From 099b85e9a95e8218b2bb9747c21901636cf4d6b3 Mon Sep 17 00:00:00 2001
From: Thomas Citharel <tcit@tcit.fr>
Date: Fri, 30 Jul 2021 17:24:57 +0200
Subject: [PATCH] Refactor audience to introduce maybe_add_followers/2

Signed-off-by: Thomas Citharel <tcit@tcit.fr>
---
 lib/federation/activity_pub/audience.ex       | 19 +++++++++++++++----
 .../federation/activity_pub/audience_test.exs |  4 ++--
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/lib/federation/activity_pub/audience.ex b/lib/federation/activity_pub/audience.ex
index a2ccaf5ca..fb98f1e23 100644
--- a/lib/federation/activity_pub/audience.ex
+++ b/lib/federation/activity_pub/audience.ex
@@ -66,16 +66,20 @@ defmodule Mobilizon.Federation.ActivityPub.Audience do
   end
 
   def get_audience(%Participant{} = participant) do
-    event = Events.get_event_with_preload!(participant.event_id)
+    %Event{} = event = Events.get_event_with_preload!(participant.event_id)
+    %Actor{} = organizer = group_or_organizer_event(event)
 
-    actor_participants_urls =
+    cc =
       event.id
       |> Mobilizon.Events.list_actors_participants_for_event()
       |> Enum.map(& &1.url)
+      |> Enum.filter(&(&1 != participant.actor.url))
+      |> maybe_add_group_members(organizer)
+      |> maybe_add_followers(organizer)
 
     %{
-      "to" => [participant.actor.url, group_or_organizer_event(event).url],
-      "cc" => actor_participants_urls
+      "to" => [participant.actor.url, organizer.url],
+      "cc" => cc
     }
   end
 
@@ -156,6 +160,13 @@ defmodule Mobilizon.Federation.ActivityPub.Audience do
 
   defp maybe_add_group_members(collection, %Actor{type: _}), do: collection
 
+  @spec maybe_add_followers(List.t(), Actor.t()) :: List.t()
+  defp maybe_add_followers(collection, %Actor{type: :Group, followers_url: followers_url}) do
+    [followers_url | collection]
+  end
+
+  defp maybe_add_followers(collection, %Actor{type: _}), do: collection
+
   def get_addressed_actors(mentioned_users, _), do: mentioned_users
 
   defp add_in_reply_to(%Comment{actor: %Actor{url: url}} = _comment), do: [url]
diff --git a/test/federation/activity_pub/audience_test.exs b/test/federation/activity_pub/audience_test.exs
index f00ced414..bf16bc0da 100644
--- a/test/federation/activity_pub/audience_test.exs
+++ b/test/federation/activity_pub/audience_test.exs
@@ -257,7 +257,7 @@ defmodule Mobilizon.Federation.ActivityPub.AudienceTest do
 
       assert %{
                "to" => [participant.actor.url, participant.event.organizer_actor.url],
-               "cc" => [participant2.actor.url, participant.actor.url]
+               "cc" => [participant2.actor.url]
              } == Audience.get_audience(participant)
     end
 
@@ -271,7 +271,7 @@ defmodule Mobilizon.Federation.ActivityPub.AudienceTest do
 
       assert %{
                "to" => [participant.actor.url, participant.event.attributed_to.url],
-               "cc" => [participant2.actor.url, participant.actor.url]
+               "cc" => [group.followers_url, group.members_url, participant2.actor.url]
              } == Audience.get_audience(participant)
     end
   end