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

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

export const VariantRules = class BaroqueRules extends ChessRules
{
  static get HasFlags() { return false; }

  static get HasEnpassant() { return false; }

  static getPpath(b)
  {
    if (b[1] == "m") //'m' for Immobilizer (I is too similar to 1)
      return "Baroque/" + b;
    return b; //usual piece
  }

  static get PIECES()
  {
    return ChessRules.PIECES.concat([V.IMMOBILIZER]);
  }

  // No castling, but checks, so keep track of kings
  setOtherVariables(fen)
  {
    this.kingPos = {'w':[-1,-1], 'b':[-1,-1]};
    const fenParts = fen.split(" ");
    const position = fenParts[0].split("/");
    for (let i=0; i<position.length; i++)
    {
      let k = 0;
      for (let j=0; j<position[i].length; j++)
      {
        switch (position[i].charAt(j))
        {
          case 'k':
            this.kingPos['b'] = [i,k];
            break;
          case 'K':
            this.kingPos['w'] = [i,k];
            break;
          default:
            let num = parseInt(position[i].charAt(j));
            if (!isNaN(num))
              k += (num-1);
        }
        k++;
      }
    }
  }

  static get IMMOBILIZER() { return 'm'; }
  // Although other pieces keep their names here for coding simplicity,
  // keep in mind that:
  //  - a "rook" is a coordinator, capturing by coordinating with the king
  //  - a "knight" is a long-leaper, capturing as in draughts
  //  - a "bishop" is a chameleon, capturing as its prey
  //  - a "queen" is a withdrawer, capturing by moving away from pieces

  // Is piece on square (x,y) immobilized?
  isImmobilized([x,y])
  {
    const piece = this.getPiece(x,y);
    const color = this.getColor(x,y);
    const oppCol = V.GetOppCol(color);
    const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
    outerLoop:
    for (let step of adjacentSteps)
    {
      const [i,j] = [x+step[0],y+step[1]];
      if (V.OnBoard(i,j) && this.board[i][j] != V.EMPTY
        && this.getColor(i,j) == oppCol)
      {
        const oppPiece = this.getPiece(i,j);
        if (oppPiece == V.IMMOBILIZER)
        {
          // Moving is impossible only if this immobilizer is not neutralized
          for (let step2 of adjacentSteps)
          {
            const [i2,j2] = [i+step2[0],j+step2[1]];
            if (i2 == x && j2 == y)
              continue; //skip initial piece!
            if (V.OnBoard(i2,j2) && this.board[i2][j2] != V.EMPTY
              && this.getColor(i2,j2) == color)
            {
              if ([V.BISHOP,V.IMMOBILIZER].includes(this.getPiece(i2,j2)))
                return false;
            }
          }
          return true; //immobilizer isn't neutralized
        }
        // Chameleons can't be immobilized twice, because there is only one immobilizer
        if (oppPiece == V.BISHOP && piece == V.IMMOBILIZER)
          return true;
      }
    }
    return false;
  }

  getPotentialMovesFrom([x,y])
  {
    // Pre-check: is thing on this square immobilized?
    if (this.isImmobilized([x,y]))
      return [];
    switch (this.getPiece(x,y))
    {
      case V.IMMOBILIZER:
        return this.getPotentialImmobilizerMoves([x,y]);
      default:
        return super.getPotentialMovesFrom([x,y]);
    }
  }

  getSlideNJumpMoves([x,y], steps, oneStep)
  {
    const color = this.getColor(x,y);
    const piece = this.getPiece(x,y);
    let moves = [];
    outerLoop:
    for (let step of steps)
    {
      let i = x + step[0];
      let j = y + step[1];
      while (V.OnBoard(i,j) && this.board[i][j] == V.EMPTY)
      {
        moves.push(this.getBasicMove([x,y], [i,j]));
        if (oneStep !== undefined)
          continue outerLoop;
        i += step[0];
        j += step[1];
      }
      // Only king can take on occupied square:
      if (piece==V.KING && V.OnBoard(i,j) && this.canTake([x,y], [i,j]))
        moves.push(this.getBasicMove([x,y], [i,j]));
    }
    return moves;
  }

  // Modify capturing moves among listed pawn moves
  addPawnCaptures(moves, byChameleon)
  {
    const steps = V.steps[V.ROOK];
    const color = this.turn;
    const oppCol = V.GetOppCol(color);
    moves.forEach(m => {
      if (!!byChameleon && m.start.x!=m.end.x && m.start.y!=m.end.y)
        return; //chameleon not moving as pawn
      // Try capturing in every direction
      for (let step of steps)
      {
        const sq2 = [m.end.x+2*step[0],m.end.y+2*step[1]];
        if (V.OnBoard(sq2[0],sq2[1]) && this.board[sq2[0]][sq2[1]] != V.EMPTY
          && this.getColor(sq2[0],sq2[1]) == color)
        {
          // Potential capture
          const sq1 = [m.end.x+step[0],m.end.y+step[1]];
          if (this.board[sq1[0]][sq1[1]] != V.EMPTY
            && this.getColor(sq1[0],sq1[1]) == oppCol)
          {
            const piece1 = this.getPiece(sq1[0],sq1[1]);
            if (!byChameleon || piece1 == V.PAWN)
            {
              m.vanish.push(new PiPo({
                x:sq1[0],
                y:sq1[1],
                c:oppCol,
                p:piece1
              }));
            }
          }
        }
      }
    });
  }

  // "Pincer"
  getPotentialPawnMoves([x,y])
  {
    let moves = super.getPotentialRookMoves([x,y]);
    this.addPawnCaptures(moves);
    return moves;
  }

  addRookCaptures(moves, byChameleon)
  {
    const color = this.turn;
    const oppCol = V.GetOppCol(color);
    const kp = this.kingPos[color];
    moves.forEach(m => {
      // Check piece-king rectangle (if any) corners for enemy pieces
      if (m.end.x == kp[0] || m.end.y == kp[1])
        return; //"flat rectangle"
      const corner1 = [m.end.x, kp[1]];
      const corner2 = [kp[0], m.end.y];
      for (let [i,j] of [corner1,corner2])
      {
        if (this.board[i][j] != V.EMPTY && this.getColor(i,j) == oppCol)
        {
          const piece = this.getPiece(i,j);
          if (!byChameleon || piece == V.ROOK)
          {
            m.vanish.push( new PiPo({
              x:i,
              y:j,
              p:piece,
              c:oppCol
            }) );
          }
        }
      }
    });
  }

  // Coordinator
  getPotentialRookMoves(sq)
  {
    let moves = super.getPotentialQueenMoves(sq);
    this.addRookCaptures(moves);
    return moves;
  }

  // Long-leaper
  getKnightCaptures(startSquare, byChameleon)
  {
    // Look in every direction for captures
    const steps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
    const color = this.turn;
    const oppCol = V.GetOppCol(color);
    let moves = [];
    const [x,y] = [startSquare[0],startSquare[1]];
    const piece = this.getPiece(x,y); //might be a chameleon!
    outerLoop:
    for (let step of steps)
    {
      let [i,j] = [x+step[0], y+step[1]];
      while (V.OnBoard(i,j) && this.board[i][j]==V.EMPTY)
      {
        i += step[0];
        j += step[1];
      }
      if (!V.OnBoard(i,j) || this.getColor(i,j)==color
        || (!!byChameleon && this.getPiece(i,j)!=V.KNIGHT))
      {
        continue;
      }
      // last(thing), cur(thing) : stop if "cur" is our color, or beyond board limits,
      // or if "last" isn't empty and cur neither. Otherwise, if cur is empty then
      // add move until cur square; if cur is occupied then stop if !!byChameleon and
      // the square not occupied by a leaper.
      let last = [i,j];
      let cur = [i+step[0],j+step[1]];
      let vanished = [ new PiPo({x:x,y:y,c:color,p:piece}) ];
      while (V.OnBoard(cur[0],cur[1]))
      {
        if (this.board[last[0]][last[1]] != V.EMPTY)
        {
          const oppPiece = this.getPiece(last[0],last[1]);
          if (!!byChameleon && oppPiece != V.KNIGHT)
            continue outerLoop;
          // Something to eat:
          vanished.push( new PiPo({x:last[0],y:last[1],c:oppCol,p:oppPiece}) );
        }
        if (this.board[cur[0]][cur[1]] != V.EMPTY)
        {
          if (this.getColor(cur[0],cur[1]) == color
            || this.board[last[0]][last[1]] != V.EMPTY) //TODO: redundant test
          {
            continue outerLoop;
          }
        }
        else
        {
          moves.push(new Move({
            appear: [ new PiPo({x:cur[0],y:cur[1],c:color,p:piece}) ],
            vanish: JSON.parse(JSON.stringify(vanished)), //TODO: required?
            start: {x:x,y:y},
            end: {x:cur[0],y:cur[1]}
          }));
        }
        last = [last[0]+step[0],last[1]+step[1]];
        cur = [cur[0]+step[0],cur[1]+step[1]];
      }
    }
    return moves;
  }

  // Long-leaper
  getPotentialKnightMoves(sq)
  {
    return super.getPotentialQueenMoves(sq).concat(this.getKnightCaptures(sq));
  }

  getPotentialBishopMoves([x,y])
  {
    let moves = super.getPotentialQueenMoves([x,y])
      .concat(this.getKnightCaptures([x,y],"asChameleon"));
    // No "king capture" because king cannot remain under check
    this.addPawnCaptures(moves, "asChameleon");
    this.addRookCaptures(moves, "asChameleon");
    this.addQueenCaptures(moves, "asChameleon");
    // Post-processing: merge similar moves, concatenating vanish arrays
    let mergedMoves = {};
    moves.forEach(m => {
      const key = m.end.x + V.size.x * m.end.y;
      if (!mergedMoves[key])
        mergedMoves[key] = m;
      else
      {
        for (let i=1; i<m.vanish.length; i++)
          mergedMoves[key].vanish.push(m.vanish[i]);
      }
    });
    // Finally return an array
    moves = [];
    Object.keys(mergedMoves).forEach(k => { moves.push(mergedMoves[k]); });
    return moves;
  }

  // Withdrawer
  addQueenCaptures(moves, byChameleon)
  {
    if (moves.length == 0)
      return;
    const [x,y] = [moves[0].start.x,moves[0].start.y];
    const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
    let capturingDirections = [];
    const color = this.turn;
    const oppCol = V.GetOppCol(color);
    adjacentSteps.forEach(step => {
      const [i,j] = [x+step[0],y+step[1]];
      if (V.OnBoard(i,j) && this.board[i][j] != V.EMPTY && this.getColor(i,j) == oppCol
        && (!byChameleon || this.getPiece(i,j) == V.QUEEN))
      {
        capturingDirections.push(step);
      }
    });
    moves.forEach(m => {
      const step = [
        m.end.x!=x ? (m.end.x-x)/Math.abs(m.end.x-x) : 0,
        m.end.y!=y ? (m.end.y-y)/Math.abs(m.end.y-y) : 0
      ];
      // NOTE: includes() and even _.isEqual() functions fail...
      // TODO: this test should be done only once per direction
      if (capturingDirections.some(dir =>
        { return (dir[0]==-step[0] && dir[1]==-step[1]); }))
      {
        const [i,j] = [x-step[0],y-step[1]];
        m.vanish.push(new PiPo({
          x:i,
          y:j,
          p:this.getPiece(i,j),
          c:oppCol
        }));
      }
    });
  }

  getPotentialQueenMoves(sq)
  {
    let moves = super.getPotentialQueenMoves(sq);
    this.addQueenCaptures(moves);
    return moves;
  }

  getPotentialImmobilizerMoves(sq)
  {
    // Immobilizer doesn't capture
    return super.getPotentialQueenMoves(sq);
  }

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

  // isAttacked() is OK because the immobilizer doesn't take

  isAttackedByPawn([x,y], colors)
  {
    // Square (x,y) must be surroundable by two enemy pieces,
    // and one of them at least should be a pawn (moving).
    const dirs = [ [1,0],[0,1] ];
    const steps = V.steps[V.ROOK];
    for (let dir of dirs)
    {
      const [i1,j1] = [x-dir[0],y-dir[1]]; //"before"
      const [i2,j2] = [x+dir[0],y+dir[1]]; //"after"
      if (V.OnBoard(i1,j1) && V.OnBoard(i2,j2))
      {
        if ((this.board[i1][j1]!=V.EMPTY && colors.includes(this.getColor(i1,j1))
          && this.board[i2][j2]==V.EMPTY)
            ||
          (this.board[i2][j2]!=V.EMPTY && colors.includes(this.getColor(i2,j2))
          && this.board[i1][j1]==V.EMPTY))
        {
          // Search a movable enemy pawn landing on the empty square
          for (let step of steps)
          {
            let [ii,jj] = (this.board[i1][j1]==V.EMPTY ? [i1,j1] : [i2,j2]);
            let [i3,j3] = [ii+step[0],jj+step[1]];
            while (V.OnBoard(i3,j3) && this.board[i3][j3]==V.EMPTY)
            {
              i3 += step[0];
              j3 += step[1];
            }
            if (V.OnBoard(i3,j3) && colors.includes(this.getColor(i3,j3))
              && this.getPiece(i3,j3) == V.PAWN && !this.isImmobilized([i3,j3]))
            {
              return true;
            }
          }
        }
      }
    }
    return false;
  }

  isAttackedByRook([x,y], colors)
  {
    // King must be on same column or row,
    // and a rook should be able to reach a capturing square
    // colors contains only one element, giving the oppCol and thus king position
    const sameRow = (x == this.kingPos[colors[0]][0]);
    const sameColumn = (y == this.kingPos[colors[0]][1]);
    if (sameRow || sameColumn)
    {
      // Look for the enemy rook (maximum 1)
      for (let i=0; i<V.size.x; i++)
      {
        for (let j=0; j<V.size.y; j++)
        {
          if (this.board[i][j] != V.EMPTY && colors.includes(this.getColor(i,j))
            && this.getPiece(i,j) == V.ROOK)
          {
            if (this.isImmobilized([i,j]))
              return false; //because only one rook
            // Can it reach a capturing square?
            // Easy but quite suboptimal way (TODO): generate all moves (turn is OK)
            const moves = this.getPotentialMovesFrom([i,j]);
            for (let move of moves)
            {
              if (sameRow && move.end.y == y || sameColumn && move.end.x == x)
                return true;
            }
          }
        }
      }
    }
    return false;
  }

  isAttackedByKnight([x,y], colors)
  {
    // Square (x,y) must be on same line as a knight,
    // and there must be empty square(s) behind.
    const steps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
    outerLoop:
    for (let step of steps)
    {
      const [i0,j0] = [x+step[0],y+step[1]];
      if (V.OnBoard(i0,j0) && this.board[i0][j0] == V.EMPTY)
      {
        // Try in opposite direction:
        let [i,j] = [x-step[0],y-step[1]];
        while (V.OnBoard(i,j))
        {
          while (V.OnBoard(i,j) && this.board[i][j] == V.EMPTY)
          {
            i -= step[0];
            j -= step[1];
          }
          if (V.OnBoard(i,j))
          {
            if (colors.includes(this.getColor(i,j)))
            {
              if (this.getPiece(i,j) == V.KNIGHT && !this.isImmobilized([i,j]))
                return true;
              continue outerLoop;
            }
            // [else] Our color, could be captured *if there was an empty space*
            if (this.board[i+step[0]][j+step[1]] != V.EMPTY)
              continue outerLoop;
            i -= step[0];
            j -= step[1];
          }
        }
      }
    }
    return false;
  }

  isAttackedByBishop([x,y], colors)
  {
    // We cheat a little here: since this function is used exclusively for king,
    // it's enough to check the immediate surrounding of the square.
    const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
    for (let step of adjacentSteps)
    {
      const [i,j] = [x+step[0],y+step[1]];
      if (V.OnBoard(i,j) && this.board[i][j]!=V.EMPTY
        && colors.includes(this.getColor(i,j)) && this.getPiece(i,j) == V.BISHOP)
      {
        return true; //bishops are never immobilized
      }
    }
    return false;
  }

  isAttackedByQueen([x,y], colors)
  {
    // Square (x,y) must be adjacent to a queen, and the queen must have
    // some free space in the opposite direction from (x,y)
    const adjacentSteps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
    for (let step of adjacentSteps)
    {
      const sq2 = [x+2*step[0],y+2*step[1]];
      if (V.OnBoard(sq2[0],sq2[1]) && this.board[sq2[0]][sq2[1]] == V.EMPTY)
      {
        const sq1 = [x+step[0],y+step[1]];
        if (this.board[sq1[0]][sq1[1]] != V.EMPTY
          && colors.includes(this.getColor(sq1[0],sq1[1]))
          && this.getPiece(sq1[0],sq1[1]) == V.QUEEN
          && !this.isImmobilized(sq1))
        {
          return true;
        }
      }
    }
    return false;
  }

  static get VALUES()
  {
    // TODO: totally experimental!
    return {
      'p': 1,
      'r': 2,
      'n': 5,
      'b': 3,
      'q': 3,
      'm': 5,
      'k': 1000
    };
  }

  static get SEARCH_DEPTH() { return 2; } //TODO?

  static GenRandInitFen()
  {
    let pieces = { "w": new Array(8), "b": new Array(8) };
    // Shuffle pieces on first and last rank
    for (let c of ["w","b"])
    {
      let positions = ArrayFun.range(8);
      // Get random squares for every piece, totally freely

      let randIndex = randInt(8);
      const bishop1Pos = positions[randIndex];
      positions.splice(randIndex, 1);

      randIndex = randInt(7);
      const bishop2Pos = positions[randIndex];
      positions.splice(randIndex, 1);

      randIndex = randInt(6);
      const knight1Pos = positions[randIndex];
      positions.splice(randIndex, 1);

      randIndex = randInt(5);
      const knight2Pos = positions[randIndex];
      positions.splice(randIndex, 1);

      randIndex = randInt(4);
      const queenPos = positions[randIndex];
      positions.splice(randIndex, 1);

      randIndex = randInt(3);
      const kingPos = positions[randIndex];
      positions.splice(randIndex, 1);

      randIndex = randInt(2);
      const rookPos = positions[randIndex];
      positions.splice(randIndex, 1);
      const immobilizerPos = positions[0];

      pieces[c][bishop1Pos] = 'b';
      pieces[c][bishop2Pos] = 'b';
      pieces[c][knight1Pos] = 'n';
      pieces[c][knight2Pos] = 'n';
      pieces[c][queenPos] = 'q';
      pieces[c][kingPos] = 'k';
      pieces[c][rookPos] = 'r';
      pieces[c][immobilizerPos] = 'm';
    }
    return pieces["b"].join("") +
      "/pppppppp/8/8/8/8/PPPPPPPP/" +
      pieces["w"].join("").toUpperCase() +
      " w 0";
  }

  getNotation(move)
  {
    const initialSquare = V.CoordsToSquare(move.start);
    const finalSquare = V.CoordsToSquare(move.end);
    let notation = undefined;
    if (move.appear[0].p == V.PAWN)
    {
      // Pawn: generally ambiguous short notation, so we use full description
      notation = "P" + initialSquare + finalSquare;
    }
    else if (move.appear[0].p == V.KING)
      notation = "K" + (move.vanish.length>1 ? "x" : "") + finalSquare;
    else
      notation = move.appear[0].p.toUpperCase() + finalSquare;
    if (move.vanish.length > 1 && move.appear[0].p != V.KING)
      notation += "X"; //capture mark (not describing what is captured...)
    return notation;
  }
}