public static string GetRecurStr(DateTime start, TimeUnitId unitId, int interval = 1, DaysOfWeek dowBits = DaysOfWeek.Any)
{
// Describe the recurrence pattern. scheduled recurrence rules.
// Ignore that start may be in the future.
// TODO ITranslatorProvider1
if (DateUtil.IsExtremeDate(start))
{
return("Never");
}
if (unitId <= TimeUnitId.None || unitId > TimeUnitId.Years) // does not repeat.
{
// "Once at " + date time
return(start.ToDtTmString());
}
if (interval <= 0)
{
interval = 1;
}
var sb = new StringBuilder();
int uniti = (int)unitId;
sb.Append(interval > 1 ? $"Every {interval} {_Units[uniti * 2]}" : _Units[(uniti * 2) + 1]); // pluralize?
switch (unitId)
{
case TimeUnitId.MilliSec: // fractional seconds.
case TimeUnitId.Seconds:
case TimeUnitId.Minutes:
return(sb.ToString()); // done. // Say no more.
case TimeUnitId.Hours:
if (start.Minute > 0)
{
sb.Append($" at {start.Minute} minutes past"); // minutes into the hour.
}
return(sb.ToString()); // done.
case TimeUnitId.Days: // daily. can use bitmask of days of the week.
if (dowBits != 0 && dowBits != DaysOfWeek.Any)
{
// Only on specific days of the week.
if (interval == 1)
{
sb.Clear();
sb.Append("Every ");
}
else
{
sb.Append(" if ");
}
int dowBit = 1;
bool hasBit = false;
for (int i = 0; i < 7; i++, dowBit <<= 1)
{
if ((((int)dowBits) & dowBit) != 0)
{
if (hasBit)
{
sb.Append(",");
}
sb.Append(((System.DayOfWeek)i).ToString());
hasBit = true;
}
}
}
break;
case TimeUnitId.Weeks: // a single day of the week.
if (interval == 1)
{
sb.Clear();
sb.Append($"Every {start.DayOfWeek.ToString()}");
break;
}
sb.Append($"on {start.DayOfWeek.ToString()}");
break;
// Approximate unit times.
case TimeUnitId.Months: // On same day of month.
if (interval == 1)
{
sb.Clear();
sb.Append($"Every {Formatter.ToOrdinal(start.Day)} of the month");
break;
}
sb.Append($" on {Formatter.ToOrdinal(start.Day)} of the month");
break;
case TimeUnitId.Quarters:
// Name the months ?? Jan, Apr, Jul, Oct
sb.Append($" on {Formatter.ToOrdinal(start.Day)} of the month");
break;
case TimeUnitId.Years:
sb.Append($" on {start.ToDtString("MMM", CultureInfo.InvariantCulture)} {start.Day:D2}");
break;
default:
return("?"); // not valid for TimeUnitId
}
sb.Append($" at {start.Hour:D2}:{start.Minute:D2}"); // at hr:minutes into the day.
return(sb.ToString());
}
public static DateTime GetNextRecur(DateTime now, DateTime start, TimeUnitId unitId, int interval = 1, DaysOfWeek dowBits = DaysOfWeek.Any)
{
// Get the next date / time in the sequence after now.
// start = anchor date. Was the last official time. for calculation of relative times, time of day, etc. kExtremeMax = never before
// interval = quantity of TimeUnitId
// dowBits = only on these days of the week.
// RETURN: kExtremeMax = never again.
// ASSUME times are GMT and have no DST weirdness.
if (DateUtil.IsExtremeDate(start))
{
return(DateUtil.kExtremeMax); // never start
}
if (now < start) // not until start date.
{
return(start);
}
if (unitId <= TimeUnitId.None || unitId > TimeUnitId.Years) // does not repeat.
{
return((now <= start) ? start : DateUtil.kExtremeMax);
}
if (interval <= 0)
{
interval = 1;
}
DateTime dtNext;
int timeUnits = _TimeUnits[(int)unitId];
if (unitId <= TimeUnitId.Weeks)
{
// Discreet/Exact time units.
long tickDiff = now.Ticks - start.Ticks;
long intervalUnits = (timeUnits * TimeSpan.TicksPerMillisecond) * interval;
long intervalsDiff = tickDiff / intervalUnits;
int intervalInc = ((tickDiff % intervalUnits) == 0) ? 0 : 1; // increment?
dtNext = new DateTime(start.Ticks + ((intervalsDiff + intervalInc) * intervalUnits));
if (unitId == TimeUnitId.Days)
{
// skips days if not on dowMask. if interval is multiple of 7 then this may never satisfy !!
for (int i = 0; true; i++)
{
if (IsDowSet(dowBits, dtNext.DayOfWeek)) // good.
{
break;
}
if (i > 7)
{
return(DateUtil.kExtremeMax); // never
}
dtNext = dtNext.AddTicks(intervalUnits);
}
}
}
else
{
// month based time. not exact/Discreet time units.
int monthsStart = start.Year * 12 + start.Month;
int monthsNow = now.Year * 12 + now.Month;
int monthsDiff = monthsNow - monthsStart;
int intervalUnits = timeUnits * interval;
int intervalsDiff = monthsDiff / intervalUnits;
int intervalInc = ((monthsDiff % intervalUnits) == 0 && start.Day == now.Day && start.TimeOfDay == now.TimeOfDay) ? 0 : 1; // increment?
dtNext = start.AddMonths((intervalsDiff + intervalInc) * intervalUnits);
}
return(dtNext);
}
