add filter override param

lib/philomena_web/plugs/filter_id_plug.ex

@@ -0,0 +1,20 @@
+defmodule PhilomenaWeb.FilterIdPlug do
+  alias Philomena.Filters.Filter
+  alias Philomena.Repo
+
+  # No options
+  def init([]), do: false
+
+  def call(conn, _opts) do
+    filter = load_filter(conn.params)
+    user = conn.assigns.current_user
+
+    case Canada.Can.can?(user, :show, filter) do
+      true  -> Plug.Conn.assign(conn, :current_filter, filter)
+      false -> conn
+    end
+  end
+
+  defp load_filter(%{"filter_id" => filter_id}), do: Repo.get(Filter, filter_id)
+  defp load_filter(_params), do: nil
+end

lib/philomena_web/router.ex

@@ -25,6 +25,7 @@ defmodule PhilomenaWeb.Router do
     plug PhilomenaWeb.ApiTokenPlug
     plug PhilomenaWeb.EnsureUserEnabledPlug
     plug PhilomenaWeb.CurrentFilterPlug
+    plug PhilomenaWeb.FilterIdPlug
     plug PhilomenaWeb.ImageFilterPlug
     plug PhilomenaWeb.PaginationPlug
   end