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[vchess.git] / client / src / variants / Grand.js

import { ChessRules } from "@/base_rules";
import { ArrayFun } from "@/utils/array";
import { randInt } from "@/utils/alea";

// NOTE: initial setup differs from the original; see
// https://www.chessvariants.com/large.dir/freeling.html
export const VariantRules = class GrandRules extends ChessRules
{
  static getPpath(b)
  {
    return ([V.MARSHALL,V.CARDINAL].includes(b[1]) ? "Grand/" : "") + b;
  }

  static IsGoodFen(fen)
  {
    if (!ChessRules.IsGoodFen(fen))
      return false;
    const fenParsed = V.ParseFen(fen);
    // 5) Check captures
    if (!fenParsed.captured || !fenParsed.captured.match(/^[0-9]{14,14}$/))
      return false;
    return true;
  }

  static IsGoodEnpassant(enpassant)
  {
    if (enpassant != "-")
    {
      const squares = enpassant.split(",");
      if (squares.length > 2)
        return false;
      for (let sq of squares)
      {
        const ep = V.SquareToCoords(sq);
        if (isNaN(ep.x) || !V.OnBoard(ep))
          return false;
      }
    }
    return true;
  }

  static ParseFen(fen)
  {
    const fenParts = fen.split(" ");
    return Object.assign(
      ChessRules.ParseFen(fen),
      { captured: fenParts[5] }
    );
  }

  getFen()
  {
    return super.getFen() + " " + this.getCapturedFen();
  }

  getCapturedFen()
  {
    let counts = [...Array(14).fill(0)];
    let i = 0;
    for (let j=0; j<V.PIECES.length; j++)
    {
      if (V.PIECES[j] == V.KING) //no king captured
        continue;
      counts[i] = this.captured["w"][V.PIECES[i]];
      counts[7+i] = this.captured["b"][V.PIECES[i]];
      i++;
    }
    return counts.join("");
  }

  setOtherVariables(fen)
  {
    super.setOtherVariables(fen);
    const fenParsed = V.ParseFen(fen);
    // Initialize captured pieces' counts from FEN
    this.captured =
    {
      "w":
      {
        [V.PAWN]: parseInt(fenParsed.captured[0]),
        [V.ROOK]: parseInt(fenParsed.captured[1]),
        [V.KNIGHT]: parseInt(fenParsed.captured[2]),
        [V.BISHOP]: parseInt(fenParsed.captured[3]),
        [V.QUEEN]: parseInt(fenParsed.captured[4]),
        [V.MARSHALL]: parseInt(fenParsed.captured[5]),
        [V.CARDINAL]: parseInt(fenParsed.captured[6]),
      },
      "b":
      {
        [V.PAWN]: parseInt(fenParsed.captured[7]),
        [V.ROOK]: parseInt(fenParsed.captured[8]),
        [V.KNIGHT]: parseInt(fenParsed.captured[9]),
        [V.BISHOP]: parseInt(fenParsed.captured[10]),
        [V.QUEEN]: parseInt(fenParsed.captured[11]),
        [V.MARSHALL]: parseInt(fenParsed.captured[12]),
        [V.CARDINAL]: parseInt(fenParsed.captured[13]),
      }
    };
  }

  static get size() { return {x:10,y:10}; }

  static get MARSHALL() { return 'm'; } //rook+knight
  static get CARDINAL() { return 'c'; } //bishop+knight

  static get PIECES()
  {
    return ChessRules.PIECES.concat([V.MARSHALL,V.CARDINAL]);
  }

  // There may be 2 enPassant squares (if pawn jump 3 squares)
  getEnpassantFen()
  {
    const L = this.epSquares.length;
    if (!this.epSquares[L-1])
      return "-"; //no en-passant
    let res = "";
    this.epSquares[L-1].forEach(sq => {
      res += V.CoordsToSquare(sq) + ",";
    });
    return res.slice(0,-1); //remove last comma
  }

  // En-passant after 2-sq or 3-sq jumps
  getEpSquare(moveOrSquare)
  {
    if (!moveOrSquare)
      return undefined;
    if (typeof moveOrSquare === "string")
    {
      const square = moveOrSquare;
      if (square == "-")
        return undefined;
      let res = [];
      square.split(",").forEach(sq => {
        res.push(V.SquareToCoords(sq));
      });
      return res;
    }
    // Argument is a move:
    const move = moveOrSquare;
    const [sx,sy,ex] = [move.start.x,move.start.y,move.end.x];
    if (this.getPiece(sx,sy) == V.PAWN && Math.abs(sx - ex) >= 2)
    {
      const step = (ex-sx) / Math.abs(ex-sx);
      let res = [{
        x: sx + step,
        y: sy
      }];
      if (sx + 2*step != ex) //3-squares move
      {
        res.push({
          x: sx + 2*step,
          y: sy
        });
      }
      return res;
    }
    return undefined; //default
  }

  getPotentialMovesFrom([x,y])
  {
    switch (this.getPiece(x,y))
    {
      case V.MARSHALL:
        return this.getPotentialMarshallMoves([x,y]);
      case V.CARDINAL:
        return this.getPotentialCardinalMoves([x,y]);
      default:
        return super.getPotentialMovesFrom([x,y])
    }
  }

  // Special pawn rules: promotions to captured friendly pieces,
  // optional on ranks 8-9 and mandatory on rank 10.
  getPotentialPawnMoves([x,y])
  {
    const color = this.turn;
    let moves = [];
    const [sizeX,sizeY] = [V.size.x,V.size.y];
    const shiftX = (color == "w" ? -1 : 1);
    const startRanks = (color == "w" ? [sizeX-2,sizeX-3] : [1,2]);
    const lastRanks = (color == "w" ? [0,1,2] : [sizeX-1,sizeX-2,sizeX-3]);
    const promotionPieces =
      [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN,V.MARSHALL,V.CARDINAL];

    // Always x+shiftX >= 0 && x+shiftX < sizeX, because no pawns on last rank
    let finalPieces = undefined;
    if (lastRanks.includes(x + shiftX))
    {
      finalPieces = promotionPieces.filter(p => this.captured[color][p] > 0);
      if (x + shiftX != lastRanks[0])
        finalPieces.push(V.PAWN);
    }
    else
      finalPieces = [V.PAWN];
    if (this.board[x+shiftX][y] == V.EMPTY)
    {
      // One square forward
      for (let piece of finalPieces)
        moves.push(this.getBasicMove([x,y], [x+shiftX,y], {c:color,p:piece}));
      if (startRanks.includes(x))
      {
        if (this.board[x+2*shiftX][y] == V.EMPTY)
        {
          // Two squares jump
          moves.push(this.getBasicMove([x,y], [x+2*shiftX,y]));
          if (x==startRanks[0] && this.board[x+3*shiftX][y] == V.EMPTY)
          {
            // Three squares jump
            moves.push(this.getBasicMove([x,y], [x+3*shiftX,y]));
          }
        }
      }
    }
    // Captures
    for (let shiftY of [-1,1])
    {
      if (y + shiftY >= 0 && y + shiftY < sizeY
        && this.board[x+shiftX][y+shiftY] != V.EMPTY
        && this.canTake([x,y], [x+shiftX,y+shiftY]))
      {
        for (let piece of finalPieces)
        {
          moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
            {c:color,p:piece}));
        }
      }
    }

    // En passant
    const Lep = this.epSquares.length;
    const epSquare = this.epSquares[Lep-1];
    if (!!epSquare)
    {
      for (let epsq of epSquare)
      {
        // TODO: some redundant checks
        if (epsq.x == x+shiftX && Math.abs(epsq.y - y) == 1)
        {
          var enpassantMove = this.getBasicMove([x,y], [epsq.x,epsq.y]);
          // WARNING: the captured pawn may be diagonally behind us,
          // if it's a 3-squares jump and we take on 1st passing square
          const px = (this.board[x][epsq.y] != V.EMPTY ? x : x - shiftX);
          enpassantMove.vanish.push({
            x: px,
            y: epsq.y,
            p: 'p',
            c: this.getColor(px,epsq.y)
          });
          moves.push(enpassantMove);
        }
      }
    }

    return moves;
  }

  // TODO: different castle?

  getPotentialMarshallMoves(sq)
  {
    return this.getSlideNJumpMoves(sq, V.steps[V.ROOK]).concat(
      this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep"));
  }

  getPotentialCardinalMoves(sq)
  {
    return this.getSlideNJumpMoves(sq, V.steps[V.BISHOP]).concat(
      this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT], "oneStep"));
  }

  isAttacked(sq, colors)
  {
    return super.isAttacked(sq, colors)
      || this.isAttackedByMarshall(sq, colors)
      || this.isAttackedByCardinal(sq, colors);
  }

  isAttackedByMarshall(sq, colors)
  {
    return this.isAttackedBySlideNJump(sq, colors, V.MARSHALL, V.steps[V.ROOK])
      || this.isAttackedBySlideNJump(
        sq, colors, V.MARSHALL, V.steps[V.KNIGHT], "oneStep");
  }

  isAttackedByCardinal(sq, colors)
  {
    return this.isAttackedBySlideNJump(sq, colors, V.CARDINAL, V.steps[V.BISHOP])
      || this.isAttackedBySlideNJump(
        sq, colors, V.CARDINAL, V.steps[V.KNIGHT], "oneStep");
  }

  updateVariables(move)
  {
    super.updateVariables(move);
    if (move.vanish.length == 2 && move.appear.length == 1)
    {
      // Capture: update this.captured
      this.captured[move.vanish[1].c][move.vanish[1].p]++;
    }
    if (move.vanish[0].p != move.appear[0].p)
    {
      // Promotion: update this.captured
      this.captured[move.vanish[0].c][move.appear[0].p]--;
    }
  }

  unupdateVariables(move)
  {
    super.unupdateVariables(move);
    if (move.vanish.length == 2 && move.appear.length == 1)
      this.captured[move.vanish[1].c][move.vanish[1].p]--;
    if (move.vanish[0].p != move.appear[0].p)
      this.captured[move.vanish[0].c][move.appear[0].p]++;
  }

  static get VALUES()
  {
    return Object.assign(
      ChessRules.VALUES,
      {'c': 5, 'm': 7} //experimental
    );
  }

  static get SEARCH_DEPTH() { return 2; }

  // TODO: this function could be generalized and shared better (how ?!...)
  static GenRandInitFen()
  {
    let pieces = { "w": new Array(10), "b": new Array(10) };
    // Shuffle pieces on first and last rank
    for (let c of ["w","b"])
    {
      let positions = ArrayFun.range(10);

      // Get random squares for bishops
      let randIndex = 2 * randInt(5);
      let bishop1Pos = positions[randIndex];
      // The second bishop must be on a square of different color
      let randIndex_tmp = 2 * randInt(5) + 1;
      let bishop2Pos = positions[randIndex_tmp];
      // Remove chosen squares
      positions.splice(Math.max(randIndex,randIndex_tmp), 1);
      positions.splice(Math.min(randIndex,randIndex_tmp), 1);

      // Get random squares for knights
      randIndex = randInt(8);
      let knight1Pos = positions[randIndex];
      positions.splice(randIndex, 1);
      randIndex = randInt(7);
      let knight2Pos = positions[randIndex];
      positions.splice(randIndex, 1);

      // Get random square for queen
      randIndex = randInt(6);
      let queenPos = positions[randIndex];
      positions.splice(randIndex, 1);

      // ...random square for marshall
      randIndex = randInt(5);
      let marshallPos = positions[randIndex];
      positions.splice(randIndex, 1);

      // ...random square for cardinal
      randIndex = randInt(4);
      let cardinalPos = positions[randIndex];
      positions.splice(randIndex, 1);

      // Rooks and king positions are now fixed, because of the ordering rook-king-rook
      let rook1Pos = positions[0];
      let kingPos = positions[1];
      let rook2Pos = positions[2];

      // Finally put the shuffled pieces in the board array
      pieces[c][rook1Pos] = 'r';
      pieces[c][knight1Pos] = 'n';
      pieces[c][bishop1Pos] = 'b';
      pieces[c][queenPos] = 'q';
      pieces[c][marshallPos] = 'm';
      pieces[c][cardinalPos] = 'c';
      pieces[c][kingPos] = 'k';
      pieces[c][bishop2Pos] = 'b';
      pieces[c][knight2Pos] = 'n';
      pieces[c][rook2Pos] = 'r';
    }
    return pieces["b"].join("") +
      "/pppppppppp/10/10/10/10/10/10/PPPPPPPPPP/" +
      pieces["w"].join("").toUpperCase() +
      " w 0 1111 - 00000000000000";
  }
}