public/javascripts/variants/Losers.js

   1 class LosersRules extends ChessRules
   2 {
   3     static get HasFlags() { return false; }
   4
   5     getPotentialPawnMoves([x,y])
   6     {
   7         let moves = super.getPotentialPawnMoves([x,y]);
   8
   9         // Complete with promotion(s) into king, if possible
  10         const color = this.turn;
  11         const shift = (color == "w" ? -1 : 1);
  12         const lastRank = (color == "w" ? 0 : V.size.x-1);
  13         if (x+shift == lastRank)
  14         {
  15             // Normal move
  16             if (this.board[x+shift][y] == V.EMPTY)
  17                 moves.push(this.getBasicMove([x,y], [x+shift,y], {c:color,p:V.KING}));
  18             // Captures
  19             if (y>0 && this.canTake([x,y], [x+shift,y-1])
  20                 && this.board[x+shift][y-1] != V.EMPTY)
  21             {
  22                 moves.push(this.getBasicMove([x,y], [x+shift,y-1], {c:color,p:V.KING}));
  23             }
  24             if (y<V.size.y-1 && this.canTake([x,y], [x+shift,y+1])
  25                 && this.board[x+shift][y+1] != V.EMPTY)
  26             {
  27                 moves.push(this.getBasicMove([x,y], [x+shift,y+1], {c:color,p:V.KING}));
  28             }
  29         }
  30
  31         return moves;
  32     }
  33
  34     getPotentialKingMoves(sq)
  35     {
  36         // No castle:
  37         return this.getSlideNJumpMoves(sq,
  38             V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep");
  39     }
  40
  41     // Stop at the first capture found (if any)
  42     atLeastOneCapture()
  43     {
  44         const color = this.turn;
  45         const oppCol = V.GetOppCol(color);
  46         for (let i=0; i<V.size.x; i++)
  47         {
  48             for (let j=0; j<V.size.y; j++)
  49             {
  50                 if (this.board[i][j] != V.EMPTY && this.getColor(i,j) != oppCol)
  51                 {
  52                     const moves = this.getPotentialMovesFrom([i,j]);
  53                     if (moves.length > 0)
  54                     {
  55                         for (let k=0; k<moves.length; k++)
  56                         {
  57                             if (moves[k].vanish.length==2 && this.filterValid([moves[k]]).length > 0)
  58                                 return true;
  59                         }
  60                     }
  61                 }
  62             }
  63         }
  64         return false;
  65     }
  66
  67     // Trim all non-capturing moves
  68     static KeepCaptures(moves)
  69     {
  70         return moves.filter(m => { return m.vanish.length == 2; });
  71     }
  72
  73     getPossibleMovesFrom(sq)
  74     {
  75         let moves = this.filterValid( this.getPotentialMovesFrom(sq) );
  76         // This is called from interface: we need to know if a capture is possible
  77         if (this.atLeastOneCapture())
  78             moves = V.KeepCaptures(moves);
  79         return moves;
  80     }
  81
  82     getAllValidMoves()
  83     {
  84         let moves = super.getAllValidMoves();
  85         if (moves.some(m => { return m.vanish.length == 2; }))
  86             moves = V.KeepCaptures(moves);
  87         return moves;
  88     }
  89
  90     underCheck(color)
  91     {
  92         return false; //No notion of check
  93     }
  94
  95     getCheckSquares(move)
  96     {
  97         return [];
  98     }
  99
 100     // No variables update because no royal king + no castling
 101     updateVariables(move) { }
 102     unupdateVariables(move) { }
 103
 104     checkGameEnd()
 105     {
 106         // No valid move: you win!
 107         return this.turn == "w" ? "1-0" : "0-1";
 108     }
 109
 110     static get VALUES()
 111     {
 112         // Experimental...
 113         return {
 114             'p': 1,
 115             'r': 7,
 116             'n': 3,
 117             'b': 3,
 118             'q': 5,
 119             'k': 5
 120         };
 121     }
 122
 123     static get SEARCH_DEPTH() { return 4; }
 124
 125     evalPosition()
 126     {
 127         return - super.evalPosition(); //better with less material
 128     }
 129
 130     static GenRandInitFen()
 131     {
 132         let pieces = { "w": new Array(8), "b": new Array(8) };
 133         // Shuffle pieces on first and last rank
 134         for (let c of ["w","b"])
 135         {
 136             let positions = _.range(8);
 137
 138             // Get random squares for bishops
 139             let randIndex = 2 * _.random(3);
 140             let bishop1Pos = positions[randIndex];
 141             // The second bishop must be on a square of different color
 142             let randIndex_tmp = 2 * _.random(3) + 1;
 143             let bishop2Pos = positions[randIndex_tmp];
 144             // Remove chosen squares
 145             positions.splice(Math.max(randIndex,randIndex_tmp), 1);
 146             positions.splice(Math.min(randIndex,randIndex_tmp), 1);
 147
 148             // Get random squares for knights
 149             randIndex = _.random(5);
 150             let knight1Pos = positions[randIndex];
 151             positions.splice(randIndex, 1);
 152             randIndex = _.random(4);
 153             let knight2Pos = positions[randIndex];
 154             positions.splice(randIndex, 1);
 155
 156             // Get random square for queen
 157             randIndex = _.random(3);
 158             let queenPos = positions[randIndex];
 159             positions.splice(randIndex, 1);
 160
 161             // Random square for king (no castle)
 162             randIndex = _.random(2);
 163             let kingPos = positions[randIndex];
 164             positions.splice(randIndex, 1);
 165
 166             // Rooks positions are now fixed
 167             let rook1Pos = positions[0];
 168             let rook2Pos = positions[1];
 169
 170             // Finally put the shuffled pieces in the board array
 171             pieces[c][rook1Pos] = 'r';
 172             pieces[c][knight1Pos] = 'n';
 173             pieces[c][bishop1Pos] = 'b';
 174             pieces[c][queenPos] = 'q';
 175             pieces[c][kingPos] = 'k';
 176             pieces[c][bishop2Pos] = 'b';
 177             pieces[c][knight2Pos] = 'n';
 178             pieces[c][rook2Pos] = 'r';
 179         }
 180         return pieces["b"].join("") +
 181             "/pppppppp/8/8/8/8/PPPPPPPP/" +
 182             pieces["w"].join("").toUpperCase() +
 183             " w -"; //no en-passant
 184     }
 185 }