private async Task DownloadFilesAsync(Uri parentUri, HtmlDocument document, IConstraint constraint)
{
IEnumerable <string> links = document.GetAllLinksExceptTagALinks();
var tasks = new List <Task>();
foreach (string link in links)
{
if (!FilterLink(link))
{
continue;
}
Uri uri = CreateUri(parentUri, link);
if (!_visitedUris.Contains(uri) && constraint.IsSourceLinkPermissible(uri))
{
_visitedUris.Add(uri);
tasks.Add(GetSourceFileAndDownloadAsync(uri));
}
}
await Task.WhenAll(tasks);
}