[GraphQL] Expose events from followed/member group activity

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

lib/mobilizon/followed_group_activity.ex

@@ -0,0 +1,43 @@
+defmodule Mobilizon.FollowedGroupActivity do
+  @moduledoc """
+  Provide recent elements from groups that profiles follow
+  """
+
+  import Ecto.Query
+  alias Mobilizon.Actors.{Actor, Follower, Member}
+  alias Mobilizon.Events.{Event, Participant}
+  alias Mobilizon.Storage.Page
+
+  def user_followed_group_events(user_id, page \\ nil, limit \\ nil) do
+    Event
+    |> distinct([e], e.id)
+    |> join(:left, [e], p in Participant, on: e.id == p.event_id)
+    |> join(:inner, [_e, p], pa in Actor, on: p.actor_id == pa.id)
+    |> join(:inner, [e], g in Actor, on: e.attributed_to_id == g.id)
+    |> join(:left, [_e, _p, _pa, g], f in Follower, on: g.id == f.target_actor_id)
+    |> join(:left, [_e, _p, _pa, g], m in Member, on: g.id == m.parent_id)
+    |> join(:inner, [_e, _p, pa, _g, f, m], a in Actor,
+      on: a.id == f.actor_id or a.id == m.actor_id
+    )
+    |> where(
+      [e, p, pa, _g, f, m, a],
+      e.begins_on > ^DateTime.utc_now() and
+        (f.approved or m.role in ^[:member, :moderator, :administrator, :creator]) and
+        a.user_id == ^user_id and
+        pa.user_id != ^user_id
+    )
+    |> preload([
+      :organizer_actor,
+      :attributed_to,
+      :tags,
+      :physical_address,
+      :picture
+    ])
+    |> select([e, g, _f, _m, a], [
+      e,
+      g,
+      a
+    ])
+    |> Page.build_page(page, limit)
+  end
+end