client/src/variants/Royalrace.js

   1 import { ChessRules } from "@/base_rules";
   2 import { ArrayFun } from "@/utils/array";
   3 import { randInt, shuffle } from "@/utils/alea";
   4
   5 export class RoyalraceRules extends ChessRules {
   6
   7   static get HasFlags() {
   8     return false;
   9   }
  10
  11   static get HasEnpassant() {
  12     return false;
  13   }
  14
  15   static get CanFlip() {
  16     return false;
  17   }
  18
  19   static get size() {
  20     return { x: 11, y: 11 };
  21   }
  22
  23   getPpath(b) {
  24     return (b[1] == V.KNIGHT ? "Enpassant/" : "") + b;
  25   }
  26
  27   static GenRandInitFen(options) {
  28     if (options.randomness == 0)
  29       return "92/92/92/92/92/92/92/92/92/qrbnp1PNBRQ/krbnp1PNBRK w 0";
  30
  31     let pieces = { w: new Array(10), b: new Array(10) };
  32     // Shuffle pieces on first and second rank
  33     for (let c of ["w", "b"]) {
  34       if (c == 'b' && options.randomness == 1) {
  35         pieces['b'] = JSON.parse(JSON.stringify(pieces['w'])).reverse();
  36         pieces['b'] =
  37           pieces['b'].splice(5,10).reverse().concat(
  38           pieces['b'].splice(0,5).reverse());
  39         break;
  40       }
  41
  42       // Reserve 4 and 5 which are pawns positions
  43       let positions = ArrayFun.range(10).filter(i => i != 4 && i != 5);
  44
  45       // Get random squares for bishops
  46       let randIndex = 2 * randInt(4);
  47       const bishop1Pos = positions[randIndex];
  48       // The second bishop must be on a square of different color
  49       let randIndex_tmp = 2 * randInt(4) + 1;
  50       const bishop2Pos = positions[randIndex_tmp];
  51       // Remove chosen squares
  52       positions.splice(Math.max(randIndex, randIndex_tmp), 1);
  53       positions.splice(Math.min(randIndex, randIndex_tmp), 1);
  54
  55       // Place the king at random on (remaining squares of) first row
  56       let maxIndex = 4;
  57       if (positions[maxIndex-1] >= 4)
  58         maxIndex--;
  59       if (positions[maxIndex-1] >= 4)
  60         maxIndex--;
  61       randIndex = randInt(maxIndex);
  62       const kingPos = positions[randIndex];
  63       positions.splice(randIndex, 1);
  64
  65       // Get random squares for knights
  66       randIndex = randInt(5);
  67       const knight1Pos = positions[randIndex];
  68       positions.splice(randIndex, 1);
  69       randIndex = randInt(4);
  70       const knight2Pos = positions[randIndex];
  71       positions.splice(randIndex, 1);
  72
  73       // Get random squares for rooks
  74       randIndex = randInt(3);
  75       const rook1Pos = positions[randIndex];
  76       positions.splice(randIndex, 1);
  77       randIndex = randInt(2);
  78       const rook2Pos = positions[randIndex];
  79       positions.splice(randIndex, 1);
  80
  81       // Queen position is now determined,
  82       // because pawns are not placed at random
  83       const queenPos = positions[0];
  84
  85       // Finally put the shuffled pieces in the board array
  86       pieces[c][rook1Pos] = "r";
  87       pieces[c][knight1Pos] = "n";
  88       pieces[c][bishop1Pos] = "b";
  89       pieces[c][queenPos] = "q";
  90       pieces[c][kingPos] = "k";
  91       pieces[c][bishop2Pos] = "b";
  92       pieces[c][knight2Pos] = "n";
  93       pieces[c][rook2Pos] = "r";
  94       pieces[c][4] = "p";
  95       pieces[c][5] = "p";
  96     }
  97     const whiteFen = pieces["w"].join("").toUpperCase();
  98     const blackFen = pieces["b"].join("");
  99     return (
 100       "92/92/92/92/92/92/92/92/92/" +
 101       blackFen.substr(5).split("").reverse().join("") +
 102       "1" +
 103       whiteFen.substr(5).split("").join("") +
 104       "/" +
 105       blackFen.substr(0,5) +
 106       "1" +
 107       whiteFen.substr(0,5).split("").reverse().join("") +
 108       " w 0"
 109     );
 110   }
 111
 112   // TODO: simplify this when base function is more general.
 113   getPotentialPawnMoves([x, y]) {
 114     // Normal moves (as a rook)
 115     let moves =
 116       this.getSlideNJumpMoves([x, y], V.steps[V.ROOK]).filter(m => {
 117         // Remove captures. Alt: redefine canTake
 118         return m.vanish.length == 1;
 119       });
 120
 121     // Captures (in both directions)
 122     for (let shiftX of [-1, 1]) {
 123       for (let shiftY of [-1, 1]) {
 124         if (
 125           V.OnBoard(x + shiftX, y + shiftY) &&
 126           this.board[x + shiftX][y + shiftY] != V.EMPTY &&
 127           this.canTake([x, y], [x + shiftX, y + shiftY])
 128         ) {
 129           moves.push(this.getBasicMove([x, y], [x + shiftX, y + shiftY]));
 130         }
 131       }
 132     }
 133
 134     return moves;
 135   }
 136
 137   getPotentialKnightMoves(sq) {
 138     // Knight becomes knightrider:
 139     return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT]);
 140   }
 141
 142   filterValid(moves) {
 143     if (moves.length == 0) return [];
 144     const color = this.turn;
 145     const oppCol = V.GetOppCol(color);
 146     return moves.filter(m => {
 147       this.play(m);
 148       // Giving check is forbidden as well:
 149       const res = !this.underCheck(color) && !this.underCheck(oppCol);
 150       this.undo(m);
 151       return res;
 152     });
 153   }
 154
 155   isAttackedByPawn([x, y], color) {
 156     // Pawns can capture forward and backward:
 157     return this.isAttackedBySlideNJump(
 158       sq, color, V.PAWN, V.steps[V.BISHOP], 1);
 159   }
 160
 161   isAttackedByKnight(sq, color) {
 162     return this.isAttackedBySlideNJump(
 163       sq, color, V.KNIGHT, V.steps[V.KNIGHT]);
 164   }
 165
 166   getCurrentScore() {
 167     // Turn has changed:
 168     const color = V.GetOppCol(this.turn);
 169     if (this.kingPos[color][0] == 0)
 170       // The opposing edge is reached!
 171       return color == "w" ? "1-0" : "0-1";
 172     if (this.atLeastOneMove()) return "*";
 173     // Stalemate (will probably never happen)
 174     return "1/2";
 175   }
 176
 177   static get SEARCH_DEPTH() {
 178     return 2;
 179   }
 180
 181   static get VALUES() {
 182     return {
 183       p: 2,
 184       r: 5,
 185       n: 3,
 186       b: 3,
 187       q: 9,
 188       k: 1000
 189     };
 190   }
 191
 192   evalPosition() {
 193     // Count material:
 194     let evaluation = super.evalPosition();
 195     // Ponder with king position:
 196     return evaluation/5 + this.kingPos["b"][0] - this.kingPos["w"][0];
 197   }
 198
 199   getNotation(move) {
 200     // Since pawns are much more mobile, treat them as other pieces:
 201     return (
 202       move.vanish[0].p.toUpperCase() +
 203       (move.vanish.length > move.appear.length ? "x" : "") +
 204       V.CoordsToSquare(move.end)
 205     );
 206   }
 207
 208 };