Broke the header link wrapping out into smaller functions

src/renderer/html_handlebars/hbs_renderer.rs

@@ -399,9 +399,41 @@ fn build_header_links(html: String, filename: &str) -> String {
 
     regex
         .replace_all(&html, |caps: &Captures| {
-            let level = &caps[1];
-            let text = &caps[2];
-            let mut id = text.to_string();
+            let level = caps[1].parse().expect(
+                "Regex should ensure we only ever get numbers here",
+            );
+
+            wrap_header_with_link(level, &caps[2], &mut id_counter, filename)
+        })
+        .into_owned()
+}
+
+fn wrap_header_with_link(level: usize, content: &str, id_counter: &mut HashMap<String, usize>, filename: &str)
+    -> String {
+    let id = id_from_content(content);
+
+    let id_count = *id_counter.get(&id).unwrap_or(&0);
+    id_counter.insert(id.clone(), id_count + 1);
+
+    let id = if id_count > 0 {
+        format!("{}-{}", id, id_count)
+    } else {
+        id
+    };
+
+    format!(
+        r#"<a class="header" href="{filename}#{id}" id="{id}"><h{level}>{text}</h{level}></a>"#,
+        level = level,
+        id = id,
+        text = content,
+        filename = filename
+    )
+}
+
+fn id_from_content(content: &str) -> String {
+    let mut content = content.to_string();
+
+    // Skip any tags or html-encoded stuff
     let repl_sub = vec![
         "<em>",
         "</em>",
@@ -416,9 +448,10 @@ fn build_header_links(html: String, filename: &str) -> String {
         "&quot;",
     ];
     for sub in repl_sub {
-                id = id.replace(sub, "");
+        content = content.replace(sub, "");
     }
-            let id = id.chars()
+
+    content.chars()
         .filter_map(|c| if c.is_alphanumeric() || c == '-' || c == '_' {
             if c.is_ascii() {
                 Some(c.to_ascii_lowercase())
@@ -430,26 +463,7 @@ fn build_header_links(html: String, filename: &str) -> String {
         } else {
             None
         })
-                .collect::<String>();
-
-            let id_count = *id_counter.get(&id).unwrap_or(&0);
-            id_counter.insert(id.clone(), id_count + 1);
-
-            let id = if id_count > 0 {
-                format!("{}-{}", id, id_count)
-            } else {
-                id
-            };
-
-            format!(
-                "<a class=\"header\" href=\"{filename}#{id}\" id=\"{id}\"><h{level}>{text}</h{level}></a>",
-                level = level,
-                id = id,
-                text = text,
-                filename = filename
-            )
-        })
-        .into_owned()
+        .collect()
 }
 
 // anchors to the same page (href="#anchor") do not work because of