/// Outcome of evaluating a user's numeric answer against pipeline rules.
enum BranchOutcome {
  /// Answer matched the expected value (within tolerance when applicable).
  match,

  /// Answer was on the positive side of the scale (e.g. preference toward +10).
  preferHigh,

  /// Answer was on the negative side of the scale.
  preferLow,

  /// Numeric answer was close but not exact.
  close,

  /// Answer was far from the target.
  miss,
}

class BranchDecision {
  const BranchDecision._();

  /// Exact match for discrete choices encoded as integers.
  static BranchOutcome discreteChoice({
    required num userResponse,
    required num correctAnswer,
  }) {
    if (userResponse.round() == correctAnswer.round()) {
      return BranchOutcome.match;
    }
    return userResponse.sign >= 0 ? BranchOutcome.preferHigh : BranchOutcome.preferLow;
  }

  /// Compares a population or temperature estimate with tolerance.
  static BranchOutcome numericEstimate({
    required num userResponse,
    required num correctAnswer,
    int tolerance = 2,
  }) {
    final int delta = (userResponse.round() - correctAnswer.round()).abs();
    if (delta == 0) {
      return BranchOutcome.match;
    }
    if (delta <= tolerance) {
      return BranchOutcome.close;
    }
    return BranchOutcome.miss;
  }

  /// Yes/no questions encoded as +10 (yes) vs -10 (no) on the slider.
  static BranchOutcome yesNo({
    required num userResponse,
    required num correctAnswer,
  }) {
    final bool userYes = userResponse > 0;
    final bool correctYes = correctAnswer > 0;
    if (userYes == correctYes) {
      return BranchOutcome.match;
    }
    return BranchOutcome.miss;
  }

  /// Interprets slider position as a preference (geography vs weather track).
  static BranchOutcome trackPreference(num userResponse) {
    if (userResponse >= 3) {
      return BranchOutcome.preferHigh;
    }
    if (userResponse <= -3) {
      return BranchOutcome.preferLow;
    }
    return BranchOutcome.close;
  }
}