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 }