public IEnumerable<DateTime> CalculateRecurrenceSet(int? skip = 0, int take = int.MaxValue,
DateTimeWindow dateTimeWindow = null)
{
// if dateTimeWindow wasn't passed; default is all time
dateTimeWindow = dateTimeWindow ?? DateTimeWindow.AllTime;
var recurrenceSet = new List<DateTime>();
DateTime precedingOccurrence = StartDateTime;
DateTime nextOccurrence;
// handle skipping a number of occurrences into the complete recurrence set
if (skip > 0)
{
// initialize to 1 because StartDateTime is used to initialize precedingOccurrence
int skipCount = 1;
while (skipCount != skip)
{
if (TryCalculateNextOccurrence(precedingOccurrence, dateTimeWindow, out nextOccurrence))
{
precedingOccurrence = nextOccurrence;
skipCount++;
}
// handle skipping more results than the number of results which exist
else
{
return recurrenceSet;
}
}
}
else if (dateTimeWindow.MinimumIncludedDateTime < StartDateTime)
{
recurrenceSet.Add(StartDateTime);
}
while (TryCalculateNextOccurrence(precedingOccurrence, dateTimeWindow, out nextOccurrence))
{
precedingOccurrence = nextOccurrence;
recurrenceSet.Add(nextOccurrence);
// handle taking only a subset of the complete recurrence set
if (recurrenceSet.Count == take)
{
break;
}
}
return recurrenceSet;
}
public bool TryCalculateNextOccurrence(DateTime precedingOccurrence, DateTimeWindow dateTimeWindow,
out DateTime nextOccurrence)
{
DateTime nextDateTimeCandidate = GetDateTimeOfNextOccurrenceCandidate(precedingOccurrence);
while (!IsDateTimeAfterEndDateTime(nextDateTimeCandidate) &&
!IsDateTimeAfterDateTimeWindow(nextDateTimeCandidate, dateTimeWindow))
{
if (!IsDateExcluded(nextDateTimeCandidate) &&
!IsDateTimeBeforeDateTimeWindow(nextDateTimeCandidate, dateTimeWindow))
{
nextOccurrence = nextDateTimeCandidate;
return true;
}
nextDateTimeCandidate = GetDateTimeOfNextOccurrenceCandidate(nextDateTimeCandidate);
}
nextOccurrence = default(DateTime);
return false;
}
private bool IsDateTimeAfterDateTimeWindow(DateTime dateTime, DateTimeWindow dateTimeWindow)
{
return dateTimeWindow.MaximumIncludedDateTime < dateTime;
}
private bool IsDateTimeBeforeDateTimeWindow(DateTime dateTime, DateTimeWindow dateTimeWindow)
{
return dateTimeWindow.MinimumIncludedDateTime > dateTime;
}
