public void DownloadAndEnqueue(string seed)
{
//validate
try
{
var validate = ValidateUrl.Validate(seed);
if (!validate.Item1)
{
return;
}
//if is in hashset
if (CrawledUrls.Contains(validate.Item2.AbsoluteUri))
{
return;
}
CrawledUrls.Add(validate.Item2.AbsoluteUri);
//download and save html file
var html = new HtmlDownloader(validate.Item2).Load();
if (html == null)
{
return;
}
//parse html file to get urls
var linkedPages = Parser.Parse(html, validate.Item2);
foreach (string linkedPage in linkedPages)
{
Queue.Enqueue(linkedPage);
}
}
catch (Exception ex) { }
}
public IEnumerable <string> Parse(HtmlDocument html, Uri url)
{
Print.Show("Parsing url:" + url.AbsoluteUri);
var linkedPages = html.DocumentNode.Descendants("a")
.Select(a => a.GetAttributeValue("href", null))
.Where(u => !String.IsNullOrEmpty(u));
Print.Show(linkedPages.Count() + " urls in" + url.AbsoluteUri);
List <string> uriList = new List <string>();
foreach (string linkedPage in linkedPages)
{
if (linkedPage.Contains("#"))
{
continue;
}
var result = ValidateUrl.Validate(linkedPage);
try
{
if (!result.Item1)
{
uriList.Add(new Uri(url, linkedPage).AbsoluteUri);
}
else
{
uriList.Add(linkedPage);
}
}
catch (Exception ex)
{
Print.Show(ex.Message);
}
}
return(uriList);
}