improve outline rendering

lib/chiya_web/controllers/page_html.ex

@@ -1,6 +1,5 @@
 defmodule ChiyaWeb.PageHTML do
   use ChiyaWeb, :html_public
-  import Phoenix.HTML.Tag, only: [content_tag: 3, content_tag: 2]
   import ChiyaWeb.Format, only: [pretty_datetime: 1, pretty_date: 1, datetime: 1]
 
   embed_templates "page_html/*"
@@ -27,30 +26,11 @@ defmodule ChiyaWeb.PageHTML do
   def tag_list(assigns)
 
   def render_outline(note) do
-    note.content
-    |> ChiyaWeb.Outline.get()
-    |> Enum.map(&do_render_outline/1)
-    |> Enum.map(&safe_to_string/1)
+    ChiyaWeb.OutlineRenderer.render_outline(note.content)
   end
 
   def has_outline?(note) do
-    outline_empty =
-      note.content
-      |> ChiyaWeb.Outline.get()
-      |> Enum.empty?()
-
-    !outline_empty
-  end
-
-  def do_render_outline(%{text: text, children: children, level: _level}) do
-    slug = Slugger.slugify_downcase(text)
-
-    content_tag(:ul, [class: "m-0"],
-      do: [
-        content_tag(:li, do: content_tag(:a, text, href: "##{slug}")),
-        Enum.map(children, &do_render_outline/1)
-      ]
-    )
+    ChiyaWeb.OutlineRenderer.has_outline?(note.content)
   end
 
   def group_tags(notes) do

lib/chiya_web/outline_renderer.ex

@@ -0,0 +1,38 @@
+defmodule ChiyaWeb.OutlineRenderer do
+  import Phoenix.HTML, only: [safe_to_string: 1]
+  import Phoenix.HTML.Tag, only: [content_tag: 3, content_tag: 2]
+
+  def render_outline(content) do
+    children =
+      content
+      |> ChiyaWeb.Outline.get()
+      |> Enum.map(&do_render_outline/1)
+
+    root = content_tag(:ul, do: children)
+
+    safe_to_string(root)
+  end
+
+  def has_outline?(content) do
+    outline_empty =
+      content
+      |> ChiyaWeb.Outline.get()
+      |> Enum.empty?()
+
+    !outline_empty
+  end
+
+  def do_render_outline(%{text: text, children: children, level: _level}) do
+    slug = Slugger.slugify_downcase(text)
+    list_item = content_tag(:li, do: content_tag(:a, text, href: "##{slug}"))
+
+    if Enum.empty?(children) do
+      [list_item]
+    else
+      [
+        list_item,
+        content_tag(:ul, do: Enum.map(children, &do_render_outline/1))
+      ]
+    end
+  end
+end