public static long DateDiff(FrequencyType frequency, iCalDateTime dt1, iCalDateTime dt2, DayOfWeek firstDayOfWeek)
{
if (frequency == FrequencyType.Yearly)
{
return(dt2.Year - dt1.Year);
}
if (frequency == FrequencyType.Monthly)
{
return((dt2.Month - dt1.Month) + (12 * (dt2.Year - dt1.Year)));
}
if (frequency == FrequencyType.Weekly)
{
// Get the week of year of the time frame we want to calculate
int firstEvalWeek = _Calendar.GetWeekOfYear(dt2.Value, System.Globalization.CalendarWeekRule.FirstFourDayWeek, firstDayOfWeek);
// Count backwards in years, calculating how many weeks' difference we have between
// first and second dates
iCalDateTime evalDate = dt2.Copy();
while (evalDate.Year > dt1.Year)
{
firstEvalWeek += _Calendar.GetWeekOfYear(new DateTime(evalDate.Year - 1, 12, 31), System.Globalization.CalendarWeekRule.FirstFourDayWeek, firstDayOfWeek);
evalDate = evalDate.AddYears(-1);
}
// Determine the difference, in weeks, between the start date and the evaluation period.
int startWeek = _Calendar.GetWeekOfYear(dt1.Value, System.Globalization.CalendarWeekRule.FirstFourDayWeek, firstDayOfWeek);
return(firstEvalWeek - startWeek);
}
TimeSpan ts = dt2 - dt1;
if (frequency == FrequencyType.Daily)
{
return(Round(ts.TotalDays));
}
if (frequency == FrequencyType.Hourly)
{
return(Round(ts.TotalHours));
}
if (frequency == FrequencyType.Minutely)
{
return(Round(ts.TotalMinutes));
}
if (frequency == FrequencyType.Secondly)
{
return(Round(ts.TotalSeconds));
}
return(0);
}
public static iCalDateTime AddFrequency(FrequencyType frequency, iCalDateTime dt, int interval)
{
switch (frequency)
{
case FrequencyType.Yearly: return(dt.AddYears(interval));
case FrequencyType.Monthly: return(dt.AddMonths(interval));
case FrequencyType.Weekly: return(dt.AddDays(interval * 7));
case FrequencyType.Daily: return(dt.AddDays(interval));
case FrequencyType.Hourly: return(dt.AddHours(interval));
case FrequencyType.Minutely: return(dt.AddMinutes(interval));
case FrequencyType.Secondly: return(dt.AddSeconds(interval));
default: return(dt);
}
}