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

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

export class AtomicRules extends ChessRules {

  static get Options() {
    return {
      check: [
        {
          label: "Balanced",
          defaut: false,
          variable: "balanced"
        }
      ],
      select: ChessRules.Options.select
    };
  }

  static AbbreviateOptions(opts) {
    return opts["balanced"] ? 'B' : '';
  }

  static GenRandInitFen(options) {
    return ChessRules.GenRandInitFen(options) + (options.balanced ? " B" : "");
  }

  setOtherVariables(fen) {
    super.setOtherVariables(fen);
    this.balanced = !!V.ParseFen(fen).balanced;
  }

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

  static IsGoodFen(fen) {
    if (!ChessRules.IsGoodFen(fen)) return false;
    const balanced = V.ParseFen(fen).balanced;
    return (!balanced || balanced == 'B');
  }

  getFen() {
    return super.getFen() + (this.balanced ? " B" : "");
  }

  hoverHighlight([x, y]) {
    return this.balanced && this.movesCount == 0 && [1, 6].includes(x);
  }

  canIplay(side, [x, y]) {
    if (this.balanced && this.movesCount == 0)
      return (this.turn == side && this.getPiece(x, y) == V.PAWN);
    return super.canIplay(side, [x, y]);
  }

  doClick(square) {
    if (!this.balanced || this.movesCount >= 1) return null;
    const [x, y] = [square[0], square[1]];
    if (![1, 6].includes(x)) return null;
    return new Move({
      appear: [],
      vanish: [
        new PiPo({
          x: x,
          y: y,
          c: this.getColor(x, y),
          p: V.PAWN
        })
      ],
      start: { x: x, y: y },
      end: { x: x, y: y }
    });
  }

  getPotentialMovesFrom([x, y]) {
    if (this.balanced && this.movesCount == 0) {
      if ([1, 6].includes(x)) {
        const c = this.getColor(x, y);
        return [
          new Move({
            appear: [],
            vanish: [
              new PiPo({ x: x, y: y, p: V.PAWN, c: c })
            ],
            start: { x: x, y: y },
            end: { x: x, y: y }
          })
        ];
      }
      return [];
    }

    let moves = super.getPotentialMovesFrom([x, y]);
    if (this.getPiece(x, y) == V.PAWN) {
      // Promotions by captures can be reduced to only one deterministic
      // move (because of the explosion).
      moves = moves.filter(m => {
        return (
          m.vanish.length == 1 ||
          [V.PAWN, V.QUEEN].includes(m.appear[0].p)
        );
      });
    }
    // Handle explosions
    moves.forEach(m => {
      // NOTE: if vanish.length==2 and appear.length==2, this is castle
      if (m.vanish.length > 1 && m.appear.length <= 1) {
        // Explosion! (TODO?: drop moves which explode our king here)
        let steps = [
          [-1, -1],
          [-1, 0],
          [-1, 1],
          [0, -1],
          [0, 1],
          [1, -1],
          [1, 0],
          [1, 1]
        ];
        for (let step of steps) {
          let x = m.end.x + step[0];
          let y = m.end.y + step[1];
          if (
            V.OnBoard(x, y) &&
            this.board[x][y] != V.EMPTY &&
            this.getPiece(x, y) != V.PAWN
          ) {
            m.vanish.push(
              new PiPo({
                p: this.getPiece(x, y),
                c: this.getColor(x, y),
                x: x,
                y: y
              })
            );
          }
        }
        m.end = { x: m.appear[0].x, y: m.appear[0].y };
        m.appear.pop(); //Nothin appears in this case
      }
    });
    return moves;
  }

  getPotentialKingMoves([x, y]) {
    // King cannot capture:
    let moves = [];
    const steps = V.steps[V.ROOK].concat(V.steps[V.BISHOP]);
    for (let step of steps) {
      const i = x + step[0];
      const j = y + step[1];
      if (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY)
        moves.push(this.getBasicMove([x, y], [i, j]));
    }
    return moves.concat(this.getCastleMoves([x, y]));
  }

  isAttacked(sq, color) {
    if (
      this.getPiece(sq[0], sq[1]) == V.KING &&
      this.isAttackedByKing(sq, color)
    ) {
      // A king next to the enemy king is immune to attacks
      return false;
    }
    return (
      this.isAttackedByPawn(sq, color) ||
      this.isAttackedByRook(sq, color) ||
      this.isAttackedByKnight(sq, color) ||
      this.isAttackedByBishop(sq, color) ||
      this.isAttackedByQueen(sq, color)
      // No "attackedByKing": it cannot take
    );
  }

  postPlay(move) {
    super.postPlay(move);
    // NOTE: (harmless) condition on movesCount for Atomic2
    if (move.appear.length == 0 && this.movesCount >= 2) {
      // Capture
      const firstRank = { w: 7, b: 0 };
      for (let c of ["w", "b"]) {
        // Did we explode king of color c ? (TODO: remove move earlier)
        if (
          Math.abs(this.kingPos[c][0] - move.end.x) <= 1 &&
          Math.abs(this.kingPos[c][1] - move.end.y) <= 1
        ) {
          this.kingPos[c] = [-1, -1];
          this.castleFlags[c] = [8, 8];
        }
        else {
          // Now check if init rook(s) exploded
          if (Math.abs(move.end.x - firstRank[c]) <= 1) {
            if (Math.abs(move.end.y - this.castleFlags[c][0]) <= 1)
              this.castleFlags[c][0] = 8;
            if (Math.abs(move.end.y - this.castleFlags[c][1]) <= 1)
              this.castleFlags[c][1] = 8;
          }
        }
      }
    }
  }

  postUndo(move) {
    super.postUndo(move);
    const c = this.turn;
    const oppCol = V.GetOppCol(c);
    // NOTE: condition on movesCount for balanced setting
    if (
      this.movesCount >= 1 &&
      [this.kingPos[c][0], this.kingPos[oppCol][0]].some(e => e < 0)
    ) {
      // There is a chance that last move blowed some king away..
      for (let psq of move.vanish) {
        if (psq.p == "k")
          this.kingPos[psq.c == c ? c : oppCol] = [psq.x, psq.y];
      }
    }
  }

  underCheck(color) {
    const oppCol = V.GetOppCol(color);
    let res = undefined;
    // If our king disappeared, move is not valid
    if (this.kingPos[color][0] < 0) res = true;
    // If opponent king disappeared, move is valid
    else if (this.kingPos[oppCol][0] < 0) res = false;
    // Otherwise, if we remain under check, move is not valid
    else res = this.isAttacked(this.kingPos[color], oppCol);
    return res;
  }

  getCheckSquares() {
    const color = this.turn;
    let res = [];
    if (
      this.kingPos[color][0] >= 0 && //king might have exploded
      this.isAttacked(this.kingPos[color], V.GetOppCol(color))
    ) {
      res = [JSON.parse(JSON.stringify(this.kingPos[color]))];
    }
    return res;
  }

  getCurrentScore() {
    const color = this.turn;
    const kp = this.kingPos[color];
    if (kp[0] < 0)
      // King disappeared
      return color == "w" ? "0-1" : "1-0";
    if (this.atLeastOneMove()) return "*";
    if (!this.isAttacked(kp, V.GetOppCol(color))) return "1/2";
    return color == "w" ? "0-1" : "1-0"; //checkmate
  }

  getNotation(move) {
    if (move.appear.length == 0 && move.vanish.length == 1)
      // First move in game (balanced == true)
      return V.CoordsToSquare(move.start) + "X";
    return super.getNotation(move);
  }

};