using System;

using NodaTime;

​

namespace TestTimeZone

{

    internal class Program

    {

        private static void Main(string[] args)

        {

            var vnTimeZone = DateTimeZoneProviders.Tzdb["Asia/Ho_Chi_Minh"];

            var utcTimeZone = DateTimeZoneProviders.Tzdb["UTC"];

            //Document timezone Việt Nam qua các thời kì https://timezonedb.com/time-zones/Asia/Ho_Chi_Minh

​

            var dateTime = new DateTime(1945, 3, 16, 15, 0, 0, 0); //+9

            var localDateTest = new LocalDateTime(dateTime.Year, dateTime.Month, dateTime.Day, dateTime.Hour, dateTime.Minute, dateTime.Second);

            var timeTestZone = vnTimeZone.AtStrictly(localDateTest);

            var result = dateTime.AddSeconds(timeTestZone.Offset.Seconds);

​

            dateTime = new DateTime(1975, 6, 12, 17, 0, 0, 0); // VN

            localDateTest = new LocalDateTime(dateTime.Year, dateTime.Month, 13, 0, 0, 0); // VN

            timeTestZone = vnTimeZone.AtStrictly(localDateTest);

​

      TimeZoneInfo sourceTZ = TimeZoneInfo.FindSystemTimeZoneById("Asia/Ho_Chi_Minh");

      TimeZoneInfo destinationTZ = TimeZoneInfo.FindSystemTimeZoneById("UTC");

​

            result = TimeZoneInfo.ConvertTime(dateTime, destinationTZ,sourceTZ );

            Console.WriteLine($"Time 1975 input UTC: {timeTestZone}");

            Console.WriteLine($"Time 1975 result   : {result}");

​

            dateTime = new DateTime(1974, 6, 13, 16, 0, 0, 0); //+8

            localDateTest = new LocalDateTime(dateTime.Year, dateTime.Month, dateTime.Day, dateTime.Hour, dateTime.Minute, dateTime.Second);

            timeTestZone = vnTimeZone.AtStrictly(localDateTest);

            result = dateTime.AddSeconds(timeTestZone.Offset.Seconds);

​

        }

    }

}