// Display list audio

        public static List <GoogleDriveFiles> Index()
        {
            Google.Apis.Drive.v3.DriveService service = GetService();

            // define parameters of request.
            Google.Apis.Drive.v3.FilesResource.ListRequest FileListRequest = service.Files.List();

            //listRequest.PageSize = 10;
            //listRequest.PageToken = 10;
            FileListRequest.Fields = "nextPageToken, files(createdTime, id, name, size, version, trashed, parents)";

            //get file list.
            IList <Google.Apis.Drive.v3.Data.File> files = FileListRequest.Execute().Files;
            List <GoogleDriveFiles> FileList             = new List <GoogleDriveFiles>();

            if (files != null && files.Count > 0)
            {
                foreach (var file in files)
                {
                    GoogleDriveFiles File = new GoogleDriveFiles
                    {
                        Id          = file.Id,
                        Name        = file.Name,
                        Size        = file.Size,
                        Version     = file.Version,
                        CreatedTime = file.CreatedTime,
                        Parents     = file.Parents
                    };


                    string path = Path.Combine(HttpContext.Current.Server.MapPath("~"), Path.GetFileName(file.Name));



                    var fileMETA = new Google.Apis.Drive.v3.Data.File()
                    {
                        Name     = file.Name,
                        MimeType = MimeMapping.GetMimeMapping(path)
                    };
                    if (fileMETA.MimeType == "audio/mpeg" || fileMETA.MimeType == "audio/wav")
                    {
                        FileList.Add(File);
                    }
                }
            }
            return(FileList);
        }
        //Delete file from the Google drive
        public static void DeleteFile(GoogleDriveFiles files)
        {
            Google.Apis.Drive.v3.DriveService service = GetService();
            try
            {
                // Initial validation.
                if (service == null)
                {
                    throw new ArgumentNullException("service");
                }

                if (files == null)
                {
                    throw new ArgumentNullException(files.Id);
                }

                // Make the request.
                service.Files.Delete(files.Id).Execute();
            }
            catch (Exception ex)
            {
                throw new Exception("Request Files.Delete failed.", ex);
            }
        }