client/src/variants/Switching.js

   1 import { ChessRules, Move, PiPo } from "@/base_rules";
   2
   3 export class SwitchingRules extends ChessRules {
   4   // Build switch move between squares x1,y1 and x2,y2
   5     getSwitchMove_s([x1, y1], [x2, y2]) {
   6         const c = this.getColor(x1, y1); //same as color at square 2
   7         const p1 = this.getPiece(x1, y1);
   8         const p2 = this.getPiece(x2, y2);
   9         let move = new Move({
  10             appear: [
  11                 new PiPo({ x: x2, y: y2, c: c, p: p1 }),
  12                 new PiPo({ x: x1, y: y1, c: c, p: p2 })
  13             ],
  14             vanish: [
  15                 new PiPo({ x: x1, y: y1, c: c, p: p1 }),
  16                 new PiPo({ x: x2, y: y2, c: c, p: p2 })
  17             ]
  18         });
  19         // Move completion: promote switched pawns (as in Magnetic)
  20         const lastRank = (c == "w" ? 0 : V.size.x - 1);
  21         let moves = [];
  22         if ((p1 == V.PAWN && x2 == lastRank) || (p2 == V.PAWN && x1 == lastRank)) {
  23             const idx = (p1 == V.PAWN ? 0 : 1);
  24             move.appear[idx].p = V.ROOK;
  25             moves.push(move);
  26             for (let piece of [V.KNIGHT, V.BISHOP, V.QUEEN]) {
  27                 let cmove = JSON.parse(JSON.stringify(move));
  28                 cmove.appear[idx].p = piece;
  29                 moves.push(cmove);
  30             }
  31             if (idx == 1) {
  32                 // Swap moves[i].appear[0] and [1] for moves presentation [TODO...]
  33                 moves.forEach(m => {
  34                     let tmp = m.appear[0];
  35                     m.appear[0] = m.appear[1];
  36                     m.appear[1] = tmp;
  37                 });
  38             }
  39         }
  40         else
  41       // Other cases
  42             moves.push(move);
  43         return moves;
  44     }
  45
  46     getPotentialMovesFrom([x,y]) {
  47         let moves = super.getPotentialMovesFrom([x,y]);
  48         const piece = this.getPiece(x,y);
  49     const color = this.turn;
  50     const oppCol = V.GetOppCol(color);
  51     const kp = this.kingPos[color];
  52         // Add switches (if not under check, from anything but the king)
  53         if (piece != V.KING && !this.isAttacked(kp, oppCol)) {
  54       const steps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
  55       for (let step of steps) {
  56         const [i, j] = [x+step[0], y+step[1]];
  57         if (
  58           V.OnBoard(i, j) &&
  59           this.board[i][j] != V.EMPTY &&
  60           this.getColor(i,j) == color &&
  61           this.getPiece(i,j) != piece
  62         ) {
  63           const switchMove_s = this.getSwitchMove_s([x,y], [i,j]);
  64           Array.prototype.push.apply(moves, switchMove_s);
  65         }
  66       }
  67     }
  68         return moves;
  69     }
  70
  71     postPlay(move) {
  72     // Did some king move?
  73     move.appear.forEach(a => {
  74       if (a.p == V.KING) {
  75         this.kingPos[a.c] = [a.x, a.y];
  76         this.castleFlags[a.c] = [V.size.y, V.size.y];
  77       }
  78     });
  79     const firstRank = (move.vanish[0].c == 'w' ? 7 : 0);
  80     for (let coords of [move.start, move.end]) {
  81       if (
  82         Object.keys(firstRank).includes(coords.x) &&
  83         this.castleFlags[firstRank[coords.x]].includes(coords.y)
  84       ) {
  85         const c = firstRank[coords.x];
  86         const flagIdx = (coords.y == this.castleFlags[c][0] ? 0 : 1);
  87         this.castleFlags[c][flagIdx] = V.size.y;
  88       }
  89     }
  90     }
  91
  92     postUndo(move) {
  93     // Did some king move?
  94     move.vanish.forEach(v => {
  95       if (v.p == V.KING) this.kingPos[v.c] = [v.x, v.y];
  96     });
  97     }
  98
  99     static get SEARCH_DEPTH() {
 100     // Branching factor is quite high
 101     return 2;
 102   }
 103
 104   getAllPotentialMoves() {
 105     // Since this function is used only for computer play,
 106     // remove duplicate switches:
 107     return super.getAllPotentialMoves().filter(m => {
 108       return (
 109         m.appear.length == 1 ||
 110         (m.appear[0].p == V.KING && m.appear[1].p == V.ROOK) ||
 111         (m.appear[1].x <= m.vanish[1].x && m.appear[1].y <= m.vanish[1].y)
 112       );
 113     });
 114   }
 115
 116   getNotation(move) {
 117     if (move.appear.length == 1)
 118       // Normal move
 119       return super.getNotation(move);
 120     if (move.appear[0].p == V.KING && move.appear[1].p == V.ROOK)
 121       // Castle
 122       return (move.end.y < move.start.y ? "0-0-0" : "0-0");
 123     // Switch
 124     return "S" + V.CoordsToSquare(move.start) + V.CoordsToSquare(move.end);
 125   }
 126 }