         moves.push(
  66           this.getBasicMove([x, y], [x + shift, y - 1], { c: color, p: V.KING })
  67         );
  68       }
  69       if (
  70         y < V.size.y - 1 &&
  71         this.board[x + shift][y + 1] != V.EMPTY &&
  72         this.canTake([x, y], [x + shift, y + 1])
  73       ) {
  74         moves.push(
  75           this.getBasicMove([x, y], [x + shift, y + 1], { c: color, p: V.KING })
  76         );
  77       }
  78     }
  79
  80     return moves;
  81   }
  82
  83   // TODO: verify this assertion
  84   atLeastOneMove() {
  85     return true; //always at least one possible move
  86   }
  87
  88   underCheck() {
  89     return false; //there is no check
  90   }
  91
  92   getCheckSquares() {
  93     return [];
  94   }
  95
  96   updateVariables(move) {
  97     super.updateVariables(move);
  98     // Treat the promotion case: (not the capture part)
  99     if (move.appear[0].p != move.vanish[0].p) {
 100       this.material[move.appear[0].c][move.appear[0].p]++;
 101       this.material[move.appear[0].c][V.PAWN]--;
 102     }
 103     if (move.vanish.length == 2 && move.appear.length == 1)
 104       //capture
 105       this.material[move.vanish[1].c][move.vanish[1].p]--;
 106   }
 107
 108   unupdateVariables(move) {
 109     super.unupdateVariables(move);
 110     if (move.appear[0].p != move.vanish[0].p) {
 111       this.material[move.appear[0].c][move.appear[0].p]--;
 112       this.material[move.appear[0].c][V.PAWN]++;
 113     }
 114     if (move.vanish.length == 2 && move.appear.length == 1)
 115       this.material[move.vanish[1].c][move.vanish[1].p]++;
 116   }
 117
 118   getCurrentScore() {
 119     if (this.atLeastOneMove()) {
 120       // game not over?
 121       const color = this.turn;
 122       if (
 123         Object.keys(this.material[color]).some(p => {
 124           return this.material[color][p] == 0;
 125         })
 126       ) {
 127         return this.turn == "w" ? "0-1" : "1-0";
 128       }
 129       return "*";
 130     }
 131
 132     return this.turn == "w" ? "0-1" : "1-0"; //NOTE: currently unreachable...
 133   }
 134
 135   evalPosition() {
 136     const color = this.turn;
 137     if (
 138       Object.keys(this.material[color]).some(p => {
 139         return this.material[color][p] == 0;
 140       })
 141     ) {
 142       // Very negative (resp. positive) if white (reps. black) pieces set is incomplete
 143       return (color == "w" ? -1 : 1) * V.INFINITY;
 144     }
 145     return super.evalPosition();
 146   }
 147 };