flutter_google_track_and_trace/lib/src/directions_repository.dart

part of flutter_google_track_and_trace;

enum TravelMode { driving, walking, bicycling, transit }

class DirectionsRepository {
  static const String _baseUrl = '/maps/api/directions/json';

  /// get the route between the two coordinates
  Future<Directions?> getDirections({
    required LatLng origin,
    required LatLng destination,
    required TravelMode mode,
    required String key,
  }) async {
    try {
      var queryParameters = {
        'origin': '${origin.latitude},${origin.longitude}',
        'destination': '${destination.latitude},${destination.longitude}',
        'key': key, // get this key from the controller
        'mode': <TravelMode, String>{
          TravelMode.driving: 'driving',
          TravelMode.bicycling: 'bicycling',
          TravelMode.transit: 'transit',
          TravelMode.walking: 'walking',
        }[mode],
      };
      var uri = Uri.https('maps.googleapis.com', _baseUrl, queryParameters);
      var response = await http.get(
        uri,
        headers: {
          HttpHeaders.contentTypeHeader: 'application/json',
        },
      );
      if (response.statusCode == 200) {
        try {
          return Directions.fromMap(jsonDecode(response.body));
        } on GoogleMapsException catch (_) {
          return null;
        }
      }
    } on HttpException catch (e) {
      debugPrint(e.message);
    }
    throw GoogleMapsException(
      'Unable to retrieve directions from Google Maps API',
    );
  }
}

class Directions {
  const Directions({
    required this.bounds,
    required this.polylinePoints,
    required this.totalDistance,
    required this.totalDuration,
  });

  /// map the json response to a [Directions] object
  factory Directions.fromMap(Map<String, dynamic> map) {
    if ((map['routes'] as List).isEmpty) {
      throw GoogleMapsException('No Routes available');
    }

    var data = Map<String, dynamic>.from((map['routes'] as List)[0]);

    var northeast = data['bounds']['northeast'];
    var southwest = data['bounds']['southwest'];
    var bounds = LatLngBounds(
      southwest: LatLng(southwest['lat'], southwest['lng']),
      northeast: LatLng(northeast['lat'], northeast['lng']),
    );

    var distance = 0;
    var duration = 0;
    if ((data['legs'] as List).isNotEmpty) {
      var leg = (data['legs'] as List)[0];
      distance = leg['distance']['value'];
      duration = leg['duration']['value'];
    }

    return Directions(
      bounds: bounds,
      polylinePoints:
          PolylinePoints().decodePolyline(data['overview_polyline']['points']),
      totalDistance: distance,
      totalDuration: duration,
    );
  }

  final LatLngBounds bounds;
  final List<PointLatLng> polylinePoints;
  final int totalDistance;
  final int totalDuration;
}

class GoogleMapsException implements Exception {
  GoogleMapsException(this.message);

  /// The unhandled [error] object.
  final String message;

  @override
  String toString() {
    return 'Error occurred in Track&Trace package:\n'
        '$message';
  }
}