public async Task<Uri> GetNext(CancellationTokenSource cancellationTokenSource)
{
try
{
if (allowedCount == 0)
return null;
if (searchOnPage == null)
{
allowedCount--;
searchOnPage = new GoogleSearchOnPage();
await searchOnPage.Initialize(new Uri(string.Format(queryString, linkNumber)), captchaWindow, linkNumber, cancellationTokenSource);
}
Uri res = searchOnPage.GetNext();
if (res != null)
linkNumber++;
else
{
searchOnPage = null;
return await GetNext(cancellationTokenSource);
}
return res;
}
catch (TaskCanceledException)
{
return null;
}
}
public GoogleSearchEngine(int allowedCount, string keywords, ICaptchaWindow captchaWindow)
{
string[] escapedKeywords = keywords.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(item => Uri.EscapeDataString(item)).ToArray();
StringBuilder builder = new StringBuilder();
builder.Append("http://www.google.com.ua/search?q=");
builder.Append(string.Join("+", escapedKeywords));
builder.Append("&start={0}");
queryString = builder.ToString();
linkNumber = 0;
this.allowedCount = allowedCount;
this.captchaWindow = captchaWindow;
searchOnPage = null;
}