Browse the Directory by category, then subcategory, as Apple does (#118)

The Directory had one row of chips holding whatever each feed's category was, a category
(Technology) or a subcategory (Tech News, Video Games) side by side: a podcast's own
<itunes:category> is stored as its subcategory, and Jev's answers (#117) are often
subcategories too, so after the first forced scan the row held 22 chips. /api/directory now
gives each feed's Apple category and subcategory, worked out from Apple's list, and the
page shows the categories, then a picked one's subcategories on a line of their own. A
category that is not Apple's, one an admin typed, stands as a category of its own.

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

src/feed.rs

@@ -1033,6 +1033,21 @@ const CATEGORIES: &[(&str, &[&str])] = &[
     ("TV & Film", &["After Shows", "Film History", "Film Interviews", "Film Reviews", "TV Reviews"]),
 ];
 
+/// Where a category sits in Apple's list, as (category, subcategory), so the Directory browses a
+/// category and then its subcategories as Apple's does (#118). A podcast's own is stored as its
+/// subcategory, and one an admin typed that is not Apple's stands as a category of its own.
+pub fn category_path(name: &str) -> (String, Option<String>) {
+    for (category, subs) in CATEGORIES {
+        if category.eq_ignore_ascii_case(name) {
+            return (category.to_string(), None);
+        }
+        if let Some(sub) = subs.iter().find(|s| s.eq_ignore_ascii_case(name)) {
+            return (category.to_string(), Some(sub.to_string()));
+        }
+    }
+    (name.to_string(), None)
+}
+
 /// A Directory category for a feed that names none of its own, which most blogs do not (#117):
 /// TypeSafe's Jev picks one of Apple's categories or subcategories from the feed's title and
 /// latest items, the subcategory being what a podcast's own category is stored as. The likeliest
@@ -1571,5 +1586,14 @@ mod tests {
         assert!(super::picked(&answer("Blogs")).is_err(), "not one of Apple's");
         assert!(super::picked(&serde_json::json!({"error": "rate limited"})).is_err());
     }
+
+    #[test]
+    fn category_path_finds_a_subcategory_s_category() {
+        use super::category_path;
+        assert_eq!(category_path("Tech News"), ("News".into(), Some("Tech News".into())));
+        assert_eq!(category_path("video games"), ("Leisure".into(), Some("Video Games".into())), "Apple's spelling");
+        assert_eq!(category_path("Technology"), ("Technology".into(), None));
+        assert_eq!(category_path("Homebrew"), ("Homebrew".into(), None), "not Apple's: its own category");
+    }
 }
 

src/web.rs

@@ -861,8 +861,10 @@ struct PopularRow {
     subscribers: i64,
     /// Yours already. Everyone counts, you included, so your own feeds are listed too.
     subscribed: bool,
-    /// The feed's own iTunes category, if it names one; most blogs do not.
+    /// Apple's category, from the feed's own iTunes category or else the catalogue's, and the
+    /// subcategory within it where there is one: the Directory browses them in that order.
     category: Option<String>,
+    subcategory: Option<String>,
     /// Any audio or video enclosure. Unlike category, every feed has an answer, so the
     /// Directory's Podcasts and Blogs between them hold everything.
     podcast: bool,
@@ -902,14 +904,16 @@ async fn popular(state: &WebState, user_id: i64, everything: bool) -> Result<Vec
         }
         let sum = listed.remove(&s.id).map(|l| l.summary).unwrap_or_default();
         let subscribed = mine.contains(&s.id);
+        // The feed's own wins; an admin's is for the feeds, mostly blogs, that name none.
+        let path = sum.category.or_else(|| s.cfg.category.clone()).map(|c| crate::feed::category_path(&c));
         out.push(PopularRow {
             id: s.id.clone(),
             title: sum.title,
             image: sum.image,
             subscribers: n,
             subscribed,
-            // The feed's own wins; an admin's is for the feeds, mostly blogs, that name none.
-            category: sum.category.or_else(|| s.cfg.category.clone()),
+            category: path.as_ref().map(|p| p.0.clone()),
+            subcategory: path.and_then(|p| p.1),
             podcast: media.contains(&s.id),
         });
     }