feat(dart): Add get access token method to client (#18)

Co-authored-by: simeng-li <simeng@silverhand.io>

Author: julian-hartl

example/pubspec.lock

@@ -504,34 +504,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.1.0"
-  webview_flutter:
-    dependency: transitive
-    description:
-      name: webview_flutter
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "3.0.4"
-  webview_flutter_android:
-    dependency: transitive
-    description:
-      name: webview_flutter_android
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.10.0"
-  webview_flutter_platform_interface:
-    dependency: transitive
-    description:
-      name: webview_flutter_platform_interface
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "1.9.3"
-  webview_flutter_wkwebview:
-    dependency: transitive
-    description:
-      name: webview_flutter_wkwebview
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "2.9.3"
   x509:
     dependency: transitive
     description:
@@ -548,4 +520,4 @@ packages:
     version: "3.1.1"
 sdks:
   dart: ">=2.17.6 <3.0.0"
-  flutter: ">=3.0.0"
+  flutter: ">=2.0.0"

lib/logto_client.dart

@@ -2,16 +2,15 @@ import 'package:flutter_web_auth/flutter_web_auth.dart';
 import 'package:http/http.dart' as http;
 import 'package:jose/jose.dart';
 
-import 'logto_core.dart' as logto_core;
 import '/src/exceptions/logto_auth_exceptions.dart';
 import '/src/interfaces/logto_interfaces.dart';
 import '/src/modules/id_token.dart';
 import '/src/modules/logto_storage_strategy.dart';
 import '/src/modules/pkce.dart';
 import '/src/modules/token_storage.dart';
-
 import '/src/utilities/constants.dart';
 import '/src/utilities/utils.dart' as utils;
+import 'logto_core.dart' as logto_core;
 
 export '/src/interfaces/logto_config.dart';
 
@@ -67,6 +66,11 @@ class LogtoClient {
     return _oidcConfig!;
   }
 
+  Future<AccessToken?> getAccessToken(
+      {List<String>? scopes, String? resource}) async {
+    return await _tokenStorage.getAccessToken(resource, scopes);
+  }
+
   bool _loading = false;
 
   Future<void> signIn(String redirectUri) async {