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TimeZoneInfoExtensions.cs
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TimeZoneInfoExtensions.cs
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using System;
namespace AlbanianXrm.DateTimes.Extensions.Extensions
{
public static class TimeZoneInfoExtensions
{
public static DateTime ConvertToUTC(this TimeZoneInfo timeZoneInfo, DateTime localDateTime)
{
var adjustment = timeZoneInfo.GetAdjustmentRule(localDateTime);
if (adjustment == null)
{
return DateTime.SpecifyKind(localDateTime.Add(-timeZoneInfo.BaseUtcOffset), DateTimeKind.Utc);
}
var timeDifference = timeZoneInfo.BaseUtcOffset;
if (timeZoneInfo.SupportsDaylightSavingTime && timeZoneInfo.IsDaylightSavingTime(localDateTime))
{
timeDifference = timeDifference.Add(adjustment.DaylightDelta);
}
return DateTime.SpecifyKind(localDateTime.Add(-timeDifference), DateTimeKind.Utc);
}
public static DateTime ConvertToLocal(this TimeZoneInfo timeZoneInfo, DateTime utcDateTime)
{
var adjustment = timeZoneInfo.GetAdjustmentRule(utcDateTime);
if (adjustment == null)
{
return DateTime.SpecifyKind(utcDateTime.Add(timeZoneInfo.BaseUtcOffset), DateTimeKind.Unspecified);
}
var timeDifference = timeZoneInfo.BaseUtcOffset;
if (timeZoneInfo.SupportsDaylightSavingTime && timeZoneInfo.IsDaylightSavingTime(utcDateTime))
{
timeDifference = timeDifference.Add(adjustment.DaylightDelta);
}
return DateTime.SpecifyKind(utcDateTime.Add(timeDifference), DateTimeKind.Unspecified);
}
public static DateTime GetDaylightTransitionAsDate(this TimeZoneInfo.TransitionTime transition, DateTime date)
{
if (transition.IsFixedDateRule)
{
return new DateTime(date.Year, transition.Month, transition.Day);
}
else
{
var transitionMonth1st = new DateTime(date.Year, transition.Month, 1);
var daysToDayOfWeek = transition.DayOfWeek - transitionMonth1st.DayOfWeek;
var weeks = daysToDayOfWeek >= 0 ? transition.Week - 1 : transition.Week;
var transitionMonthDay = transitionMonth1st.AddDays(daysToDayOfWeek);
if (transitionMonthDay.AddDays(7 * weeks).Month != transition.Month)
{
weeks -= 1;
}
return transitionMonthDay.AddDays(7 * weeks);
}
}
public static TimeZoneInfo.AdjustmentRule GetAdjustmentRule(this TimeZoneInfo localTimezone, DateTime date)
{
var adjustments = localTimezone.GetAdjustmentRules();
// Iterate adjustment rules for time zone
foreach (TimeZoneInfo.AdjustmentRule adjustment in adjustments)
{
// Determine if this adjustment rule covers year desired
if (adjustment.DateStart <= date && adjustment.DateEnd >= date)
return adjustment;
}
return null;
}
}
}