client/src/variants/Knightmate2.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class Knightmate2Rules extends ChessRules {
   4
   5   static get HasFlags() {
   6     return false;
   7   }
   8
   9   static get COMMONER() {
  10     return "c";
  11   }
  12
  13   static get PIECES() {
  14     return ChessRules.PIECES.concat([V.COMMONER]);
  15   }
  16
  17   getPpath(b) {
  18     return ([V.KING, V.COMMONER].includes(b[1]) ? "Knightmate/" : "") + b;
  19   }
  20
  21   static IsGoodPosition(position) {
  22     if (position.length == 0) return false;
  23     const rows = position.split("/");
  24     if (rows.length != V.size.x) return false;
  25     let kings = { "k": 0, "K": 0 };
  26     for (let row of rows) {
  27       let sumElts = 0;
  28       for (let i = 0; i < row.length; i++) {
  29         if (['K','k'].includes(row[i])) kings[row[i]]++;
  30         if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
  31         else {
  32           const num = parseInt(row[i], 10);
  33           if (isNaN(num) || num <= 0) return false;
  34           sumElts += num;
  35         }
  36       }
  37       if (sumElts != V.size.y) return false;
  38     }
  39     // 1 or 2 kings should be on board.
  40     if (Object.values(kings).some(k => ![1, 2].includes(k))) return false;
  41     return true;
  42   }
  43
  44   scanKings() {}
  45
  46   static GenRandInitFen(randomness) {
  47     return (
  48       ChessRules.GenRandInitFen(randomness)
  49       .replace(/k/g, 'c').replace(/K/g, 'C')
  50       .replace(/n/g, 'k').replace(/N/g, 'K')
  51     );
  52   }
  53
  54   getPotentialMovesFrom([x, y]) {
  55     switch (this.getPiece(x, y)) {
  56       case V.COMMONER:
  57         return this.getPotentialCommonerMoves([x, y]);
  58       default:
  59         return super.getPotentialMovesFrom([x, y]);
  60     }
  61   }
  62
  63   getPotentialCommonerMoves(sq) {
  64     return this.getSlideNJumpMoves(
  65       sq,
  66       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
  67       "oneStep"
  68     );
  69   }
  70
  71   getPotentialKingMoves(sq) {
  72     return super.getPotentialKnightMoves(sq);
  73   }
  74
  75   isAttacked(sq, color) {
  76     return (
  77       this.isAttackedByCommoner(sq, color) ||
  78       this.isAttackedByPawn(sq, color) ||
  79       this.isAttackedByRook(sq, color) ||
  80       this.isAttackedByBishop(sq, color) ||
  81       this.isAttackedByQueen(sq, color) ||
  82       this.isAttackedByKing(sq, color)
  83     );
  84   }
  85
  86   isAttackedByKing(sq, color) {
  87     return this.isAttackedBySlideNJump(
  88       sq,
  89       color,
  90       V.KING,
  91       V.steps[V.KNIGHT],
  92       "oneStep"
  93     );
  94   }
  95
  96   isAttackedByCommoner(sq, color) {
  97     return this.isAttackedBySlideNJump(
  98       sq,
  99       color,
 100       V.COMMONER,
 101       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
 102       "oneStep"
 103     );
 104   }
 105
 106   postPlay() {}
 107   postUndo() {}
 108
 109   // NOTE: 4 next functions (almost) copy-paste from Spartan Chess
 110   getKingsPos(color) {
 111     let kings = [];
 112     for (let i=0; i<8; i++) {
 113       for (let j=0; j<8; j++) {
 114         if (
 115           this.board[i][j] != V.EMPTY &&
 116           this.getColor(i, j) == color &&
 117           this.getPiece(i, j) == V.KING
 118         ) {
 119           kings.push({ x: i, y: j });
 120         }
 121       }
 122     }
 123     return kings;
 124   }
 125
 126   getCheckSquares() {
 127     const color = this.turn;
 128     const oppCol = V.GetOppCol(color);
 129     const kings = this.getKingsPos(color);
 130     let res = [];
 131     for (let i of [0, 1]) {
 132       if (
 133         kings.length >= i+1 &&
 134         this.isAttacked([kings[i].x, kings[i].y], oppCol)
 135       ) {
 136         res.push([kings[i].x, kings[i].y]);
 137       }
 138     }
 139     return res;
 140   }
 141
 142   filterValid(moves) {
 143     if (moves.length == 0) return [];
 144     const color = moves[0].vanish[0].c;
 145     const oppCol = V.GetOppCol(color);
 146     // Check if both kings under attack.
 147     // If yes, moves must remove at least one attack.
 148     const kings = this.getKingsPos(color);
 149     return moves.filter(m => {
 150       this.play(m);
 151       let attacks = 0;
 152       for (let k of kings) {
 153         const curKingPos =
 154           this.board[k.x][k.y] == V.EMPTY
 155             ? [m.appear[0].x, m.appear[0].y] //king moved
 156             : [k.x, k.y]
 157         if (this.isAttacked(curKingPos, oppCol)) attacks++;
 158         else break; //no need to check further
 159       }
 160       this.undo(m);
 161       return (
 162         (kings.length == 2 && attacks <= 1) ||
 163         (kings.length == 1 && attacks == 0)
 164       );
 165     });
 166   }
 167
 168   getCurrentScore() {
 169     if (super.atLeastOneMove()) return "*";
 170     // Count kings on board
 171     const color = this.turn;
 172     const oppCol = V.GetOppCol(color);
 173     const kings = this.getKingsPos(color);
 174     if (
 175       this.isAttacked([kings[0].x, kings[0].y], oppCol) ||
 176       (kings.length == 2 && this.isAttacked([kings[1].x, kings[1].y], oppCol))
 177     ) {
 178       return (color == 'w' ? "0-1" : "1-0");
 179     }
 180     return "1/2"; //stalemate
 181   }
 182
 183   static get VALUES() {
 184     return {
 185       p: 1,
 186       r: 5,
 187       c: 5, //the commoner is valuable
 188       b: 3,
 189       q: 9,
 190       k: 1000
 191     };
 192   }
 193
 194 };