client/src/variants/Magnetic.js

   1 import { ChessRules, PiPo } from "@/base_rules";
   2
   3 export const VariantRules = class  MagneticRules extends ChessRules
   4 {
   5     static get HasEnpassant() { return false; }
   6
   7     getPotentialMovesFrom([x,y])
   8     {
   9         let standardMoves = super.getPotentialMovesFrom([x,y]);
  10         let moves = [];
  11         standardMoves.forEach(m => {
  12             let newMove_s = this.applyMagneticLaws(m);
  13             if (newMove_s.length == 1)
  14                 moves.push(newMove_s[0]);
  15             else //promotion
  16                 moves = moves.concat(newMove_s);
  17         });
  18         return moves;
  19     }
  20
  21     // Complete a move with magnetic actions
  22     // TODO: job is done multiple times for (normal) promotions.
  23     applyMagneticLaws(move)
  24     {
  25         if (move.appear[0].p == V.KING && move.appear.length==1)
  26             return [move]; //kings are not charged
  27         const aIdx = (move.appear[0].p != V.KING ? 0 : 1); //if castling, rook is charged
  28         const [x,y] = [move.appear[aIdx].x, move.appear[aIdx].y];
  29         const color = this.turn;
  30         const lastRank = (color=="w" ? 0 : 7);
  31         const standardMove = JSON.parse(JSON.stringify(move));
  32         this.play(standardMove);
  33         for (let step of [[-1,0],[1,0],[0,-1],[0,1]])
  34         {
  35             let [i,j] = [x+step[0],y+step[1]];
  36             while (V.OnBoard(i,j))
  37             {
  38                 if (this.board[i][j] != V.EMPTY)
  39                 {
  40                     // Found something. Same color or not?
  41                     if (this.getColor(i,j) != color)
  42                     {
  43                         // Attraction
  44                         if ((Math.abs(i-x)>=2 || Math.abs(j-y)>=2) && this.getPiece(i,j) != V.KING)
  45                         {
  46                             move.vanish.push(
  47                                 new PiPo({
  48                                     p:this.getPiece(i,j),
  49                                     c:this.getColor(i,j),
  50                                     x:i,
  51                                     y:j
  52                                 })
  53                             );
  54                             move.appear.push(
  55                                 new PiPo({
  56                                     p:this.getPiece(i,j),
  57                                     c:this.getColor(i,j),
  58                                     x:x+step[0],
  59                                     y:y+step[1]
  60                                 })
  61                             );
  62                         }
  63                     }
  64                     else
  65                     {
  66                         // Repulsion
  67                         if (this.getPiece(i,j) != V.KING)
  68                         {
  69                             // Push it until we meet an obstacle or edge of the board
  70                             let [ii,jj] = [i+step[0],j+step[1]];
  71                             while (V.OnBoard(ii,jj))
  72                             {
  73                                 if (this.board[ii][jj] != V.EMPTY)
  74                                     break;
  75                                 ii += step[0];
  76                                 jj += step[1];
  77                             }
  78                             ii -= step[0];
  79                             jj -= step[1];
  80                             if (Math.abs(ii-i)>=1 || Math.abs(jj-j)>=1)
  81                             {
  82                                 move.vanish.push(
  83                                     new PiPo({
  84                                         p:this.getPiece(i,j),
  85                                         c:this.getColor(i,j),
  86                                         x:i,
  87                                         y:j
  88                                     })
  89                                 );
  90                                 move.appear.push(
  91                                     new PiPo({
  92                                         p:this.getPiece(i,j),
  93                                         c:this.getColor(i,j),
  94                                         x:ii,
  95                                         y:jj
  96                                     })
  97                                 );
  98                             }
  99                         }
 100                     }
 101                     break;
 102                 }
 103                 i += step[0];
 104                 j += step[1];
 105             }
 106         }
 107         this.undo(standardMove);
 108         let moves = [];
 109         // Scan move for pawn (max 1) on 8th rank
 110         for (let i=1; i<move.appear.length; i++)
 111         {
 112             if (move.appear[i].p==V.PAWN && move.appear[i].c==color
 113                 && move.appear[i].x==lastRank)
 114             {
 115                 move.appear[i].p = V.ROOK;
 116                 moves.push(move);
 117                 for (let piece of [V.KNIGHT, V.BISHOP, V.QUEEN])
 118                 {
 119                     let cmove = JSON.parse(JSON.stringify(move));
 120                     cmove.appear[i].p = piece;
 121                     moves.push(cmove);
 122                 }
 123                 // Swap appear[i] and appear[0] for moves presentation (TODO: this is awkward)
 124                 moves.forEach(m => {
 125                     let tmp = m.appear[0];
 126                     m.appear[0] = m.appear[i];
 127                     m.appear[i] = tmp;
 128                 });
 129                 break;
 130             }
 131         }
 132         if (moves.length == 0) //no pawn on 8th rank
 133             moves.push(move);
 134         return moves;
 135     }
 136
 137     atLeastOneMove()
 138     {
 139         if (this.kingPos[this.turn][0] < 0)
 140             return false;
 141         return true; //TODO: is it right?
 142     }
 143
 144     underCheck(color)
 145     {
 146         return false; //there is no check
 147     }
 148
 149     getCheckSquares(move)
 150     {
 151         return [];
 152     }
 153
 154     updateVariables(move)
 155     {
 156         super.updateVariables(move);
 157         const c = move.vanish[0].c;
 158         if (move.vanish.length >= 2 && move.vanish[1].p == V.KING)
 159         {
 160             // We took opponent king !
 161             const oppCol = V.GetOppCol(c);
 162             this.kingPos[oppCol] = [-1,-1];
 163             this.castleFlags[oppCol] = [false,false];
 164         }
 165         // Did we magnetically move our (init) rooks or opponents' ones ?
 166         const firstRank = (c == "w" ? 7 : 0);
 167         const oppFirstRank = 7 - firstRank;
 168         const oppCol = V.GetOppCol(c);
 169         move.vanish.forEach(psq => {
 170             if (psq.x == firstRank && this.INIT_COL_ROOK[c].includes(psq.y))
 171                 this.castleFlags[c][psq.y==this.INIT_COL_ROOK[c][0] ? 0 : 1] = false;
 172             else if (psq.x == oppFirstRank && this.INIT_COL_ROOK[oppCol].includes(psq.y))
 173                 this.castleFlags[oppCol][psq.y==this.INIT_COL_ROOK[oppCol][0] ? 0 : 1] = false;
 174         });
 175     }
 176
 177     unupdateVariables(move)
 178     {
 179         super.unupdateVariables(move);
 180         const c = move.vanish[0].c;
 181         const oppCol = V.GetOppCol(c);
 182         if (this.kingPos[oppCol][0] < 0)
 183         {
 184             // Last move took opponent's king
 185             for (let psq of move.vanish)
 186             {
 187                 if (psq.p == 'k')
 188                 {
 189                     this.kingPos[oppCol] = [psq.x, psq.y];
 190                     break;
 191                 }
 192             }
 193         }
 194     }
 195
 196     getCurrentScore()
 197     {
 198         const color = this.turn;
 199         const kp = this.kingPos[color];
 200         if (kp[0] < 0) //king disappeared
 201             return (color == "w" ? "0-1" : "1-0");
 202     if (this.atLeastOneMove()) // game not over
 203       return "*";
 204     return "1/2"; //no moves but kings still there
 205     }
 206
 207     static get THRESHOLD_MATE()
 208     {
 209         return 500; //checkmates evals may be slightly below 1000
 210     }
 211 }