import 'dart:math';

String formatDuration(Duration duration) {
  final days = duration.inDays;
  final hours = duration.inHours.remainder(24);
  final minutes = duration.inMinutes.remainder(60);
  final seconds = duration.inSeconds.remainder(60);

  String plural(int thing) => thing == 1 ? '' : 's';

  if (days > 0) {
    return '$days day${plural(days)}, $hours hour${plural(hours)}';
  } else if (hours > 0) {
    return '$hours hour${plural(hours)}, $minutes minute${plural(minutes)}';
  } else if (minutes > 0) {
    return '$minutes minute${plural(minutes)}, $seconds second${plural(seconds)}';
  } else {
    return '$seconds second${plural(seconds)}';
  }
}

String formatDistance(int distanceInMeters) {
  if (distanceInMeters < 1000) {
    // If the distance is less than 1 kilometer, display it in meters.
    return '${distanceInMeters}m';
  } else {
    // If the distance is 1 kilometer or more, display it in kilometers and meters.
    final kilometers = distanceInMeters ~/ 1000; // Integer division to get whole kilometers.
    final meters = distanceInMeters % 1000; // Remainder to get the remaining meters.
    if (meters == 0) {
      // If there are no remaining meters, display only kilometers.
      return '${kilometers}km';
    } else {
      // If there are remaining meters, display both kilometers and meters.
      return '${kilometers}km ${meters}m';
    }
  }
}


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

double radiansToDegrees(double radians) {
  return radians * (180 / pi);
}

double bearingBetween(double lat1, double lon1, double lat2, double lon2) {
  var dLon = degreesToRadians(lon2 - lon1);
  var y = sin(dLon) * cos(degreesToRadians(lat2));
  var x = cos(degreesToRadians(lat1)) * sin(degreesToRadians(lat2)) -
      sin(degreesToRadians(lat1)) * cos(degreesToRadians(lat2)) * cos(dLon);
  var angle = atan2(y, x);
  return (radiansToDegrees(angle) + 360) % 360;
}

double distanceBetween(
    double lat1, double lon1, double lat2, double lon2, String unit) {
  const earthRadius = 6371; // in km
  // assuming earth is a perfect sphere(it's not)

  // Convert degrees to radians
  final lat1Rad = degreesToRadians(lat1);
  final lon1Rad = degreesToRadians(lon1);
  final lat2Rad = degreesToRadians(lat2);
  final lon2Rad = degreesToRadians(lon2);

  final dLat = lat2Rad - lat1Rad;
  final dLon = lon2Rad - lon1Rad;

  // Haversine formula
  final a = pow(sin(dLat / 2), 2) +
      cos(lat1Rad) * cos(lat2Rad) * pow(sin(dLon / 2), 2);
  final c = 2 * atan2(sqrt(a), sqrt(1 - a));

  final distance = earthRadius * c;

  return toRequestedUnit(unit, distance);

  // return distance; // in km
}

double toRequestedUnit(String unit, double distanceInKm) {
  switch (unit) {
    case 'kilometers':
      return distanceInKm;
    case 'meters':
      return distanceInKm * 1000;
    case 'miles':
      return (distanceInKm * 1000) / 1609.344;
    case 'yards':
      return distanceInKm * 1093.61;
    case '':
      return distanceInKm;
  }
  return distanceInKm;
}