/// <summary>
/// Returns the list of days specified by the <see cref="DaysOfWeek"/>, relative to a given date.
/// </summary>
/// <param name="date">The date on which the relative days must be calculated.</param>
/// <returns>The list of days relative to the specified <paramref name="date"/>.</returns>
protected List <int> GetRelativeDaysOfWeekTo(DateTime date)
{
var baseOffset = date.DaysFromStartOfTheWeek(FirstDayOfWeek);
var offsets = new List <int>(DateUtils.DaysPerWeek);
foreach (var day in DaysOfWeek.AsEnumerable())
{
offsets.Add(day.DaysFromStartOfTheWeek(FirstDayOfWeek) - baseOffset);
}
offsets.Sort();
return(offsets);
}