private void FromReaderToFile(StreamReader src, FileStream dest,
ref DownloaderMetric metric, ref Stopwatch stopwatch, CancellationToken ct)
{
var buffer = new byte[32 * 1024];
int bytesRead;
while ((bytesRead = src.BaseStream.Read(buffer, 0, buffer.Length)) > 0)
{
if (ct.IsCancellationRequested)
{
dest.Flush(true);
dest.Close();
dest.Dispose();
return;
}
dest.Write(buffer, 0, bytesRead);
metric.DownloadedBytes += bytesRead;
metric.ElapsedTime = stopwatch.Elapsed;
OnDownloading?.Invoke(metric);
}
OnDownloadCompleted?.Invoke(metric);
dest.Flush(true);
dest.Close();
dest.Dispose();
}
private async Task ProcessDownloadAsync(Uri uri, string filename, CancellationToken ct)
{
try
{
dynamic request = null;
#region Get file size
if (uri.Scheme == Uri.UriSchemeHttp)
{
request = WebRequest.Create(uri) as HttpWebRequest;
request !.Method = WebRequestMethods.Http.Head;
}
else if (uri.Scheme == Uri.UriSchemeFtp)
{
request = WebRequest.Create(uri) as FtpWebRequest;
request !.Method = WebRequestMethods.Ftp.GetFileSize;
}
var metric = new DownloaderMetric
{
FileName = Path.GetFileName(filename)
};
using (var response = await request !.GetResponseAsync())
{
metric.TotalBytes = response.ContentLength;
}
#endregion
// Set start download position
long startPos = 0;
var fi = new FileInfo(filename);
if (fi.Exists)
{
if (metric.TotalBytes > fi.Length)
{
metric.DownloadedBytes = startPos = fi.Length - 1024;
}
else if (metric.TotalBytes == fi.Length)
{
return;
}
}
#region Read Content Stream Asynchronously
if (uri.Scheme == Uri.UriSchemeHttp)
{
request = WebRequest.Create(uri) as HttpWebRequest;
request = (HttpWebRequest)request;
request !.Method = WebRequestMethods.Http.Get;
request.AddRange(startPos, metric.TotalBytes);
}
else if (uri.Scheme == Uri.UriSchemeFtp)
{
request = WebRequest.Create(uri) as FtpWebRequest;
request !.Method = WebRequestMethods.Ftp.DownloadFile;
request.ContentOffset = startPos;
}
var stopwatch = new Stopwatch();
stopwatch.Start();
if (!Directory.Exists(Path.GetDirectoryName(filename)))
{
Directory.CreateDirectory(Path.GetDirectoryName(filename) !);
}
var fileStream = new FileStream(filename, FileMode.OpenOrCreate, FileAccess.ReadWrite)
{
Position = metric.DownloadedBytes
};
await Task.Run(async() =>
{
if (ct.IsCancellationRequested)
{
return;
}
using var streamReader = new StreamReader((await request.GetResponseAsync()).GetResponseStream());
OnDownloadStart?.Invoke(metric);
FromReaderToFile(streamReader, fileStream, ref metric, ref stopwatch, ct);
OnDownloadCompleted?.Invoke(metric);
}, ct);
#endregion
}
catch (OperationCanceledException)
{
const string msg = "Download cancelled by user";
OnError?.Invoke(new DownloaderClientException(msg));
}
catch (Exception ex)
{
const string msg = "An unexpected error occurred.";
OnError?.Invoke(
new DownloaderClientException($"{msg}\n\nDownload failed. See inner exception for details.", ex));
}
}
