using System;

using System.Globalization;

​

public class Program

{

    private static TimeZoneInfo OsloTimeZone { get; } = TimeZoneInfo.FindSystemTimeZoneById("Europe/Oslo");

    public static void Main()

    {

        var now = new DateTime(2022, 10, 30, 10, 00, 00);

        var auctionDeliveryStartUtc = now.Date.AddDays(1).ToUtc(sourceTimeZone: OsloTimeZone); // ex: 2022-05-25T22:00:00

        var auctionDeliveryEndUtc = now.Date.AddDays(2).ToUtc(sourceTimeZone: OsloTimeZone).AddHours(-1); // ex: 2022-05-26T21:00:00

        Console.WriteLine(auctionDeliveryStartUtc);

        Console.WriteLine(auctionDeliveryEndUtc);

    }

}

​

public static class DateTimeExtensions

{

    public static DateTime ToTimeZone(this DateTime date, TimeZoneInfo sourceTimeZone, TimeZoneInfo destinationTimeZone)

    {

        var dateUnspecified = DateTime.SpecifyKind(date, DateTimeKind.Unspecified);

        return TimeZoneInfo.ConvertTime(dateUnspecified, sourceTimeZone, destinationTimeZone);

    }

​

    public static DateTime ToUtc(this DateTime date, TimeZoneInfo sourceTimeZone)

    {

        return date.ToTimeZone(sourceTimeZone, TimeZoneInfo.Utc);

    }

​

    public static bool IsWeekend(this DateTime dateTime)

    {

        return dateTime.DayOfWeek == DayOfWeek.Saturday || dateTime.DayOfWeek == DayOfWeek.Sunday;

    }

​

    public static string ToLogDateTimeFormat(this DateTime dateTime)

    {

        return dateTime.ToString(StringExtensions.WideDateHourMinuteSecondFormat, CultureInfo.InvariantCulture);

    }

​

    public static string ToLogDateFormat(this DateTime dateTime)

    {

        return dateTime.ToString(StringExtensions.WideDateFormat, CultureInfo.InvariantCulture);

    }

​

    public static string ToLogDateFormat(this DateOnly date)

    {

        return date.ToString(StringExtensions.WideDateFormat, CultureInfo.InvariantCulture);

    }

​

    public static string ToTightDateTimeFormat(this DateTime dateTime)

    {

        return dateTime.ToString(StringExtensions.TightDateTimeFormat, CultureInfo.InvariantCulture);

    }

​

    public static string ToFormattedString(this DateTime dateTime, string format)

    {

        return dateTime.ToString(format, CultureInfo.InvariantCulture);

    }

}

​

public static class StringExtensions

{

    internal const string DayFirstDateFormat = "dd/MM/yyyy";

    internal const string WideDayFirstDateHourMinuteFormat = "dd/MM/yyyy HH:mm";

    internal const string TightDateFormat = "yyyyMMdd";

    internal const string TightDateHourMinuteFormat = "yyyyMMddHHmm";

    internal const string TightDateTimeFormat = "yyyyMMddHHmmss";

    internal const string HourMinuteSecondFormat = @"hh\:mm\:ss";

    internal const string WideDateHourMinuteFormat = "yyyy-MM-dd HH:mm";

    internal const string WideDateFormat = "yyyy-MM-dd";

    internal const string WideDateHourMinuteSecondFormat = "yyyy-MM-dd HH:mm:ss";

}