public static Instant NextValid(
this Instant instant,
Month month = Month.Every,
Week week = Week.Every,
Day day = Day.Every,
WeekDay weekDay = WeekDay.Every,
Hour hour = Hour.Zeroth,
Minute minute = Minute.Zeroth,
Second second = Second.Zeroth,
[CanBeNull] CalendarSystem calendarSystem = null,
[CanBeNull] DateTimeZone timeZone = null)
{
// Never case, if any are set to never, we'll never get a valid date.
if ((month == Month.Never) ||
(week == Week.Never) ||
(day == Day.Never) ||
(weekDay == WeekDay.Never) ||
(hour == Hour.Never) ||
(minute == Minute.Never) ||
(second == Second.Never))
{
return(Instant.MaxValue);
}
if (calendarSystem == null)
{
calendarSystem = CalendarSystem.Iso;
}
if (timeZone == null)
{
timeZone = DateTimeZone.Utc;
}
Debug.Assert(calendarSystem != null);
Debug.Assert(timeZone != null);
// Move to next second.
instant = instant.CeilingSecond();
// Every second case.
if ((month == Month.Every) &&
(day == Day.Every) &&
(weekDay == WeekDay.Every) &&
(hour == Hour.Every) &&
(minute == Minute.Every) &&
(second == Second.Every) &&
(week == Week.Every))
{
return(instant);
}
// Get days and months.
int[] days = Days(day).OrderBy(dy => dy).ToArray();
int[] months = month.Months().ToArray();
// Remove months where the first day isn't in the month.
int firstDay = days.First();
if (firstDay > 28)
{
// 2000 is a leap year, so February has 29 days.
months = months.Where(mn => calendarSystem.GetDaysInMonth(2000, mn) >= firstDay).ToArray();
if (months.Length < 1)
{
return(Instant.MaxValue);
}
}
// Get zoned date time.
ZonedDateTime zdt = new ZonedDateTime(instant, timeZone, calendarSystem);
int y = zdt.Year;
int m = zdt.Month;
int d = zdt.Day;
int h = zdt.Hour;
int n = zdt.Minute;
int s = zdt.Second;
int[] weeks = week.Weeks().ToArray();
IsoDayOfWeek[] weekDays = weekDay.WeekDays().ToArray();
int[] hours = hour.Hours().OrderBy(i => i).ToArray();
int[] minutes = minute.Minutes().OrderBy(i => i).ToArray();
int[] seconds = second.Seconds().ToArray();
do
{
foreach (int currentMonth in months)
{
if (currentMonth < m)
{
continue;
}
if (currentMonth > m)
{
d = 1;
h = n = s = 0;
}
m = currentMonth;
foreach (int currentDay in days)
{
if (currentDay < d)
{
continue;
}
if (currentDay > d)
{
h = n = s = 0;
}
d = currentDay;
// Check day is valid for this month.
if (d > calendarSystem.GetDaysInMonth(y, m))
{
break;
}
// We have a potential day, check week and week day
zdt = timeZone.AtLeniently(new LocalDateTime(y, m, d, h, n, s, calendarSystem));
if ((week != Week.Every) &&
(!weeks.Contains(zdt.WeekOfWeekYear)))
{
continue;
}
if ((weekDay != WeekDay.Every) &&
(!weekDays.Contains(zdt.IsoDayOfWeek)))
{
continue;
}
// We have a date match, check time.
foreach (int currentHour in hours)
{
if (currentHour < h)
{
continue;
}
if (currentHour > h)
{
n = s = 0;
}
h = currentHour;
foreach (int currentMinute in minutes)
{
if (currentMinute < n)
{
continue;
}
if (currentMinute > n)
{
s = 0;
}
n = currentMinute;
foreach (int currentSecond in seconds)
{
if (currentSecond < s)
{
continue;
}
return
(timeZone.AtLeniently(
new LocalDateTime(y, m, d, h, n, currentSecond, calendarSystem)).ToInstant());
}
n = s = 0;
}
h = n = s = 0;
}
d = 1;
}
d = 1;
h = n = s = 0;
}
y++;
// Don't bother checking max year.
if (y >= calendarSystem.MaxYear)
{
return(Instant.MaxValue);
}
// Start next year
m = d = 1;
h = n = s = 0;
} while (true);
}
