Flutter InApp Authentication

flutter_inapp_authentication

import 'dart:async';


import 'package:flutter/material.dart';
import "package:http/http.dart" as http;
import "package:googleapis_auth/auth_io.dart" as auth;
import 'package:googleapis/calendar/v3.dart' as calendar;
import 'package:google_sign_in/google_sign_in.dart';

final GoogleSignIn _googleSignIn =
    new GoogleSignIn(scopes: [calendar.CalendarApi.CalendarScope]);

final scopes = [calendar.CalendarApi.CalendarScope];

...
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class _MyHomePageState extends State<MyHomePage> {
  calendar.CalendarApi calendarApi;
  _testSignInWithGoogle() async {
    final GoogleSignInAccount googleUser = await _googleSignIn.signIn();

    final GoogleSignInAuthentication googleAuth =
        await googleUser.authentication;
        
  auth.AccessToken token = auth.AccessToken("Bearer", googleAuth.accessToken,
        DateTime.now().add(Duration(days: 1)).toUtc());
    auth.AccessCredentials(token, googleUser.id, scopes);
    http.BaseClient _client = http.Client();
    auth.AuthClient _authClient = auth.authenticatedClient(
        _client, auth.AccessCredentials(token, googleUser.id, scopes));
    calendarApi = new calendar.CalendarApi(_authClient);
    
    }
    
      @override
  void initState() {
    super.initState();
    _testSignInWithGoogle();
   }
   
   ...
   ...