client/src/variants/Allmate.js

   1 import { ChessRules, PiPo, Move } from "@/base_rules";
   2
   3 export class AllmateRules extends ChessRules {
   4
   5   static get HasEnpassant() {
   6     return false;
   7   }
   8
   9   getCheckSquares() {
  10     // No notion of check
  11     return [];
  12   }
  13
  14   static GenRandInitFen(options) {
  15     return ChessRules.GenRandInitFen(options).slice(0, -2);
  16   }
  17
  18   getPotentialMovesFrom([x, y]) {
  19     let moves = super.getPotentialMovesFrom([x, y]);
  20     // Remove standard captures (without removing castling):
  21     moves = moves.filter(m => {
  22       return m.vanish.length == 1 || m.appear.length == 2;
  23     });
  24
  25     // Augment moves with "mate-captures":
  26     // TODO: this is coded in a highly inefficient way...
  27     const color = this.turn;
  28     const oppCol = V.GetOppCol(this.turn);
  29     moves.forEach(m => {
  30       this.play(m);
  31       let allAttacks = [];
  32
  33       // While something has been captured:
  34       // remove it, and keep looking for captures
  35       outerLoop: while (true) {
  36
  37         // 1) What is attacked?
  38         let attacked = {};
  39         for (let i=0; i<V.size.x; i++) {
  40           for (let j=0; j<V.size.y; j++) {
  41             if (this.getColor(i,j) == oppCol && this.isAttacked([i,j], color))
  42               attacked[i+"_"+j] = [i,j];
  43           }
  44         }
  45         if (Object.keys(attacked).length == 0) break outerLoop;
  46
  47         // 2) Among attacked pieces, which cannot escape capture?
  48         // Avoid "oppMoves = this.getAllValidMoves();" => infinite recursion
  49         for (let i=0; i<V.size.x; i++) {
  50           for (let j=0; j<V.size.y; j++) {
  51             if (this.getColor(i,j) == oppCol) {
  52               let oppMoves = [];
  53               switch (this.getPiece(i, j)) {
  54                 case V.PAWN:
  55                   oppMoves = this.getPotentialPawnMoves([i, j]);
  56                   break;
  57                 case V.ROOK:
  58                   oppMoves = this.getPotentialRookMoves([i, j]);
  59                   break;
  60                 case V.KNIGHT:
  61                   oppMoves = this.getPotentialKnightMoves([i, j]);
  62                   break;
  63                 case V.BISHOP:
  64                   oppMoves = this.getPotentialBishopMoves([i, j]);
  65                   break;
  66                 case V.QUEEN:
  67                   oppMoves = this.getPotentialQueenMoves([i, j]);
  68                   break;
  69                 case V.KING:
  70                   // Do not allow castling to escape from check
  71                   oppMoves = super.getSlideNJumpMoves(
  72                     [i, j], V.steps[V.ROOK].concat(V.steps[V.BISHOP]), 1);
  73                   break;
  74               }
  75               for (let om of oppMoves) {
  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 and remove pieces from board:
  95         Object.keys(attacked).forEach(k => {
  96           allAttacks.push({
  97             sq: attacked[k],
  98             p: this.getPiece(attacked[k][0], attacked[k][1])
  99           });
 100           this.board[attacked[k][0]][attacked[k][1]] = V.EMPTY;
 101         });
 102       }
 103
 104       // Put removed pieces back on board:
 105       allAttacks.forEach(v => {
 106         this.board[v.sq[0]][v.sq[1]] = oppCol + v.p;
 107       });
 108       this.undo(m);
 109       allAttacks.forEach(v => {
 110         m.vanish.push(
 111           new PiPo({
 112             x: v.sq[0],
 113             y: v.sq[1],
 114             c: oppCol,
 115             p: v.p
 116           })
 117         );
 118       });
 119     });
 120
 121     return moves;
 122   }
 123
 124   // No "under check" conditions in castling
 125   getCastleMoves(sq) {
 126     return super.getCastleMoves(sq, null, "castleInCheck");
 127   }
 128
 129   // TODO: allow pieces to "commit suicide"? (Currently yes except king)
 130   filterValid(moves) {
 131     // Remove moves which let the king mate-captured:
 132     if (moves.length == 0) return [];
 133     const color = this.turn;
 134     const oppCol = V.GetOppCol(color);
 135     return moves.filter(m => {
 136       let res = true;
 137       this.play(m);
 138       if (this.underCheck(color)) {
 139         res = false;
 140         const attacked = this.kingPos[color];
 141         // Try to find a move to escape check
 142         // TODO: very inefficient method.
 143         outerLoop: for (let i=0; i<V.size.x; i++) {
 144           for (let j=0; j<V.size.y; j++) {
 145             if (this.getColor(i,j) == color) {
 146               let emoves = [];
 147               // Artficial turn change to "play twice":
 148               this.turn = color;
 149               switch (this.getPiece(i, j)) {
 150                 case V.PAWN:
 151                   emoves = this.getPotentialPawnMoves([i, j]);
 152                   break;
 153                 case V.ROOK:
 154                   emoves = this.getPotentialRookMoves([i, j]);
 155                   break;
 156                 case V.KNIGHT:
 157                   emoves = this.getPotentialKnightMoves([i, j]);
 158                   break;
 159                 case V.BISHOP:
 160                   emoves = this.getPotentialBishopMoves([i, j]);
 161                   break;
 162                 case V.QUEEN:
 163                   emoves = this.getPotentialQueenMoves([i, j]);
 164                   break;
 165                 case V.KING:
 166                   emoves = this.getPotentialKingMoves([i, j]);
 167                   break;
 168               }
 169               this.turn = oppCol;
 170               for (let em of emoves) {
 171                 V.PlayOnBoard(this.board, em);
 172                 let sq = attacked;
 173                 if (em.start.x == attacked[0] && em.start.y == attacked[1])
 174                   // King moved:
 175                   sq = [em.appear[0].x, em.appear[0].y];
 176                 if (!this.isAttacked(sq, oppCol))
 177                   res = true;
 178                 V.UndoOnBoard(this.board, em);
 179                 if (res)
 180                   // No need to explore more moves
 181                   break outerLoop;
 182               }
 183             }
 184           }
 185         }
 186       }
 187       this.undo(m);
 188       return res;
 189     });
 190   }
 191
 192   postPlay(move) {
 193     super.postPlay(move);
 194     if (move.vanish.length >= 2 && move.appear.length == 1) {
 195       for (let i = 1; i<move.vanish.length; i++) {
 196         const v = move.vanish[i];
 197         // Did opponent king disappeared?
 198         if (v.p == V.KING)
 199           this.kingPos[this.turn] = [-1, -1];
 200         // Or maybe a rook?
 201         else if (v.p == V.ROOK) {
 202           if (v.y < this.kingPos[v.c][1])
 203             this.castleFlags[v.c][0] = 8;
 204           else
 205             // v.y > this.kingPos[v.c][1]
 206             this.castleFlags[v.c][1] = 8;
 207         }
 208       }
 209     }
 210   }
 211
 212   preUndo(move) {
 213     super.preUndo(move);
 214     const oppCol = this.turn;
 215     if (move.vanish.length >= 2 && move.appear.length == 1) {
 216       // Did opponent king disappeared?
 217       const psq = move.vanish.find(v => v.p == V.KING && v.c == oppCol)
 218       if (psq)
 219         this.kingPos[psq.c] = [psq.x, psq.y];
 220     }
 221   }
 222
 223   getCurrentScore() {
 224     const color = this.turn;
 225     const kp = this.kingPos[color];
 226     if (kp[0] < 0)
 227       // King disappeared
 228       return color == "w" ? "0-1" : "1-0";
 229     if (this.atLeastOneMove()) return "*";
 230     // Kings still there, no moves:
 231     return "1/2";
 232   }
 233
 234   static get SEARCH_DEPTH() {
 235     return 1;
 236   }
 237
 238   getNotation(move) {
 239     let notation = super.getNotation(move);
 240     // Add a capture mark (not describing what is captured...):
 241     if (move.vanish.length > 1 && move.appear.length == 1) {
 242       if (!!(notation.match(/^[a-h]x/)))
 243         // Pawn capture: remove initial "b" in bxc4 for example
 244         notation = notation.substr(1);
 245       notation = notation.replace("x","") + "X";
 246     }
 247     return notation;
 248   }
 249
 250 };