/// <summary>
/// Get the starting page for tallying for the provided quest, using either
/// the explicitly determined page number, or the calculated page number
/// based on the starting post and the quest's post per page.
/// </summary>
/// <param name="quest">The quest this info is for.</param>
/// <returns>Returns the page number to start tallying.</returns>
public int GetStartPage(IQuest quest)
{
if (ByNumber)
{
return(quest?.GetPageNumberOf(Number) ?? 1);
}
return(Page);
}
/// <summary>
/// Determines the page number range that will be loaded for the quest.
/// Returns a tuple of first page number, last page number, and pages to scan.
/// </summary>
/// <param name="quest">The quest being tallied.</param>
/// <param name="adapter">The forum adapter for the quest.</param>
/// <param name="threadRangeInfo">The thread range info, as provided by the adapter.</param>
/// <param name="token">The cancellation token.</param>
/// <returns>Returns a tuple of the page number info that was determined.</returns>
private async Task <Tuple <int, int, int> > GetPagesToScanAsync(
IQuest quest, IForumAdapter adapter, ThreadRangeInfo threadRangeInfo, CancellationToken token)
{
IPageProvider pageProvider = ViewModels.ViewModelService.MainViewModel.PageProvider;
int firstPageNumber = threadRangeInfo.GetStartPage(quest);
int lastPageNumber = 0;
int pagesToScan = 0;
if (threadRangeInfo.Pages > 0)
{
// If the startInfo obtained the thread pages info, just use that.
lastPageNumber = threadRangeInfo.Pages;
}
else if (quest.ReadToEndOfThread || threadRangeInfo.IsThreadmarkSearchResult)
{
// If we're reading to the end of the thread (end post 0, or based on a threadmark),
// then we need to load the first page to find out how many pages there are in the thread.
// Make sure to bypass the cache, since it may have changed since the last load.
string firstPageUrl = adapter.GetUrlForPage(firstPageNumber, quest.PostsPerPage);
HtmlDocument page = await pageProvider.GetPage(firstPageUrl, $"Page {firstPageNumber}",
CachingMode.BypassCache, ShouldCache.Yes, SuppressNotifications.No, token)
.ConfigureAwait(false);
if (page == null)
{
throw new InvalidOperationException($"Unable to load web page: {firstPageUrl}");
}
lastPageNumber = adapter.GetThreadInfo(page).Pages;
}
else
{
// If we're not reading to the end of the thread, just calculate
// what the last page number will be. Pages to scan will be the
// difference in pages +1.
lastPageNumber = quest.GetPageNumberOf(quest.EndPost);
}
pagesToScan = lastPageNumber - firstPageNumber + 1;
Tuple <int, int, int> result = new Tuple <int, int, int>(firstPageNumber, lastPageNumber, pagesToScan);
return(result);
}