/// <summary>Answer current card and fetch next one.</summary>
/// <param name="grade">Answer grade</param>
/// <returns>Whether any cards are available</returns>
/// <exception cref="System.InvalidOperationException">No card available (Current is null).</exception>
public Task <bool> AnswerAsync(Grade grade)
{
// Card sanity check
Card card = Current;
if (card == null)
{
throw new InvalidOperationException("Card unavailable");
}
// Compute evaluation time & create review log
ReviewLog log = CreateLog(card);
// Answer
NextAction[CurrentList] = () => CurrentList.MoveNextAsync();
CurrentList = null;
CardAction cardAction = card.Answer(grade);
// Complete log with updated values
CompleteLog(log, card, grade);
// If this was a new card, add to learning list
if (log.LastState == PracticeState.New)
{
ReviewCollectionLearn.AddManual(card);
}
#pragma warning disable 4014
// Save changes to Database
UpdateCardAsync(log, card, cardAction);
#pragma warning restore 4014
ReviewCollectionNew.DismissSiblings(card);
ReviewCollectionLearn.DismissSiblings(card);
ReviewCollectionDue.DismissSiblings(card);
return(DoNextAsync());
}