Hootlex\Friendships\Traits\Friendable::friendsOfFriendsQueryBuilder PHP Method

    private function friendsOfFriendsQueryBuilder($groupSlug = '')
    {
        $friendships = $this->findFriendships(Status::ACCEPTED)->get(['sender_id', 'recipient_id']);
        $recipients = $friendships->pluck('recipient_id')->all();
        $senders = $friendships->pluck('sender_id')->all();
        $friendIds = array_unique(array_merge($recipients, $senders));
        $fofs = Friendship::where('status', Status::ACCEPTED)->where(function ($query) use($friendIds) {
            $query->where(function ($q) use($friendIds) {
                $q->whereIn('sender_id', $friendIds);
            })->orWhere(function ($q) use($friendIds) {
                $q->whereIn('recipient_id', $friendIds);
            });
        })->whereGroup($this, $groupSlug)->get(['sender_id', 'recipient_id']);
        $fofIds = array_unique(array_merge($fofs->pluck('sender_id')->all(), $fofs->pluck('recipient_id')->all()));
        //      Alternative way using collection helpers
        //        $fofIds = array_unique(
        //            $fofs->map(function ($item) {
        //                return [$item->sender_id, $item->recipient_id];
        //            })->flatten()->all()
        //        );
        return $this->whereIn('id', $fofIds)->whereNotIn('id', $friendIds);
    }