public Task <DownloadData> QueueDownload(UriString url, UriString md5Url, NPath targetDirectory)
{
var destinationFile = targetDirectory.Combine(url.Filename);
var destinationMd5 = targetDirectory.Combine(md5Url.Filename);
var result = new DownloadData(url, destinationFile);
Action <ITask <NPath>, NPath, bool, Exception> verifyDownload = (t, res, success, ex) =>
{
var count = Interlocked.Increment(ref finishedTaskCount);
isSuccessful &= success;
if (!success)
{
exception = ex;
}
if (count == queuedTasks.Count)
{
if (!isSuccessful)
{
DownloadFailed(result, exception);
}
else
{
if (!Utils.VerifyFileIntegrity(destinationFile, destinationMd5))
{
destinationMd5.Delete();
destinationFile.Delete();
DownloadFailed(result, new DownloadException($"Verification of {url} failed"));
}
else
{
DownloadComplete(result);
}
}
}
};
var md5Exists = destinationMd5.FileExists();
var fileExists = destinationFile.FileExists();
if (!md5Exists)
{
destinationMd5.DeleteIfExists();
var md5Download = new DownloadTask(cancellationToken, fs, md5Url, targetDirectory)
.Catch(e => DownloadFailed(result, e));
md5Download.OnEnd += verifyDownload;
queuedTasks.Add(md5Download);
}
if (!fileExists)
{
var fileDownload = new DownloadTask(cancellationToken, fs, url, targetDirectory)
.Catch(e => DownloadFailed(result, e));
fileDownload.OnStart += _ => DownloadStart?.Invoke(result);
fileDownload.OnEnd += verifyDownload;
queuedTasks.Add(fileDownload);
}
if (fileExists && md5Exists)
{
var verification = new FuncTask <NPath>(cancellationToken, () => destinationFile);
verification.OnEnd += verifyDownload;
queuedTasks.Add(verification);
}
return(aggregateDownloads.Task);
}