handle already following more gracefully

lib/vonbraun/control.ex

@@ -1,14 +1,9 @@
 defmodule Vonbraun.Control do
   require Logger
+  alias Vonbraun.ActivityPub.Object
   alias Vonbraun.ActivityPubReq
   alias Vonbraun.Ecto.Schema.Actor
 
-  defp self_id() do
-    domain = Application.fetch_env!(:vonbraun, :domain)
-    nickname = Application.fetch_env!(:vonbraun, :nickname)
-    "https://#{domain}/users/#{nickname}"
-  end
-
   @spec follow(String.t()) ::
           :ok
           | {:error,
@@ -23,25 +18,7 @@ defmodule Vonbraun.Control do
          {:parse_inbox, inbox = %URI{}} <- {:parse_inbox, URI.parse(raw_inbox)},
          {:pending, {:ok, %{:blocks_me => nil, :following_state => "pending"}}} <-
            {:pending, Actor.mark_pending_follow(followee_actor_id, "pending")} do
-      domain = Application.fetch_env!(:vonbraun, :domain)
-      # Is it a bad idea making this absolute?
-      activity_id = "https://#{domain}/id/follow:#{URI.encode(followee_actor_id)}"
-
-      payload =
-        %{
-          "@context" => "https://www.w3.org/ns/activitystreams",
-          "id" => activity_id,
-          "to" => [
-            followee_actor_id
-          ],
-          "cc" => [],
-          "bcc" => [],
-          "bto" => [],
-          "type" => "Follow",
-          "actor" => self_id(),
-          "object" => followee_actor_id
-        }
-        |> Jason.encode!()
+      payload = Object.follow_activity(followee_actor_id) |> Jason.encode!()
 
       case ActivityPubReq.post(inbox, payload) do
         {:ok, %{:status => status, :body => body}} when status >= 200 and status <= 299 ->