client/client_OLD/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         return this.turn + this.subTurn;
  23     }
  24
  25     // There may be 2 enPassant squares (if 2 pawns jump 2 squares in same turn)
  26     getEnpassantFen()
  27     {
  28         const L = this.epSquares.length;
  29         if (this.epSquares[L-1].every(epsq => epsq === undefined))
  30             return "-"; //no en-passant
  31         let res = "";
  32         this.epSquares[L-1].forEach(epsq => {
  33             if (!!epsq)
  34                 res += V.CoordsToSquare(epsq) + ",";
  35         });
  36         return res.slice(0,-1); //remove last comma
  37     }
  38
  39     setOtherVariables(fen)
  40     {
  41         const parsedFen = V.ParseFen(fen);
  42         this.setFlags(parsedFen.flags);
  43         if (parsedFen.enpassant == "-")
  44             this.epSquares = [ [undefined] ];
  45         else
  46         {
  47             let res = [];
  48             const squares = parsedFen.enpassant.split(",");
  49             for (let sq of squares)
  50                 res.push(V.SquareToCoords(sq));
  51             this.epSquares = [ res ];
  52         }
  53         this.scanKingsRooks(fen);
  54         // Extract subTurn from turn indicator: "w" (first move), or
  55         // "w1" or "w2" white subturn 1 or 2, and same for black
  56         const fullTurn = V.ParseFen(fen).turn;
  57         this.turn = fullTurn[0];
  58         this.subTurn = (fullTurn[1] || 0); //"w0" = special code for first move in game
  59     }
  60
  61     getPotentialPawnMoves([x,y])
  62     {
  63         const color = this.turn;
  64         let moves = [];
  65         const [sizeX,sizeY] = [V.size.x,V.size.y];
  66         const shiftX = (color == "w" ? -1 : 1);
  67         const firstRank = (color == 'w' ? sizeX-1 : 0);
  68         const startRank = (color == "w" ? sizeX-2 : 1);
  69         const lastRank = (color == "w" ? 0 : sizeX-1);
  70         const finalPieces = x + shiftX == lastRank
  71             ? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN]
  72             : [V.PAWN];
  73
  74         // One square forward
  75         if (this.board[x+shiftX][y] == V.EMPTY)
  76         {
  77             for (let piece of finalPieces)
  78             {
  79                 moves.push(this.getBasicMove([x,y], [x+shiftX,y],
  80                     {c:color,p:piece}));
  81             }
  82             // Next condition because pawns on 1st rank can generally jump
  83             if ([startRank,firstRank].includes(x)
  84                 && this.board[x+2*shiftX][y] == V.EMPTY)
  85             {
  86                 // Two squares jump
  87                 moves.push(this.getBasicMove([x,y], [x+2*shiftX,y]));
  88             }
  89         }
  90         // Captures
  91         for (let shiftY of [-1,1])
  92         {
  93             if (y + shiftY >= 0 && y + shiftY < sizeY
  94                 && this.board[x+shiftX][y+shiftY] != V.EMPTY
  95                 && this.canTake([x,y], [x+shiftX,y+shiftY]))
  96             {
  97                 for (let piece of finalPieces)
  98                 {
  99                     moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
 100                         {c:color,p:piece}));
 101                 }
 102             }
 103         }
 104
 105         // En passant: always OK if subturn 1,
 106         // OK on subturn 2 only if enPassant was played at subturn 1
 107         // (and if there are two e.p. squares available).
 108         const Lep = this.epSquares.length;
 109         const epSquares = this.epSquares[Lep-1]; //always at least one element
 110         let epSqs = [];
 111         epSquares.forEach(sq => {
 112             if (!!sq)
 113                 epSqs.push(sq);
 114         });
 115         if (epSqs.length == 0)
 116             return moves;
 117         const oppCol = V.GetOppCol(color);
 118         for (let sq of epSqs)
 119         {
 120             if (this.subTurn == 1 || (epSqs.length == 2 &&
 121                 // Was this en-passant capture already played at subturn 1 ?
 122                 // (Or maybe the opponent filled the en-passant square with a piece)
 123                 this.board[epSqs[0].x][epSqs[0].y] != V.EMPTY))
 124             {
 125                 if (sq.x == x+shiftX && Math.abs(sq.y - y) == 1
 126                     // Add condition "enemy pawn must be present"
 127                     && this.getPiece(x,sq.y) == V.PAWN && this.getColor(x,sq.y) == oppCol)
 128                 {
 129                     let epMove = this.getBasicMove([x,y], [sq.x,sq.y]);
 130                     epMove.vanish.push({
 131                         x: x,
 132                         y: sq.y,
 133                         p: 'p',
 134                         c: oppCol
 135                     });
 136                     moves.push(epMove);
 137                 }
 138             }
 139         }
 140
 141         return moves;
 142     }
 143
 144     play(move)
 145     {
 146         move.flags = JSON.stringify(this.aggregateFlags());
 147         move.turn = this.turn + this.subturn;
 148         V.PlayOnBoard(this.board, move);
 149         const epSq = this.getEpSquare(move);
 150         if (this.subTurn == 0) //first move in game
 151         {
 152             this.turn = "b";
 153             this.epSquares.push([epSq]);
 154         }
 155         // Does this move give check on subturn 1? If yes, skip subturn 2
 156         else if (this.subTurn==1 && this.underCheck(V.GetOppCol(this.turn)))
 157         {
 158             this.turn = V.GetOppCol(this.turn);
 159             this.epSquares.push([epSq]);
 160             move.checkOnSubturn1 = true;
 161         }
 162         else
 163         {
 164             if (this.subTurn == 2)
 165             {
 166                 this.turn = V.GetOppCol(this.turn);
 167                 let lastEpsq = this.epSquares[this.epSquares.length-1];
 168                 lastEpsq.push(epSq);
 169             }
 170             else
 171                 this.epSquares.push([epSq]);
 172             this.subTurn = 3 - this.subTurn;
 173         }
 174         this.updateVariables(move);
 175     }
 176
 177     undo(move)
 178     {
 179         this.disaggregateFlags(JSON.parse(move.flags));
 180         V.UndoOnBoard(this.board, move);
 181         if (move.turn[1] == '0' || move.checkOnSubturn1 || this.subTurn == 2)
 182             this.epSquares.pop();
 183         else //this.subTurn == 1
 184         {
 185             let lastEpsq = this.epSquares[this.epSquares.length-1];
 186             lastEpsq.pop();
 187         }
 188         this.turn = move.turn[0];
 189         this.subTurn = parseInt(move.turn[1]);
 190         this.unupdateVariables(move);
 191     }
 192
 193     // NOTE:  GenRandInitFen() is OK,
 194     // since at first move turn indicator is just "w"
 195
 196     static get VALUES()
 197     {
 198         return {
 199             'p': 1,
 200             'r': 5,
 201             'n': 3,
 202             'b': 3,
 203             'q': 7, //slightly less than in orthodox game
 204             'k': 1000
 205         };
 206     }
 207
 208     // No alpha-beta here, just adapted min-max at depth 2(+1)
 209     getComputerMove()
 210     {
 211         if (this.subTurn == 2)
 212             return null; //TODO: imperfect interface setup
 213
 214         const maxeval = V.INFINITY;
 215         const color = this.turn;
 216         const oppCol = V.GetOppCol(this.turn);
 217
 218         // Search best (half) move for opponent turn
 219         const getBestMoveEval = () => {
 220             const turnBefore = this.turn + this.subTurn;
 221             let moves = this.getAllValidMoves();
 222             if (moves.length == 0)
 223             {
 224                 const score = this.checkGameEnd();
 225                 if (score == "1/2")
 226                     return 0;
 227                 return maxeval * (score == "1-0" ? 1 : -1);
 228             }
 229             let res = (oppCol == "w" ? -maxeval : maxeval);
 230             for (let m of moves)
 231             {
 232                 this.play(m);
 233                 // Now turn is oppCol,2 if m doesn't give check
 234                 // Otherwise it's color,1. In both cases the next test makes sense
 235                 if (!this.atLeastOneMove())
 236                 {
 237                     const score = this.checkGameEnd();
 238                     if (score == "1/2")
 239                         res = (oppCol == "w" ? Math.max(res, 0) : Math.min(res, 0));
 240                     else
 241                     {
 242                         // Found a mate
 243                         this.undo(m);
 244                         return maxeval * (score == "1-0" ? 1 : -1);
 245                     }
 246                 }
 247                 const evalPos = this.evalPosition();
 248                 res = (oppCol == "w" ? Math.max(res, evalPos) : Math.min(res, evalPos));
 249                 this.undo(m);
 250             }
 251             return res;
 252         };
 253
 254         let moves11 = this.getAllValidMoves();
 255         let doubleMoves = [];
 256         // Rank moves using a min-max at depth 2
 257         for (let i=0; i<moves11.length; i++)
 258         {
 259             this.play(moves11[i]);
 260             if (this.turn != color)
 261             {
 262                 // We gave check with last move: search the best opponent move
 263                 doubleMoves.push({moves:[moves11[i]], eval:getBestMoveEval()});
 264             }
 265             else
 266             {
 267                 let moves12 = this.getAllValidMoves();
 268                 for (let j=0; j<moves12.length; j++)
 269                 {
 270                     this.play(moves12[j]);
 271                     doubleMoves.push({
 272                         moves:[moves11[i],moves12[j]],
 273                         eval:getBestMoveEval()});
 274                     this.undo(moves12[j]);
 275                 }
 276             }
 277             this.undo(moves11[i]);
 278         }
 279
 280         doubleMoves.sort( (a,b) => {
 281             return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 282         let candidates = [0]; //indices of candidates moves
 283         for (let i=1;
 284             i<doubleMoves.length && doubleMoves[i].eval == doubleMoves[0].eval;
 285             i++)
 286         {
 287             candidates.push(i);
 288         }
 289
 290         const selected = doubleMoves[_.sample(candidates, 1)].moves;
 291         if (selected.length == 1)
 292             return selected[0];
 293         return selected;
 294     }
 295 }