/// <summary>
/// This is used to find the starting point for the daily frequency
/// </summary>
/// <param name="r">A reference to the recurrence</param>
/// <param name="start">The recurrence start date</param>
/// <param name="end">The recurrence end date</param>
/// <param name="from">The start date of the range limiting the instances generated</param>
/// <param name="to">The end date of the range limiting the instances generated</param>
/// <returns>The first instance date or null if there are no more instances</returns>
public RecurDateTime FindStart(Recurrence r, RecurDateTime start, RecurDateTime end, RecurDateTime from,
RecurDateTime to)
{
RecurDateTime rdt = new RecurDateTime(start);
int adjust;
// Get the difference between the recurrence start and the limiting range start
DateTime dtStart = start.ToDateTime().Date, dtFrom = from.ToDateTime().Date;
// Adjust the date so that it's in range
if (dtStart < dtFrom)
{
TimeSpan ts = dtFrom - dtStart;
adjust = ts.Days + r.Interval - 1;
rdt.AddDays(adjust - (adjust % r.Interval));
}
if (RecurDateTime.Compare(rdt, end, RecurDateTime.DateTimePart.Day) > 0 ||
RecurDateTime.Compare(rdt, to, RecurDateTime.DateTimePart.Day) > 0)
{
return(null);
}
return(rdt);
}
/// <summary>
/// This is used to find the starting point for the minutely frequency
/// </summary>
/// <param name="r">A reference to the recurrence</param>
/// <param name="start">The recurrence start date</param>
/// <param name="end">The recurrence end date</param>
/// <param name="from">The start date of the range limiting the instances generated</param>
/// <param name="to">The end date of the range limiting the instances generated</param>
/// <returns>The first instance date or null if there are no more instances</returns>
public RecurDateTime FindStart(Recurrence r, RecurDateTime start, RecurDateTime end, RecurDateTime from,
RecurDateTime to)
{
RecurDateTime rdt = new RecurDateTime(start);
int adjust;
if (RecurDateTime.Compare(start, from, RecurDateTime.DateTimePart.Hour) < 0)
{
// Get the difference between the recurrence start and the limiting range start
DateTime dtStart = start.ToDateTime().AddSeconds(0 - start.Second),
dtFrom = from.ToDateTime().AddSeconds(0 - from.Second);
// Adjust the date/time so that it's in range
TimeSpan ts = dtFrom - dtStart;
adjust = (int)ts.TotalMinutes + r.Interval - 1;
rdt.AddMinutes(adjust - (adjust % r.Interval));
}
if (RecurDateTime.Compare(rdt, end, RecurDateTime.DateTimePart.Hour) > 0 ||
RecurDateTime.Compare(rdt, to, RecurDateTime.DateTimePart.Hour) > 0)
{
return(null);
}
return(rdt);
}
/// <summary>
/// This is used to find the starting point for the weekly frequency
/// </summary>
/// <param name="r">A reference to the recurrence</param>
/// <param name="start">The recurrence start date</param>
/// <param name="end">The recurrence end date</param>
/// <param name="from">The start date of the range limiting the instances generated</param>
/// <param name="to">The end date of the range limiting the instances generated</param>
/// <returns>The first instance date or null if there are no more instances</returns>
public RecurDateTime FindStart(Recurrence r, RecurDateTime start, RecurDateTime end, RecurDateTime from,
RecurDateTime to)
{
RecurDateTime rdtWeek, rdt = new RecurDateTime(start);
int adjust;
// Get the difference between the recurrence start and the limiting range start
DateTime dtStart = start.ToDateTime().Date.AddDays(0 - r.weekdayOffset);
DateTime dtFrom = from.ToDateTime().Date;
dtFrom = dtFrom.AddDays(0 - ((int)dtFrom.DayOfWeek + 7 - (int)r.WeekStart) % 7);
// Adjust the date so that it's in range
if (dtStart < dtFrom)
{
TimeSpan ts = dtFrom - dtStart;
adjust = (ts.Days / 7) + r.Interval - 1;
rdt.AddDays((adjust - (adjust % r.Interval)) * 7);
}
// If the start of the week is after the ranges, stop now
rdtWeek = new RecurDateTime(rdt);
rdtWeek.AddDays(0 - r.weekdayOffset);
if (RecurDateTime.Compare(rdtWeek, end, RecurDateTime.DateTimePart.Day) > 0 ||
RecurDateTime.Compare(rdtWeek, to, RecurDateTime.DateTimePart.Day) > 0)
{
return(null);
}
return(rdt);
}