Add offset support for listing pages and counting pages (#381)

* Add offset support when listing pages

* Add page counting function

* Add sort option

lib/beacon/content.ex

@@ -748,35 +748,40 @@ defmodule Beacon.Content do
   ## Options
 
     * `:per_page` - limit how many records are returned, or pass `:infinity` to return all records.
+    * `:offset` - offsets the number of rows selected from the result.
     * `:query` - search pages by path or title.
     * `:preloads` - a list of preloads to load.
+    * `:sort` - column in which the result will be ordered by.
 
   """
   @doc type: :pages
   @spec list_pages(Site.t(), keyword()) :: [Page.t()]
   def list_pages(site, opts \\ []) do
     per_page = Keyword.get(opts, :per_page, 20)
+    offset = Keyword.get(opts, :offset, 0)
     search = Keyword.get(opts, :query)
     preloads = Keyword.get(opts, :preloads, [])
+    sort = Keyword.get(opts, :sort, :title)
 
     site
     |> query_list_pages_base()
     |> query_list_pages_limit(per_page)
+    |> query_list_pages_offset(offset)
     |> query_list_pages_search(search)
     |> query_list_pages_preloads(preloads)
+    |> query_list_pages_sort(sort)
     |> Repo.all()
   end
 
-  defp query_list_pages_base(site) do
-    from p in Page,
-      where: p.site == ^site,
-      order_by: [asc: p.order, asc: fragment("length(?)", p.path)]
-  end
+  defp query_list_pages_base(site), do: from(p in Page, where: p.site == ^site)
 
   defp query_list_pages_limit(query, limit) when is_integer(limit), do: from(q in query, limit: ^limit)
   defp query_list_pages_limit(query, :infinity = _limit), do: query
   defp query_list_pages_limit(query, _per_page), do: from(q in query, limit: 20)
 
+  defp query_list_pages_offset(query, offset) when is_integer(offset), do: from(q in query, offset: ^offset)
+  defp query_list_pages_offset(query, _offset), do: from(q in query, offset: 0)
+
   defp query_list_pages_search(query, search) when is_binary(search) do
     from(q in query, where: ilike(q.path, ^"%#{search}%") or ilike(q.title, ^"%#{search}%"))
   end
@@ -789,6 +794,18 @@ defmodule Beacon.Content do
 
   defp query_list_pages_preloads(query, _preloads), do: query
 
+  defp query_list_pages_sort(query, sort), do: from(q in query, order_by: [asc: ^sort])
+
+  @doc """
+  Counts the total number of pages based on the amount of pages.
+  """
+  @spec count_pages(Site.t()) :: integer()
+  def count_pages(site) do
+    query = from p in Page, where: p.site == ^site, select: count(p.id)
+
+    Repo.one(query)
+  end
+
   @doc """
   Returns all published pages for `site`.