client/src/variants/Extinction.js

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