Introduce the group activity section

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

lib/service/activity/event.ex

@@ -0,0 +1,39 @@
+defmodule Mobilizon.Service.Activity.Event do
+  @moduledoc """
+  Insert an event activity
+  """
+  alias Mobilizon.Actors
+  alias Mobilizon.Events.Event
+  alias Mobilizon.Service.Activity
+  alias Mobilizon.Service.Workers.ActivityBuilder
+
+  @behaviour Activity
+
+  @impl Activity
+  def insert_activity(event, options \\ [])
+
+  def insert_activity(
+        %Event{attributed_to_id: attributed_to_id, organizer_actor_id: organizer_actor_id} =
+          event,
+        options
+      )
+      when not is_nil(attributed_to_id) do
+    actor = Actors.get_actor(organizer_actor_id)
+    group = Actors.get_actor(attributed_to_id)
+    subject = Keyword.fetch!(options, :subject)
+
+    ActivityBuilder.enqueue(:build_activity, %{
+      "type" => "event",
+      "subject" => subject,
+      "subject_params" => %{event_uuid: event.uuid, event_title: event.title},
+      "group_id" => group.id,
+      "author_id" => actor.id,
+      "object_type" => "event",
+      "object_id" => if(subject != "event_deleted", do: to_string(event.id), else: nil),
+      "inserted_at" => DateTime.utc_now()
+    })
+  end
+
+  @impl Activity
+  def insert_activity(_, _), do: {:ok, nil}
+end