package service import "golang_course/lessons/interfaces/producer_interface/storage" type MessageSender struct { repository storage.ClientStorage } func NewMessageSender(repository storage.ClientStorage) MessageSender { return MessageSender{ repository: repository, } } func (s *MessageSender) SendMessage(userId int, message string) error { _, err := s.repository.GetClient(userId) if err != nil { return err } // send message to client return nil }