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

import { ChessRules, Move, PiPo } from "@/base_rules";

export class CheckeredRules extends ChessRules {

  static get Options() {
    return Object.assign(
      {},
      ChessRules.Options,
      {
        check: [
          {
            label: "With switch",
            defaut: true,
            variable: "switch"
          }
        ]
      }
    );
  }

  static AbbreviateOptions(opts) {
    return (!opts["switch"] ? "NS" : "");
  }

  static board2fen(b) {
    const checkered_codes = {
      p: "s",
      q: "t",
      r: "u",
      b: "c",
      n: "o"
    };
    if (b[0] == "c") return checkered_codes[b[1]];
    return ChessRules.board2fen(b);
  }

  static fen2board(f) {
    // Tolerate upper-case versions of checkered pieces (why not?)
    const checkered_pieces = {
      s: "p",
      S: "p",
      t: "q",
      T: "q",
      u: "r",
      U: "r",
      c: "b",
      C: "b",
      o: "n",
      O: "n"
    };
    if (Object.keys(checkered_pieces).includes(f))
      return "c" + checkered_pieces[f];
    return ChessRules.fen2board(f);
  }

  static get PIECES() {
    return ChessRules.PIECES.concat(["s", "t", "u", "c", "o"]);
  }

  getPpath(b) {
    return (b[0] == "c" ? "Checkered/" : "") + b;
  }

  setOtherVariables(fen) {
    super.setOtherVariables(fen);
    // Local stack of non-capturing checkered moves:
    this.cmoves = [];
    const cmove = V.ParseFen(fen).cmove;
    if (cmove == "-") this.cmoves.push(null);
    else {
      this.cmoves.push({
        start: ChessRules.SquareToCoords(cmove.substr(0, 2)),
        end: ChessRules.SquareToCoords(cmove.substr(2))
      });
    }
    // Stage 1: as Checkered2. Stage 2: checkered pieces are autonomous
    const stageInfo = V.ParseFen(fen).stage;
    this.stage = parseInt(stageInfo[0], 10);
    this.canSwitch = (this.stage == 1 && stageInfo[1] != '-');
    this.sideCheckered = (this.stage == 2 ? stageInfo[1] : undefined);
  }

  static IsGoodFen(fen) {
    if (!ChessRules.IsGoodFen(fen)) return false;
    const fenParts = fen.split(" ");
    if (fenParts.length != 7) return false;
    if (fenParts[5] != "-" && !fenParts[5].match(/^([a-h][1-8]){2}$/))
      return false;
    if (!fenParts[6].match(/^[12][wb-]?$/)) return false;
    return true;
  }

  static IsGoodFlags(flags) {
    // 4 for castle + 16 for pawns
    return !!flags.match(/^[a-z]{4,4}[01]{16,16}$/);
  }

  setFlags(fenflags) {
    super.setFlags(fenflags); //castleFlags
    this.pawnFlags = {
      w: [...Array(8)], //pawns can move 2 squares?
      b: [...Array(8)]
    };
    const flags = fenflags.substr(4); //skip first 4 letters, for castle
    for (let c of ["w", "b"]) {
      for (let i = 0; i < 8; i++)
        this.pawnFlags[c][i] = flags.charAt((c == "w" ? 0 : 8) + i) == "1";
    }
  }

  aggregateFlags() {
    return [this.castleFlags, this.pawnFlags];
  }

  disaggregateFlags(flags) {
    this.castleFlags = flags[0];
    this.pawnFlags = flags[1];
  }

  getEpSquare(moveOrSquare) {
    // At stage 2, all pawns can be captured en-passant
    if (
      this.stage == 2 ||
      typeof moveOrSquare !== "object" ||
      (moveOrSquare.appear.length > 0 && moveOrSquare.appear[0].c != 'c')
    )
      return super.getEpSquare(moveOrSquare);
    // Checkered or switch move: no en-passant
    return undefined;
  }

  getCmove(move) {
    // No checkered move to undo at stage 2:
    if (this.stage == 1 && move.vanish.length == 1 && move.appear[0].c == "c")
      return { start: move.start, end: move.end };
    return null;
  }

  canTake([x1, y1], [x2, y2]) {
    const color1 = this.getColor(x1, y1);
    const color2 = this.getColor(x2, y2);
    if (this.stage == 2) {
      // Black & White <-- takes --> Checkered
      const color1 = this.getColor(x1, y1);
      const color2 = this.getColor(x2, y2);
      return color1 != color2 && [color1, color2].includes('c');
    }
    // Checkered aren't captured
    return (
      color1 != color2 &&
      color2 != "c" &&
      (color1 != "c" || color2 != this.turn)
    );
  }

  getPotentialMovesFrom([x, y], noswitch) {
    let standardMoves = super.getPotentialMovesFrom([x, y]);
    if (this.stage == 1) {
      const color = this.turn;
      // Post-processing: apply "checkerization" of standard moves
      const lastRank = (color == "w" ? 0 : 7);
      let moves = [];
      // King is treated differently: it never turn checkered
      if (this.getPiece(x, y) == V.KING) {
        // If at least one checkered piece, allow switching:
        if (
          this.canSwitch && !noswitch &&
          this.board.some(b => b.some(cell => cell[0] == 'c'))
        ) {
          const oppCol = V.GetOppCol(color);
          moves.push(
            new Move({
              start: { x: x, y: y },
              end: { x: this.kingPos[oppCol][0], y: this.kingPos[oppCol][1] },
              appear: [],
              vanish: []
            })
          );
        }
        return standardMoves.concat(moves);
      }
      standardMoves.forEach(m => {
        if (m.vanish[0].p == V.PAWN) {
          if (
            Math.abs(m.end.x - m.start.x) == 2 &&
            !this.pawnFlags[this.turn][m.start.y]
          ) {
            return; //skip forbidden 2-squares jumps
          }
          if (
            this.board[m.end.x][m.end.y] == V.EMPTY &&
            m.vanish.length == 2 &&
            this.getColor(m.start.x, m.start.y) == "c"
          ) {
            return; //checkered pawns cannot take en-passant
          }
        }
        if (m.vanish.length == 1)
          // No capture
          moves.push(m);
        else {
          // A capture occured (m.vanish.length == 2)
          m.appear[0].c = "c";
          moves.push(m);
          if (
            // Avoid promotions (already treated):
            m.appear[0].p != m.vanish[1].p &&
            (m.vanish[0].p != V.PAWN || m.end.x != lastRank)
          ) {
            // Add transformation into captured piece
            let m2 = JSON.parse(JSON.stringify(m));
            m2.appear[0].p = m.vanish[1].p;
            moves.push(m2);
          }
        }
      });
      return moves;
    }
    return standardMoves;
  }

  getPotentialPawnMoves([x, y]) {
    const color = this.getColor(x, y);
    if (this.stage == 2) {
      const saveTurn = this.turn;
      if (this.sideCheckered == this.turn) {
        // Cannot change PawnSpecs.bidirectional, so cheat a little:
        this.turn = 'w';
        const wMoves = super.getPotentialPawnMoves([x, y]);
        this.turn = 'b';
        const bMoves = super.getPotentialPawnMoves([x, y]);
        this.turn = saveTurn;
        return wMoves.concat(bMoves);
      }
      // Playing with both colors:
      this.turn = color;
      const moves = super.getPotentialPawnMoves([x, y]);
      this.turn = saveTurn;
      return moves;
    }
    let moves = super.getPotentialPawnMoves([x, y]);
    // Post-process: set right color for checkered moves
    if (color == 'c') {
      moves.forEach(m => {
        m.appear[0].c = 'c'; //may be done twice if capture
        m.vanish[0].c = 'c';
      });
    }
    return moves;
  }

  canIplay(side, [x, y]) {
    if (this.stage == 2) {
      const color = this.getColor(x, y);
      return (
        this.turn == this.sideCheckered
          ? color == 'c'
          : ['w', 'b'].includes(color)
      );
    }
    return side == this.turn && [side, "c"].includes(this.getColor(x, y));
  }

  // Does m2 un-do m1 ? (to disallow undoing checkered moves)
  oppositeMoves(m1, m2) {
    return (
      !!m1 &&
      m2.appear[0].c == "c" &&
      m2.appear.length == 1 &&
      m2.vanish.length == 1 &&
      m1.start.x == m2.end.x &&
      m1.end.x == m2.start.x &&
      m1.start.y == m2.end.y &&
      m1.end.y == m2.start.y
    );
  }

  filterValid(moves) {
    if (moves.length == 0) return [];
    const color = this.turn;
    const oppCol = V.GetOppCol(color);
    const L = this.cmoves.length; //at least 1: init from FEN
    const stage = this.stage; //may change if switch
    return moves.filter(m => {
      // Checkered cannot be under check (no king)
      if (stage == 2 && this.sideCheckered == color) return true;
      this.play(m);
      let res = true;
      if (stage == 1) {
        if (m.appear.length == 0 && m.vanish.length == 0) {
          // Special "switch" move: kings must not be attacked by checkered.
          // Not checking for oppositeMoves here: checkered are autonomous
          res = (
            !this.isAttacked(this.kingPos['w'], ['c']) &&
            !this.isAttacked(this.kingPos['b'], ['c']) &&
            this.getAllPotentialMoves().length > 0
          );
        }
        else res = !this.oppositeMoves(this.cmoves[L - 1], m);
      }
      if (res && m.appear.length > 0) res = !this.underCheck(color);
      // At stage 2, side with B & W can be undercheck with both kings:
      if (res && stage == 2) res = !this.underCheck(oppCol);
      this.undo(m);
      return res;
    });
  }

  getAllPotentialMoves() {
    const color = this.turn;
    const oppCol = V.GetOppCol(color);
    let potentialMoves = [];
    for (let i = 0; i < V.size.x; i++) {
      for (let j = 0; j < V.size.y; j++) {
        const colIJ = this.getColor(i, j);
        if (
          this.board[i][j] != V.EMPTY &&
          (
            (this.stage == 1 && colIJ != oppCol) ||
            (this.stage == 2 &&
              (
                (this.sideCheckered == color && colIJ == 'c') ||
                (this.sideCheckered != color && ['w', 'b'].includes(colIJ))
              )
            )
          )
        ) {
          Array.prototype.push.apply(
            potentialMoves,
            this.getPotentialMovesFrom([i, j])
          );
        }
      }
    }
    return potentialMoves;
  }

  atLeastOneMove() {
    const color = this.turn;
    const oppCol = V.GetOppCol(color);
    for (let i = 0; i < V.size.x; i++) {
      for (let j = 0; j < V.size.y; j++) {
        const colIJ = this.getColor(i, j);
        if (
          this.board[i][j] != V.EMPTY &&
          (
            (this.stage == 1 && colIJ != oppCol) ||
            (this.stage == 2 &&
              (
                (this.sideCheckered == color && colIJ == 'c') ||
                (this.sideCheckered != color && ['w', 'b'].includes(colIJ))
              )
            )
          )
        ) {
          const moves = this.getPotentialMovesFrom([i, j], "noswitch");
          if (moves.length > 0) {
            for (let k = 0; k < moves.length; k++)
              if (this.filterValid([moves[k]]).length > 0) return true;
          }
        }
      }
    }
    return false;
  }

  // colors: array, 'w' and 'c' or 'b' and 'c' at stage 1,
  // just 'c' (or unused) at stage 2
  isAttacked(sq, colors) {
    if (!Array.isArray(colors)) colors = [colors];
    return (
      this.isAttackedByPawn(sq, colors) ||
      this.isAttackedByRook(sq, colors) ||
      this.isAttackedByKnight(sq, colors) ||
      this.isAttackedByBishop(sq, colors) ||
      this.isAttackedByQueen(sq, colors) ||
      this.isAttackedByKing(sq, colors)
    );
  }

  isAttackedByPawn([x, y], colors) {
    for (let c of colors) {
      let shifts = [];
      if (this.stage == 1) {
        const color = (c == "c" ? this.turn : c);
        shifts = [color == "w" ? 1 : -1];
      }
      else {
        // Stage 2: checkered pawns are bidirectional
        if (c == 'c') shifts = [-1, 1];
        else shifts = [c == "w" ? 1 : -1];
      }
      for (let pawnShift of shifts) {
        if (x + pawnShift >= 0 && x + pawnShift < 8) {
          for (let i of [-1, 1]) {
            if (
              y + i >= 0 &&
              y + i < 8 &&
              this.getPiece(x + pawnShift, y + i) == V.PAWN &&
              this.getColor(x + pawnShift, y + i) == c
            ) {
              return true;
            }
          }
        }
      }
    }
    return false;
  }

  isAttackedBySlideNJump([x, y], colors, piece, steps, oneStep) {
    for (let step of steps) {
      let rx = x + step[0],
          ry = y + step[1];
      while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
        rx += step[0];
        ry += step[1];
      }
      if (
        V.OnBoard(rx, ry) &&
        this.getPiece(rx, ry) === piece &&
        colors.includes(this.getColor(rx, ry))
      ) {
        return true;
      }
    }
    return false;
  }

  isAttackedByRook(sq, colors) {
    return this.isAttackedBySlideNJump(sq, colors, V.ROOK, V.steps[V.ROOK]);
  }

  isAttackedByKnight(sq, colors) {
    return this.isAttackedBySlideNJump(
      sq, colors, V.KNIGHT, V.steps[V.KNIGHT], "oneStep");
  }

  isAttackedByBishop(sq, colors) {
    return this.isAttackedBySlideNJump(
      sq, colors, V.BISHOP, V.steps[V.BISHOP]);
  }

  isAttackedByQueen(sq, colors) {
    return this.isAttackedBySlideNJump(
      sq, colors, V.QUEEN, V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
  }

  isAttackedByKing(sq, colors) {
    return this.isAttackedBySlideNJump(
      sq, colors, V.KING,
      V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep"
    );
  }

  underCheck(color) {
    if (this.stage == 1)
      return this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"]);
    if (color == this.sideCheckered) return false;
    return (
      this.isAttacked(this.kingPos['w'], ["c"]) ||
      this.isAttacked(this.kingPos['b'], ["c"])
    );
  }

  getCheckSquares() {
    const color = this.turn;
    if (this.stage == 1) {
      // Artifically change turn, for checkered pawns
      this.turn = V.GetOppCol(color);
      const kingAttacked =
        this.isAttacked(
          this.kingPos[color],
          [V.GetOppCol(color), "c"]
        );
      let res = kingAttacked
        ? [JSON.parse(JSON.stringify(this.kingPos[color]))]
        : [];
      this.turn = color;
      return res;
    }
    if (this.sideCheckered == color) return [];
    let res = [];
    for (let c of ['w', 'b']) {
      if (this.isAttacked(this.kingPos[c], ['c']))
        res.push(JSON.parse(JSON.stringify(this.kingPos[c])));
    }
    return res;
  }

  play(move) {
    move.flags = JSON.stringify(this.aggregateFlags());
    this.epSquares.push(this.getEpSquare(move));
    V.PlayOnBoard(this.board, move);
    if (move.appear.length > 0 || move.vanish.length > 0)
    {
      this.turn = V.GetOppCol(this.turn);
      this.movesCount++;
    }
    this.postPlay(move);
  }

  postPlay(move) {
    if (move.appear.length == 0 && move.vanish.length == 0) {
      this.stage = 2;
      this.sideCheckered = this.turn;
    }
    else {
      const c = move.vanish[0].c;
      const piece = move.vanish[0].p;
      if (piece == V.KING) {
        this.kingPos[c][0] = move.appear[0].x;
        this.kingPos[c][1] = move.appear[0].y;
      }
      super.updateCastleFlags(move, piece);
      if (
        [1, 6].includes(move.start.x) &&
        move.vanish[0].p == V.PAWN &&
        Math.abs(move.end.x - move.start.x) == 2
      ) {
        // This move turns off a 2-squares pawn flag
        this.pawnFlags[move.start.x == 6 ? "w" : "b"][move.start.y] = false;
      }
    }
    this.cmoves.push(this.getCmove(move));
  }

  undo(move) {
    this.epSquares.pop();
    this.disaggregateFlags(JSON.parse(move.flags));
    V.UndoOnBoard(this.board, move);
    if (move.appear.length > 0 || move.vanish.length > 0)
    {
      this.turn = V.GetOppCol(this.turn);
      this.movesCount--;
    }
    this.postUndo(move);
  }

  postUndo(move) {
    if (move.appear.length == 0 && move.vanish.length == 0) this.stage = 1;
    else super.postUndo(move);
    this.cmoves.pop();
  }

  getCurrentScore() {
    const color = this.turn;
    if (this.stage == 1) {
      if (this.atLeastOneMove()) return "*";
      // Artifically change turn, for checkered pawns
      this.turn = V.GetOppCol(this.turn);
      const res =
        this.isAttacked(this.kingPos[color], [V.GetOppCol(color), "c"])
          ? color == "w"
            ? "0-1"
            : "1-0"
          : "1/2";
      this.turn = V.GetOppCol(this.turn);
      return res;
    }
    // Stage == 2:
    if (this.sideCheckered == this.turn) {
      // Check if remaining checkered pieces: if none, I lost
      if (this.board.some(b => b.some(cell => cell[0] == 'c'))) {
        if (!this.atLeastOneMove()) return "1/2";
        return "*";
      }
      return color == 'w' ? "0-1" : "1-0";
    }
    if (this.atLeastOneMove()) return "*";
    let res = this.isAttacked(this.kingPos['w'], ["c"]);
    if (!res) res = this.isAttacked(this.kingPos['b'], ["c"]);
    if (res) return color == 'w' ? "0-1" : "1-0";
    return "1/2";
  }

  evalPosition() {
    let evaluation = 0;
    // Just count material for now, considering checkered neutral at stage 1.
    const baseSign = (this.turn == 'w' ? 1 : -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) {
          const sqColor = this.getColor(i, j);
          if (this.stage == 1) {
            if (["w", "b"].includes(sqColor)) {
              const sign = sqColor == "w" ? 1 : -1;
              evaluation += sign * V.VALUES[this.getPiece(i, j)];
            }
          }
          else {
            const sign =
              this.sideCheckered == this.turn
                ? (sqColor == 'c' ? 1 : -1) * baseSign
                : (sqColor == 'c' ? -1 : 1) * baseSign;
            evaluation += sign * V.VALUES[this.getPiece(i, j)];
          }
        }
      }
    }
    return evaluation;
  }

  static GenRandInitFen(options) {
    const baseFen = ChessRules.GenRandInitFen(options);
    return (
      // Add 16 pawns flags + empty cmove + stage == 1:
      baseFen.slice(0, -2) + "1111111111111111 - - 1" +
      (!options["switch"] ? '-' : "")
    );
  }

  static ParseFen(fen) {
    const fenParts = fen.split(" ");
    return Object.assign(
      ChessRules.ParseFen(fen),
      {
        cmove: fenParts[5],
        stage: fenParts[6]
      }
    );
  }

  getCmoveFen() {
    const L = this.cmoves.length;
    return (
      !this.cmoves[L - 1]
        ? "-"
        : ChessRules.CoordsToSquare(this.cmoves[L - 1].start) +
          ChessRules.CoordsToSquare(this.cmoves[L - 1].end)
    );
  }

  getStageFen() {
    if (this.stage == 1) return "1" + (!this.canSwitch ? '-' : "");
    // Stage == 2:
    return "2" + this.sideCheckered;
  }

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

  getFenForRepeat() {
    return (
      super.getFenForRepeat() + "_" +
      this.getCmoveFen() + "_" + this.getStageFen()
    );
  }

  getFlagsFen() {
    let fen = super.getFlagsFen();
    // Add pawns flags
    for (let c of ["w", "b"])
      for (let i = 0; i < 8; i++) fen += (this.pawnFlags[c][i] ? "1" : "0");
    return fen;
  }

  static get SEARCH_DEPTH() {
    return 2;
  }

  getComputerMove() {
    // To simplify, prevent the bot from switching (TODO...)
    return (
      super.getComputerMove(
        this.getAllValidMoves().filter(m => m.appear.length > 0)
      )
    );
  }

  getNotation(move) {
    if (move.appear.length == 0 && move.vanish.length == 0) return "S";
    if (move.appear.length == 2) {
      // Castle
      if (move.end.y < move.start.y) return "0-0-0";
      return "0-0";
    }

    const finalSquare = V.CoordsToSquare(move.end);
    const piece = this.getPiece(move.start.x, move.start.y);
    let notation = "";
    if (piece == V.PAWN) {
      if (move.vanish.length > 1) {
        const startColumn = V.CoordToColumn(move.start.y);
        notation = startColumn + "x" + finalSquare;
      } else notation = finalSquare;
    } else {
      // Piece movement
      notation =
        piece.toUpperCase() +
        (move.vanish.length > 1 ? "x" : "") +
        finalSquare;
    }
    if (move.appear[0].p != move.vanish[0].p)
      notation += "=" + move.appear[0].p.toUpperCase();
    return notation;
  }

};