flutter-rp-example/lib/services/auth/auth.dart

import 'dart:async';

import 'package:flutter/foundation.dart';
import 'package:flutter_web_auth_2/flutter_web_auth_2.dart';
import 'dart:convert' show jsonDecode;
import 'package:http/http.dart' as http;
import 'package:shared_preferences/shared_preferences.dart';


class User {
  const User(
      {required this.firstname, required this.lastname, required this.email});
  final String firstname;
  final String lastname;
  final String email;

  static User fromJson(jsonDecode) {
    if (jsonDecode == "") {
      return const User(firstname: '', lastname: '', email: '');
    }
    return User(
        firstname: jsonDecode['firstname'],
        lastname: jsonDecode['lastname'],
        email: jsonDecode['email']);
  }

  Map<String, dynamic> toJson() => {
        'firstname': firstname,
        'lastname': lastname,
        'email': email,
      };
}

class TokenRefresher {
  final AuthService authService;
  final Duration refreshInterval;
  late Timer _timer;

  TokenRefresher(this.authService, {required this.refreshInterval});

  void start() {
    _timer = Timer.periodic(refreshInterval, (timer) async {
      try {
        await authService.doRefreshToken();
      } catch (e) {
        if (kDebugMode) {
          print('Failed to refresh token');
        }
      }
    });
  }

  void stop() {
    _timer.cancel();
  }
}

class AuthService {
  String clientId;
  String host;
  String redirectUri;
  String realm;
  String callbackUrlScheme;
  User? user;
  TokenRefresher? tokenRefresher;
  String? accessToken = ''; 
  String? refreshToken = '';

  AuthService(
      {required this.host,
      required this.realm,
      required this.clientId,
      required this.redirectUri,
      required this.callbackUrlScheme}) ;

  // Add init method to initialize the AuthService, it retrives the access token from the shared preferences
  Future<void> init() async {
    final prefs = await SharedPreferences.getInstance();
    accessToken = prefs.getString('accessToken');
    refreshToken = prefs.getString('refreshToken');
  }

  Future<bool> login() async {
    // Build the url
    final url =
        Uri.https(host, '/auth/realms/$realm/protocol/openid-connect/auth', {
      'response_type': 'code',
      'client_id': clientId,
      'redirect_uri': '$callbackUrlScheme:/$redirectUri',
      'scope': 'openid',
    });

    // Present the dialog to the user
    try {
      final result = await FlutterWebAuth2.authenticate(
          url: url.toString(), callbackUrlScheme: callbackUrlScheme);
      // Extract code from resulting url
      final code = Uri.parse(result).queryParameters['code'];

      // Use this code to get an access token
      final tokenUrl =
          Uri.https(host, '/auth/realms/$realm/protocol/openid-connect/token');
      var response = await http.post(tokenUrl, body: {
        'client_id': clientId,
        'grant_type': 'authorization_code',
        'code': code,
        'redirect_uri': '$callbackUrlScheme:/$redirectUri',
      });
      if (response.statusCode != 200) {
        throw Exception('Failed to login');
      }

      // Get the access token from the response
      await setAccessToken(jsonDecode(response.body)['access_token'] as String);
      await setRefreshToken(jsonDecode(response.body)['refresh_token'] as String);
    } catch (e) {
      return false;
    }

    tokenRefresher = TokenRefresher(this, refreshInterval: const Duration(seconds: 60));
    tokenRefresher!.start();

    return true;
  }

  Future<bool> logout() async {
    if (accessToken == null || accessToken == "") {
      throw Exception('Not logged in');
    }

    final logoutUrl =
        Uri.https(host, '/auth/realms/$realm/protocol/openid-connect/logout');

    final response = await http.post(logoutUrl, body: {
      'client_id': clientId,
      'refresh_token': refreshToken,
    });
    if (response.statusCode != 204) {
      throw Exception('Failed to logout');
    }

    final prefs = await SharedPreferences.getInstance();
    await prefs.clear();
    user = null;

    tokenRefresher!.stop();

    return true;
  }

  Future<bool> doRefreshToken() async {
    if (refreshToken == "") {
      throw Exception('Not logged in');
    }

    final tokenUrl =
        Uri.https(host, '/auth/realms/$realm/protocol/openid-connect/token');
    final response = await http.post(tokenUrl, body: {
      'client_id': clientId,
      'grant_type': 'refresh_token',
      'refresh_token': refreshToken,
    });
    if (response.statusCode != 200) {
      throw Exception('Failed to refresh token: ${response.body}');
    }

    // Get the access token from the response
    await setAccessToken(jsonDecode(response.body)['access_token'] as String);
    await setRefreshToken(jsonDecode(response.body)['refresh_token'] as String);
    return true;
  }

  Future<bool> isLoggedIn() async {
    user = await getUser();
    return user != null;
  }

  Future<void> setAccessToken(String token) async {
    final prefs = await SharedPreferences.getInstance();
    accessToken = token;
  }

  Future<void> setRefreshToken(String token) async {
    final prefs = await SharedPreferences.getInstance();
    prefs.setString('refreshToken', token);
    refreshToken = token;
  }

  Future<User?> getUser() async {
    if (this.user != null) {
      return this.user!;
    }

    final userInfoEndpoint =
        Uri.https(host, '/auth/realms/$realm/protocol/openid-connect/userinfo');
    var response = await http.get(userInfoEndpoint, headers: {
      'Authorization': 'Bearer $accessToken',
    });
    if (response.statusCode != 200) {
      return null;
    }
    final userMap = jsonDecode(response.body) as Map<String, dynamic>;
    var user = User(
        firstname: userMap['given_name'] as String,
        lastname: userMap['family_name'] as String,
        email: userMap['email'] as String);

    this.user = user;

    return user;
  }
}