client/src/variants/Alice.js

   1 import { ChessRules } from "@/base_rules";
   2 import { ArrayFun } from "@/utils/array";
   3
   4 // NOTE: alternative implementation, probably cleaner = use only 1 board
   5 // TODO? atLeastOneMove() would be more efficient if rewritten here
   6 // (less sideBoard computations)
   7 export class AliceRules extends ChessRules {
   8   static get ALICE_PIECES() {
   9     return {
  10       s: "p",
  11       t: "q",
  12       u: "r",
  13       c: "b",
  14       o: "n",
  15       l: "k"
  16     };
  17   }
  18   static get ALICE_CODES() {
  19     return {
  20       p: "s",
  21       q: "t",
  22       r: "u",
  23       b: "c",
  24       n: "o",
  25       k: "l"
  26     };
  27   }
  28
  29   static get PIECES() {
  30     return ChessRules.PIECES.concat(Object.keys(V.ALICE_PIECES));
  31   }
  32
  33   getPpath(b) {
  34     return (Object.keys(V.ALICE_PIECES).includes(b[1]) ? "Alice/" : "") + b;
  35   }
  36
  37   getEpSquare(moveOrSquare) {
  38     if (!moveOrSquare) return undefined;
  39     if (typeof moveOrSquare === "string") {
  40       const square = moveOrSquare;
  41       if (square == "-") return undefined;
  42       return V.SquareToCoords(square);
  43     }
  44     // Argument is a move:
  45     const move = moveOrSquare;
  46     const s = move.start,
  47           e = move.end;
  48     if (
  49       s.y == e.y &&
  50       Math.abs(s.x - e.x) == 2 &&
  51       // Special conditions: a pawn can be on the other side
  52       ['p','s'].includes(move.appear[0].p) &&
  53       ['p','s'].includes(move.vanish[0].p)
  54     ) {
  55       return {
  56         x: (s.x + e.x) / 2,
  57         y: s.y
  58       };
  59     }
  60     return undefined; //default
  61   }
  62
  63   // king can be l or L (on the other mirror side)
  64   static IsGoodPosition(position) {
  65     if (position.length == 0) return false;
  66     const rows = position.split("/");
  67     if (rows.length != V.size.x) return false;
  68     let kings = { "k": 0, "K": 0, 'l': 0, 'L': 0 };
  69     for (let row of rows) {
  70       let sumElts = 0;
  71       for (let i = 0; i < row.length; i++) {
  72         if (['K','k','L','l'].includes(row[i])) kings[row[i]]++;
  73         if (V.PIECES.includes(row[i].toLowerCase())) sumElts++;
  74         else {
  75           const num = parseInt(row[i], 10);
  76           if (isNaN(num)) return false;
  77           sumElts += num;
  78         }
  79       }
  80       if (sumElts != V.size.y) return false;
  81     }
  82     if (kings['k'] + kings['l'] != 1 || kings['K'] + kings['L'] != 1)
  83       return false;
  84     return true;
  85   }
  86
  87   setOtherVariables(fen) {
  88     super.setOtherVariables(fen);
  89     const rows = V.ParseFen(fen).position.split("/");
  90     if (this.kingPos["w"][0] < 0 || this.kingPos["b"][0] < 0) {
  91       // INIT_COL_XXX won't be required if Alice kings are found
  92       // (it means 'king moved')
  93       for (let i = 0; i < rows.length; i++) {
  94         let k = 0; //column index on board
  95         for (let j = 0; j < rows[i].length; j++) {
  96           switch (rows[i].charAt(j)) {
  97             case "l":
  98               this.kingPos["b"] = [i, k];
  99               break;
 100             case "L":
 101               this.kingPos["w"] = [i, k];
 102               break;
 103             default: {
 104               const num = parseInt(rows[i].charAt(j), 10);
 105               if (!isNaN(num)) k += num - 1;
 106             }
 107           }
 108           k++;
 109         }
 110       }
 111     }
 112   }
 113
 114   // Return the (standard) color+piece notation at a square for a board
 115   getSquareOccupation(i, j, mirrorSide) {
 116     const piece = this.getPiece(i, j);
 117     if (mirrorSide == 1 && Object.keys(V.ALICE_CODES).includes(piece))
 118       return this.board[i][j];
 119     if (mirrorSide == 2 && Object.keys(V.ALICE_PIECES).includes(piece))
 120       return this.getColor(i, j) + V.ALICE_PIECES[piece];
 121     return "";
 122   }
 123
 124   // Build board of the given (mirror)side
 125   getSideBoard(mirrorSide) {
 126     // Build corresponding board from complete board
 127     let sideBoard = ArrayFun.init(V.size.x, V.size.y, "");
 128     for (let i = 0; i < V.size.x; i++) {
 129       for (let j = 0; j < V.size.y; j++)
 130         sideBoard[i][j] = this.getSquareOccupation(i, j, mirrorSide);
 131     }
 132     return sideBoard;
 133   }
 134
 135   // NOTE: castle & enPassant
 136   // https://www.chessvariants.com/other.dir/alice.html
 137   getPotentialMovesFrom([x, y], sideBoard) {
 138     const pieces = Object.keys(V.ALICE_CODES);
 139     const codes = Object.keys(V.ALICE_PIECES);
 140     const mirrorSide = pieces.includes(this.getPiece(x, y)) ? 1 : 2;
 141     if (!sideBoard) sideBoard = [this.getSideBoard(1), this.getSideBoard(2)];
 142     const color = this.getColor(x, y);
 143
 144     // Search valid moves on sideBoard
 145     const saveBoard = this.board;
 146     this.board = sideBoard[mirrorSide - 1];
 147     const moves = super.getPotentialMovesFrom([x, y]).filter(m => {
 148       // Filter out king moves which result in under-check position on
 149       // current board (before mirror traversing)
 150       let aprioriValid = true;
 151       if (m.appear[0].p == V.KING) {
 152         this.play(m);
 153         if (this.underCheck(color, sideBoard)) aprioriValid = false;
 154         this.undo(m);
 155       }
 156       return aprioriValid;
 157     });
 158     this.board = saveBoard;
 159
 160     // Finally filter impossible moves
 161     const res = moves.filter(m => {
 162       if (m.appear.length == 2) {
 163         // Castle: appear[i] must be an empty square on the other board
 164         for (let psq of m.appear) {
 165           if (
 166             this.getSquareOccupation(psq.x, psq.y, 3 - mirrorSide) != V.EMPTY
 167           ) {
 168             return false;
 169           }
 170         }
 171       } else if (this.board[m.end.x][m.end.y] != V.EMPTY) {
 172         // Attempt to capture
 173         const piece = this.getPiece(m.end.x, m.end.y);
 174         if (
 175           (mirrorSide == 1 && codes.includes(piece)) ||
 176           (mirrorSide == 2 && pieces.includes(piece))
 177         ) {
 178           return false;
 179         }
 180       }
 181       // If the move is computed on board1, m.appear change for Alice pieces.
 182       if (mirrorSide == 1) {
 183         m.appear.forEach(psq => {
 184           // forEach: castling taken into account
 185           psq.p = V.ALICE_CODES[psq.p]; //goto board2
 186         });
 187       }
 188       else {
 189         // Move on board2: mark vanishing pieces as Alice
 190         m.vanish.forEach(psq => {
 191           psq.p = V.ALICE_CODES[psq.p];
 192         });
 193       }
 194       // Fix en-passant captures
 195       if (
 196         m.vanish[0].p == V.PAWN &&
 197         m.vanish.length == 2 &&
 198         this.board[m.end.x][m.end.y] == V.EMPTY
 199       ) {
 200         m.vanish[1].c = V.GetOppCol(this.turn);
 201         const [epX, epY] = [m.vanish[1].x, m.vanish[1].y];
 202         m.vanish[1].p = this.getPiece(epX, epY);
 203       }
 204       return true;
 205     });
 206     return res;
 207   }
 208
 209   filterValid(moves, sideBoard) {
 210     if (moves.length == 0) return [];
 211     if (!sideBoard) sideBoard = [this.getSideBoard(1), this.getSideBoard(2)];
 212     const color = this.turn;
 213     return moves.filter(m => {
 214       this.playSide(m, sideBoard); //no need to track flags
 215       const res = !this.underCheck(color, sideBoard);
 216       this.undoSide(m, sideBoard);
 217       return res;
 218     });
 219   }
 220
 221   getAllValidMoves() {
 222     const color = this.turn;
 223     let potentialMoves = [];
 224     const sideBoard = [this.getSideBoard(1), this.getSideBoard(2)];
 225     for (var i = 0; i < V.size.x; i++) {
 226       for (var j = 0; j < V.size.y; j++) {
 227         if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == color) {
 228           Array.prototype.push.apply(
 229             potentialMoves,
 230             this.getPotentialMovesFrom([i, j], sideBoard)
 231           );
 232         }
 233       }
 234     }
 235     return this.filterValid(potentialMoves, sideBoard);
 236   }
 237
 238   // Play on sideboards [TODO: only one sideBoard required]
 239   playSide(move, sideBoard) {
 240     const pieces = Object.keys(V.ALICE_CODES);
 241     move.vanish.forEach(psq => {
 242       const mirrorSide = pieces.includes(psq.p) ? 1 : 2;
 243       sideBoard[mirrorSide - 1][psq.x][psq.y] = V.EMPTY;
 244     });
 245     move.appear.forEach(psq => {
 246       const mirrorSide = pieces.includes(psq.p) ? 1 : 2;
 247       const piece = mirrorSide == 1 ? psq.p : V.ALICE_PIECES[psq.p];
 248       sideBoard[mirrorSide - 1][psq.x][psq.y] = psq.c + piece;
 249       if (piece == V.KING) this.kingPos[psq.c] = [psq.x, psq.y];
 250     });
 251   }
 252
 253   // Undo on sideboards
 254   undoSide(move, sideBoard) {
 255     const pieces = Object.keys(V.ALICE_CODES);
 256     move.appear.forEach(psq => {
 257       const mirrorSide = pieces.includes(psq.p) ? 1 : 2;
 258       sideBoard[mirrorSide - 1][psq.x][psq.y] = V.EMPTY;
 259     });
 260     move.vanish.forEach(psq => {
 261       const mirrorSide = pieces.includes(psq.p) ? 1 : 2;
 262       const piece = mirrorSide == 1 ? psq.p : V.ALICE_PIECES[psq.p];
 263       sideBoard[mirrorSide - 1][psq.x][psq.y] = psq.c + piece;
 264       if (piece == V.KING) this.kingPos[psq.c] = [psq.x, psq.y];
 265     });
 266   }
 267
 268   // sideBoard: arg containing both boards (see getAllValidMoves())
 269   underCheck(color, sideBoard) {
 270     const kp = this.kingPos[color];
 271     const mirrorSide = sideBoard[0][kp[0]][kp[1]] != V.EMPTY ? 1 : 2;
 272     let saveBoard = this.board;
 273     this.board = sideBoard[mirrorSide - 1];
 274     let res = this.isAttacked(kp, [V.GetOppCol(color)]);
 275     this.board = saveBoard;
 276     return res;
 277   }
 278
 279   getCheckSquares() {
 280     const color = this.turn;
 281     const pieces = Object.keys(V.ALICE_CODES);
 282     const kp = this.kingPos[color];
 283     const mirrorSide = pieces.includes(this.getPiece(kp[0], kp[1])) ? 1 : 2;
 284     let sideBoard = this.getSideBoard(mirrorSide);
 285     let saveBoard = this.board;
 286     this.board = sideBoard;
 287     let res = this.isAttacked(this.kingPos[color], [V.GetOppCol(color)])
 288       ? [JSON.parse(JSON.stringify(this.kingPos[color]))]
 289       : [];
 290     this.board = saveBoard;
 291     return res;
 292   }
 293
 294   postPlay(move) {
 295     super.postPlay(move); //standard king
 296     const piece = move.vanish[0].p;
 297     const c = move.vanish[0].c;
 298     // "l" = Alice king
 299     if (piece == "l") {
 300       this.kingPos[c][0] = move.appear[0].x;
 301       this.kingPos[c][1] = move.appear[0].y;
 302       this.castleFlags[c] = [8, 8];
 303     }
 304   }
 305
 306   postUndo(move) {
 307     super.postUndo(move);
 308     const c = move.vanish[0].c;
 309     if (move.vanish[0].p == "l")
 310       this.kingPos[c] = [move.start.x, move.start.y];
 311   }
 312
 313   getCurrentScore() {
 314     if (this.atLeastOneMove()) return "*";
 315     const pieces = Object.keys(V.ALICE_CODES);
 316     const color = this.turn;
 317     const kp = this.kingPos[color];
 318     const mirrorSide = pieces.includes(this.getPiece(kp[0], kp[1])) ? 1 : 2;
 319     let sideBoard = this.getSideBoard(mirrorSide);
 320     let saveBoard = this.board;
 321     this.board = sideBoard;
 322     let res = "*";
 323     if (!this.isAttacked(this.kingPos[color], [V.GetOppCol(color)]))
 324       res = "1/2";
 325     else res = color == "w" ? "0-1" : "1-0";
 326     this.board = saveBoard;
 327     return res;
 328   }
 329
 330   static get VALUES() {
 331     return Object.assign(
 332       {
 333         s: 1,
 334         u: 5,
 335         o: 3,
 336         c: 3,
 337         t: 9,
 338         l: 1000
 339       },
 340       ChessRules.VALUES
 341     );
 342   }
 343
 344   static get SEARCH_DEPTH() {
 345     return 2;
 346   }
 347
 348   getNotation(move) {
 349     if (move.appear.length == 2 && move.appear[0].p == V.KING) {
 350       if (move.end.y < move.start.y) return "0-0-0";
 351       return "0-0";
 352     }
 353
 354     const finalSquare = V.CoordsToSquare(move.end);
 355     const piece = this.getPiece(move.start.x, move.start.y);
 356
 357     const captureMark = move.vanish.length > move.appear.length ? "x" : "";
 358     let pawnMark = "";
 359     if (["p", "s"].includes(piece) && captureMark.length == 1)
 360       pawnMark = V.CoordToColumn(move.start.y); //start column
 361
 362     // Piece or pawn movement
 363     let notation = piece.toUpperCase() + pawnMark + captureMark + finalSquare;
 364     if (["s", "p"].includes(piece) && !["s", "p"].includes(move.appear[0].p))
 365       // Promotion
 366       notation += "=" + move.appear[0].p.toUpperCase();
 367     return notation;
 368   }
 369 };