A feed with no artwork takes its site's icon (#70)

When a feed names no image and none is stored, the scan fetches the
channel's site link (RSS <link>, Atom rel=alternate) and uses the
apple-touch-icon or icon it names, falling back to /favicon.ico when that
answers with an image.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/feed.rs

@@ -11,6 +11,8 @@ pub struct ParsedFeed {
     pub title: Option<String>,
     pub ttl_mins: Option<u64>,
     pub image: Option<String>,
+    /// The site the feed belongs to, where a favicon can stand in for missing artwork.
+    pub site: Option<String>,
     /// The channel's first `<itunes:category>`, for the Directory's chips.
     pub category: Option<String>,
     pub entries: Vec<Entry>,
@@ -349,6 +351,56 @@ fn alternate_feed_link(bytes: &[u8]) -> Option<String> {
     None
 }
 
+/// Artwork for a feed that has none: the icon its site's page names, or else the site's
+/// `/favicon.ico`. None if neither is there.
+pub async fn site_icon(client: &reqwest::Client, site: &str) -> Option<String> {
+    let timeout = std::time::Duration::from_secs(20);
+    let resp = client.get(site).timeout(timeout).send().await.ok()?;
+    // Relative to where the page ended up, not where it was asked for: a site that redirects
+    // to /en/ would otherwise have its icon looked for in the wrong place.
+    let base = resp.url().clone();
+    if resp.status().is_success()
+        && let Ok(page) = resp.bytes().await
+        && let Some(href) = page_icon(&page)
+        && let Ok(url) = base.join(&href)
+    {
+        return Some(url.into());
+    }
+    let ico = base.join("/favicon.ico").ok()?;
+    let resp = client.get(ico.clone()).timeout(timeout).send().await.ok()?;
+    let is_image = resp
+        .headers()
+        .get(reqwest::header::CONTENT_TYPE)
+        .and_then(|v| v.to_str().ok())
+        .is_some_and(|t| t.starts_with("image/"));
+    // A site with no favicon often answers 200 with its home page, which is not an icon.
+    (resp.status().is_success() && is_image).then(|| ico.into())
+}
+
+/// The icon a web page names in its `<link>` tags, the larger apple-touch-icon first: a plain
+/// `icon` is often 16 pixels, which blurs at the size the list draws artwork.
+fn page_icon(bytes: &[u8]) -> Option<String> {
+    let text = String::from_utf8_lossy(bytes);
+    // ASCII only, so byte offsets in the lowered copy stay valid in the original.
+    let lower = text.to_ascii_lowercase();
+    let (mut touch, mut icon) = (None, None);
+    let mut pos = 0;
+    while let Some(at) = lower[pos..].find("<link") {
+        let start = pos + at;
+        let Some(end) = lower[start..].find('>').map(|e| start + e) else { break };
+        pos = end + 1;
+        let tag = &text[start..end];
+        let Some(rel) = tag_attr(tag, "rel").map(|r| r.to_ascii_lowercase()) else { continue };
+        let rels: Vec<&str> = rel.split_whitespace().collect();
+        if touch.is_none() && rels.iter().any(|r| r.starts_with("apple-touch-icon")) {
+            touch = tag_attr(tag, "href");
+        } else if icon.is_none() && rels.contains(&"icon") {
+            icon = tag_attr(tag, "href");
+        }
+    }
+    touch.or(icon).filter(|h| !h.is_empty())
+}
+
 /// The value of one attribute in an HTML/XML start tag, however it is quoted.
 fn tag_attr(tag: &str, name: &str) -> Option<String> {
     let key = format!("{name}=");
@@ -538,6 +590,7 @@ fn from_rss(ch: rss::Channel, bytes: &[u8]) -> ParsedFeed {
             .and_then(|i| i.image())
             .map(str::to_owned)
             .or_else(|| ch.image().map(|i| i.url().to_owned())),
+        site: non_empty(Some(ch.link().trim())),
         // Only the iTunes one: Apple's list is fixed, while a plain <category> is freeform and
         // would fill the Directory with one-off tags. The subcategory where there is one: Apple
         // files every tabletop and gaming show under Leisure, which says little; Games says it.
@@ -603,6 +656,12 @@ fn from_atom(feed: atom_syndication::Feed) -> ParsedFeed {
         title: title_text(Some(feed.title().as_str())),
         ttl_mins: None,
         image: feed.logo().or_else(|| feed.icon()).map(str::to_owned),
+        site: feed
+            .links()
+            .iter()
+            .find(|l| l.rel() == "alternate")
+            .map(|l| l.href().trim().to_owned())
+            .filter(|h| !h.is_empty()),
         category: None,
         entries,
     }
@@ -1157,6 +1216,16 @@ mod tests {
         assert_eq!(f.entries[2].enclosures.len(), 0, "an item may have none");
     }
 
+    #[test]
+    fn page_icon_prefers_the_touch_icon() {
+        let page = br#"<head><link rel="stylesheet" href="/a.css">
+            <link rel="shortcut icon" href="/fav.ico">
+            <LINK REL="apple-touch-icon-precomposed" sizes="180x180" href='/touch.png'></head>"#;
+        assert_eq!(page_icon(page).as_deref(), Some("/touch.png"));
+        assert_eq!(page_icon(br#"<link rel="icon" href="i.svg">"#).as_deref(), Some("i.svg"));
+        assert_eq!(page_icon(br#"<link rel="stylesheet" href="/a.css">"#), None);
+    }
+
     #[test]
     fn an_items_picture_comes_from_the_most_deliberate_source() {
         let xml = br#"<?xml version="1.0"?>