/// <summary>
/// Loads the HTML pages that are relevant to a quest's tally.
/// </summary>
/// <param name="quest">The quest being loaded.</param>
/// <param name="adapter">The quest's forum adapter, used to forum the URLs to load.</param>
/// <param name="threadRangeInfo">The range info that determines which pages to load.</param>
/// <param name="token">The cancellation token.</param>
/// <returns>Returns a list of tasks that are handling the async loading of the requested pages.</returns>
private async Task <List <Task <HtmlDocument> > > LoadQuestPagesAsync(
IQuest quest, IForumAdapter adapter, ThreadRangeInfo threadRangeInfo, CancellationToken token)
{
var scanInfo = await GetPagesToScanAsync(quest, adapter, threadRangeInfo, token).ConfigureAwait(false);
int firstPageNumber = scanInfo.Item1;
int lastPageNumber = scanInfo.Item2;
int pagesToScan = scanInfo.Item3;
// We will store the loaded pages in a new List.
List <Task <HtmlDocument> > pages = new List <Task <HtmlDocument> >();
IPageProvider pageProvider = ViewModels.ViewModelService.MainViewModel.PageProvider;
// Initiate the async tasks to load the pages
if (pagesToScan > 0)
{
// Initiate tasks for all pages other than the first page (which we already loaded)
var results = from pageNum in Enumerable.Range(firstPageNumber, pagesToScan)
let pageUrl = adapter.GetUrlForPage(pageNum, quest.PostsPerPage)
let shouldCache = (pageNum == lastPageNumber) ? ShouldCache.No : ShouldCache.Yes
select pageProvider.GetPage(pageUrl, $"Page {pageNum}", CachingMode.UseCache, shouldCache, SuppressNotifications.No, token);
pages.AddRange(results.ToList());
}
return(pages);
}
/// <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);
}