Open external H5 links in system browser

lib/main.dart

@@ -475,6 +475,8 @@ class _H5ShellPageState extends State<H5ShellPage> with WidgetsBindingObserver {
         _hideShellCover(generation);
       } else if (decoded is Map && decoded['type'] == 'keyboard-bridge-ready') {
         unawaited(_syncKeyboardState());
+      } else if (decoded is Map && decoded['type'] == 'openExternalUrl') {
+        unawaited(_openExternalUrl(decoded['url']?.toString()));
       }
     } catch (_) {
       if (message.message == 'first-screen-ready') {
@@ -512,6 +514,8 @@ class _H5ShellPageState extends State<H5ShellPage> with WidgetsBindingObserver {
           unawaited(openAppSettings());
         case 'keyboard-bridge-ready':
           unawaited(_syncKeyboardState());
+        case 'openExternalUrl':
+          unawaited(_openExternalUrl(decoded['url']?.toString()));
       }
     } catch (_) {
       // Ignore malformed shell messages from web content.
@@ -939,18 +943,52 @@ class _H5ShellPageState extends State<H5ShellPage> with WidgetsBindingObserver {
       return NavigationDecision.prevent;
     }
 
-    const webSchemes = {'http', 'https', 'about', 'data'};
-    if (webSchemes.contains(uri.scheme)) {
+    const inWebViewSchemes = {'about', 'data'};
+    if (inWebViewSchemes.contains(uri.scheme) || _isCurrentH5Origin(uri)) {
       return NavigationDecision.navigate;
     }
 
+    if (uri.scheme == 'http' || uri.scheme == 'https') {
+      await _openExternalUri(uri);
+      return NavigationDecision.prevent;
+    }
+
+    await _openExternalUri(uri);
+    return NavigationDecision.prevent;
+  }
+
+  bool _isCurrentH5Origin(Uri uri) {
+    final currentUri = Uri.tryParse(_currentSlot.line.url);
+    if (currentUri == null) {
+      return false;
+    }
+
+    return uri.scheme == currentUri.scheme &&
+        uri.host == currentUri.host &&
+        uri.port == currentUri.port;
+  }
+
+  Future<void> _openExternalUrl(String? rawUrl) async {
+    final url = rawUrl?.trim();
+    if (url == null || url.isEmpty) {
+      return;
+    }
+
+    final uri = Uri.tryParse(url);
+    if (uri == null || !uri.hasScheme) {
+      return;
+    }
+
+    await _openExternalUri(uri);
+  }
+
+  Future<void> _openExternalUri(Uri uri) async {
     try {
       await launchUrl(uri, mode: LaunchMode.externalApplication);
     } catch (_) {
       // Ignore unsupported custom schemes so the WebView does not navigate to
       // an error page.
     }
-    return NavigationDecision.prevent;
   }
 
   Future<void> _handleBackNavigation() async {