Introduce the group activity section

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

lib/service/activity/posts.ex

@@ -0,0 +1,37 @@
+defmodule Mobilizon.Service.Activity.Post do
+  @moduledoc """
+  Insert an post activity
+  """
+  alias Mobilizon.Actors
+  alias Mobilizon.Posts.Post
+  alias Mobilizon.Service.Activity
+  alias Mobilizon.Service.Workers.ActivityBuilder
+
+  @behaviour Activity
+
+  @impl Activity
+  def insert_activity(post, options \\ [])
+
+  def insert_activity(
+        %Post{attributed_to_id: attributed_to_id, author_id: author_id} = post,
+        options
+      )
+      when not is_nil(attributed_to_id) do
+    author = Actors.get_actor(author_id)
+    group = Actors.get_actor(attributed_to_id)
+    subject = Keyword.fetch!(options, :subject)
+
+    ActivityBuilder.enqueue(:build_activity, %{
+      "type" => "post",
+      "subject" => subject,
+      "subject_params" => %{post_slug: post.slug, post_title: post.title},
+      "group_id" => group.id,
+      "author_id" => author.id,
+      "object_type" => "post",
+      "object_id" => if(subject != "post_deleted", do: to_string(post.id), else: nil),
+      "inserted_at" => DateTime.utc_now()
+    })
+  end
+
+  def insert_activity(_, _), do: {:ok, nil}
+end