private static DATE_TIME DetermineDateLimit(this RECUR rule, DATE_TIME start, int window)
{
if (rule.FREQ == FREQ.SECONDLY && rule.INTERVAL < 24 * 60 * 60)
return start.ToDateTime().AddMinutes(window).ToDATE_TIME(start.TimeZoneId);
if (rule.FREQ == FREQ.MINUTELY && rule.INTERVAL < 24 * 60)
return start.ToDateTime().AddHours(window).ToDATE_TIME(start.TimeZoneId);
if (rule.FREQ == FREQ.HOURLY && rule.INTERVAL < 24)
return start.ToDateTime().AddDays(window).ToDATE_TIME(start.TimeZoneId);
return start.ToDateTime().AddMonths(window).ToDATE_TIME(start.TimeZoneId);
}
public static List<DATE_TIME> GenerateRecurrentDates(this RECUR rule, DATE_TIME start, uint window = 6)
{
var limit = rule.DetermineDateLimit(start, (int)window);
IEnumerable<DATE_TIME> results = Enumerable.Empty<DATE_TIME>();
var current = start;
if (rule.UNTIL != default(DATE_TIME))
{
while (current <= rule.UNTIL)
{
results = results.Concat(rule.GenerateDates(current, limit));
if (results.Any())
{
current = results.Last();
}
else
{
current = limit <= rule.UNTIL
? limit
: new DATE_TIME(
rule.UNTIL.FULLYEAR,
rule.UNTIL.MONTH,
rule.UNTIL.MDAY + 1,
rule.UNTIL.HOUR,
rule.UNTIL.MINUTE,
rule.UNTIL.SECOND,
rule.UNTIL.Type,
rule.UNTIL.TimeZoneId);
}
limit = rule.DetermineDateLimit(current, (int)window);
}
results = results.Where(x => x <= rule.UNTIL);
}
else if (rule.COUNT != 0)
{
while (results.Count() < rule.COUNT)
{
results = results.Concat(rule.GenerateDates(current, limit));
current = results.Last();
limit = rule.DetermineDateLimit(current, (int)window);
}
results = results.OrderBy(r => r).Take((int)rule.COUNT);
}
else
{
results = results.Concat(rule.GenerateDates(current, limit)); ;
if (!results.NullOrEmpty()) current = results.Last();
else current = new DATE_TIME(
rule.UNTIL.FULLYEAR,
rule.UNTIL.MONTH,
rule.UNTIL.MDAY + 1,
rule.UNTIL.HOUR,
rule.UNTIL.MINUTE,
rule.UNTIL.SECOND,
rule.UNTIL.Type,
rule.UNTIL.TimeZoneId);
}
return results.Except(start.ToSingleton()).ToList();
}
private static List<DATE_TIME> GenerateDates(this RECUR rule, DATE_TIME start, DATE_TIME end)
{
var dates = new List<DATE_TIME> { start };
switch (rule.FREQ)
{
case FREQ.SECONDLY:
{
while (start < end) dates.Add(start = start.AddSeconds(rule.INTERVAL));
dates = dates
.LimitByMonth(rule)
.LimitByYearDay(rule)
.LimitByMonthDay(rule)
.LimitByDay(rule)
.LimitByHour(rule)
.LimitByMinute(rule)
.LimitBySecond(rule)
.LimitBySetPos(rule).ToList();
break;
}
case FREQ.MINUTELY:
{
while (start < end) dates.Add(start = start.AddMinutes(rule.INTERVAL));
dates
.LimitByMonth(rule)
.LimitByYearDay(rule)
.LimitByMonthDay(rule)
.LimitByDay(rule)
.LimitByHour(rule)
.LimitByMinute(rule)
.ExpandBySecond(rule)
.LimitBySetPos(rule);
break;
}
case FREQ.HOURLY:
{
while (start < end) dates.Add(start = start.AddHours(rule.INTERVAL));
dates
.LimitByMonth(rule)
.LimitByYearDay(rule)
.LimitByMonthDay(rule)
.LimitByDay(rule)
.LimitByHour(rule)
.ExpandByMinute(rule)
.ExpandBySecond(rule)
.LimitBySetPos(rule);
break;
}
case FREQ.DAILY:
{
while (start < end) dates.Add(start = start.AddDays(rule.INTERVAL));
dates = dates
.LimitByMonth(rule)
.LimitByYearDay(rule)
.LimitByMonthDay(rule)
.LimitByDay(rule)
.ExpandByHour(rule)
.ExpandByMinute(rule)
.ExpandBySecond(rule)
.LimitBySetPos(rule)
.ToList();
break;
}
case FREQ.WEEKLY:
{
while (start < end) dates.Add(start = start.AddDays(7 * rule.INTERVAL));
dates
.LimitByMonth(rule)
.ExpandByDayWeekly(rule)
.ExpandByHour(rule)
.ExpandByMinute(rule)
.ExpandBySecond(rule)
.LimitBySetPos(rule)
;
break;
}
case FREQ.MONTHLY:
{
while (start < end) dates.Add(start = start.AddMonths((int)rule.INTERVAL));
dates.LimitByMonth(rule);
if (rule.BYMONTHDAY.Any())
{
dates.LimitByDayMonthly(rule);
}
else
{
dates.ExpandByMonth(rule);
}
dates.ExpandByDayMonthly(rule)
.ExpandByHour(rule)
.ExpandByMinute(rule)
.ExpandBySecond(rule)
.LimitBySetPos(rule);
break;
}
case FREQ.YEARLY:
{
while (start < end) dates.Add(start = start.AddYears((int)rule.INTERVAL));
dates = dates
.ExpandByMonth(rule)
.ExpandByWeekNo(rule)
.ExpandByYearDay(rule)
.ExpandByMonthDay(rule).ToList();
if (rule.BYYEARDAY.Any() || rule.BYMONTHDAY.Any())
{
dates.LimitByDayYearly(rule);
}
else
{
if (rule.BYWEEKNO.Any())
{
dates.ExpandByDayWeekly(rule);
}
else
{
if (rule.BYMONTH.Any())
dates.ExpandByDayMonthly(rule);
else
dates.ExpandByDayYearly(rule);
}
}
dates
.ExpandByHour(rule)
.ExpandByMinute(rule)
.ExpandBySecond(rule)
.LimitBySetPos(rule);
break;
}
}
return dates;
}
