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 //      console.log("play " + this.getNotation(move));
 152 //      console.log(this.turn + " "+ this.subTurn);
 153         if (!!ingame)
 154             move.notation = [this.getNotation(move), this.getLongNotation(move)];
 155         move.flags = JSON.stringify(this.aggregateFlags());
 156         let lastEpsq = this.epSquares[this.epSquares.length-1];
 157         const epSq = this.getEpSquare(move);
 158         if (lastEpsq.length == 1)
 159             lastEpsq.push(epSq);
 160         else
 161         {
 162             // New turn
 163             let newEpsqs = [epSq];
 164             if (this.startAtFirstMove && this.moves.length == 0)
 165                 newEpsqs.push(undefined); //at first move, to force length==2 (TODO)
 166             this.epSquares.push(newEpsqs);
 167         }
 168         V.PlayOnBoard(this.board, move);
 169         if (this.startAtFirstMove && this.moves.length == 0)
 170             this.turn = "b";
 171         // Does this move give check on subturn 1? If yes, skip subturn 2
 172         else if (this.subTurn==1 && this.underCheck(this.getOppCol(this.turn)))
 173         {
 174             this.epSquares[this.epSquares.length-1].push(undefined);
 175             this.turn = this.getOppCol(this.turn);
 176             move.checkOnSubturn1 = true;
 177         }
 178         else
 179         {
 180             if (this.subTurn == 2)
 181                 this.turn = this.getOppCol(this.turn);
 182             this.subTurn = 3 - this.subTurn;
 183         }
 184         this.moves.push(move);
 185         this.updateVariables(move);
 186         if (!!ingame)
 187             move.hash = hex_md5(this.getFen());
 188         //console.log(move.checkOnSubturn1 + " " +this.turn + " "+ this.subTurn);
 189     }
 190
 191     undo(move)
 192     {
 193         this.disaggregateFlags(JSON.parse(move.flags));
 194         let lastEpsq = this.epSquares[this.epSquares.length-1];
 195         if (lastEpsq.length == 2)
 196         {
 197             if (!!move.checkOnSubturn1 ||
 198                 (this.startAtFirstMove && this.moves.length == 1))
 199             {
 200                 this.epSquares.pop(); //remove real + artificial e.p. squares
 201             }
 202             else
 203                 lastEpsq.pop();
 204         }
 205         else
 206             this.epSquares.pop();
 207         V.UndoOnBoard(this.board, move);
 208         if (this.startAtFirstMove && this.moves.length == 1)
 209             this.turn = "w";
 210         else if (move.checkOnSubturn1)
 211         {
 212             this.turn = this.getOppCol(this.turn);
 213             this.subTurn = 1;
 214         }
 215         else
 216         {
 217             if (this.subTurn == 1)
 218                 this.turn = this.getOppCol(this.turn);
 219             this.subTurn = 3 - this.subTurn;
 220         }
 221         this.moves.pop();
 222         this.unupdateVariables(move);
 223 //      console.log("UNDO " + this.getNotation(move));
 224 //      console.log(this.turn + " "+ this.subTurn);
 225     }
 226
 227     // NOTE:  GenRandInitFen() is OK,
 228     // since at first move turn indicator is just "w"
 229
 230     // No alpha-beta here, just adapted min-max at depth 2(+1)
 231     getComputerMove()
 232     {
 233         if (this.subTurn == 2)
 234             return null; //TODO: imperfect interface setup
 235
 236         const maxeval = V.INFINITY;
 237         const color = this.turn;
 238         const oppCol = this.getOppCol(this.turn);
 239
 240         // Search best (half) move for opponent turn
 241         const getBestMoveEval = () => {
 242             let moves = this.getAllValidMoves();
 243             if (moves.length == 0)
 244             {
 245                 const score = this.checkGameEnd();
 246                 if (score == "1/2")
 247                     return 0;
 248                 return maxeval * (score == "1-0" ? 1 : -1);
 249             }
 250             let res = (oppCol == "w" ? -maxeval : maxeval);
 251             for (let m of moves)
 252             {
 253                 this.play(m);
 254                 this.turn = color; //very artificial...
 255                 if (!this.atLeastOneMove())
 256                 {
 257                     const score = this.checkGameEnd();
 258                     if (score == "1/2")
 259                         res = (oppCol == "w" ? Math.max(res, 0) : Math.min(res, 0));
 260                     else
 261                     {
 262                         // Found a mate
 263                         this.turn = oppCol;
 264                         this.undo(m);
 265                         return maxeval * (score == "1-0" ? 1 : -1);
 266                     }
 267                 }
 268                 const evalPos = this.evalPosition();
 269                 res = (oppCol == "w" ? Math.max(res, evalPos) : Math.min(res, evalPos));
 270                 this.turn = oppCol;
 271                 this.undo(m);
 272             }
 273             return res;
 274         };
 275
 276         let moves11 = this.getAllValidMoves();
 277         let doubleMoves = [];
 278         // Rank moves using a min-max at depth 2
 279         for (let i=0; i<moves11.length; i++)
 280         {
 281             moves11[i].eval = (color=="w" ? -1 : 1) * maxeval;
 282             this.play(moves11[i]);
 283             if (this.turn != color)
 284             {
 285                 // We gave check with last move: search the best opponent move
 286                 doubleMoves.push({moves:[moves11[i]], eval:getBestMoveEval()});
 287             }
 288             else
 289             {
 290                 let moves12 = this.getAllValidMoves();
 291                 for (let j=0; j<moves12.length; j++)
 292                 {
 293                     this.play(moves12[j]);
 294                     doubleMoves.push({
 295                         moves:[moves11[i],moves12[j]],
 296                         eval:getBestMoveEval()});
 297                     this.undo(moves12[j]);
 298                 }
 299             }
 300             this.undo(moves11[i]);
 301         }
 302
 303         doubleMoves.sort( (a,b) => {
 304             return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 305         let candidates = [0]; //indices of candidates moves
 306         for (let i=1;
 307             i<doubleMoves.length && doubleMoves[i].eval == doubleMoves[0].eval;
 308             i++)
 309         {
 310             candidates.push(i);
 311         }
 312
 313         const selected = doubleMoves[_.sample(candidates, 1)].moves;
 314         if (selected.length == 1)
 315             return selected[0];
 316         return selected;
 317     }
 318 }
 319
 320 const VariantRules = MarseilleRules;