client/src/variants/Allmate1.js

   1 import { ChessRules, PiPo, Move } from "@/base_rules";
   2
   3 export const VariantRules = class Allmate1Rules 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() {
  14     return ChessRules.GenRandInitFen().replace(/ -$/, "");
  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       // Avoid "oppMoves = this.getAllValidMoves();" => infinite recursion
  42       outerLoop: for (let i=0; i<V.size.x; i++) {
  43         for (let j=0; j<V.size.y; j++) {
  44           if (this.getColor(i,j) == oppCol) {
  45             let oppMoves = [];
  46             switch (this.getPiece(i, j)) {
  47               case V.PAWN:
  48                 oppMoves = this.getPotentialPawnMoves([i, j]);
  49                 break;
  50               case V.ROOK:
  51                 oppMoves = this.getPotentialRookMoves([i, j]);
  52                 break;
  53               case V.KNIGHT:
  54                 oppMoves = this.getPotentialKnightMoves([i, j]);
  55                 break;
  56               case V.BISHOP:
  57                 oppMoves = this.getPotentialBishopMoves([i, j]);
  58                 break;
  59               case V.QUEEN:
  60                 oppMoves = this.getPotentialQueenMoves([i, j]);
  61                 break;
  62               case V.KING:
  63                 oppMoves = this.getPotentialKingMoves([i, j]);
  64                 break;
  65             }
  66             for (let om of oppMoves) {
  67               V.PlayOnBoard(this.board, om);
  68               Object.values(attacked).forEach(sq => {
  69                 const origSq = [sq[0], sq[1]];
  70                 if (om.start.x == sq[0] && om.start.y == sq[1])
  71                   // Piece moved:
  72                   sq = [om.appear[0].x, om.appear[0].y];
  73                 if (!this.isAttacked(sq, [color]))
  74                   delete attacked[origSq[0]+"_"+origSq[1]];
  75               });
  76               V.UndoOnBoard(this.board, om);
  77               if (Object.keys(attacked).length == 0)
  78                 // No need to explore more moves
  79                 break outerLoop;
  80             }
  81           }
  82         }
  83       }
  84
  85       // 3) Add mate-captures:
  86       Object.values(attacked).forEach(sq => {
  87         m.vanish.push(new PiPo({
  88           x: sq[0],
  89           y: sq[1],
  90           c: oppCol,
  91           p: this.getPiece(sq[0], sq[1])
  92         }));
  93       });
  94
  95       this.undo(m);
  96     });
  97
  98     return moves;
  99   }
 100
 101   // No "under check" conditions in castling
 102   getCastleMoves([x, y]) {
 103     const c = this.getColor(x, y);
 104     if (x != (c == "w" ? V.size.x - 1 : 0) || y != this.INIT_COL_KING[c])
 105       return []; //x isn't first rank, or king has moved (shortcut)
 106
 107     // Castling ?
 108     const oppCol = V.GetOppCol(c);
 109     let moves = [];
 110     let i = 0;
 111     // King, then rook:
 112     const finalSquares = [
 113       [2, 3],
 114       [V.size.y - 2, V.size.y - 3]
 115     ];
 116     castlingCheck: for (
 117       let castleSide = 0;
 118       castleSide < 2;
 119       castleSide++ //large, then small
 120     ) {
 121       if (!this.castleFlags[c][castleSide]) continue;
 122       // If this code is reached, rooks and king are on initial position
 123
 124       // Nothing on the path of the king ? (and no checks)
 125       const finDist = finalSquares[castleSide][0] - y;
 126       let step = finDist / Math.max(1, Math.abs(finDist));
 127       for (let i = y; i != finalSquares[castleSide][0]; i += step) {
 128         if (
 129           this.board[x][i] != V.EMPTY &&
 130             // NOTE: next check is enough, because of chessboard constraints
 131             (this.getColor(x, i) != c ||
 132               ![V.KING, V.ROOK].includes(this.getPiece(x, i)))
 133         ) {
 134           continue castlingCheck;
 135         }
 136       }
 137
 138       // Nothing on the path to the rook?
 139       step = castleSide == 0 ? -1 : 1;
 140       for (i = y + step; i != this.INIT_COL_ROOK[c][castleSide]; i += step) {
 141         if (this.board[x][i] != V.EMPTY) continue castlingCheck;
 142       }
 143       const rookPos = this.INIT_COL_ROOK[c][castleSide];
 144
 145       // Nothing on final squares, except maybe king and castling rook?
 146       for (i = 0; i < 2; i++) {
 147         if (
 148           this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
 149           this.getPiece(x, finalSquares[castleSide][i]) != V.KING &&
 150           finalSquares[castleSide][i] != rookPos
 151         ) {
 152           continue castlingCheck;
 153         }
 154       }
 155
 156       // If this code is reached, castle is valid
 157       moves.push(
 158         new Move({
 159           appear: [
 160             new PiPo({ x: x, y: finalSquares[castleSide][0], p: V.KING, c: c }),
 161             new PiPo({ x: x, y: finalSquares[castleSide][1], p: V.ROOK, c: c })
 162           ],
 163           vanish: [
 164             new PiPo({ x: x, y: y, p: V.KING, c: c }),
 165             new PiPo({ x: x, y: rookPos, p: V.ROOK, c: c })
 166           ],
 167           end:
 168             Math.abs(y - rookPos) <= 2
 169               ? { x: x, y: rookPos }
 170               : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) }
 171         })
 172       );
 173     }
 174
 175     return moves;
 176   }
 177
 178   // TODO: allow pieces to "commit suicide"? (Currently yes except king)
 179   filterValid(moves) {
 180     // Remove moves which let the king mate-captured:
 181     if (moves.length == 0) return [];
 182     const color = this.turn;
 183     const oppCol = V.GetOppCol(color);
 184     return moves.filter(m => {
 185       let res = true;
 186       this.play(m);
 187       if (this.underCheck(color)) {
 188         res = false;
 189         const attacked = this.kingPos[color];
 190         // Try to find a move to escape check
 191         // TODO: very inefficient method.
 192         outerLoop: for (let i=0; i<V.size.x; i++) {
 193           for (let j=0; j<V.size.y; j++) {
 194             if (this.getColor(i,j) == color) {
 195               let emoves = [];
 196               // Artficial turn change to "play twice":
 197               this.turn = color;
 198               switch (this.getPiece(i, j)) {
 199                 case V.PAWN:
 200                   emoves = this.getPotentialPawnMoves([i, j]);
 201                   break;
 202                 case V.ROOK:
 203                   emoves = this.getPotentialRookMoves([i, j]);
 204                   break;
 205                 case V.KNIGHT:
 206                   emoves = this.getPotentialKnightMoves([i, j]);
 207                   break;
 208                 case V.BISHOP:
 209                   emoves = this.getPotentialBishopMoves([i, j]);
 210                   break;
 211                 case V.QUEEN:
 212                   emoves = this.getPotentialQueenMoves([i, j]);
 213                   break;
 214                 case V.KING:
 215                   emoves = this.getPotentialKingMoves([i, j]);
 216                   break;
 217               }
 218               this.turn = oppCol;
 219               for (let em of emoves) {
 220                 V.PlayOnBoard(this.board, em);
 221                 let sq = attacked;
 222                 if (em.start.x == attacked[0] && em.start.y == attacked[1])
 223                   // King moved:
 224                   sq = [em.appear[0].x, em.appear[0].y];
 225                 if (!this.isAttacked(sq, [oppCol]))
 226                   res = true;
 227                 V.UndoOnBoard(this.board, em);
 228                 if (res)
 229                   // No need to explore more moves
 230                   break outerLoop;
 231               }
 232             }
 233           }
 234         }
 235       }
 236       this.undo(m);
 237       return res;
 238     });
 239   }
 240
 241   updateVariables(move) {
 242     super.updateVariables(move);
 243     const color = V.GetOppCol(this.turn);
 244     if (move.vanish.length >= 2 && move.appear.length == 1) {
 245       move.vanish.forEach(v => {
 246         if (v.c == color)
 247           return;
 248         // Did opponent king disappeared?
 249         if (v.p == V.KING)
 250           this.kingPos[this.turn] = [-1, -1];
 251         // Or maybe a rook?
 252         else if (v.p == V.ROOK) {
 253           if (v.y < this.INIT_COL_KING[v.c])
 254             this.castleFlags[v.c][0] = false;
 255           else
 256             // v.y > this.INIT_COL_KING[v.c]
 257             this.castleFlags[v.c][1] = false;
 258         }
 259       });
 260     }
 261   }
 262
 263   unupdateVariables(move) {
 264     super.unupdateVariables(move);
 265     const color = this.turn;
 266     if (move.vanish.length >= 2 && move.appear.length == 1) {
 267       // Did opponent king disappeared?
 268       const psq = move.vanish.find(v => v.p == V.KING && v.c != color)
 269       if (psq)
 270         this.kingPos[psq.c] = [psq.x, psq.y];
 271     }
 272   }
 273
 274   getCurrentScore() {
 275     const color = this.turn;
 276     const kp = this.kingPos[color];
 277     if (kp[0] < 0)
 278       // King disappeared
 279       return color == "w" ? "0-1" : "1-0";
 280     if (this.atLeastOneMove())
 281       return "*";
 282     // Kings still there, no moves:
 283     return "1/2";
 284   }
 285
 286   static get SEARCH_DEPTH() {
 287     return 2;
 288   }
 289
 290   getNotation(move) {
 291     let notation = super.getNotation(move);
 292     // Add a capture mark (not describing what is captured...):
 293     if (move.vanish.length > 1 && move.appear.length == 1) {
 294       if (notation.match(/^[a-h]x/))
 295         // Pawn capture: remove initial "b" in bxc4 for example
 296         notation = notation.substr(1);
 297       notation = notation.replace("x","") + "X";
 298     }
 299     return notation;
 300   }
 301 };