Pleroma/lib/pleroma/web/activity_pub/relay.ex

defmodule Pleroma.Web.ActivityPub.Relay do
  alias Pleroma.{User, Object, Activity}
  alias Pleroma.Web.ActivityPub.ActivityPub
  require Logger

  def get_actor do
    User.get_or_create_instance_user()
  end

  def follow(target_instance) do
    with %User{} = local_user <- get_actor(),
         %User{} = target_user <- User.get_or_fetch_by_ap_id(target_instance),
         {:ok, activity} <- ActivityPub.follow(local_user, target_user) do
      Logger.info("relay: followed instance: #{target_instance}; id=#{activity.data["id"]}")
      {:ok, activity}
    else
      e ->
        Logger.error("error: #{inspect(e)}")
        {:error, e}
    end
  end

  def unfollow(target_instance) do
    with %User{} = local_user <- get_actor(),
         %User{} = target_user <- User.get_or_fetch_by_ap_id(target_instance),
         {:ok, activity} <- ActivityPub.unfollow(local_user, target_user) do
      Logger.info("relay: unfollowed instance: #{target_instance}: id=#{activity.data["id"]}")
      {:ok, activity}
    else
      e ->
        Logger.error("error: #{inspect(e)}")
        {:error, e}
    end
  end

  def publish(%Activity{data: %{"type" => "Create"}} = activity) do
    with %User{} = user <- get_actor(),
         %Object{} = object <- Object.normalize(activity.data["object"]) do
      ActivityPub.announce(user, object)
    else
      e -> Logger.error("error: #{inspect(e)}")
    end
  end

  def publish(_), do: nil
end