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] ];
  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             this.epSquares = [ res ];
  54         }
  55         this.scanKingsRooks(fen);
  56         // Extract subTurn from turn indicator: "w" (first move), or
  57         // "w1" or "w2" white subturn 1 or 2, and same for black
  58         const fullTurn = V.ParseFen(fen).turn;
  59         this.startAtFirstMove = (fullTurn == "w");
  60         this.turn = fullTurn[0];
  61         this.subTurn = (fullTurn[1] || 1);
  62     }
  63
  64     getPotentialPawnMoves([x,y])
  65     {
  66         const color = this.turn;
  67         let moves = [];
  68         const [sizeX,sizeY] = [V.size.x,V.size.y];
  69         const shiftX = (color == "w" ? -1 : 1);
  70         const firstRank = (color == 'w' ? sizeX-1 : 0);
  71         const startRank = (color == "w" ? sizeX-2 : 1);
  72         const lastRank = (color == "w" ? 0 : sizeX-1);
  73         const finalPieces = x + shiftX == lastRank
  74             ? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN]
  75             : [V.PAWN];
  76
  77         // One square forward
  78         if (this.board[x+shiftX][y] == V.EMPTY)
  79         {
  80             for (let piece of finalPieces)
  81             {
  82                 moves.push(this.getBasicMove([x,y], [x+shiftX,y],
  83                     {c:color,p:piece}));
  84             }
  85             // Next condition because pawns on 1st rank can generally jump
  86             if ([startRank,firstRank].includes(x)
  87                 && this.board[x+2*shiftX][y] == V.EMPTY)
  88             {
  89                 // Two squares jump
  90                 moves.push(this.getBasicMove([x,y], [x+2*shiftX,y]));
  91             }
  92         }
  93         // Captures
  94         for (let shiftY of [-1,1])
  95         {
  96             if (y + shiftY >= 0 && y + shiftY < sizeY
  97                 && this.board[x+shiftX][y+shiftY] != V.EMPTY
  98                 && this.canTake([x,y], [x+shiftX,y+shiftY]))
  99             {
 100                 for (let piece of finalPieces)
 101                 {
 102                     moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
 103                         {c:color,p:piece}));
 104                 }
 105             }
 106         }
 107
 108         // En passant: always OK if subturn 1,
 109         // OK on subturn 2 only if enPassant was played at subturn 1
 110         // (and if there are two e.p. squares available).
 111         const Lep = this.epSquares.length;
 112         const epSquares = this.epSquares[Lep-1]; //always at least one element
 113         let epSqs = [];
 114         epSquares.forEach(sq => {
 115             if (!!sq)
 116                 epSqs.push(sq);
 117         });
 118         if (epSqs.length == 0)
 119             return moves;
 120         const oppCol = this.getOppCol(color);
 121         for (let sq of epSqs)
 122         {
 123             if (this.subTurn == 1 || (epSqs.length == 2 &&
 124                 // Was this en-passant capture already played at subturn 1 ?
 125                 // (Or maybe the opponent filled the en-passant square with a piece)
 126                 this.board[epSqs[0].x][epSqs[0].y] != V.EMPTY))
 127             {
 128                 if (sq.x == x+shiftX && Math.abs(sq.y - y) == 1
 129                     // Add condition "enemy pawn must be present"
 130                     && this.getPiece(x,sq.y) == V.PAWN && this.getColor(x,sq.y) == oppCol)
 131                 {
 132                     let epMove = this.getBasicMove([x,y], [sq.x,sq.y]);
 133                     epMove.vanish.push({
 134                         x: x,
 135                         y: sq.y,
 136                         p: 'p',
 137                         c: oppCol
 138                     });
 139                     moves.push(epMove);
 140                 }
 141             }
 142         }
 143
 144         return moves;
 145     }
 146
 147     play(move, ingame)
 148     {
 149         if (!!ingame)
 150         {
 151             move.notation = [this.getNotation(move), this.getLongNotation(move)];
 152             // In this special case, we also need the "move color":
 153             move.color = this.turn;
 154         }
 155         move.flags = JSON.stringify(this.aggregateFlags());
 156         V.PlayOnBoard(this.board, move);
 157         const epSq = this.getEpSquare(move);
 158         if (this.startAtFirstMove && this.moves.length == 0)
 159         {
 160             this.turn = "b";
 161             this.epSquares.push([epSq]);
 162         }
 163         // Does this move give check on subturn 1? If yes, skip subturn 2
 164         else if (this.subTurn==1 && this.underCheck(this.getOppCol(this.turn)))
 165         {
 166             this.turn = this.getOppCol(this.turn);
 167             this.epSquares.push([epSq]);
 168             move.checkOnSubturn1 = true;
 169         }
 170         else
 171         {
 172             if (this.subTurn == 2)
 173             {
 174                 this.turn = this.getOppCol(this.turn);
 175                 let lastEpsq = this.epSquares[this.epSquares.length-1];
 176                 lastEpsq.push(epSq);
 177             }
 178             else
 179                 this.epSquares.push([epSq]);
 180             this.subTurn = 3 - this.subTurn;
 181         }
 182         this.moves.push(move);
 183         this.updateVariables(move);
 184         if (!!ingame)
 185             move.hash = hex_md5(this.getFen());
 186     }
 187
 188     undo(move)
 189     {
 190         this.disaggregateFlags(JSON.parse(move.flags));
 191         V.UndoOnBoard(this.board, move);
 192         if (this.startAtFirstMove && this.moves.length == 1)
 193         {
 194             this.turn = "w";
 195             this.epSquares.pop();
 196         }
 197         else if (move.checkOnSubturn1)
 198         {
 199             this.turn = this.getOppCol(this.turn);
 200             this.subTurn = 1;
 201             this.epSquares.pop();
 202         }
 203         else
 204         {
 205             if (this.subTurn == 1)
 206             {
 207                 this.turn = this.getOppCol(this.turn);
 208                 let lastEpsq = this.epSquares[this.epSquares.length-1];
 209                 lastEpsq.pop();
 210             }
 211             else
 212                 this.epSquares.pop();
 213             this.subTurn = 3 - this.subTurn;
 214         }
 215         this.moves.pop();
 216         this.unupdateVariables(move);
 217     }
 218
 219     // NOTE:  GenRandInitFen() is OK,
 220     // since at first move turn indicator is just "w"
 221
 222     static get VALUES()
 223     {
 224         return {
 225             'p': 1,
 226             'r': 5,
 227             'n': 3,
 228             'b': 3,
 229             'q': 7, //slightly less than in orthodox game
 230             'k': 1000
 231         };
 232     }
 233
 234     // No alpha-beta here, just adapted min-max at depth 2(+1)
 235     getComputerMove()
 236     {
 237         if (this.subTurn == 2)
 238             return null; //TODO: imperfect interface setup
 239
 240         const maxeval = V.INFINITY;
 241         const color = this.turn;
 242         const oppCol = this.getOppCol(this.turn);
 243
 244         // Search best (half) move for opponent turn
 245         const getBestMoveEval = () => {
 246             const turnBefore = this.turn + this.subTurn;
 247             let moves = this.getAllValidMoves();
 248             if (moves.length == 0)
 249             {
 250                 const score = this.checkGameEnd();
 251                 if (score == "1/2")
 252                     return 0;
 253                 return maxeval * (score == "1-0" ? 1 : -1);
 254             }
 255             let res = (oppCol == "w" ? -maxeval : maxeval);
 256             for (let m of moves)
 257             {
 258                 this.play(m);
 259                 // Now turn is oppCol,2 if m doesn't give check
 260                 // Otherwise it's color,1. In both cases the next test makes sense
 261                 if (!this.atLeastOneMove())
 262                 {
 263                     const score = this.checkGameEnd();
 264                     if (score == "1/2")
 265                         res = (oppCol == "w" ? Math.max(res, 0) : Math.min(res, 0));
 266                     else
 267                     {
 268                         // Found a mate
 269                         this.undo(m);
 270                         return maxeval * (score == "1-0" ? 1 : -1);
 271                     }
 272                 }
 273                 const evalPos = this.evalPosition();
 274                 res = (oppCol == "w" ? Math.max(res, evalPos) : Math.min(res, evalPos));
 275                 this.undo(m);
 276             }
 277             return res;
 278         };
 279
 280         let moves11 = this.getAllValidMoves();
 281         let doubleMoves = [];
 282         // Rank moves using a min-max at depth 2
 283         for (let i=0; i<moves11.length; i++)
 284         {
 285             this.play(moves11[i]);
 286             if (this.turn != color)
 287             {
 288                 // We gave check with last move: search the best opponent move
 289                 doubleMoves.push({moves:[moves11[i]], eval:getBestMoveEval()});
 290             }
 291             else
 292             {
 293                 let moves12 = this.getAllValidMoves();
 294                 for (let j=0; j<moves12.length; j++)
 295                 {
 296                     this.play(moves12[j]);
 297                     doubleMoves.push({
 298                         moves:[moves11[i],moves12[j]],
 299                         eval:getBestMoveEval()});
 300                     this.undo(moves12[j]);
 301                 }
 302             }
 303             this.undo(moves11[i]);
 304         }
 305
 306         doubleMoves.sort( (a,b) => {
 307             return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 308         let candidates = [0]; //indices of candidates moves
 309         for (let i=1;
 310             i<doubleMoves.length && doubleMoves[i].eval == doubleMoves[0].eval;
 311             i++)
 312         {
 313             candidates.push(i);
 314         }
 315
 316         const selected = doubleMoves[_.sample(candidates, 1)].moves;
 317         if (selected.length == 1)
 318             return selected[0];
 319         return selected;
 320     }
 321
 322     getPGN(mycolor, score, fenStart, mode)
 323     {
 324         let pgn = "";
 325         pgn += '[Site "vchess.club"]\n';
 326         const opponent = mode=="human" ? "Anonymous" : "Computer";
 327         pgn += '[Variant "' + variant + '"]\n';
 328         pgn += '[Date "' + getDate(new Date()) + '"]\n';
 329         const whiteName = ["human","computer"].includes(mode)
 330             ? (mycolor=='w'?'Myself':opponent)
 331             : "analyze";
 332         const blackName = ["human","computer"].includes(mode)
 333             ? (mycolor=='b'?'Myself':opponent)
 334             : "analyze";
 335         pgn += '[White "' + whiteName + '"]\n';
 336         pgn += '[Black "' + blackName + '"]\n';
 337         pgn += '[FenStart "' + fenStart + '"]\n';
 338         pgn += '[Fen "' + this.getFen() + '"]\n';
 339         pgn += '[Result "' + score + '"]\n\n';
 340
 341         let counter = 1;
 342         let i = 0;
 343         while (i < this.moves.length)
 344         {
 345             pgn += (counter++) + ".";
 346             for (let color of ["w","b"])
 347             {
 348                 let move = "";
 349                 while (i < this.moves.length && this.moves[i].color == color)
 350                     move += this.moves[i++].notation[0] + ",";
 351                 move = move.slice(0,-1); //remove last comma
 352                 pgn += move + (i < this.moves.length-1 ? " " : "");
 353             }
 354         }
 355         pgn += "\n\n";
 356
 357         // "Complete moves" PGN (helping in ambiguous cases)
 358         counter = 1;
 359         i = 0;
 360         while (i < this.moves.length)
 361         {
 362             pgn += (counter++) + ".";
 363             for (let color of ["w","b"])
 364             {
 365                 let move = "";
 366                 while (i < this.moves.length && this.moves[i].color == color)
 367                     move += this.moves[i++].notation[1] + ",";
 368                 move = move.slice(0,-1); //remove last comma
 369                 pgn += move + (i < this.moves.length-1 ? " " : "");
 370             }
 371         }
 372
 373         return pgn + "\n";
 374     }
 375 }
 376
 377 const VariantRules = MarseilleRules;