rog_app/lib/services/maxtrix_service.dart

import 'dart:convert';
import 'package:get/get.dart';
import 'package:http/http.dart' as http;
import 'package:rogapp/model/destination.dart';
import 'package:rogapp/pages/destination/destination_controller.dart';


class MatrixService{

  static Future<Map<String, dynamic>>  getDestinations(List<Destination> destinations) async {

    final DestinationController destinationController = Get.find<DestinationController>();

    String locs = "";
    String origin = "";
    String destination = "";
    int i = 0;
    for(Destination d in destinations){

      print("---- getting matrix for ${d} ------------");

      if(i==0){
        origin = "${d.lat}, ${d.lon}";
        i++;
        continue;
      }

      if(i == (destinations.length - 1)){
        destination = "${d.lat}, ${d.lon}";
        i++;
        continue;
      }

      print("lat is ${d.lat}, long is ${d.lon}");
      locs += "${d.lat}, ${d.lon}|";
      i++;
    }

    locs = "optimize:false|${locs}";

    String _mode = "walking";
    switch (destinationController.travelMode.value) {
      case 1:
        _mode = "driving";
        break;
      case 2:
        _mode = "transit";
      break;
      default:
        _mode = "walking";
        break;
    }

    Map<String, dynamic> cats = {};
    String url = "https://maps.googleapis.com/maps/api/directions/json?destination=${destination}&mode=${_mode}&waypoints=${locs}&origin=${origin}&key=AIzaSyAUBI1ablMKuJwGj2-kSuEhvYxvB1A-mOE";
    print('@@@@@@+++ matrix_service GETDESTINATIONS -  GET,  @@@@@@ ${url}');
    final http.Response response = await http.get(
      Uri.parse(url),
      headers: <String, String>{
        'Content-Type': 'application/json; charset=UTF-8',
      }
    );

    if (response.statusCode == 200) {
      cats = json.decode(utf8.decode(response.bodyBytes));
    }
    return cats;
  }


}