[Windows] Add support for custom callback schemes

flutter_web_auth_2/example/lib/main.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 import 'dart:io' show HttpServer, Platform;
 
+import 'package:desktop_webview_window/desktop_webview_window.dart';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
@@ -63,7 +64,12 @@ const html = '''
 </html>
 ''';
 
-void main() => runApp(const MyApp());
+void main(List<String> args) {
+  if (runWebViewTitleBarWidget(args)) {
+    return;
+  }
+  runApp(const MyApp());
+}
 
 class MyApp extends StatefulWidget {
   const MyApp({Key? key}) : super(key: key);
@@ -95,7 +101,7 @@ class MyAppState extends State<MyApp> {
 
       // Windows needs some callback URL on localhost
       req.response.write(
-        (Platform.isWindows || Platform.isLinux)
+        (Platform.isLinux)
             ? html.replaceFirst(
                 'CALLBACK_URL_HERE',
                 'http://localhost:43824/success?code=1337',
@@ -122,9 +128,7 @@ class MyAppState extends State<MyApp> {
 
     // Windows needs some callback URL on localhost
     final callbackUrlScheme =
-        !kIsWeb && (Platform.isWindows || Platform.isLinux)
-            ? 'http://localhost:43824'
-            : 'foobar';
+        !kIsWeb && (Platform.isLinux) ? 'http://localhost:43824' : 'foobar';
 
     try {
       final result = await FlutterWebAuth2.authenticate(
@@ -157,7 +161,9 @@ class MyAppState extends State<MyApp> {
                 Text('Status: $_status\n'),
                 const SizedBox(height: 80),
                 ElevatedButton(
-                  onPressed: authenticate,
+                  onPressed: () async {
+                    await authenticate();
+                  },
                   child: const Text('Authenticate'),
                 ),
               ],

flutter_web_auth_2/example/pubspec.yaml

@@ -8,6 +8,7 @@ environment:
 
 dependencies:
   cupertino_icons: ^1.0.3
+  desktop_webview_window: ^0.2.3
   flutter:
     sdk: flutter
   flutter_web_auth_2: ^3.0.0

flutter_web_auth_2/lib/flutter_web_auth_2.dart

@@ -10,6 +10,7 @@ export 'src/options.dart';
 export 'src/unsupported.dart'
     if (dart.library.io) 'src/server.dart'
     if (dart.library.html) 'src/web.dart';
+export 'src/windows.dart';
 
 class _OnAppLifecycleResumeObserver extends WidgetsBindingObserver {
   final Function onResumed;

flutter_web_auth_2/lib/src/windows.dart

@@ -0,0 +1,76 @@
+import 'dart:async';
+
+import 'package:desktop_webview_window/desktop_webview_window.dart';
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_web_auth_2_platform_interface/flutter_web_auth_2_platform_interface.dart';
+import 'package:path_provider/path_provider.dart';
+
+class FlutterWebAuth2WindowsPlugin extends FlutterWebAuth2Platform {
+  bool authenticated = false;
+  Webview? webview;
+
+  static void registerWith() {
+    FlutterWebAuth2Platform.instance = FlutterWebAuth2WindowsPlugin();
+  }
+
+  @override
+  Future<String> authenticate({
+    required String url,
+    required String callbackUrlScheme,
+    required Map<String, dynamic> options,
+  }) async {
+    if (!await WebviewWindow.isWebviewAvailable()) {
+      //Microsofts WebView2 must be installed for this to work
+      throw StateError('Webview is not available');
+    }
+    //Reset
+    authenticated = false;
+    webview?.close();
+
+    final c = Completer<String>();
+    debugPrint(
+      '''Launching webview with url: $url, callbackUrlScheme: $callbackUrlScheme, tmpDir: ${(await getTemporaryDirectory()).path}''',
+    );
+    webview = await WebviewWindow.create(
+      configuration: CreateConfiguration(
+        windowHeight: 720,
+        windowWidth: 1280,
+        title: 'Authenticate',
+        titleBarTopPadding: 0,
+        userDataFolderWindows: (await getTemporaryDirectory()).path,
+      ),
+    );
+    webview!.addOnUrlRequestCallback((url) {
+      final uri = Uri.parse(url);
+      if (uri.scheme == callbackUrlScheme) {
+        authenticated = true;
+        webview?.close();
+        /**
+         * Not setting the webview to null will cause a crash if the 
+         * application tries to open another webview
+         */
+        webview = null;
+        c.complete(url);
+      }
+    });
+    unawaited(
+      webview!.onClose.whenComplete(
+        () {
+          /**
+           * Not setting the webview to null will cause a crash if the 
+           * application tries to open another webview
+           */
+          webview = null;
+          if (!authenticated) {
+            c.completeError(
+              PlatformException(code: 'CANCELED', message: 'User canceled'),
+            );
+          }
+        },
+      ),
+    );
+    webview!.launch(url);
+    return c.future;
+  }
+}

flutter_web_auth_2/pubspec.yaml

@@ -24,11 +24,13 @@ environment:
   flutter: ">=3.0.0"
 
 dependencies:
+  desktop_webview_window: ^0.2.3
   flutter:
     sdk: flutter
   flutter_web_auth_2_platform_interface: ^3.0.0
   flutter_web_plugins:
     sdk: flutter
+  path_provider: ^2.1.2
   url_launcher: ^6.1.6
   window_to_front: ^0.0.3
 
@@ -54,5 +56,5 @@ flutter:
         pluginClass: FlutterWebAuth2WebPlugin
         fileName: src/web.dart
       windows:
-        dartPluginClass: FlutterWebAuth2ServerPlugin
-        fileName: src/server.dart
+        dartPluginClass: FlutterWebAuth2WindowsPlugin
+        fileName: src/windows.dart