client/src/variants/Allmate2.js

   1 import { ChessRules, PiPo, Move } from "@/base_rules";
   2
   3 export class Allmate2Rules extends ChessRules {
   4   static get HasEnpassant() {
   5     return false;
   6   }
   7
   8   getCheckSquares() {
   9     // No notion of check
  10     return [];
  11   }
  12
  13   static GenRandInitFen(randomness) {
  14     return ChessRules.GenRandInitFen(randomness).slice(0, -2);
  15   }
  16
  17   getPotentialMovesFrom([x, y]) {
  18     let moves = super.getPotentialMovesFrom([x, y]);
  19     // Remove standard captures (without removing castling):
  20     moves = moves.filter(m => {
  21       return m.vanish.length == 1 || m.appear.length == 2;
  22     });
  23
  24     // Augment moves with "mate-captures":
  25     // TODO: this is coded in a highly inefficient way...
  26     const color = this.turn;
  27     const oppCol = V.GetOppCol(this.turn);
  28     moves.forEach(m => {
  29       this.play(m);
  30
  31       // 1) What is attacked?
  32       let attacked = {};
  33       for (let i=0; i<V.size.x; i++) {
  34         for (let j=0; j<V.size.y; j++) {
  35           if (this.getColor(i,j) == oppCol && this.isAttacked([i,j], color))
  36             attacked[i+"_"+j] = [i,j];
  37         }
  38       }
  39
  40       // 2) Among attacked pieces, which cannot escape capture?
  41       // --> without (normal-)capturing: difference with Allmate1 variant
  42       // Avoid "oppMoves = this.getAllValidMoves();" => infinite recursion
  43       outerLoop: for (let i=0; i<V.size.x; i++) {
  44         for (let j=0; j<V.size.y; j++) {
  45           if (this.getColor(i,j) == oppCol) {
  46             let oppMoves = [];
  47             switch (this.getPiece(i, j)) {
  48               case V.PAWN:
  49                 oppMoves = this.getPotentialPawnMoves([i, j]);
  50                 break;
  51               case V.ROOK:
  52                 oppMoves = this.getPotentialRookMoves([i, j]);
  53                 break;
  54               case V.KNIGHT:
  55                 oppMoves = this.getPotentialKnightMoves([i, j]);
  56                 break;
  57               case V.BISHOP:
  58                 oppMoves = this.getPotentialBishopMoves([i, j]);
  59                 break;
  60               case V.QUEEN:
  61                 oppMoves = this.getPotentialQueenMoves([i, j]);
  62                 break;
  63               case V.KING:
  64                 // Do not allow castling to escape from check
  65                 oppMoves = super.getSlideNJumpMoves(
  66                   [x, y],
  67                   V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
  68                   "oneStep"
  69                 );
  70                 break;
  71             }
  72             for (let om of oppMoves) {
  73               if (om.vanish.length == 2 && om.appear.length == 1)
  74                 // Skip captures: forbidden in this mode
  75                 continue;
  76               V.PlayOnBoard(this.board, om);
  77               Object.values(attacked).forEach(sq => {
  78                 const origSq = [sq[0], sq[1]];
  79                 if (om.start.x == sq[0] && om.start.y == sq[1])
  80                   // Piece moved:
  81                   sq = [om.appear[0].x, om.appear[0].y];
  82                 if (!this.isAttacked(sq, color))
  83                   delete attacked[origSq[0]+"_"+origSq[1]];
  84               });
  85               V.UndoOnBoard(this.board, om);
  86               if (Object.keys(attacked).length == 0)
  87                 // No need to explore more moves
  88                 break outerLoop;
  89             }
  90           }
  91         }
  92       }
  93
  94       // 3) Add mate-captures:
  95       Object.values(attacked).forEach(sq => {
  96         m.vanish.push(new PiPo({
  97           x: sq[0],
  98           y: sq[1],
  99           c: oppCol,
 100           p: this.getPiece(sq[0], sq[1])
 101         }));
 102       });
 103
 104       this.undo(m);
 105     });
 106
 107     return moves;
 108   }
 109
 110   // No "under check" conditions in castling
 111   getCastleMoves(sq) {
 112     return super.getCastleMoves(sq, "castleInCheck");
 113   }
 114
 115   // TODO: allow pieces to "commit suicide"? (Currently yes except king)
 116   filterValid(moves) {
 117     // Remove moves which let the king mate-captured:
 118     if (moves.length == 0) return [];
 119     const color = this.turn;
 120     const oppCol = V.GetOppCol(color);
 121     return moves.filter(m => {
 122       let res = true;
 123       this.play(m);
 124       if (this.underCheck(color)) {
 125         res = false;
 126         const attacked = this.kingPos[color];
 127         // Try to find a move to escape check
 128         // TODO: very inefficient method.
 129         outerLoop: for (let i=0; i<V.size.x; i++) {
 130           for (let j=0; j<V.size.y; j++) {
 131             if (this.getColor(i,j) == color) {
 132               let emoves = [];
 133               // Artficial turn change to "play twice":
 134               this.turn = color;
 135               switch (this.getPiece(i, j)) {
 136                 case V.PAWN:
 137                   emoves = this.getPotentialPawnMoves([i, j]);
 138                   break;
 139                 case V.ROOK:
 140                   emoves = this.getPotentialRookMoves([i, j]);
 141                   break;
 142                 case V.KNIGHT:
 143                   emoves = this.getPotentialKnightMoves([i, j]);
 144                   break;
 145                 case V.BISHOP:
 146                   emoves = this.getPotentialBishopMoves([i, j]);
 147                   break;
 148                 case V.QUEEN:
 149                   emoves = this.getPotentialQueenMoves([i, j]);
 150                   break;
 151                 case V.KING:
 152                   emoves = this.getPotentialKingMoves([i, j]);
 153                   break;
 154               }
 155               this.turn = oppCol;
 156               for (let em of emoves) {
 157                 V.PlayOnBoard(this.board, em);
 158                 let sq = attacked;
 159                 if (em.start.x == attacked[0] && em.start.y == attacked[1])
 160                   // King moved:
 161                   sq = [em.appear[0].x, em.appear[0].y];
 162                 if (!this.isAttacked(sq, oppCol))
 163                   res = true;
 164                 V.UndoOnBoard(this.board, em);
 165                 if (res)
 166                   // No need to explore more moves
 167                   break outerLoop;
 168               }
 169             }
 170           }
 171         }
 172       }
 173       this.undo(m);
 174       return res;
 175     });
 176   }
 177
 178   postPlay(move) {
 179     super.postPlay(move);
 180     if (move.vanish.length >= 2 && move.appear.length == 1) {
 181       for (let i = 1; i<move.vanish.length; i++) {
 182         const v = move.vanish[i];
 183         // Did opponent king disappeared?
 184         if (v.p == V.KING)
 185           this.kingPos[this.turn] = [-1, -1];
 186         // Or maybe a rook?
 187         else if (v.p == V.ROOK) {
 188           if (v.y < this.INIT_COL_KING[v.c])
 189             this.castleFlags[v.c][0] = 8;
 190           else
 191             // v.y > this.INIT_COL_KING[v.c]
 192             this.castleFlags[v.c][1] = 8;
 193         }
 194       }
 195     }
 196   }
 197
 198   preUndo(move) {
 199     super.preUndo(move);
 200     const oppCol = this.turn;
 201     if (move.vanish.length >= 2 && move.appear.length == 1) {
 202       // Did opponent king disappeared?
 203       const psq = move.vanish.find(v => v.p == V.KING && v.c == oppCol)
 204       if (psq)
 205         this.kingPos[psq.c] = [psq.x, psq.y];
 206     }
 207   }
 208
 209   getCurrentScore() {
 210     const color = this.turn;
 211     const kp = this.kingPos[color];
 212     if (kp[0] < 0)
 213       // King disappeared
 214       return color == "w" ? "0-1" : "1-0";
 215     if (this.atLeastOneMove()) return "*";
 216     // Kings still there, no moves:
 217     return "1/2";
 218   }
 219
 220   static get SEARCH_DEPTH() {
 221     return 1;
 222   }
 223
 224   getNotation(move) {
 225     let notation = super.getNotation(move);
 226     // Add a capture mark (not describing what is captured...):
 227     if (move.vanish.length > 1 && move.appear.length == 1) {
 228       if (!!(notation.match(/^[a-h]x/)))
 229         // Pawn capture: remove initial "b" in bxc4 for example
 230         notation = notation.substr(1);
 231       notation = notation.replace("x","") + "X";
 232     }
 233     return notation;
 234   }
 235 };