client/src/variants/Cannibal.js

   1 import { ChessRules, Move, PiPo } from "@/base_rules";
   2
   3 export class CannibalRules extends ChessRules {
   4   static get KING_CODE() {
   5     return {
   6       'p': 's',
   7       'r': 'u',
   8       'n': 'o',
   9       'b': 'c',
  10       'q': 't'
  11     };
  12   }
  13
  14   static get KING_DECODE() {
  15     return {
  16       's': 'p',
  17       'u': 'r',
  18       'o': 'n',
  19       'c': 'b',
  20       't': 'q'
  21     };
  22   }
  23
  24   // Kings may be disguised:
  25   getPiece(x, y) {
  26     const piece = this.board[x][y].charAt(1);
  27     if (Object.keys(V.KING_DECODE).includes(piece))
  28       return V.KING_DECODE[piece];
  29     return piece;
  30   }
  31
  32   getPpath(b) {
  33     return (Object.keys(V.KING_DECODE).includes(b[1]) ? "Cannibal/" : "") + b;
  34   }
  35
  36   static IsGoodPosition(position) {
  37     if (position.length == 0) return false;
  38     const rows = position.split("/");
  39     if (rows.length != V.size.x) return false;
  40     let kings = { "w": 0, "b": 0 };
  41     const allPiecesCodes = V.PIECES.concat(Object.keys(V.KING_DECODE));
  42     const kingBlackCodes = Object.keys(V.KING_DECODE).concat(['k']);
  43     const kingWhiteCodes =
  44       Object.keys(V.KING_DECODE).map(k => k.toUpperCase()).concat(['K']);
  45     for (let row of rows) {
  46       let sumElts = 0;
  47       for (let i = 0; i < row.length; i++) {
  48         if (kingBlackCodes.includes(row[i])) kings['b']++;
  49         else if (kingWhiteCodes.includes(row[i])) kings['w']++;
  50         if (allPiecesCodes.includes(row[i].toLowerCase())) sumElts++;
  51         else {
  52           const num = parseInt(row[i], 10);
  53           if (isNaN(num)) return false;
  54           sumElts += num;
  55         }
  56       }
  57       if (sumElts != V.size.y) return false;
  58     }
  59     // Both kings should be on board, only one of each color:
  60     if (Object.values(kings).some(v => v != 1)) return false;
  61     return true;
  62   }
  63
  64   // Kings may be disguised:
  65   setOtherVariables(fen) {
  66     super.setOtherVariables(fen);
  67     const rows = V.ParseFen(fen).position.split("/");
  68     if (this.kingPos["w"][0] < 0 || this.kingPos["b"][0] < 0) {
  69       for (let i = 0; i < rows.length; i++) {
  70         let k = 0; //column index on board
  71         for (let j = 0; j < rows[i].length; j++) {
  72           const piece = rows[i].charAt(j);
  73           if (Object.keys(V.KING_DECODE).includes(piece.toLowerCase())) {
  74             const color = (piece.charCodeAt(0) <= 90 ? 'w' : 'b');
  75             this.kingPos[color] = [i, k];
  76           } else {
  77             const num = parseInt(rows[i].charAt(j), 10);
  78             if (!isNaN(num)) k += num - 1;
  79           }
  80           k++;
  81         }
  82       }
  83     }
  84   }
  85
  86   // Trim all non-capturing moves
  87   static KeepCaptures(moves) {
  88     return moves.filter(m => m.vanish.length == 2 && m.appear.length == 1);
  89   }
  90
  91   // Stop at the first capture found (if any)
  92   atLeastOneCapture() {
  93     const color = this.turn;
  94     const oppCol = V.GetOppCol(color);
  95     for (let i = 0; i < V.size.x; i++) {
  96       for (let j = 0; j < V.size.y; j++) {
  97         if (
  98           this.board[i][j] != V.EMPTY &&
  99           this.getColor(i, j) != oppCol &&
 100           this.filterValid(this.getPotentialMovesFrom([i, j])).some(m =>
 101             // Warning: discard castle moves
 102             m.vanish.length == 2 && m.appear.length == 1)
 103         ) {
 104           return true;
 105         }
 106       }
 107     }
 108     return false;
 109   }
 110
 111   // Because of the disguised kings, getPiece() could be wrong:
 112   // use board[x][y][1] instead (always valid).
 113   getBasicMove([sx, sy], [ex, ey], tr) {
 114     const initColor = this.getColor(sx, sy);
 115     const initPiece = this.board[sx][sy].charAt(1);
 116     let mv = new Move({
 117       appear: [
 118         new PiPo({
 119           x: ex,
 120           y: ey,
 121           c: tr ? tr.c : initColor,
 122           p: tr ? tr.p : initPiece
 123         })
 124       ],
 125       vanish: [
 126         new PiPo({
 127           x: sx,
 128           y: sy,
 129           c: initColor,
 130           p: initPiece
 131         })
 132       ]
 133     });
 134
 135     // The opponent piece disappears if we take it
 136     if (this.board[ex][ey] != V.EMPTY) {
 137       mv.vanish.push(
 138         new PiPo({
 139           x: ex,
 140           y: ey,
 141           c: this.getColor(ex, ey),
 142           p: this.board[ex][ey].charAt(1)
 143         })
 144       );
 145
 146       // If the captured piece has a different nature: take it as well
 147       if (mv.vanish[0].p != mv.vanish[1].p) {
 148         if (
 149           mv.vanish[0].p == V.KING ||
 150           Object.keys(V.KING_DECODE).includes(mv.vanish[0].p)
 151         ) {
 152           mv.appear[0].p = V.KING_CODE[mv.vanish[1].p];
 153         } else mv.appear[0].p = mv.vanish[1].p;
 154       }
 155     }
 156     else if (!!tr && mv.vanish[0].p != V.PAWN)
 157       // Special case of a non-capturing king-as-pawn promotion
 158       mv.appear[0].p = V.KING_CODE[tr.p];
 159
 160     return mv;
 161   }
 162
 163   getPotentialMovesFrom([x, y]) {
 164     const piece = this.board[x][y].charAt(1);
 165     if (Object.keys(V.KING_DECODE).includes(piece))
 166       return super.getPotentialMovesFrom([x, y], V.KING_DECODE[piece]);
 167     return super.getPotentialMovesFrom([x, y], piece);
 168   }
 169
 170   addPawnMoves([x1, y1], [x2, y2], moves) {
 171     let finalPieces = [V.PAWN];
 172     const color = this.turn;
 173     const lastRank = (color == "w" ? 0 : V.size.x - 1);
 174     if (x2 == lastRank) {
 175       if (this.board[x2][y2] != V.EMPTY)
 176         // Cannibal rules: no choice if capture
 177         finalPieces = [this.getPiece(x2, y2)];
 178       else finalPieces = V.PawnSpecs.promotions;
 179     }
 180     let tr = null;
 181     for (let piece of finalPieces) {
 182       tr = (piece != V.PAWN ? { c: color, p: piece } : null);
 183       moves.push(this.getBasicMove([x1, y1], [x2, y2], tr));
 184     }
 185   }
 186
 187   getPossibleMovesFrom(sq) {
 188     let moves = this.filterValid(this.getPotentialMovesFrom(sq));
 189     const captureMoves = V.KeepCaptures(moves);
 190     if (captureMoves.length > 0) return captureMoves;
 191     if (this.atLeastOneCapture()) return [];
 192     return moves;
 193   }
 194
 195   getAllValidMoves() {
 196     const moves = super.getAllValidMoves();
 197     if (moves.some(m => m.vanish.length == 2 && m.appear.length == 1))
 198       return V.KeepCaptures(moves);
 199     return moves;
 200   }
 201
 202   postPlay(move) {
 203     const c = V.GetOppCol(this.turn);
 204     const piece = move.appear[0].p;
 205     // Update king position + flags
 206     if (piece == V.KING || Object.keys(V.KING_DECODE).includes(piece)) {
 207       this.kingPos[c][0] = move.appear[0].x;
 208       this.kingPos[c][1] = move.appear[0].y;
 209       this.castleFlags[c] = [V.size.y, V.size.y];
 210     }
 211     // Next call is still required because the king may eat an opponent's rook
 212     // TODO: castleFlags will be turned off twice then.
 213     super.updateCastleFlags(move, piece);
 214   }
 215
 216   postUndo(move) {
 217     // (Potentially) Reset king position
 218     const c = this.getColor(move.start.x, move.start.y);
 219     const piece = move.appear[0].p;
 220     if (piece == V.KING || Object.keys(V.KING_DECODE).includes(piece))
 221       this.kingPos[c] = [move.start.x, move.start.y];
 222   }
 223
 224   static get VALUES() {
 225     return {
 226       p: 1,
 227       r: 5,
 228       n: 3,
 229       b: 3,
 230       q: 9,
 231       k: 5
 232     };
 233   }
 234
 235   getNotation(move) {
 236     let notation = super.getNotation(move);
 237     const lastRank = (move.appear[0].c == "w" ? 0 : 7);
 238     if (
 239       move.end.x != lastRank &&
 240       this.getPiece(move.start.x, move.start.y) == V.PAWN &&
 241       move.vanish.length == 2 &&
 242       move.appear[0].p != V.PAWN
 243     ) {
 244       // Fix "promotion" (transform indicator) from base_rules notation
 245       notation = notation.slice(0, -2);
 246     }
 247     return notation;
 248   }
 249 };