func (s *videoService) update(movieTitle string, wg *sync.WaitGroup) {
        movie, _, err := s.getMovieAndTvSeriesInfo(movieTitle) // returns *Movie, *TVSeries, error
        if err == nil {
                err = s.repo.SaveMovie(movie)
                // if there is no error while saving movie
                if err == nil {
                        wg.Done()
                }
        }
}

func (s *videoService) Save() error {
        log.Infoln("Updating movie database...")

        // check if video dir path ends with slash
        videoDirPath := env.EnvString("VIDEO_DIR")
        if !strings.HasSuffix(videoDirPath, "/") {
                videoDirPath += "/"
        }
        videos, err := s.getVideos(videoDirPath)
        if err != nil {
                log.Error("Unable to get list of movies")
                return err
        }

        var wg sync.WaitGroup

        for _, v := range videos {
                wg.Add(1)
                go s.update(v, &wg)
        }

        wg.Wait()
        log.Infoln("The movie database has been updated.")
        return nil
}