Improve image URL handling

lib/src/foundation/primitives/models/media.dart

@@ -1,4 +1,5 @@
 import 'package:thunder/src/foundation/primitives/enums/media_type.dart';
+import 'package:thunder/src/foundation/utils/media_url_utils.dart';
 
 /// The Media class represents information for a given media source.
 class Media {
@@ -40,7 +41,7 @@ class Media {
   String? contentType;
 
   /// Gets the full-size image URL, if any
-  String? get imageUrl => _isImageUrl(mediaUrl ?? '') ? mediaUrl : thumbnailUrl;
+  String? get imageUrl => isSupportedImageUrl(mediaUrl ?? '') ? mediaUrl : thumbnailUrl;
 
   @override
   String toString() {
@@ -58,24 +59,3 @@ class Media {
       ''';
   }
 }
-
-bool _isImageUrl(String url) {
-  final imageExtensions = <String>[
-    '.png',
-    '.jpg',
-    '.jpeg',
-    '.gif',
-    '.bmp',
-    '.webp',
-    '.avif',
-    '@jpeg',
-  ];
-
-  if (url.contains('/image_proxy')) return true;
-
-  final uri = Uri.tryParse(url);
-  if (uri == null) return false;
-
-  final path = uri.path.toLowerCase();
-  return imageExtensions.any(path.endsWith);
-}

lib/src/foundation/utils/media_url_utils.dart

@@ -0,0 +1,60 @@
+const List<String> imageExtensions = <String>['.png', '.jpg', '.jpeg', '.gif', '.bmp', '.webp', '.avif', '@jpeg'];
+
+/// Extracts the target URL from known image proxy services.
+/// Currently supports:
+/// - `image_proxy` with a `url` query parameter
+/// - DuckDuckGo's `external-content.duckduckgo.com` with a `u` query parameter
+String? extractProxyTargetUrl(Uri uri) {
+  final urlTarget = uri.queryParameters['url'];
+  if (uri.path.contains('/image_proxy') && urlTarget?.isNotEmpty == true) {
+    return urlTarget;
+  }
+
+  final duckDuckGoTarget = uri.queryParameters['u'];
+  if (uri.host == 'external-content.duckduckgo.com' && uri.path.startsWith('/iu') && duckDuckGoTarget?.isNotEmpty == true) {
+    return duckDuckGoTarget;
+  }
+
+  return null;
+}
+
+/// Resolves the original image URL by recursively extracting proxy targets until no more proxies are found.
+String resolveProxyImageUrl(String url) {
+  String currentUrl = url;
+
+  while (true) {
+    final uri = Uri.tryParse(currentUrl);
+    if (uri == null) return currentUrl;
+
+    final proxyTargetUrl = extractProxyTargetUrl(uri);
+    if (proxyTargetUrl == null) return currentUrl;
+
+    final parsedUri = Uri.tryParse(proxyTargetUrl);
+    if (parsedUri == null) return currentUrl;
+
+    currentUrl = parsedUri.toString();
+  }
+}
+
+/// Checks if the given URL is a supported image URL, either directly or through a proxy.
+bool isImageProxyUrlResolved(String url) {
+  final uri = Uri.tryParse(url);
+  if (uri == null) return false;
+
+  return extractProxyTargetUrl(uri) != null;
+}
+
+/// Checks if the URL has a supported image file extension.
+bool hasImageFileExtension(String url) {
+  final uri = Uri.tryParse(url);
+  if (uri == null) return false;
+
+  final path = uri.path.toLowerCase();
+  return imageExtensions.any(path.endsWith);
+}
+
+/// Determines if the given URL is a supported image URL, either directly or through a proxy.
+bool isSupportedImageUrl(String url) {
+  if (isImageProxyUrlResolved(url)) return true;
+  return hasImageFileExtension(resolveProxyImageUrl(url));
+}

lib/src/foundation/utils/utils.dart

@@ -1,4 +1,5 @@
 export 'cache/image_cache_utils.dart';
 export 'cache/image_dimension_cache.dart';
 export 'cache/platform_version_cache.dart';
+export 'media_url_utils.dart';
 export 'utils_internal.dart';

lib/src/shared/content/utils/media/media_utils.dart

@@ -18,69 +18,24 @@ import 'package:image_picker/image_picker.dart';
 import 'package:image_dimension_parser/image_dimension_parser.dart';
 
 import 'package:thunder/src/foundation/primitives/primitives.dart';
+import 'package:thunder/src/foundation/utils/media_url_utils.dart';
 import 'package:thunder/src/app/state/thunder/thunder_bloc.dart';
 import 'package:thunder/src/shared/content/widgets/media/experimental_image_viewer.dart';
 import 'package:thunder/src/shared/content/widgets/media/image_viewer.dart';
 
 final Map<String, Size> _imageDimensionsCache = <String, Size>{};
 
 /// Given a URL, returns the original URL if it is a proxy URL.
-String fetchProxyImageUrl(String url) {
-  String currentUrl = url;
-
-  while (true) {
-    Uri uri;
-
-    try {
-      uri = Uri.parse(currentUrl);
-    } catch (e) {
-      return currentUrl;
-    }
-
-    if (isImageProxyUrl(currentUrl)) {
-      Uri? parsedUri = Uri.tryParse(uri.queryParameters['url'] ?? '');
-
-      if (parsedUri != null) {
-        currentUrl = parsedUri.toString();
-        continue;
-      }
-    }
-
-    return currentUrl;
-  }
-}
+String fetchProxyImageUrl(String url) => resolveProxyImageUrl(url);
 
 /// Checks if the given URL is an image proxy URL.
 bool isImageProxyUrl(String url) {
-  try {
-    final uri = Uri.parse(url);
-    return uri.path.contains('/image_proxy') && uri.queryParameters.containsKey('url');
-  } catch (e) {
-    return false;
-  }
+  return isImageProxyUrlResolved(url);
 }
 
 /// Determines if the given URL is an image URL.
 bool isImageUrl(String url) {
-  final imageExtensions = ['.png', '.jpg', '.jpeg', '.gif', '.bmp', '.webp', '.avif', '@jpeg'];
-
-  if (isImageProxyUrl(url)) return true;
-
-  Uri uri;
-
-  try {
-    uri = Uri.parse(url);
-  } catch (e) {
-    return false;
-  }
-
-  for (final extension in imageExtensions) {
-    if (uri.path.toLowerCase().endsWith(extension)) {
-      return true;
-    }
-  }
-
-  return false;
+  return isSupportedImageUrl(url);
 }
 
 /// Determines if the given URL is an SVG.

lib/src/shared/content/widgets/media/media_view.dart

@@ -156,10 +156,18 @@ class _MediaViewState extends State<MediaView> with TickerProviderStateMixin {
     handleVideoLink(context, url: url);
   }
 
+  String? get _resolvedImageUrl => widget.media.imageUrl ?? widget.media.mediaUrl ?? widget.media.originalUrl ?? widget.media.thumbnailUrl;
+
+  String? get _resolvedPreviewUrl => widget.media.thumbnailUrl ?? widget.media.imageUrl ?? widget.media.mediaUrl ?? widget.media.originalUrl;
+
   /// Overlays the image as an ImageViewer.
   void showImage() {
     _markPostAsRead();
-    _openImage(url: widget.media.imageUrl);
+
+    final url = _resolvedImageUrl;
+    if (url != null) {
+      _openImage(url: url);
+    }
   }
 
   double getMinHeight() {
@@ -209,6 +217,7 @@ class _MediaViewState extends State<MediaView> with TickerProviderStateMixin {
 
     final imageUrlCandidate = widget.media.imageUrl ?? widget.media.mediaUrl ?? widget.media.originalUrl;
     final isImage = isImageUrl(imageUrlCandidate ?? '');
+    final previewUrl = _resolvedPreviewUrl;
 
     // If hiding thumbnails is enabled or if the media has no image URL,
     // display a link preview instead in comfortable mode.
@@ -317,7 +326,7 @@ class _MediaViewState extends State<MediaView> with TickerProviderStateMixin {
                           opacity: _overlayAnimationController,
                           child: buildImageViewerWidget(
                             context,
-                            url: widget.media.thumbnailUrl ?? widget.media.mediaUrl,
+                            url: previewUrl,
                             postId: widget.postId,
                             navigateToPost: widget.navigateToPost,
                             isPeek: true,
@@ -340,6 +349,19 @@ class _MediaViewState extends State<MediaView> with TickerProviderStateMixin {
       );
     }
 
+    if (widget.media.mediaType == MediaType.image && previewUrl == null) {
+      if (widget.media.originalUrl != null) {
+        return LinkInformation(
+          viewMode: widget.viewMode,
+          url: widget.media.originalUrl,
+          mediaType: widget.media.mediaType,
+          showEdgeToEdgeImages: widget.edgeToEdgeImages,
+        );
+      }
+
+      return const SizedBox.shrink();
+    }
+
     if (widget.media.mediaType == MediaType.video) {
       child = InkWell(
         splashColor: theme.colorScheme.primary.withValues(alpha: 0.4),
@@ -406,7 +428,7 @@ class _MediaViewState extends State<MediaView> with TickerProviderStateMixin {
             alignment: Alignment.center,
             children: [
               ImagePreview(
-                url: widget.media.thumbnailUrl ?? widget.media.imageUrl ?? widget.media.originalUrl!,
+                url: previewUrl!,
                 contentType: widget.media.contentType,
                 width: width,
                 height: height,