/// <summary>
/// Create <see cref="DateInfo"/> by special year, month and offset info.<br />
/// 根据指定的年月和偏移信息创建 <see cref="DateInfo"/>
/// </summary>
/// <param name="year"></param>
/// <param name="month"></param>
/// <param name="weekAtMonth"></param>
/// <param name="dayOfWeek"></param>
/// <returns></returns>
public static DateInfo OffsetByWeek(int year, int month, int weekAtMonth, int dayOfWeek)
{
if (weekAtMonth == 0 || weekAtMonth > 5)
{
throw new ArgumentException("weekAtMonth is invalid.", nameof(weekAtMonth));
}
var targetDay = DateTimeCalcHelper.GetTargetDays(year, month, weekAtMonth, dayOfWeek);
if (targetDay > DateInfo.DaysInMonth(year, month))
{
return(DateInfo.InfinitePast);
}
return(DateInfoFactory.Create(year, month, targetDay));
}
/// <summary>
/// Create <see cref="DateInfo"/> by special year, month and offset info.<br />
/// 根据指定的年月和偏移信息创建 <see cref="DateInfo"/>
/// </summary>
/// <param name="year"></param>
/// <param name="month"></param>
/// <param name="weekAtMonth"></param>
/// <param name="dayOfWeek"></param>
/// <param name="result"></param>
/// <returns></returns>
public static bool TryOffsetByWeek(int year, int month, int weekAtMonth, int dayOfWeek, out DateInfo result)
{
if (weekAtMonth == 0 || weekAtMonth > 5)
{
throw new ArgumentException("weekAtMonth is invalid.", nameof(weekAtMonth));
}
var targetDay = DateTimeCalcHelper.GetTargetDays(year, month, weekAtMonth, dayOfWeek);
var invalid = targetDay > DateTime.DaysInMonth(year, month);
result = invalid
? DateTime.MinValue
: DateTimeFactory.Create(year, month, targetDay);
return(!invalid);
}
/// <summary>
/// Add quarters. <br />
/// 添加一个季度。
/// </summary>
/// <param name="dt"></param>
/// <param name="months"></param>
/// <param name="options"></param>
/// <returns></returns>
/// <exception cref="ArgumentNullException"></exception>
public static DateInfo OffsetByMonths(DateInfo dt, int months, DateTimeOffsetOptions options = DateTimeOffsetOptions.Absolute)
{
if (options == DateTimeOffsetOptions.Absolute)
{
return(dt + months.Months());
}
var(year, month) = DateTimeCalcHelper.Calc(dt.Year, dt.Month, months);
var firstDayOfMonth = dt.SetDate(year, month, 1);
var lastDayOfMonth = firstDayOfMonth.LastDayOfMonth().Day;
var day = dt.Day > lastDayOfMonth ? lastDayOfMonth : dt.Day;
return(dt.SetDate(year, month, day));
}
