Remove empty sections after other removals

Signed-off-by: Evan Lloyd New-Schmidt <evan@new-schmidt.com>

src/html.rs

@@ -125,6 +125,8 @@ pub fn simplify_html(document: &mut Html, lang: &str) {
     }
     remove_ids(document, to_remove.drain(..));
 
+    remove_empty_sections(document);
+
     remove_comments(document);
 
     expand_links(document);
@@ -152,6 +154,39 @@ fn remove_comments(document: &mut Html) {
     remove_ids(document, to_remove.drain(..));
 }
 
+fn remove_empty_sections(document: &mut Html) {
+    let mut to_remove = Vec::new();
+    for el in document.select(&HEADERS) {
+        // TODO: does select match on detached nodes?
+        let Some(parent) = el.parent() else { continue; };
+
+        if !parent
+            .value()
+            .as_element()
+            .map(|p| p.name() == "section")
+            .unwrap_or_default()
+        {
+            trace!("Skipping header without section name: {:?}", parent);
+            continue;
+        }
+
+        if el
+            .next_siblings()
+            .filter_map(ElementRef::wrap)
+            .all(|e| is_empty_or_whitespace(&e) || HEADERS.matches(&e))
+        {
+            trace!(
+                "Removing empty section {} {:?}",
+                el.value().name(),
+                el.text().collect::<String>()
+            );
+            to_remove.push(parent.id());
+        }
+    }
+
+    remove_ids(document, to_remove);
+}
+
 fn remove_attrs(document: &mut Html) {
     // TODO: See if finding and skipping detached nodes is significantly faster.
     let mut to_remove = Vec::new();

tests/data/Q748282-en/output.html

@@ -92,7 +92,4 @@
   <p>
     Archaeologists have found the earliest anatomically modern humans in Europe in the Crimean Mountains' Buran-Kaya caves. The fossils are 32,000 years old, with the artifacts linked to the Gravettian culture. The fossils have cut marks suggesting a post-mortem defleshing ritual.
   </p>
-  <h2 id="Gallery">
-    Gallery
-  </h2>
 </html>