client/src/variants/Wormhole.js

   1 import { ChessRules } from "@/base_rules";
   2
   3 export class WormholeRules extends ChessRules {
   4   static get HasFlags() {
   5     return false;
   6   }
   7
   8   static get HasEnpassant() {
   9     return false;
  10   }
  11
  12   static get HOLE() {
  13     return "xx";
  14   }
  15
  16   static board2fen(b) {
  17     if (b[0] == 'x') return 'x';
  18     return ChessRules.board2fen(b);
  19   }
  20
  21   static fen2board(f) {
  22     if (f == 'x') return V.HOLE;
  23     return ChessRules.fen2board(f);
  24   }
  25
  26   getPpath(b) {
  27     if (b[0] == 'x') return "Wormhole/hole";
  28     return b;
  29   }
  30
  31   static IsGoodPosition(position) {
  32     if (position.length == 0) return false;
  33     const rows = position.split("/");
  34     if (rows.length != V.size.x) return false;
  35     let kings = { "k": 0, "K": 0 };
  36     for (let row of rows) {
  37       let sumElts = 0;
  38       for (let i = 0; i < row.length; i++) {
  39         if (['K','k'].includes(row[i])) kings[row[i]]++;
  40         if (['x'].concat(V.PIECES).includes(row[i].toLowerCase())) sumElts++;
  41         else {
  42           const num = parseInt(row[i], 10);
  43           if (isNaN(num)) return false;
  44           sumElts += num;
  45         }
  46       }
  47       if (sumElts != V.size.y) return false;
  48     }
  49     if (Object.values(kings).some(v => v != 1)) return false;
  50     return true;
  51   }
  52
  53   getSquareAfter(square, movement) {
  54     let shift1, shift2;
  55     if (Array.isArray(movement[0])) {
  56       // A knight
  57       shift1 = movement[0];
  58       shift2 = movement[1];
  59     } else {
  60       shift1 = movement;
  61       shift2 = null;
  62     }
  63     const tryMove = (init, shift) => {
  64       let step = [
  65         shift[0] / Math.abs(shift[0]) || 0,
  66         shift[1] / Math.abs(shift[1]) || 0,
  67       ];
  68       const nbSteps = Math.max(Math.abs(shift[0]), Math.abs(shift[1]));
  69       let stepsAchieved = 0;
  70       let sq = [init[0] + step[0], init[1] + step[1]];
  71       while (V.OnBoard(sq[0],sq[1])) {
  72         if (this.board[sq[0]][sq[1]] != V.HOLE)
  73           stepsAchieved++;
  74         if (stepsAchieved < nbSteps) {
  75           sq[0] += step[0];
  76           sq[1] += step[1];
  77         }
  78         else break;
  79       }
  80       if (stepsAchieved < nbSteps)
  81         // The move is impossible
  82         return null;
  83       return sq;
  84     };
  85     // First, apply shift1
  86     let dest = tryMove(square, shift1);
  87     if (dest && shift2)
  88       // A knight: apply second shift
  89       dest = tryMove(dest, shift2);
  90     return dest;
  91   }
  92
  93   // NOTE (TODO?): some extra work done in some function because informations
  94   // on one step should ease the computation for a step in the same direction.
  95   static get steps() {
  96     return {
  97       r: [
  98         [-1, 0],
  99         [1, 0],
 100         [0, -1],
 101         [0, 1],
 102         [-2, 0],
 103         [2, 0],
 104         [0, -2],
 105         [0, 2]
 106       ],
 107       // Decompose knight movements into one step orthogonal + one diagonal
 108       n: [
 109         [[0, -1], [-1, -1]],
 110         [[0, -1], [1, -1]],
 111         [[-1, 0], [-1,-1]],
 112         [[-1, 0], [-1, 1]],
 113         [[0, 1], [-1, 1]],
 114         [[0, 1], [1, 1]],
 115         [[1, 0], [1, -1]],
 116         [[1, 0], [1, 1]]
 117       ],
 118       b: [
 119         [-1, -1],
 120         [-1, 1],
 121         [1, -1],
 122         [1, 1],
 123         [-2, -2],
 124         [-2, 2],
 125         [2, -2],
 126         [2, 2]
 127       ],
 128       k: [
 129         [-1, 0],
 130         [1, 0],
 131         [0, -1],
 132         [0, 1],
 133         [-1, -1],
 134         [-1, 1],
 135         [1, -1],
 136         [1, 1]
 137       ]
 138     };
 139   }
 140
 141   getJumpMoves([x, y], steps) {
 142     let moves = [];
 143     for (let step of steps) {
 144       const sq = this.getSquareAfter([x,y], step);
 145       if (sq &&
 146         (
 147           this.board[sq[0]][sq[1]] == V.EMPTY ||
 148           this.canTake([x, y], sq)
 149         )
 150       ) {
 151           moves.push(this.getBasicMove([x, y], sq));
 152       }
 153     }
 154     return moves;
 155   }
 156
 157   // What are the pawn moves from square x,y ?
 158   getPotentialPawnMoves([x, y]) {
 159     const color = this.turn;
 160     let moves = [];
 161     const [sizeX, sizeY] = [V.size.x, V.size.y];
 162     const shiftX = color == "w" ? -1 : 1;
 163     const startRank = color == "w" ? sizeX - 2 : 1;
 164     const lastRank = color == "w" ? 0 : sizeX - 1;
 165
 166     const sq1 = this.getSquareAfter([x,y], [shiftX,0]);
 167     if (sq1 && this.board[sq1[0]][y] == V.EMPTY) {
 168       // One square forward (cannot be a promotion)
 169       moves.push(this.getBasicMove([x, y], [sq1[0], y]));
 170       if (x == startRank) {
 171         // If two squares after is available, then move is possible
 172         const sq2 = this.getSquareAfter([x,y], [2*shiftX,0]);
 173         if (sq2 && this.board[sq2[0]][y] == V.EMPTY)
 174           // Two squares jump
 175           moves.push(this.getBasicMove([x, y], [sq2[0], y]));
 176       }
 177     }
 178     // Captures
 179     for (let shiftY of [-1, 1]) {
 180       const sq = this.getSquareAfter([x,y], [shiftX,shiftY]);
 181       if (
 182         !!sq &&
 183         this.board[sq[0]][sq[1]] != V.EMPTY &&
 184         this.canTake([x, y], [sq[0], sq[1]])
 185       ) {
 186         const finalPieces = sq[0] == lastRank
 187           ? [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN]
 188           : [V.PAWN];
 189         for (let piece of finalPieces) {
 190           moves.push(
 191             this.getBasicMove([x, y], [sq[0], sq[1]], {
 192               c: color,
 193               p: piece
 194             })
 195           );
 196         }
 197       }
 198     }
 199
 200     return moves;
 201   }
 202
 203   getPotentialRookMoves(sq) {
 204     return this.getJumpMoves(sq, V.steps[V.ROOK]);
 205   }
 206
 207   getPotentialKnightMoves(sq) {
 208     return this.getJumpMoves(sq, V.steps[V.KNIGHT]);
 209   }
 210
 211   getPotentialBishopMoves(sq) {
 212     return this.getJumpMoves(sq, V.steps[V.BISHOP]);
 213   }
 214
 215   getPotentialQueenMoves(sq) {
 216     return this.getJumpMoves(
 217       sq,
 218       V.steps[V.ROOK].concat(V.steps[V.BISHOP])
 219     );
 220   }
 221
 222   getPotentialKingMoves(sq) {
 223     return this.getJumpMoves(sq, V.steps[V.KING]);
 224   }
 225
 226   isAttackedByJump([x, y], color, piece, steps) {
 227     for (let step of steps) {
 228       const sq = this.getSquareAfter([x,y], step);
 229       if (
 230         sq &&
 231         this.getPiece(sq[0], sq[1]) == piece &&
 232         this.getColor(sq[0], sq[1]) == color
 233       ) {
 234         return true;
 235       }
 236     }
 237     return false;
 238   }
 239
 240   isAttackedByPawn([x, y], color) {
 241     const pawnShift = (color == "w" ? 1 : -1);
 242     for (let i of [-1, 1]) {
 243       const sq = this.getSquareAfter([x,y], [pawnShift,i]);
 244       if (
 245         sq &&
 246         this.getPiece(sq[0], sq[1]) == V.PAWN &&
 247         this.getColor(sq[0], sq[1]) == color
 248       ) {
 249         return true;
 250       }
 251     }
 252     return false;
 253   }
 254
 255   isAttackedByRook(sq, color) {
 256     return this.isAttackedByJump(sq, color, V.ROOK, V.steps[V.ROOK]);
 257   }
 258
 259   isAttackedByKnight(sq, color) {
 260     // NOTE: knight attack is not symmetric in this variant:
 261     // steps order need to be reversed.
 262     return this.isAttackedByJump(
 263       sq,
 264       color,
 265       V.KNIGHT,
 266       V.steps[V.KNIGHT].map(s => s.reverse())
 267     );
 268   }
 269
 270   isAttackedByBishop(sq, color) {
 271     return this.isAttackedByJump(sq, color, V.BISHOP, V.steps[V.BISHOP]);
 272   }
 273
 274   isAttackedByQueen(sq, color) {
 275     return this.isAttackedByJump(
 276       sq,
 277       color,
 278       V.QUEEN,
 279       V.steps[V.ROOK].concat(V.steps[V.BISHOP])
 280     );
 281   }
 282
 283   isAttackedByKing(sq, color) {
 284     return this.isAttackedByJump(sq, color, V.KING, V.steps[V.KING]);
 285   }
 286
 287   // NOTE: altering move in getBasicMove doesn't work and wouldn't be logical.
 288   // This is a side-effect on board generated by the move.
 289   static PlayOnBoard(board, move) {
 290     board[move.vanish[0].x][move.vanish[0].y] = V.HOLE;
 291     for (let psq of move.appear) board[psq.x][psq.y] = psq.c + psq.p;
 292   }
 293
 294   getCurrentScore() {
 295     if (this.atLeastOneMove()) return "*";
 296     // No valid move: I lose
 297     return this.turn == "w" ? "0-1" : "1-0";
 298   }
 299
 300   static get SEARCH_DEPTH() {
 301     return 2;
 302   }
 303
 304   evalPosition() {
 305     let evaluation = 0;
 306     for (let i = 0; i < V.size.x; i++) {
 307       for (let j = 0; j < V.size.y; j++) {
 308         if (![V.EMPTY,V.HOLE].includes(this.board[i][j])) {
 309           const sign = this.getColor(i, j) == "w" ? 1 : -1;
 310           evaluation += sign * V.VALUES[this.getPiece(i, j)];
 311         }
 312       }
 313     }
 314     return evaluation;
 315   }
 316
 317   getNotation(move) {
 318     const piece = this.getPiece(move.start.x, move.start.y);
 319     // Indicate start square + dest square, because holes distort the board
 320     let notation =
 321       (piece != V.PAWN ? piece.toUpperCase() : "") +
 322       V.CoordsToSquare(move.start) +
 323       (move.vanish.length > move.appear.length ? "x" : "") +
 324       V.CoordsToSquare(move.end);
 325     if (piece == V.PAWN && move.appear[0].p != V.PAWN)
 326       // Promotion
 327       notation += "=" + move.appear[0].p.toUpperCase();
 328     return notation;
 329   }
 330 };