PhysiGo/app/lib/navigation/widgets/navigation_map.dart

import 'dart:async';
import 'dart:math';

import 'package:flutter/material.dart';
import 'package:flutter_map/flutter_map.dart';
import 'package:flutter_map_location_marker/flutter_map_location_marker.dart';
import 'package:geolocator/geolocator.dart';
import 'package:latlong2/latlong.dart';

class NavigationMap extends StatefulWidget {
  final Stream<List<LatLng>> waypointsCoordinates;
  final Stream<int> currentWaypointIndexStream;
  const NavigationMap({
    required this.waypointsCoordinates,
    required this.currentWaypointIndexStream,
    Key? key,
  }) : super(key: key);

  @override
  State<NavigationMap> createState() => _NavigationMapState();
}

class _NavigationMapState extends State<NavigationMap> {
  /// Lines drawn on the map to indicate the path
  List<LatLng> _polylines = [];
  /// Used to differentiate the path before and after the user
  int _currentWaypointIndex = 0;
  final List<StreamSubscription<dynamic>> _streamsSubscription = [];
  late CenterOnLocationUpdate _centerOnLocationUpdate;
  late StreamController<double> _centerCurrentLocationStreamController;

  @override
  void initState() {
    super.initState();
    _centerOnLocationUpdate = CenterOnLocationUpdate.always;
    _centerCurrentLocationStreamController = StreamController<double>();
    _streamsSubscription.add(widget.waypointsCoordinates.listen(_updatePolylines));
    _streamsSubscription.add(widget.currentWaypointIndexStream.listen(_updateWaypointIndex));
  }

  void _updatePolylines(List<LatLng> waypointsCoordinates) {
    setState(() {
      _polylines = waypointsCoordinates.map((waypoint) => LatLng(waypoint.latitude, waypoint.longitude)).toList();
    });
  }

  void _updateWaypointIndex(int newWaypointIndex) {
    setState(() {
      _currentWaypointIndex = newWaypointIndex;
    });
  }

  @override
  Widget build(BuildContext context) {
    return SizedBox(
      height: MediaQuery.of(context).size.height * 0.8,
      child: FlutterMap(
        options: MapOptions(
          center: LatLng(0, 0),
          zoom: 15,
          minZoom: 10,
          maxZoom: 18,
          onPositionChanged: (MapPosition position, bool hasGesture) {
            if (hasGesture) {
              setState(() => _centerOnLocationUpdate = CenterOnLocationUpdate.never);
            }
          },
        ),
        children: [
          TileLayerWidget(
            options: TileLayerOptions(
              urlTemplate: "https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png",
              subdomains: ['a', 'b', 'c'],
            ),
          ),
          LocationMarkerLayerWidget(
            plugin: LocationMarkerPlugin(
              centerOnLocationUpdate: _centerOnLocationUpdate,
              centerCurrentLocationStream: _centerCurrentLocationStreamController.stream,
            ),
            options: LocationMarkerLayerOptions(
              marker: const DefaultLocationMarker(
                color: Colors.blue,
              ),
              positionStream: const LocationMarkerDataStreamFactory().geolocatorPositionStream(
                stream: Geolocator.getPositionStream(
                  locationSettings: const LocationSettings(
                    accuracy: LocationAccuracy.bestForNavigation,
                    distanceFilter: 1,
                  ),
                ),
              ),
            ),
          ),
          PolylineLayerWidget(
            options: PolylineLayerOptions(
              polylines: [
                Polyline(
                  points: _polylines.sublist(max(0, _currentWaypointIndex - 1)),
                  color: Colors.red,
                  strokeWidth: 10,
                ),
                Polyline(
                  points: _polylines.sublist(0, max(0, _currentWaypointIndex)),
                  color: Colors.green,
                  strokeWidth: 10,
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }

  @override
  void dispose() {
    for (final streamSubscription in _streamsSubscription) {
      streamSubscription.cancel();
    }
    super.dispose();
  }
}