import 'dart:math';

/// أدوات حساب المسافات والاتجاهات الجغرافية
class GeoUtils {
  static const double _earthRadiusMeters = 6371000;

  /// Haversine formula - حساب المسافة بين نقطتين
  static double haversineDistance(
    double lat1, double lng1,
    double lat2, double lng2,
  ) {
    final dLat = _toRad(lat2 - lat1);
    final dLng = _toRad(lng2 - lng1);
    final a = sin(dLat / 2) * sin(dLat / 2) +
        cos(_toRad(lat1)) * cos(_toRad(lat2)) *
        sin(dLng / 2) * sin(dLng / 2);
    final c = 2 * atan2(sqrt(a), sqrt(1 - a));
    return _earthRadiusMeters * c;
  }

  /// Calculate bearing between two points (degrees from north)
  static double bearing(
    double lat1, double lng1,
    double lat2, double lng2,
  ) {
    final dLng = _toRad(lng2 - lng1);
    final y = sin(dLng) * cos(_toRad(lat2));
    final x = cos(_toRad(lat1)) * sin(_toRad(lat2)) -
        sin(_toRad(lat1)) * cos(_toRad(lat2)) * cos(dLng);
    return (_toDeg(atan2(y, x)) + 360) % 360;
  }

  /// Calculate speed between two points (m/s)
  static double speed(
    double lat1, double lng1, DateTime t1,
    double lat2, double lng2, DateTime t2,
  ) {
    final dist = haversineDistance(lat1, lng1, lat2, lng2);
    final seconds = t2.difference(t1).inMilliseconds / 1000.0;
    if (seconds <= 0) return 0;
    return dist / seconds;
  }

  static double _toRad(double deg) => deg * pi / 180;
  static double _toDeg(double rad) => rad * 180 / pi;
}