import 'dart:math' as math;

class LocationCalculations {
  /// Calculate distance between two points using Haversine formula
  /// Returns distance in kilometers
  static double calculateDistanceKm(
      double startLatitude,
      double startLongitude,
      double endLatitude,
      double endLongitude,
      ) {
    const double earthRadius = 6371; // Earth's radius in kilometers

    // Convert degrees to radians
    double startLatRad = _degreesToRadians(startLatitude);
    double startLonRad = _degreesToRadians(startLongitude);
    double endLatRad = _degreesToRadians(endLatitude);
    double endLonRad = _degreesToRadians(endLongitude);

    // Calculate differences
    double deltaLat = endLatRad - startLatRad;
    double deltaLon = endLonRad - startLonRad;

    // Haversine formula
    double a = math.sin(deltaLat / 2) * math.sin(deltaLat / 2) +
        math.cos(startLatRad) * math.cos(endLatRad) *
            math.sin(deltaLon / 2) * math.sin(deltaLon / 2);

    double c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a));

    // Calculate distance
    double distance = earthRadius * c;

    return distance;
  }

  /// Calculate distance in meters
  static double calculateDistanceMeters(
      double startLatitude,
      double startLongitude,
      double endLatitude,
      double endLongitude,
      ) {
    return calculateDistanceKm(
      startLatitude,
      startLongitude,
      endLatitude,
      endLongitude,
    ) * 1000; // Convert km to meters
  }

  /// Convert degrees to radians
  static double _degreesToRadians(double degrees) {
    return degrees * (math.pi / 180);
  }

  /// Calculate estimated time based on distance (assuming average speed of 40 km/h in city)
  static double calculateEstimatedTimeMinutes(double distanceKm, {double avgSpeedKmh = 40.0}) {
    return (distanceKm / avgSpeedKmh) * 60; // Convert hours to minutes
  }
}