private async Task <UserLatestUpdateTime> GetUserLatestUpdateTime(string userId)
{
var zero = new UserLatestUpdateTime
{
UserId = userId,
LatestUpdateTime = DateTime.MinValue
};
return(await _userLatestUpdateTimesRepository.GetAsync(userId) ?? zero);
}
private IAsyncEnumerable <Update> GetNewUpdates(
IEnumerable <Update> updates,
UserLatestUpdateTime userLatestUpdateTime)
{
var newUpdates = updates
.Where(IsNew(userLatestUpdateTime))
.OrderBy(update => update.CreationDate)
.ToAsyncEnumerable();
if (_config.StoreSentUpdates)
{
return(newUpdates.WhereAwait(NotSent));
}
return(newUpdates);
}
public async Task AddOrUpdateAsync(string userId, DateTime latestUpdateTime)
{
var updateTime = new UserLatestUpdateTime
{
UserId = userId,
LatestUpdateTime = latestUpdateTime
};
UserLatestUpdateTime newEntity = await _collection
.FindOneAndReplaceAsync(
userLatestUpdateTime => userLatestUpdateTime.UserId == userId,
updateTime);
if (newEntity == null)
{
await _collection.InsertOneAsync(updateTime);
}
}
private async IAsyncEnumerable <Update> GetUpdates(
string userId,
[EnumeratorCancellation] CancellationToken cancellationToken)
{
IEnumerable <Update> updates = await _updatesProvider.GetUpdatesAsync(userId);
List <Update> sortedUpdates = updates
.Reverse()
.OrderBy(update => update.CreationDate).ToList();
UserLatestUpdateTime userLatestUpdateTime = await GetUserLatestUpdateTime(userId);
ConfiguredCancelableAsyncEnumerable <Update> newUpdates = GetNewUpdates(sortedUpdates, userLatestUpdateTime)
.WithCancellation(cancellationToken);
await foreach (Update update in newUpdates)
{
yield return(update.Media?.Any() == true
? await WithExtractedVideo(update, cancellationToken)
: update);
}
}
private static Func <Update, bool> IsNew(UserLatestUpdateTime userLatestUpdateTime)
{
return(update => update.CreationDate != null &&
update.CreationDate > userLatestUpdateTime.LatestUpdateTime);
}