public static IEnumerable<DateTime> RecurrencyDays(
RecurrencyFrequency frequency, DateTime start, DateTime end, DateTime startEventDate, DateTime? endEventDate = null)
{
var startRecurrencyDate = StartRecurrencyDate(frequency, start, startEventDate);
if (!startRecurrencyDate.HasValue)
{
return Enumerable.Empty<DateTime>();
}
if (frequency == RecurrencyFrequency.None)
{
return new[] { startRecurrencyDate.Value };
}
IList<DateTime> recurrencies = new List<DateTime>();
var endRangeDate = endEventDate.HasValue ? Comparer.Min(end, endEventDate) : end;
while (startRecurrencyDate <= endRangeDate)
{
recurrencies.Add(startRecurrencyDate.Value);
startRecurrencyDate = NextDate(startRecurrencyDate.Value, frequency);
}
return recurrencies;
}
public static IEnumerable <DateTime> RecurrencyDays(
RecurrencyFrequency frequency, DateTime start, DateTime end, DateTime startEventDate, DateTime?endEventDate = null)
{
var startRecurrencyDate = StartRecurrencyDate(frequency, start, startEventDate);
if (!startRecurrencyDate.HasValue)
{
return(Enumerable.Empty <DateTime>());
}
if (frequency == RecurrencyFrequency.None)
{
return(new[] { startRecurrencyDate.Value });
}
IList <DateTime> recurrencies = new List <DateTime>();
var endRangeDate = endEventDate.HasValue ? Comparer.Min(end, endEventDate) : end;
while (startRecurrencyDate <= endRangeDate)
{
recurrencies.Add(startRecurrencyDate.Value);
startRecurrencyDate = NextDate(startRecurrencyDate.Value, frequency);
}
return(recurrencies);
}
public static DateTime? StartRecurrencyDate(RecurrencyFrequency recurrency, DateTime start, DateTime eventDate)
{
if (eventDate >= start)
{
return eventDate;
}
DateTime? startRecurrencyDate;
switch (recurrency)
{
case RecurrencyFrequency.None:
return null;
case RecurrencyFrequency.Daily:
return start;
case RecurrencyFrequency.Weekly:
startRecurrencyDate = start.FirstDayOfWeek(eventDate.DayOfWeek);
break;
case RecurrencyFrequency.Biweekly:
startRecurrencyDate = start.FirstDayOfWeek(eventDate.DayOfWeek);
var deltaDays = start.Subtract(eventDate).TotalDays.RoundToInt();
startRecurrencyDate = startRecurrencyDate.Value.AddDays(14 - deltaDays);
break;
case RecurrencyFrequency.Monthly:
startRecurrencyDate = new DateTime(start.Year, eventDate.Month, eventDate.Day);
break;
case RecurrencyFrequency.Yearly:
startRecurrencyDate = new DateTime(start.Year, eventDate.Month, eventDate.Day);
break;
default:
new ArgumentException("The specified recurrency is not valid.").Throw();
return null;
}
while (startRecurrencyDate < start)
{
startRecurrencyDate = NextDate(startRecurrencyDate.Value, recurrency);
}
return startRecurrencyDate.Value.Date.Add(eventDate.TimeOfDay);
}
public static DateTime?StartRecurrencyDate(RecurrencyFrequency recurrency, DateTime start, DateTime eventDate)
{
if (eventDate >= start)
{
return(eventDate);
}
DateTime?startRecurrencyDate;
switch (recurrency)
{
case RecurrencyFrequency.None:
return(null);
case RecurrencyFrequency.Daily:
return(start);
case RecurrencyFrequency.Weekly:
startRecurrencyDate = start.FirstDayOfWeek(eventDate.DayOfWeek);
break;
case RecurrencyFrequency.Biweekly:
startRecurrencyDate = start.FirstDayOfWeek(eventDate.DayOfWeek);
var deltaDays = start.Subtract(eventDate).TotalDays.RoundToInt();
startRecurrencyDate = startRecurrencyDate.Value.AddDays(14 - deltaDays);
break;
case RecurrencyFrequency.Monthly:
startRecurrencyDate = new DateTime(start.Year, eventDate.Month, eventDate.Day);
break;
case RecurrencyFrequency.Yearly:
startRecurrencyDate = new DateTime(start.Year, eventDate.Month, eventDate.Day);
break;
default:
throw new ArgumentException("The specified recurrency is not valid.");
}
while (startRecurrencyDate < start)
{
startRecurrencyDate = NextDate(startRecurrencyDate.Value, recurrency);
}
return(startRecurrencyDate.Value.Date.Add(eventDate.TimeOfDay));
}
public static DateTime NextDate(this DateTime date, RecurrencyFrequency frequency)
{
var addTimeSpan = timeSpanToAddBasedOnFrequency[frequency];
return addTimeSpan(date);
}
public static DateTime NextDate(this DateTime date, RecurrencyFrequency frequency)
{
var addTimeSpan = timeSpanToAddBasedOnFrequency[frequency];
return(addTimeSpan(date));
}
