Flutter Authentication Flow

home_page.dart

import 'dart:async';
import 'package:auth_flow/app/utils/auth_utils.dart';
import 'package:auth_flow/app/utils/network_utils.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

class HomePage extends StatefulWidget {
  static final String routeName = 'home';

  @override
  State<StatefulWidget> createState() {
    return new _HomePageState();
  }

}

class _HomePageState extends State<HomePage> {
  GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
  Future<SharedPreferences> _prefs = SharedPreferences.getInstance();

  SharedPreferences _sharedPreferences;
  var _authToken, _id, _name, _homeResponse;

  @override
  void initState() {
    super.initState();
    _fetchSessionAndNavigate();
  }

  _fetchSessionAndNavigate() async {
    _sharedPreferences = await _prefs;
    String authToken = AuthUtils.getToken(_sharedPreferences);
    var id = _sharedPreferences.getInt(AuthUtils.userIdKey);
    var name = _sharedPreferences.getString(AuthUtils.nameKey);

    print(authToken);

    _fetchHome(authToken);

    setState(() {
      _authToken = authToken;
      _id = id;
      _name = name;
    });

    if(_authToken == null) {
      _logout();
    }
  }

  _fetchHome(String authToken) async {
    var responseJson = await NetworkUtils.fetch(authToken, '/api/v1/home');

    if(responseJson == null) {

      NetworkUtils.showSnackBar(_scaffoldKey, 'Something went wrong!');

    } else if(responseJson == 'NetworkError') {

      NetworkUtils.showSnackBar(_scaffoldKey, null);

    } else if(responseJson['errors'] != null) {

      _logout();

    }

    setState(() {
      _homeResponse = responseJson.toString();
    });
  }

  _logout() {
    NetworkUtils.logoutUser(_scaffoldKey.currentContext, _sharedPreferences);
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      key: _scaffoldKey,
      appBar: new AppBar(
        title: new Text('Home'),
      ),
      body: new Container(
        margin: const EdgeInsets.symmetric(horizontal: 16.0),
        child: new Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: <Widget>[
            new Container(
              padding: const EdgeInsets.all(8.0),
              child: new Text(
                "USER_ID: $_id \nUSER_NAME: $_name \nHOME_RESPONSE: $_homeResponse",
                style: new TextStyle(
                  fontSize: 24.0,
                  color: Colors.grey.shade700
                ),
              ),
            ),
            new MaterialButton(
              color: Theme.of(context).primaryColor,
              child: new Text(
                'Logout',
                style: new TextStyle(
                  color: Colors.white
                ),
              ),
              onPressed: _logout
            ),
          ]
        ),
      )
    );
  }

}