client/src/variants/Circular.js

   1 import { ChessRules, PiPo, Move } from "@/base_rules";
   2 import { ArrayFun } from "@/utils/array";
   3 import { randInt, shuffle } from "@/utils/alea";
   4
   5 export const VariantRules = class CircularRules extends ChessRules {
   6   static get HasEnpassant() {
   7     return false;
   8   }
   9
  10   static get CanFlip() {
  11     return false;
  12   }
  13
  14   setFlags(fenflags) {
  15     this.pawnFlags = {
  16       w: [...Array(8).fill(true)], //pawns can move 2 squares?
  17       b: [...Array(8).fill(true)]
  18     };
  19     for (let c of ["w", "b"]) {
  20       for (let i = 0; i < 8; i++)
  21         this.pawnFlags[c][i] = fenflags.charAt((c == "w" ? 0 : 8) + i) == "1";
  22     }
  23   }
  24
  25   aggregateFlags() {
  26     return this.pawnFlags;
  27   }
  28
  29   disaggregateFlags(flags) {
  30     this.pawnFlags = flags;
  31   }
  32
  33   static GenRandInitFen(randomness) {
  34     if (randomness == 0)
  35       return "8/8/pppppppp/rnbqkbnr/8/8/PPPPPPPP/RNBQKBNR w 0 1111111111111111";
  36
  37     let pieces = { w: new Array(8), b: new Array(8) };
  38     // Shuffle pieces on first and fifth rank
  39     for (let c of ["w", "b"]) {
  40       if (c == 'b' && randomness == 1) {
  41         pieces['b'] = pieces['w'];
  42         break;
  43       }
  44
  45       let positions = ArrayFun.range(8);
  46
  47       // Get random squares for bishops
  48       let randIndex = 2 * randInt(4);
  49       const bishop1Pos = positions[randIndex];
  50       // The second bishop must be on a square of different color
  51       let randIndex_tmp = 2 * randInt(4) + 1;
  52       const bishop2Pos = positions[randIndex_tmp];
  53       // Remove chosen squares
  54       positions.splice(Math.max(randIndex, randIndex_tmp), 1);
  55       positions.splice(Math.min(randIndex, randIndex_tmp), 1);
  56
  57       // Get random squares for knights
  58       randIndex = randInt(6);
  59       const knight1Pos = positions[randIndex];
  60       positions.splice(randIndex, 1);
  61       randIndex = randInt(5);
  62       const knight2Pos = positions[randIndex];
  63       positions.splice(randIndex, 1);
  64
  65       // Get random square for queen
  66       randIndex = randInt(4);
  67       const queenPos = positions[randIndex];
  68       positions.splice(randIndex, 1);
  69
  70       // Rooks and king positions are now fixed,
  71       // because of the ordering rook-king-rook
  72       const rook1Pos = positions[0];
  73       const kingPos = positions[1];
  74       const rook2Pos = positions[2];
  75
  76       // Finally put the shuffled pieces in the board array
  77       pieces[c][rook1Pos] = "r";
  78       pieces[c][knight1Pos] = "n";
  79       pieces[c][bishop1Pos] = "b";
  80       pieces[c][queenPos] = "q";
  81       pieces[c][kingPos] = "k";
  82       pieces[c][bishop2Pos] = "b";
  83       pieces[c][knight2Pos] = "n";
  84       pieces[c][rook2Pos] = "r";
  85     }
  86     return (
  87       "8/8/pppppppp/" +
  88       pieces["b"].join("") +
  89       "/8/8/PPPPPPPP/" +
  90       pieces["w"].join("").toUpperCase() +
  91       // 16 flags: can pawns advance 2 squares?
  92       " w 0 1111111111111111"
  93     );
  94   }
  95
  96   // Output basically x % 8 (circular board)
  97   static ComputeX(x) {
  98     let res = x % V.size.x;
  99     if (res < 0)
 100       res += V.size.x;
 101     return res;
 102   }
 103
 104   getSlideNJumpMoves([x, y], steps, oneStep) {
 105     let moves = [];
 106     outerLoop: for (let step of steps) {
 107       let i = V.ComputeX(x + step[0]);
 108       let j = y + step[1];
 109       while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
 110         moves.push(this.getBasicMove([x, y], [i, j]));
 111         if (oneStep !== undefined) continue outerLoop;
 112         i = V.ComputeX(i + step[0]);
 113         j += step[1];
 114       }
 115       if (V.OnBoard(i, j) && this.canTake([x, y], [i, j]))
 116         moves.push(this.getBasicMove([x, y], [i, j]));
 117     }
 118     return moves;
 119   }
 120
 121   getPotentialPawnMoves([x, y]) {
 122     const color = this.turn;
 123     let moves = [];
 124     const [sizeX, sizeY] = [V.size.x, V.size.y];
 125     // All pawns go in the same direction!
 126     const shiftX = -1;
 127     const startRank = color == "w" ? sizeX - 2 : 2;
 128
 129     // One square forward
 130     const nextRow = V.ComputeX(x + shiftX);
 131     if (this.board[nextRow][y] == V.EMPTY) {
 132       moves.push(this.getBasicMove([x, y], [nextRow, y]));
 133       if (
 134         x == startRank &&
 135         this.pawnFlags[color][y] &&
 136         this.board[x + 2 * shiftX][y] == V.EMPTY
 137       ) {
 138         // Two squares jump
 139         moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
 140       }
 141     }
 142     // Captures
 143     for (let shiftY of [-1, 1]) {
 144       if (
 145         y + shiftY >= 0 &&
 146         y + shiftY < sizeY &&
 147         this.board[nextRow][y + shiftY] != V.EMPTY &&
 148         this.canTake([x, y], [nextRow, y + shiftY])
 149       ) {
 150         moves.push(this.getBasicMove([x, y], [nextRow, y + shiftY]));
 151       }
 152     }
 153
 154     return moves;
 155   }
 156
 157   getPotentialKingMoves(sq) {
 158     return this.getSlideNJumpMoves(
 159       sq,
 160       V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
 161       "oneStep"
 162     );
 163   }
 164
 165   filterValid(moves) {
 166     const filteredMoves = super.filterValid(moves);
 167     // If at least one full move made, everything is allowed:
 168     if (this.movesCount >= 2) return filteredMoves;
 169     // Else, forbid check:
 170     const oppCol = V.GetOppCol(this.turn);
 171     return filteredMoves.filter(m => {
 172       this.play(m);
 173       const res = !this.underCheck(oppCol);
 174       this.undo(m);
 175       return res;
 176     });
 177   }
 178
 179   isAttackedByPawn([x, y], colors) {
 180     const pawnShift = 1;
 181     const attackerRow = V.ComputeX(x + pawnShift);
 182     for (let c of colors) {
 183       for (let i of [-1, 1]) {
 184         if (
 185           y + i >= 0 &&
 186           y + i < V.size.y &&
 187           this.getPiece(attackerRow, y + i) == V.PAWN &&
 188           this.getColor(attackerRow, y + i) == c
 189         ) {
 190           return true;
 191         }
 192       }
 193     }
 194     return false;
 195   }
 196
 197   isAttackedBySlideNJump([x, y], colors, piece, steps, oneStep) {
 198     for (let step of steps) {
 199       let rx = V.ComputeX(x + step[0]),
 200           ry = y + step[1];
 201       while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
 202         rx = V.ComputeX(rx + step[0]);
 203         ry += step[1];
 204       }
 205       if (
 206         V.OnBoard(rx, ry) &&
 207         this.getPiece(rx, ry) === piece &&
 208         colors.includes(this.getColor(rx, ry))
 209       ) {
 210         return true;
 211       }
 212     }
 213     return false;
 214   }
 215
 216   getFlagsFen() {
 217     // Return pawns flags
 218     let flags = "";
 219     for (let c of ["w", "b"]) {
 220       for (let i = 0; i < 8; i++) flags += this.pawnFlags[c][i] ? "1" : "0";
 221     }
 222     return flags;
 223   }
 224
 225   updateVariables(move) {
 226     const c = move.vanish[0].c;
 227     const secondRank = {"w":6, "b":2};
 228     // Update king position + flags
 229     if (move.vanish[0].p == V.KING && move.appear.length > 0) {
 230       this.kingPos[c][0] = move.appear[0].x;
 231       this.kingPos[c][1] = move.appear[0].y;
 232     }
 233     else if (move.vanish[0].p == V.PAWN && secondRank[c] == move.start.x)
 234       // This move turns off a 2-squares pawn flag
 235       this.pawnFlags[c][move.start.y] = false;
 236   }
 237
 238   static get VALUES() {
 239     return {
 240       p: 1,
 241       r: 5,
 242       n: 3,
 243       b: 4,
 244       q: 10,
 245       k: 1000
 246     };
 247   }
 248
 249   static get SEARCH_DEPTH() {
 250     return 2;
 251   }
 252 };