client/src/variants/Forward.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class ForwardRules extends ChessRules {
   4   static get PawnSpecs() {
   5     return Object.assign(
   6       {},
   7       ChessRules.PawnSpecs,
   8       {
   9         bidirectional: true,
  10         captureBackward: true,
  11         promotions: [V.PAWN]
  12       }
  13     );
  14   }
  15
  16   static get PROMOTED() {
  17     return ['s', 'u', 'o', 'c', 't', 'l'];
  18   }
  19
  20   static get PIECES() {
  21     return ChessRules.PIECES.concat(V.PROMOTED);
  22   }
  23
  24   getPpath(b) {
  25     return (V.PROMOTED.includes(b[1]) ? "Forward/" : "") + b;
  26   }
  27
  28   scanKings(fen) {
  29     this.INIT_COL_KING = { w: -1, b: -1 };
  30     // Squares of white and black king:
  31     this.kingPos = { w: [-1, -1], b: [-1, -1] };
  32     const fenRows = V.ParseFen(fen).position.split("/");
  33     const startRow = { 'w': V.size.x - 1, 'b': 0 };
  34     for (let i = 0; i < fenRows.length; i++) {
  35       let k = 0; //column index on board
  36       for (let j = 0; j < fenRows[i].length; j++) {
  37         switch (fenRows[i].charAt(j)) {
  38           case "k":
  39           case "l":
  40             this.kingPos["b"] = [i, k];
  41             this.INIT_COL_KING["b"] = k;
  42             break;
  43           case "K":
  44           case "L":
  45             this.kingPos["w"] = [i, k];
  46             this.INIT_COL_KING["w"] = k;
  47             break;
  48           default: {
  49             const num = parseInt(fenRows[i].charAt(j), 10);
  50             if (!isNaN(num)) k += num - 1;
  51           }
  52         }
  53         k++;
  54       }
  55     }
  56   }
  57
  58   getPotentialMovesFrom(sq) {
  59     const piece = this.getPiece(sq[0], sq[1]);
  60     if (V.PROMOTED.includes(piece)) {
  61       switch (piece) {
  62         case 's':
  63           return (
  64             super.getPotentialPawnMoves(sq)
  65             // Promoted pawns back on initial rank don't jump 2 squares:
  66             .filter(m => Math.abs(m.end.x - m.start.x) == 1)
  67           );
  68         case 'u': return super.getPotentialRookMoves(sq);
  69         case 'o': return super.getPotentialKnightMoves(sq);
  70         case 'c': return super.getPotentialBishopMoves(sq);
  71         case 't': return super.getPotentialQueenMoves(sq);
  72         case 'l': return super.getPotentialKingMoves(sq);
  73       }
  74     }
  75     // Unpromoted piece: only go forward
  76     const color = this.turn;
  77     let moves =
  78       super.getPotentialMovesFrom(sq)
  79       .filter(m => {
  80         const delta = m.end.x - m.start.x;
  81         return ((color == 'w' && delta <= 0) || (color == 'b' && delta >= 0));
  82       });
  83     // Apply promotions:
  84     const lastRank = (color == 'w' ? 0 : 7);
  85     moves.forEach(m => {
  86       if (m.end.x == lastRank) {
  87         const pIdx = ChessRules.PIECES.findIndex(p => p == m.appear[0].p);
  88         m.appear[0].p = V.PROMOTED[pIdx];
  89       }
  90     });
  91     return moves;
  92   }
  93
  94   isAttackedBySlideNJump([x, y], color, piece, steps, oneStep) {
  95     const pIdx = ChessRules.PIECES.findIndex(p => p == piece);
  96     const ppiece = V.PROMOTED[pIdx];
  97     const forward = (color == 'w' ? -1 : 1);
  98     for (let step of steps) {
  99       let rx = x + step[0],
 100           ry = y + step[1];
 101       while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
 102         rx += step[0];
 103         ry += step[1];
 104       }
 105       if (V.OnBoard(rx, ry) && this.getColor(rx, ry) == color) {
 106         const pieceR = this.getPiece(rx, ry);
 107         if (
 108           pieceR == ppiece ||
 109           (pieceR == piece && (step[0] == 0 || -step[0] == forward))
 110         ) {
 111           return true;
 112         }
 113       }
 114     }
 115     return false;
 116   }
 117
 118   postPlay(move) {
 119     super.postPlay(move);
 120     if (move.appear[0].p == "l")
 121       this.kingPos[move.appear[0].c] = [move.appear[0].x, move.appear[0].y];
 122   }
 123
 124   postUndo(move) {
 125     super.postUndo(move);
 126     if (move.appear[0].p == "l")
 127       this.kingPos[this.turn] = [move.start.x, move.start.y];
 128   }
 129
 130   static get VALUES() {
 131     return Object.assign(
 132       {
 133         s: 2,
 134         u: 8,
 135         o: 5,
 136         c: 5,
 137         t: 15,
 138         l: 1500
 139       },
 140       ChessRules.VALUES
 141     );
 142   }
 143 };