public/javascripts/variants/Marseille.js

   1 class MarseilleRules extends ChessRules
   2 {
   3     static IsGoodEnpassant(enpassant)
   4     {
   5         if (enpassant != "-")
   6         {
   7             const squares = enpassant.split(",");
   8             if (squares.length > 2)
   9                 return false;
  10             for (let sq of squares)
  11             {
  12                 const ep = V.SquareToCoords(sq);
  13                 if (isNaN(ep.x) || !V.OnBoard(ep))
  14                     return false;
  15             }
  16         }
  17         return true;
  18     }
  19
  20     getTurnFen()
  21     {
  22         if (this.startAtFirstMove && this.moves.length==0)
  23             return "w";
  24         return this.turn + this.subTurn;
  25     }
  26
  27     // There may be 2 enPassant squares (if 2 pawns jump 2 squares in same turn)
  28     getEnpassantFen()
  29     {
  30         const L = this.epSquares.length;
  31         if (this.epSquares[L-1].every(epsq => epsq === undefined))
  32             return "-"; //no en-passant
  33         let res = "";
  34         this.epSquares[L-1].forEach(epsq => {
  35             if (!!epsq)
  36                 res += V.CoordsToSquare(epsq) + ",";
  37         });
  38         return res.slice(0,-1); //remove last comma
  39     }
  40
  41     setOtherVariables(fen)
  42     {
  43         const parsedFen = V.ParseFen(fen);
  44         this.setFlags(parsedFen.flags);
  45         if (parsedFen.enpassant == "-")
  46             this.epSquares = [ [undefined,undefined] ];
  47         else
  48         {
  49             let res = [];
  50             const squares = parsedFen.enpassant.split(",");
  51             for (let sq of squares)
  52                 res.push(V.SquareToCoords(sq));
  53             if (res.length == 1)
  54                 res.push(undefined); //always 2 slots in epSquares[i]
  55             this.epSquares = [ res ];
  56         }
  57         this.scanKingsRooks(fen);
  58         // Extract subTurn from turn indicator: "w" (first move), or
  59         // "w1" or "w2" white subturn 1 or 2, and same for black
  60         const fullTurn = V.ParseFen(fen).turn;
  61         this.startAtFirstMove = (fullTurn == "w");
  62         this.turn = fullTurn[0];
  63         this.subTurn = (fullTurn[1] || 1);
  64     }
  65
  66     getPotentialPawnMoves([x,y])
  67     {
  68         const color = this.turn;
  69         let moves = [];
  70         const [sizeX,sizeY] = [V.size.x,V.size.y];
  71         const shiftX = (color == "w" ? -1 : 1);
  72         const firstRank = (color == 'w' ? sizeX-1 : 0);
  73         const startRank = (color == "w" ? sizeX-2 : 1);
  74         const lastRank = (color == "w" ? 0 : sizeX-1);
  75         const pawnColor = this.getColor(x,y); //can be different for checkered
  76
  77         if (x+shiftX >= 0 && x+shiftX < sizeX) //TODO: always true
  78         {
  79             const finalPieces = x + shiftX == lastRank
  80                 ? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN]
  81                 : [V.PAWN]
  82             // One square forward
  83             if (this.board[x+shiftX][y] == V.EMPTY)
  84             {
  85                 for (let piece of finalPieces)
  86                 {
  87                     moves.push(this.getBasicMove([x,y], [x+shiftX,y],
  88                         {c:pawnColor,p:piece}));
  89                 }
  90                 // Next condition because pawns on 1st rank can generally jump
  91                 if ([startRank,firstRank].includes(x)
  92                     && this.board[x+2*shiftX][y] == V.EMPTY)
  93                 {
  94                     // Two squares jump
  95                     moves.push(this.getBasicMove([x,y], [x+2*shiftX,y]));
  96                 }
  97             }
  98             // Captures
  99             for (let shiftY of [-1,1])
 100             {
 101                 if (y + shiftY >= 0 && y + shiftY < sizeY
 102                     && this.board[x+shiftX][y+shiftY] != V.EMPTY
 103                     && this.canTake([x,y], [x+shiftX,y+shiftY]))
 104                 {
 105                     for (let piece of finalPieces)
 106                     {
 107                         moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
 108                             {c:pawnColor,p:piece}));
 109                     }
 110                 }
 111             }
 112         }
 113
 114         // En passant: always OK if subturn 1,
 115         // OK on subturn 2 only if enPassant was played at subturn 1
 116         // (and if there are two e.p. squares available).
 117         const Lep = this.epSquares.length;
 118         const epSquares = this.epSquares[Lep-1]; //always at least one element
 119         let epSqs = [];
 120         epSquares.forEach(sq => {
 121             if (!!sq)
 122                 epSqs.push(sq);
 123         });
 124         if (epSqs.length == 0)
 125             return moves;
 126         for (let sq of epSqs)
 127         {
 128             if (this.subTurn == 1 || (epSqs.length == 2 &&
 129                 // Was this en-passant capture already played at subturn 1 ?
 130                 this.board[epSqs[0].x][epSqs[0].y] != V.EMPTY))
 131             {
 132                 if (sq.x == x+shiftX && Math.abs(sq.y - y) == 1)
 133                 {
 134                     let epMove = this.getBasicMove([x,y], [sq.x,sq.y]);
 135                     epMove.vanish.push({
 136                         x: x,
 137                         y: sq.y,
 138                         p: 'p',
 139                         c: this.getColor(x,sq.y)
 140                     });
 141                     moves.push(epMove);
 142                 }
 143             }
 144         }
 145
 146         return moves;
 147     }
 148
 149     play(move, ingame)
 150     {
 151         if (!!ingame)
 152         {
 153             move.notation = [this.getNotation(move), this.getLongNotation(move)];
 154             // In this special case, we also need the "move color":
 155             move.color = this.turn;
 156         }
 157         move.flags = JSON.stringify(this.aggregateFlags());
 158         let lastEpsq = this.epSquares[this.epSquares.length-1];
 159         const epSq = this.getEpSquare(move);
 160         if (lastEpsq.length == 1)
 161             lastEpsq.push(epSq);
 162         else
 163         {
 164             // New turn
 165             let newEpsqs = [epSq];
 166             if (this.startAtFirstMove && this.moves.length == 0)
 167                 newEpsqs.push(undefined); //at first move, to force length==2 (TODO)
 168             this.epSquares.push(newEpsqs);
 169         }
 170         V.PlayOnBoard(this.board, move);
 171         if (this.startAtFirstMove && this.moves.length == 0)
 172             this.turn = "b";
 173         // Does this move give check on subturn 1? If yes, skip subturn 2
 174         else if (this.subTurn==1 && this.underCheck(this.getOppCol(this.turn)))
 175         {
 176             this.epSquares[this.epSquares.length-1].push(undefined);
 177             this.turn = this.getOppCol(this.turn);
 178             move.checkOnSubturn1 = true;
 179         }
 180         else
 181         {
 182             if (this.subTurn == 2)
 183                 this.turn = this.getOppCol(this.turn);
 184             this.subTurn = 3 - this.subTurn;
 185         }
 186         this.moves.push(move);
 187         this.updateVariables(move);
 188         if (!!ingame)
 189             move.hash = hex_md5(this.getFen());
 190     }
 191
 192     undo(move)
 193     {
 194         this.disaggregateFlags(JSON.parse(move.flags));
 195         let lastEpsq = this.epSquares[this.epSquares.length-1];
 196         if (lastEpsq.length == 2)
 197         {
 198             if (!!move.checkOnSubturn1 ||
 199                 (this.startAtFirstMove && this.moves.length == 1))
 200             {
 201                 this.epSquares.pop(); //remove real + artificial e.p. squares
 202             }
 203             else
 204                 lastEpsq.pop();
 205         }
 206         else
 207             this.epSquares.pop();
 208         V.UndoOnBoard(this.board, move);
 209         if (this.startAtFirstMove && this.moves.length == 1)
 210             this.turn = "w";
 211         else if (move.checkOnSubturn1)
 212         {
 213             this.turn = this.getOppCol(this.turn);
 214             this.subTurn = 1;
 215         }
 216         else
 217         {
 218             if (this.subTurn == 1)
 219                 this.turn = this.getOppCol(this.turn);
 220             this.subTurn = 3 - this.subTurn;
 221         }
 222         this.moves.pop();
 223         this.unupdateVariables(move);
 224     }
 225
 226     // NOTE:  GenRandInitFen() is OK,
 227     // since at first move turn indicator is just "w"
 228
 229     // No alpha-beta here, just adapted min-max at depth 2(+1)
 230     getComputerMove()
 231     {
 232         if (this.subTurn == 2)
 233             return null; //TODO: imperfect interface setup
 234
 235         const maxeval = V.INFINITY;
 236         const color = this.turn;
 237         const oppCol = this.getOppCol(this.turn);
 238
 239         // Search best (half) move for opponent turn
 240         const getBestMoveEval = () => {
 241             let moves = this.getAllValidMoves();
 242             if (moves.length == 0)
 243             {
 244                 const score = this.checkGameEnd();
 245                 if (score == "1/2")
 246                     return 0;
 247                 return maxeval * (score == "1-0" ? 1 : -1);
 248             }
 249             let res = (oppCol == "w" ? -maxeval : maxeval);
 250             for (let m of moves)
 251             {
 252                 this.play(m);
 253                 this.turn = color; //very artificial...
 254                 if (!this.atLeastOneMove())
 255                 {
 256                     const score = this.checkGameEnd();
 257                     if (score == "1/2")
 258                         res = (oppCol == "w" ? Math.max(res, 0) : Math.min(res, 0));
 259                     else
 260                     {
 261                         // Found a mate
 262                         this.turn = oppCol;
 263                         this.undo(m);
 264                         return maxeval * (score == "1-0" ? 1 : -1);
 265                     }
 266                 }
 267                 const evalPos = this.evalPosition();
 268                 res = (oppCol == "w" ? Math.max(res, evalPos) : Math.min(res, evalPos));
 269                 this.turn = oppCol;
 270                 this.undo(m);
 271             }
 272             return res;
 273         };
 274
 275         let moves11 = this.getAllValidMoves();
 276         let doubleMoves = [];
 277         // Rank moves using a min-max at depth 2
 278         for (let i=0; i<moves11.length; i++)
 279         {
 280             moves11[i].eval = (color=="w" ? -1 : 1) * maxeval;
 281             this.play(moves11[i]);
 282             if (this.turn != color)
 283             {
 284                 // We gave check with last move: search the best opponent move
 285                 doubleMoves.push({moves:[moves11[i]], eval:getBestMoveEval()});
 286             }
 287             else
 288             {
 289                 let moves12 = this.getAllValidMoves();
 290                 for (let j=0; j<moves12.length; j++)
 291                 {
 292                     this.play(moves12[j]);
 293                     doubleMoves.push({
 294                         moves:[moves11[i],moves12[j]],
 295                         eval:getBestMoveEval()});
 296                     this.undo(moves12[j]);
 297                 }
 298             }
 299             this.undo(moves11[i]);
 300         }
 301
 302         doubleMoves.sort( (a,b) => {
 303             return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 304         let candidates = [0]; //indices of candidates moves
 305         for (let i=1;
 306             i<doubleMoves.length && doubleMoves[i].eval == doubleMoves[0].eval;
 307             i++)
 308         {
 309             candidates.push(i);
 310         }
 311
 312         const selected = doubleMoves[_.sample(candidates, 1)].moves;
 313         if (selected.length == 1)
 314             return selected[0];
 315         return selected;
 316     }
 317
 318     getPGN(mycolor, score, fenStart, mode)
 319     {
 320         let pgn = "";
 321         pgn += '[Site "vchess.club"]<br>';
 322         const opponent = mode=="human" ? "Anonymous" : "Computer";
 323         pgn += '[Variant "' + variant + '"]<br>';
 324         pgn += '[Date "' + getDate(new Date()) + '"]<br>';
 325         pgn += '[White "' + (mycolor=='w'?'Myself':opponent) + '"]<br>';
 326         pgn += '[Black "' + (mycolor=='b'?'Myself':opponent) + '"]<br>';
 327         pgn += '[FenStart "' + fenStart + '"]<br>';
 328         pgn += '[Fen "' + this.getFen() + '"]<br>';
 329         pgn += '[Result "' + score + '"]<br><br>';
 330
 331         let counter = 1;
 332         let i = 0;
 333         while (i < this.moves.length)
 334         {
 335             pgn += (counter++) + ".";
 336             for (let color of ["w","b"])
 337             {
 338                 let move = "";
 339                 while (i < this.moves.length && this.moves[i].color == color)
 340                     move += this.moves[i++].notation[0] + ",";
 341                 move = move.slice(0,-1); //remove last comma
 342                 pgn += move + (i < this.moves.length-1 ? " " : "");
 343             }
 344         }
 345         pgn += "<br><br>";
 346
 347         // "Complete moves" PGN (helping in ambiguous cases)
 348         counter = 1;
 349         i = 0;
 350         while (i < this.moves.length)
 351         {
 352             pgn += (counter++) + ".";
 353             for (let color of ["w","b"])
 354             {
 355                 let move = "";
 356                 while (i < this.moves.length && this.moves[i].color == color)
 357                     move += this.moves[i++].notation[1] + ",";
 358                 move = move.slice(0,-1); //remove last comma
 359                 pgn += move + (i < this.moves.length-1 ? " " : "");
 360             }
 361         }
 362
 363         return pgn;
 364     }
 365
 366 }
 367
 368 const VariantRules = MarseilleRules;