/// <summary>
/// A publicly available method for creating a single instance of this cache
/// if one doesn't already exist, or getting a reference to the single instance.
/// </summary>
/// <returns>
/// A reference to the single instance of this cache class.
/// </returns>
public static UploadedFileCache GetInstance()
{
//create if not exists
if (s_Instance == null)
{
s_Instance = new UploadedFileCache();
}
return(s_Instance);
}
/// <summary>
/// A clean-up method. Call the <see cref="UploadedFileCache.DeleteOldFiles"/> method
/// to remove all old files from intermediate file storage every time the event is fired.
/// Call the <see cref="BlobManager.RemoveExpiredTemporaryBlobs"/> method to remove
/// all old temporary blobs from cloud storage every other time the event is fired.
/// </summary>
/// <param name="sender">The timer object that called this event.</param>
/// <param name="e">Any "Timer's up" arguments. Not used.</param>
private void Timer_Elapsed(object sender, ElapsedEventArgs e)
{
UploadedFileCache.DeleteOldFiles();
//Only call when true, alternate each time
//effectively a 30 min timer for purging blobs
if (s_ShouldPurgeBlobs)
{
BlobManager.RemoveExpiredTemporaryBlobs();
}
s_ShouldPurgeBlobs = !s_ShouldPurgeBlobs;
}
/// <summary>
/// Method called automatically upon startup. Initial app setup logic and configuration
/// goes here.
/// </summary>
/// <param name="app">The AE web app</param>
public void Configuration(IAppBuilder app)
{
ConfigureAuth(app);
//define intermediate upload directory as ~/UploadedFiles/
string uploadDir = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "UploadedFiles");
//news up a static instance of FileCache
UploadedFileCache uploadedFiles = UploadedFileCache.GetInstance();
uploadedFiles.BasePath = uploadDir;
//make sure public blob container exists
BlobManager blobManager = new BlobManager();
blobManager.GetOrCreateBlobContainer("public");
//start app self-cleaning timer
TimerInit();
}
/// <summary>
/// The user has requested a blob to be downloaded as a file format that doesn't currently
/// exist in cloud storage. Download the existing format, run conversion software, and
/// re-upload the zipped contents of the conversion.
/// </summary>
/// <param name="fromBlob"></param>
/// <param name="userName"></param>
/// <param name="fileName"></param>
/// <param name="path"></param>
/// <param name="requestExtension"></param>
/// <returns>
/// <ul>
/// <li>The error detail about the failed conversion</li>
/// <li>The name of the zip file blob containing conversion results.</li>
/// </ul>
/// </returns>
private string ConvertBlobToBlob(CloudBlockBlob fromBlob, string userName, string fileName, string path, string requestExtension)
{
Guid subDir;
CloudBlockBlob toBlob = null;
CloudBlobContainer container = fromBlob.Parent.Container;
string getFileName = $"{fileName.Remove(fileName.LastIndexOf('.'))}";
string zipFolderName = $"{getFileName}-{requestExtension.Substring(1)}.zip";
UploadedFileCache uploadedFiles = UploadedFileCache.GetInstance();
if (!uploadedFiles.DeleteAndRemoveFile(userName, fileName))
{ //couldn't delete old tracked instance
return("Error: Unable to download .fbx blob for conversion.");
}
else if ((subDir = uploadedFiles.SaveFile(fromBlob, userName, fileName)) != Guid.Empty)
{ //successfully downloaded original - run conversion and zip results
if (ConvertAndZip(path, subDir.ToString(), requestExtension, fileName, zipFolderName))
{
//upload converted zipped file to blob storage
if (UploadBlobToUserContainer(userName, zipFolderName, path))
{ //get reference to blob and get download link
toBlob = container.GetBlockBlobReference(zipFolderName);
return(toBlob.Name);
}
else
{
return($"Error: unable to process converted file: {getFileName}.");
}
}
else
{
return($"Error: unable to convert {fileName} to type {requestExtension}.");
}
}
else
{
return("Error: Unable to download .fbx blob for conversion.");
}
}