Refactor Mobilizon.Federation.ActivityPub and add typespecs

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/mobilizon/events/event.ex

@@ -35,7 +35,7 @@ defmodule Mobilizon.Events.Event do
   alias Mobilizon.Web.Router.Helpers, as: Routes
 
   @type t :: %__MODULE__{
-          id: String.t(),
+          id: integer(),
           url: String.t(),
           local: boolean,
           begins_on: DateTime.t(),
@@ -47,16 +47,16 @@ defmodule Mobilizon.Events.Event do
           draft: boolean,
           visibility: EventVisibility.t(),
           join_options: JoinOptions.t(),
-          publish_at: DateTime.t(),
+          publish_at: DateTime.t() | nil,
           uuid: Ecto.UUID.t(),
-          online_address: String.t(),
+          online_address: String.t() | nil,
           phone_address: String.t(),
           category: String.t(),
           options: EventOptions.t(),
           organizer_actor: Actor.t(),
           attributed_to: Actor.t() | nil,
-          physical_address: Address.t(),
-          picture: Media.t(),
+          physical_address: Address.t() | nil,
+          picture: Media.t() | nil,
           media: [Media.t()],
           tracks: [Track.t()],
           sessions: [Session.t()],