client/src/variants/Fanorona.js

   1 import { ChessRules, Move, PiPo } from "@/base_rules";
   2 import { randInt } from "@/utils/alea";
   3
   4 export class FanoronaRules extends ChessRules {
   5
   6   static get HasFlags() {
   7     return false;
   8   }
   9
  10   static get HasEnpassant() {
  11     return false;
  12   }
  13
  14   static get Monochrome() {
  15     return true;
  16   }
  17
  18   static get Lines() {
  19     let lines = [];
  20     // Draw all inter-squares lines, shifted:
  21     for (let i = 0; i < V.size.x; i++)
  22       lines.push([[i+0.5, 0.5], [i+0.5, V.size.y-0.5]]);
  23     for (let j = 0; j < V.size.y; j++)
  24       lines.push([[0.5, j+0.5], [V.size.x-0.5, j+0.5]]);
  25     const columnDiags = [
  26       [[0.5, 0.5], [2.5, 2.5]],
  27       [[0.5, 2.5], [2.5, 0.5]],
  28       [[2.5, 0.5], [4.5, 2.5]],
  29       [[4.5, 0.5], [2.5, 2.5]]
  30     ];
  31     for (let j of [0, 2, 4, 6]) {
  32       lines = lines.concat(
  33         columnDiags.map(L => [[L[0][0], L[0][1] + j], [L[1][0], L[1][1] + j]])
  34       );
  35     }
  36     return lines;
  37   }
  38
  39   static get Notoodark() {
  40     return true;
  41   }
  42
  43   static GenRandInitFen() {
  44     return "ppppppppp/ppppppppp/pPpP1pPpP/PPPPPPPPP/PPPPPPPPP w 0";
  45   }
  46
  47   setOtherVariables(fen) {
  48     // Local stack of captures during a turn (squares + directions)
  49     this.captures = [ [] ];
  50   }
  51
  52   static get size() {
  53     return { x: 5, y: 9 };
  54   }
  55
  56   getPiece() {
  57     return V.PAWN;
  58   }
  59
  60   static IsGoodPosition(position) {
  61     if (position.length == 0) return false;
  62     const rows = position.split("/");
  63     if (rows.length != V.size.x) return false;
  64     for (let row of rows) {
  65       let sumElts = 0;
  66       for (let i = 0; i < row.length; i++) {
  67         if (row[i].toLowerCase() == V.PAWN) sumElts++;
  68         else {
  69           const num = parseInt(row[i], 10);
  70           if (isNaN(num) || num <= 0) return false;
  71           sumElts += num;
  72         }
  73       }
  74       if (sumElts != V.size.y) return false;
  75     }
  76     return true;
  77   }
  78
  79   getPpath(b) {
  80     return "Fanorona/" + b;
  81   }
  82
  83   getPPpath(m) {
  84     // m.vanish.length >= 2, first capture gives direction
  85     const ref = (Math.abs(m.vanish[1].x - m.start.x) == 1 ? m.start : m.end);
  86     const step = [m.vanish[1].x - ref.x, m.vanish[1].y - ref.y];
  87     const normalizedStep = [
  88       step[0] / Math.abs(step[0]),
  89       step[1] / Math.abs(step[1])
  90     ];
  91     return (
  92       "Fanorona/arrow_" +
  93       (normalizedStep[0] || 0) + "_" + (normalizedStep[1] || 0)
  94     );
  95   }
  96
  97   // After moving, add stones captured in "step" direction from new location
  98   // [x, y] to mv.vanish (if any captured stone!)
  99   addCapture([x, y], step, move) {
 100     let [i, j] = [x + step[0], y + step[1]];
 101     const oppCol = V.GetOppCol(move.vanish[0].c);
 102     while (
 103       V.OnBoard(i, j) &&
 104       this.board[i][j] != V.EMPTY &&
 105       this.getColor(i, j) == oppCol
 106     ) {
 107       move.vanish.push(new PiPo({ x: i, y: j, c: oppCol, p: V.PAWN }));
 108       i += step[0];
 109       j += step[1];
 110     }
 111     return (move.vanish.length >= 2);
 112   }
 113
 114   getPotentialMovesFrom([x, y]) {
 115     const L0 = this.captures.length;
 116     const captures = this.captures[L0 - 1];
 117     const L = captures.length;
 118     if (L > 0) {
 119       var c = captures[L-1];
 120       if (x != c.square.x + c.step[0] || y != c.square.y + c.step[1])
 121         return [];
 122     }
 123     const oppCol = V.GetOppCol(this.turn);
 124     let steps = V.steps[V.ROOK];
 125     if ((x + y) % 2 == 0) steps = steps.concat(V.steps[V.BISHOP]);
 126     let moves = [];
 127     for (let s of steps) {
 128       if (L > 0 && c.step[0] == s[0] && c.step[1] == s[1]) {
 129         // Add a move to say "I'm done capturing"
 130         moves.push(
 131           new Move({
 132             appear: [],
 133             vanish: [],
 134             start: { x: x, y: y },
 135             end: { x: x - s[0], y: y - s[1] }
 136           })
 137         );
 138         continue;
 139       }
 140       let [i, j] = [x + s[0], y + s[1]];
 141       if (captures.some(c => c.square.x == i && c.square.y == j)) continue;
 142       if (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
 143         // The move is potentially allowed. Might lead to 2 different captures
 144         let mv = super.getBasicMove([x, y], [i, j]);
 145         const capt = this.addCapture([i, j], s, mv);
 146         if (capt) {
 147           moves.push(mv);
 148           mv = super.getBasicMove([x, y], [i, j]);
 149         }
 150         const capt_bw = this.addCapture([x, y], [-s[0], -s[1]], mv);
 151         if (capt_bw) moves.push(mv);
 152         // Captures take priority (if available)
 153         if (!capt && !capt_bw && L == 0) moves.push(mv);
 154       }
 155     }
 156     return moves;
 157   }
 158
 159   atLeastOneCapture() {
 160     const color = this.turn;
 161     const oppCol = V.GetOppCol(color);
 162     const L0 = this.captures.length;
 163     const captures = this.captures[L0 - 1];
 164     const L = captures.length;
 165     if (L > 0) {
 166       // If some adjacent enemy stone, with free space to capture it,
 167       // toward a square not already visited, through a different step
 168       // from last one: then yes.
 169       const c = captures[L-1];
 170       const [x, y] = [c.square.x + c.step[0], c.square.y + c.step[1]];
 171       let steps = V.steps[V.ROOK];
 172       if ((x + y) % 2 == 0) steps = steps.concat(V.steps[V.BISHOP]);
 173       // TODO: half of the steps explored are redundant
 174       for (let s of steps) {
 175         if (s[0] == c.step[0] && s[1] == c.step[1]) continue;
 176         const [i, j] = [x + s[0], y + s[1]];
 177         if (
 178           !V.OnBoard(i, j) ||
 179           this.board[i][j] != V.EMPTY ||
 180           captures.some(c => c.square.x == i && c.square.y == j)
 181         ) {
 182           continue;
 183         }
 184         if (
 185           V.OnBoard(i + s[0], j + s[1]) &&
 186           this.board[i + s[0]][j + s[1]] != V.EMPTY &&
 187           this.getColor(i + s[0], j + s[1]) == oppCol
 188         ) {
 189           return true;
 190         }
 191         if (
 192           V.OnBoard(x - s[0], y - s[1]) &&
 193           this.board[x - s[0]][y - s[1]] != V.EMPTY &&
 194           this.getColor(x - s[0], y - s[1]) == oppCol
 195         ) {
 196           return true;
 197         }
 198       }
 199       return false;
 200     }
 201     for (let i = 0; i < V.size.x; i++) {
 202       for (let j = 0; j < V.size.y; j++) {
 203         if (
 204           this.board[i][j] != V.EMPTY &&
 205           this.getColor(i, j) == color &&
 206           // TODO: this could be more efficient
 207           this.getPotentialMovesFrom([i, j]).some(m => m.vanish.length >= 2)
 208         ) {
 209           return true;
 210         }
 211       }
 212     }
 213     return false;
 214   }
 215
 216   static KeepCaptures(moves) {
 217     return moves.filter(m => m.vanish.length >= 2);
 218   }
 219
 220   getPossibleMovesFrom(sq) {
 221     let moves = this.getPotentialMovesFrom(sq);
 222     const L0 = this.captures.length;
 223     const captures = this.captures[L0 - 1];
 224     if (captures.length > 0) return this.getPotentialMovesFrom(sq);
 225     const captureMoves = V.KeepCaptures(moves);
 226     if (captureMoves.length > 0) return captureMoves;
 227     if (this.atLeastOneCapture()) return [];
 228     return moves;
 229   }
 230
 231   getAllValidMoves() {
 232     const moves = super.getAllValidMoves();
 233     if (moves.some(m => m.vanish.length >= 2)) return V.KeepCaptures(moves);
 234     return moves;
 235   }
 236
 237   filterValid(moves) {
 238     return moves;
 239   }
 240
 241   getCheckSquares() {
 242     return [];
 243   }
 244
 245   play(move) {
 246     const color = this.turn;
 247     move.turn = color; //for undo
 248     V.PlayOnBoard(this.board, move);
 249     const L0 = this.captures.length;
 250     let captures = this.captures[L0 - 1];
 251     if (move.vanish.length >= 2) {
 252       captures.push({
 253         square: move.start,
 254         step: [move.end.x - move.start.x, move.end.y - move.start.y]
 255       });
 256       if (this.atLeastOneCapture())
 257         // There could be other captures (optional)
 258         // This field is mostly useful for computer play.
 259         move.notTheEnd = true;
 260       else captures.pop(); //useless now
 261     }
 262     if (!move.notTheEnd) {
 263       this.turn = V.GetOppCol(color);
 264       this.movesCount++;
 265       this.captures.push([]);
 266     }
 267   }
 268
 269   undo(move) {
 270     V.UndoOnBoard(this.board, move);
 271     if (move.turn != this.turn) {
 272       this.turn = move.turn;
 273       this.movesCount--;
 274       this.captures.pop();
 275     }
 276     else {
 277       const L0 = this.captures.length;
 278       let captures = this.captures[L0 - 1];
 279       captures.pop();
 280     }
 281   }
 282
 283   getCurrentScore() {
 284     const color = this.turn;
 285     // If no stones on board, I lose
 286     if (
 287       this.board.every(b => {
 288         return b.every(cell => {
 289           return (cell == "" || cell[0] != color);
 290         });
 291       })
 292     ) {
 293       return (color == 'w' ? "0-1" : "1-0");
 294     }
 295     return "*";
 296   }
 297
 298   getComputerMove() {
 299     const moves = this.getAllValidMoves();
 300     if (moves.length == 0) return null;
 301     const color = this.turn;
 302     // Capture available? If yes, play it
 303     let captures = moves.filter(m => m.vanish.length >= 2);
 304     let mvArray = [];
 305     while (captures.length >= 1) {
 306       // Then just pick random captures (trying to maximize)
 307       let candidates = captures.filter(c => !!c.notTheEnd);
 308       let mv = null;
 309       if (candidates.length >= 1) mv = candidates[randInt(candidates.length)];
 310       else mv = captures[randInt(captures.length)];
 311       this.play(mv);
 312       mvArray.push(mv);
 313       captures = (this.turn == color ? this.getAllValidMoves() : []);
 314     }
 315     if (mvArray.length >= 1) {
 316       for (let i = mvArray.length - 1; i >= 0; i--) this.undo(mvArray[i]);
 317       return mvArray;
 318     }
 319     // Just play a random move, which if possible does not let a capture
 320     let candidates = [];
 321     for (let m of moves) {
 322       this.play(m);
 323       if (!this.atLeastOneCapture()) candidates.push(m);
 324       this.undo(m);
 325     }
 326     if (candidates.length >= 1) return candidates[randInt(candidates.length)];
 327     return moves[randInt(moves.length)];
 328   }
 329
 330   getNotation(move) {
 331     if (move.appear.length == 0) return "stop";
 332     return (
 333       V.CoordsToSquare(move.start) +
 334       V.CoordsToSquare(move.end) +
 335       (move.vanish.length >= 2 ? "X" : "")
 336     );
 337   }
 338
 339 };