public static DateTime OffsetBy(this DateTime dt, int offsetVal, DateTimeOffsetStyles styles)
{
return(styles switch
{
DateTimeOffsetStyles.Day => DateTimeCalc.OffsetByDays(dt, offsetVal),
DateTimeOffsetStyles.Week => DateTimeCalc.OffsetByWeeks(dt, offsetVal),
DateTimeOffsetStyles.Month => DateTimeCalc.OffsetByMonths(dt, offsetVal, DateTimeOffsetOptions.Relatively),
DateTimeOffsetStyles.Quarters => DateTimeCalc.OffsetByQuarters(dt, offsetVal, DateTimeOffsetOptions.Relatively),
DateTimeOffsetStyles.Year => DateTimeCalc.OffsetByYears(dt, offsetVal, DateTimeOffsetOptions.Relatively),
_ => DateTimeCalc.OffsetByDays(dt, offsetVal)
});
public static DateTime CreateByWeek(int year, int month, DayOfWeek dayOfWeek, int occurrence) => DateTimeCalc.OffsetByWeek(year, month, occurrence, dayOfWeek.CastToInt(0));
public static DateTime CreatePreviousDayByWeek(DateTime dt, DayOfWeek dayOfWeek) => DateTimeCalc.OffsetByWeekBefore(dt, dayOfWeek);
public static DateTime CreatePreviousDayByWeek(int year, int month, int day, DayOfWeek dayOfWeek) => DateTimeCalc.OffsetByWeekBefore(Create(year, month, day), dayOfWeek);
public static DateTime CreateNextDayByWeek(DateTime dt, DayOfWeek dayOfWeek) => DateTimeCalc.OffsetByWeekAfter(dt, dayOfWeek);
public static DateTime CreateNextDayByWeek(int year, int month, int day, DayOfWeek dayOfWeek) => DateTimeCalc.OffsetByWeekAfter(Create(year, month, day), dayOfWeek);
public static DateTime CreateFirstDayOfMonth(int year, int month, int dayOfWeek) => DateTimeCalc.OffsetByWeek(year, month, 1, dayOfWeek);
/// <summary>
/// To get the latest weekday for example Monday in a month.<br />
/// 寻找一个月中的最后一个工作日（如周一）
/// </summary>
/// <param name="year"></param>
/// <param name="month"></param>
/// <param name="dayOfWeek"></param>
/// <returns></returns>
public static DateTime CreateLastDayOfMonth(int year, int month, int dayOfWeek)
{
return(DateTimeCalc.TryOffsetByWeek(year, month, 5, dayOfWeek, out var resultedDay)
? resultedDay
: DateTimeCalc.OffsetByWeek(year, month, 4, dayOfWeek));
}
public static DateTime AddDuration(this DateTime dt, Duration duration) => DateTimeCalc.OffsetByDuration(dt, duration);
public static DateTime AddQuarters(this DateTime dt, int quarters) => DateTimeCalc.OffsetByQuarters(dt, quarters);
public static DateTime AddWeeks(this DateTime dt, int weeks) => DateTimeCalc.OffsetByWeeks(dt, weeks);
