centralize ajax determination

lib/philomena_web/plugs/check_captcha_plug.ex

@@ -22,7 +22,7 @@ defmodule PhilomenaWeb.CheckCaptchaPlug do
           :error,
           "There was an error verifying you're not a robot. Please try again."
         )
-        |> do_failure_response(ajax?(conn))
+        |> do_failure_response(conn.assigns.ajax?)
         |> halt()
     end
   end
@@ -54,13 +54,6 @@ defmodule PhilomenaWeb.CheckCaptchaPlug do
     redirect(conn, external: conn.assigns.referrer)
   end
 
-  def ajax?(conn) do
-    case get_req_header(conn, "x-requested-with") do
-      [value] -> String.downcase(value) == "xmlhttprequest"
-      _ -> false
-    end
-  end
-
   def captcha_enabled? do
     Application.get_env(:philomena, :captcha) != false
   end

lib/philomena_web/plugs/limit_plug.ex

@@ -43,7 +43,7 @@ defmodule PhilomenaWeb.LimitPlug do
       is_staff(conn.assigns.current_user) and skip_staff ->
         conn
 
-      ajax?(conn) ->
+      conn.assigns.ajax? ->
         conn
         |> Controller.put_flash(:error, error)
         |> Conn.send_resp(:multiple_choices, "")
@@ -78,13 +78,6 @@ defmodule PhilomenaWeb.LimitPlug do
     end
   end
 
-  defp ajax?(conn) do
-    case Conn.get_req_header(conn, "x-requested-with") do
-      [value] -> String.downcase(value) == "xmlhttprequest"
-      _ -> false
-    end
-  end
-
   defp increment_after_post(conn, key, time) do
     Conn.register_before_send(conn, fn conn ->
       # Phoenix status returns 200 for form validation errors

lib/philomena_web/plugs/referrer_plug.ex

@@ -17,14 +17,22 @@ defmodule PhilomenaWeb.ReferrerPlug do
   @doc false
   @spec call(Conn.t(), any()) :: Conn.t()
   def call(conn, _opts) do
-    case Conn.get_req_header(conn, "referer") do
-      [] ->
     conn
-        |> Conn.assign(:referrer, "/")
+    |> Conn.assign(:referrer, referer(conn))
+    |> Conn.assign(:ajax?, ajax?(conn))
+  end
 
-      [referrer] ->
-        conn
-        |> Conn.assign(:referrer, referrer)
+  defp referer(conn) do
+    case Conn.get_req_header(conn, "referer") do
+      [] -> "/"
+      [referrer] -> referrer
+    end
+  end
+
+  defp ajax?(conn) do
+    case Conn.get_req_header(conn, "x-requested-with") do
+      [value] -> String.downcase(value) == "xmlhttprequest"
+      _ -> false
     end
   end
 end