1 files changed, 57 insertions, 0 deletions
diff --git a/youtube/static/js/common.js b/youtube/static/js/common.js
index 599d578..bcd1539 100644
--- a/youtube/static/js/common.js
+++ b/youtube/static/js/common.js
@@ -114,3 +114,60 @@ function copyTextToClipboard(text) {
 window.addEventListener('DOMContentLoaded', function() {
     cur_track_idx = getDefaultTranscriptTrackIdx();
 });
+
+/**
+ * Thumbnail fallback handler
+ * Tries lower quality thumbnails when higher quality fails (404)
+ * Priority: hq720.jpg -> sddefault.jpg -> hqdefault.jpg -> mqdefault.jpg -> default.jpg
+ */
+function thumbnail_fallback(img) {
+    const src = img.src || img.dataset.src;
+    if (!src) return;
+
+    // Handle YouTube video thumbnails
+    if (src.includes('/i.ytimg.com/')) {
+        // Extract video ID from URL
+        const match = src.match(/\/vi\/([^/]+)/);
+        if (!match) return;
+
+        const videoId = match[1];
+        const imgPrefix = settings_img_prefix || '';
+
+        // Define fallback order (from highest to lowest quality)
+        const fallbacks = [
+            'hq720.jpg',
+            'sddefault.jpg',
+            'hqdefault.jpg',
+            'mqdefault.jpg',
+            'default.jpg'
+        ];
+
+        // Find current quality and try next fallback
+        for (let i = 0; i < fallbacks.length; i++) {
+            if (src.includes(fallbacks[i])) {
+                // Try next quality
+                if (i < fallbacks.length - 1) {
+                    const newSrc = imgPrefix + 'https://i.ytimg.com/vi/' + videoId + '/' + fallbacks[i + 1];
+                    if (img.dataset.src) {
+                        img.dataset.src = newSrc;
+                    } else {
+                        img.src = newSrc;
+                    }
+                }
+                break;
+            }
+        }
+    }
+    // Handle YouTube channel avatars (ggpht.com)
+    else if (src.includes('ggpht.com') || src.includes('yt3.ggpht.com')) {
+        // Try to increase avatar size (s88 -> s240)
+        const newSrc = src.replace(/=s\d+-c-k/, '=s240-c-k-c0x00ffffff-no-rj');
+        if (newSrc !== src) {
+            if (img.dataset.src) {
+                img.dataset.src = newSrc;
+            } else {
+                img.src = newSrc;
+            }
+        }
+    }
+}