From b12cea5ead60562350d35177467ba293c85dfe71 Mon Sep 17 00:00:00 2001
From: Thomas Citharel <tcit@tcit.fr>
Date: Tue, 2 Nov 2021 19:48:38 +0100
Subject: [PATCH] Allow to get group followed events after a certain date

Signed-off-by: Thomas Citharel <tcit@tcit.fr>
---
 lib/graphql/resolvers/user.ex            | 10 ++++++++--
 lib/graphql/schema/user.ex               |  4 ++++
 lib/mobilizon/followed_group_activity.ex | 21 +++++++++++++++++----
 3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/lib/graphql/resolvers/user.ex b/lib/graphql/resolvers/user.ex
index 0330cf18e..430bc6b48 100644
--- a/lib/graphql/resolvers/user.ex
+++ b/lib/graphql/resolvers/user.ex
@@ -633,11 +633,17 @@ defmodule Mobilizon.GraphQL.Resolvers.User do
      }}
   end
 
-  def user_followed_group_events(%User{id: user_id}, %{page: page, limit: limit}, %{
+  def user_followed_group_events(%User{id: user_id}, %{page: page, limit: limit} = args, %{
         context: %{current_user: %User{id: logged_in_user_id}}
       })
       when user_id == logged_in_user_id do
-    activities = FollowedGroupActivity.user_followed_group_events(user_id, page, limit)
+    activities =
+      FollowedGroupActivity.user_followed_group_events(
+        user_id,
+        Map.get(args, :after_datetime),
+        page,
+        limit
+      )
 
     activities = %Page{
       activities
diff --git a/lib/graphql/schema/user.ex b/lib/graphql/schema/user.ex
index e954f05d6..cb567e289 100644
--- a/lib/graphql/schema/user.ex
+++ b/lib/graphql/schema/user.ex
@@ -117,6 +117,10 @@ defmodule Mobilizon.GraphQL.Schema.UserType do
         description: "The limit of follow group events per page"
       )
 
+      arg(:after_datetime, :datetime,
+        description: "Filter follow group events by event start datetime"
+      )
+
       resolve(&User.user_followed_group_events/3)
     end
 
diff --git a/lib/mobilizon/followed_group_activity.ex b/lib/mobilizon/followed_group_activity.ex
index 0c8d5a6c6..7ef7e7774 100644
--- a/lib/mobilizon/followed_group_activity.ex
+++ b/lib/mobilizon/followed_group_activity.ex
@@ -8,7 +8,13 @@ defmodule Mobilizon.FollowedGroupActivity do
   alias Mobilizon.Events.{Event, Participant}
   alias Mobilizon.Storage.Page
 
-  def user_followed_group_events(user_id, page \\ nil, limit \\ nil) do
+  @spec user_followed_group_events(
+          integer() | String.t(),
+          DateTime.t() | nil,
+          integer() | nil,
+          integer() | nil
+        ) :: Page.t(Event.t())
+  def user_followed_group_events(user_id, after_datetime, page \\ nil, limit \\ nil) do
     Event
     |> distinct([e], e.id)
     |> join(:left, [e], p in Participant, on: e.id == p.event_id)
@@ -19,10 +25,10 @@ defmodule Mobilizon.FollowedGroupActivity do
     |> join(:inner, [_e, _p, pa, _g, f, m], a in Actor,
       on: a.id == f.actor_id or a.id == m.actor_id
     )
+    |> add_after_datetime_filter(after_datetime)
     |> 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
+      [_e, p, pa, _g, f, m, a],
+      (f.approved or m.role in ^[:member, :moderator, :administrator, :creator]) and
         a.user_id == ^user_id and
         pa.user_id != ^user_id
     )
@@ -40,4 +46,11 @@ defmodule Mobilizon.FollowedGroupActivity do
     ])
     |> Page.build_page(page, limit)
   end
+
+  @spec add_after_datetime_filter(Ecto.Query.t(), DateTime.t() | nil) :: Ecto.Query.t()
+  defp add_after_datetime_filter(query, nil),
+    do: where(query, [e], e.begins_on > ^DateTime.utc_now())
+
+  defp add_after_datetime_filter(query, %DateTime{} = datetime),
+    do: where(query, [e], e.begins_on > ^datetime)
 end