Auth0 manager - dart side - for medium article

auth0_manager_for_web.dart

import 'dart:async';
import 'dart:convert';
import 'dart:js' as js;

import 'package:my_app/providers/user_provider/model/user.dart';
import 'package:my_app/providers/user_provider/user_provider.dart';

import 'auth_manager.dart';

void _alert(dynamic param) {
  js.context.callMethod('alert', [param]);
}

class Auth0ManagerForWeb extends AuthManager {
  js.JsObject get jsAuthManager {
    if (js.context['authManager'] == null) {
      js.context['authManager'] = js.context.callMethod('createAuth0Manager', [
        js.JsObject.jsify({
          'domain': AuthManager.domain,
          'clientID': AuthManager.clientID,
          'responseType': AuthManager.responseType,
          'redirectUri': AuthManager.redirectUri,
          'scope': AuthManager.scope,
        }),
        //onAuthSuccess
        _alert,
        //onError
        _alert,
      ]);
    }

    return js.context['authManager'];
  }

  @override
  Future<User> login([Map<String, String> authResponse]) async {
    if (authResponse == null) {
      jsAuthManager.callMethod('login');
      return null;
    } else {
      return userFromTokens(
          authResponse['id_token'], authResponse['access_token']);
    }
  }

  @override
  Future<void> logout() async {
    jsAuthManager.callMethod('logout', [UserProvider.instance.logout]);
  }

  @override
  Future<User> userFromTokens(String idToken, String accessToken) async {
    final jsCompleter = Completer<Map<String, dynamic>>();

    final onUserInfo = (dynamic err, dynamic info) {
      final json =
          jsonDecode(js.context['JSON'].callMethod('stringify', [info]));
      jsCompleter.complete(json);
    };

    jsAuthManager.callMethod('getUserInfo', [accessToken, onUserInfo]);

    final info = await jsCompleter.future;
    if (info == null) {
      return null;
    }
    if (info is Map) {
      info.addAll({
        'id_token': idToken,
        'access_token': accessToken,
      });
    }
    final user = User.fromJson(Map<String, dynamic>.from(info));
    return user;
  }
}