Add EnsureAuthenticatedPlug

lib/pleroma/plugs/ensure_authenticated_plug.ex

@@ -0,0 +1,19 @@
+defmodule Pleroma.Plugs.EnsureAuthenticatedPlug do
+  import Plug.Conn
+  alias Pleroma.User
+
+  def init(options) do
+    options
+  end
+
+  def call(%{assigns: %{user: %User{}}} = conn, _) do
+    conn
+  end
+
+  def call(conn, _) do
+    conn
+    |> put_resp_content_type("application/json")
+    |> send_resp(403, Jason.encode!(%{error: "Invalid credentials."}))
+    |> halt
+  end
+end