Add `thread_visibility` to migrations

2 files changed, 135 insertions, 3 deletions

diff --git a/priv/repo/migrations/20191007073319_create_following_relationships.exs b/priv/repo/migrations/20191007073319_create_following_relationships.exs
index 8ffc870d9..7daaf0575 100644
--- a/priv/repo/migrations/20191007073319_create_following_relationships.exs
+++ b/priv/repo/migrations/20191007073319_create_following_relationships.exs
@@ -1,9 +1,6 @@
 defmodule Pleroma.Repo.Migrations.CreateFollowingRelationships do
   use Ecto.Migration
 
-  # had to disable these to be able to restore `following` index concurrently
-  # https://hexdocs.pm/ecto_sql/Ecto.Migration.html#index/3-adding-dropping-indexes-concurrently
-
   def change do
     create_if_not_exists table(:following_relationships) do
       add(:follower_id, references(:users, type: :uuid, on_delete: :delete_all), null: false)
@@ -15,5 +12,138 @@ defmodule Pleroma.Repo.Migrations.CreateFollowingRelationships do
 
     create_if_not_exists(index(:following_relationships, :follower_id))
     create_if_not_exists(unique_index(:following_relationships, [:follower_id, :following_id]))
+
+    execute(update_thread_visibility(), restore_thread_visibility())
+  end
+
+  # The only difference with the original verion: `actor_user` replaced with `actor_user_following`
+  def update_thread_visibility do
+    """
+    CREATE OR REPLACE FUNCTION thread_visibility(actor varchar, activity_id varchar) RETURNS boolean AS $$
+    DECLARE
+      public varchar := 'https://www.w3.org/ns/activitystreams#Public';
+      child objects%ROWTYPE;
+      activity activities%ROWTYPE;
+      author_fa varchar;
+      valid_recipients varchar[];
+      actor_user_following varchar[];
+    BEGIN
+      --- Fetch actor following
+      SELECT array_agg(following.follower_address) INTO actor_user_following FROM following_relationships
+      JOIN users ON users.id = following_relationships.follower_id
+      JOIN users AS following ON following.id = following_relationships.following_id
+      WHERE users.ap_id = actor;
+
+      --- Fetch our initial activity.
+      SELECT * INTO activity FROM activities WHERE activities.data->>'id' = activity_id;
+
+      LOOP
+        --- Ensure that we have an activity before continuing.
+        --- If we don't, the thread is not satisfiable.
+        IF activity IS NULL THEN
+          RETURN false;
+        END IF;
+
+        --- We only care about Create activities.
+        IF activity.data->>'type' != 'Create' THEN
+          RETURN true;
+        END IF;
+
+        --- Normalize the child object into child.
+        SELECT * INTO child FROM objects
+        INNER JOIN activities ON COALESCE(activities.data->'object'->>'id', activities.data->>'object') = objects.data->>'id'
+        WHERE COALESCE(activity.data->'object'->>'id', activity.data->>'object') = objects.data->>'id';
+
+        --- Fetch the author's AS2 following collection.
+        SELECT COALESCE(users.follower_address, '') INTO author_fa FROM users WHERE users.ap_id = activity.actor;
+
+        --- Prepare valid recipients array.
+        valid_recipients := ARRAY[actor, public];
+        IF ARRAY[author_fa] && actor_user_following THEN
+          valid_recipients := valid_recipients || author_fa;
+        END IF;
+
+        --- Check visibility.
+        IF NOT valid_recipients && activity.recipients THEN
+          --- activity not visible, break out of the loop
+          RETURN false;
+        END IF;
+
+        --- If there's a parent, load it and do this all over again.
+        IF (child.data->'inReplyTo' IS NOT NULL) AND (child.data->'inReplyTo' != 'null'::jsonb) THEN
+          SELECT * INTO activity FROM activities
+          INNER JOIN objects ON COALESCE(activities.data->'object'->>'id', activities.data->>'object') = objects.data->>'id'
+          WHERE child.data->>'inReplyTo' = objects.data->>'id';
+        ELSE
+          RETURN true;
+        END IF;
+      END LOOP;
+    END;
+    $$ LANGUAGE plpgsql IMMUTABLE;
+    """
+  end
+
+  # priv/repo/migrations/20190515222404_add_thread_visibility_function.exs
+  def restore_thread_visibility do
+    """
+    CREATE OR REPLACE FUNCTION thread_visibility(actor varchar, activity_id varchar) RETURNS boolean AS $$
+    DECLARE
+      public varchar := 'https://www.w3.org/ns/activitystreams#Public';
+      child objects%ROWTYPE;
+      activity activities%ROWTYPE;
+      actor_user users%ROWTYPE;
+      author_fa varchar;
+      valid_recipients varchar[];
+    BEGIN
+      --- Fetch our actor.
+      SELECT * INTO actor_user FROM users WHERE users.ap_id = actor;
+
+      --- Fetch our initial activity.
+      SELECT * INTO activity FROM activities WHERE activities.data->>'id' = activity_id;
+
+      LOOP
+        --- Ensure that we have an activity before continuing.
+        --- If we don't, the thread is not satisfiable.
+        IF activity IS NULL THEN
+          RETURN false;
+        END IF;
+
+        --- We only care about Create activities.
+        IF activity.data->>'type' != 'Create' THEN
+          RETURN true;
+        END IF;
+
+        --- Normalize the child object into child.
+        SELECT * INTO child FROM objects
+        INNER JOIN activities ON COALESCE(activities.data->'object'->>'id', activities.data->>'object') = objects.data->>'id'
+        WHERE COALESCE(activity.data->'object'->>'id', activity.data->>'object') = objects.data->>'id';
+
+        --- Fetch the author's AS2 following collection.
+        SELECT COALESCE(users.follower_address, '') INTO author_fa FROM users WHERE users.ap_id = activity.actor;
+
+        --- Prepare valid recipients array.
+        valid_recipients := ARRAY[actor, public];
+        IF ARRAY[author_fa] && actor_user.following THEN
+          valid_recipients := valid_recipients || author_fa;
+        END IF;
+
+        --- Check visibility.
+        IF NOT valid_recipients && activity.recipients THEN
+          --- activity not visible, break out of the loop
+          RETURN false;
+        END IF;
+
+        --- If there's a parent, load it and do this all over again.
+        IF (child.data->'inReplyTo' IS NOT NULL) AND (child.data->'inReplyTo' != 'null'::jsonb) THEN
+          SELECT * INTO activity FROM activities
+          INNER JOIN objects ON COALESCE(activities.data->'object'->>'id', activities.data->>'object') = objects.data->>'id'
+          WHERE child.data->>'inReplyTo' = objects.data->>'id';
+        ELSE
+          RETURN true;
+        END IF;
+      END LOOP;
+    END;
+    $$ LANGUAGE plpgsql IMMUTABLE;
+    """
   end
 end
diff --git a/priv/repo/migrations/20191008132427_drop_users_following.exs b/priv/repo/migrations/20191008132427_drop_users_following.exs
index 17805db36..21c0af9f4 100644
--- a/priv/repo/migrations/20191008132427_drop_users_following.exs
+++ b/priv/repo/migrations/20191008132427_drop_users_following.exs
@@ -1,6 +1,8 @@
 defmodule Pleroma.Repo.Migrations.DropUsersFollowing do
   use Ecto.Migration
 
+  # had to disable these to be able to restore `following` index concurrently
+  # https://hexdocs.pm/ecto_sql/Ecto.Migration.html#index/3-adding-dropping-indexes-concurrently
   @disable_ddl_transaction true
   @disable_migration_lock true