import 'dart:math';

///
/// Convert decimal coordinate to degrees minutes seconds (DMS).
///
String convertDecimalToDMS(double decimalValue, {required bool isLatitude}) {
  bool isNegative = decimalValue < 0;
  double absoluteValue = decimalValue.abs();

  int degrees = absoluteValue.toInt();
  double minutesDecimal = (absoluteValue - degrees) * 60;
  int minutes = minutesDecimal.toInt();
  double secondsDecimal = (minutesDecimal - minutes) * 60;
  double seconds = double.parse(secondsDecimal.toStringAsFixed(2));

  String direction;
  if (isLatitude) {
    direction = isNegative ? 'S' : 'N';
  } else {
    direction = isNegative ? 'W' : 'E';
  }

  // return formatted string
  return '${degrees.abs()}° ${minutes.abs()}\' ${seconds.abs().toStringAsFixed(2)}" $direction';
}

///
/// Distance in kilometers between two location coordinates
///
double calculateDistance(double lat1, double lon1, double lat2, double lon2) {
  const R = 6371; // earth radius in kilometers

  // distance between latitudes and longitudes
  final dLat = _degreesToRadians(lat2 - lat1);
  final dLon = _degreesToRadians(lon2 - lon1);

  final a = sin(dLat / 2) * sin(dLat / 2) +
      cos(_degreesToRadians(lat1)) * cos(_degreesToRadians(lat2)) *
          sin(dLon / 2) * sin(dLon / 2);
  final c = 2 * atan2(sqrt(a), sqrt(1 - a));

  return R * c;
}

double _degreesToRadians(double degrees) {
  return degrees * pi / 180;
}