Convert UTC to Local with historic accuracy by country

Question

I have:

• A Country (for instance Namibia)
• A DateTime stored in UTC (Let's say 23 October 1955 12:01 PM)

I want to write a function to translate the UTC datetime to local Namibian datetime with historic accuracy, taking into consideration daylight savings time.

I can not use timezones as some countries actually move timezones (Namibia for instance falls under WAT (UTC+1) during winter and WAST (UTC+2) during summer.

Any CSharp functions that can achieve this? Bonus points if this can be achieved by only passing the country's two-letter country code (for instance "NA").

The ideal function signature should be either:

public static DateTime UtcToLocal(this DateTime UtcDateTime, string CountryCode)

or

public static string UtcToLocal(this DateTime UtcDateTime, string CountryCode)

UPDATE

As pointed out in the comments section below, some countries are bound to multiple TimeZones (US for instance). So, the method signatures should rather look as follows:

public static DateTime UtcToLocal(this DateTime UtcDateTime, string TZ_Environment_ZoneName)

Answer 1

As discussed, I used the TimeZoneInfo class to perform the conversion.

public static class DateExtenders
        {
            public static DateTime UtcToLocal(this DateTime UtcDateTime, string TimezoneName)
            {
                return
                    TimeZoneInfo.ConvertTimeFromUtc(UtcDateTime, TimeZoneInfo.GetSystemTimeZones().Where(tz => TimezoneName.Equals(tz.StandardName)).Single());
            }        
        }

The value of the TimeZoneName can be any of the following values:

• Dateline Standard Time
• UTC-11
• Hawaiian Standard Time
• Alaskan Standard Time
• Pacific Standard Time (Mexico)
• Pacific Standard Time
• US Mountain Standard Time
• Mountain Standard Time (Mexico)
• Mountain Standard Time
• Central America Standard Time
• Central Standard Time
• Central Standard Time (Mexico)
• Canada Central Standard Time
• SA Pacific Standard Time
• Eastern Standard Time
• US Eastern Standard Time
• Venezuela Standard Time
• Paraguay Standard Time
• Atlantic Standard Time
• Central Brazilian Standard Time
• SA Western Standard Time
• Pacific SA Standard Time
• Newfoundland Standard Time
• E. South America Standard Time
• Argentina Standard Time
• SA Eastern Standard Time
• Greenland Standard Time
• Montevideo Standard Time
• Bahia Standard Time
• UTC-02
• Mid-Atlantic Standard Time
• Azores Standard Time
• Cabo Verde Standard Time
• Morocco Standard Time
• Coordinated Universal Time
• GMT Standard Time
• Greenwich Standard Time
• W. Europe Standard Time
• Central Europe Standard Time
• Romance Standard Time
• Central European Standard Time
• W. Central Africa Standard Time
• Namibia Standard Time
• Jordan Standard Time
• GTB Standard Time
• Middle East Standard Time
• Egypt Standard Time
• Syria Standard Time
• E. Europe Standard Time
• South Africa Standard Time
• FLE Standard Time
• Turkey Standard Time
• Jerusalem Standard Time
• Russia TZ 1 Standard Time
• Libya Standard Time
• Arabic Standard Time
• Arab Standard Time
• Belarus Standard Time
• Russia TZ 2 Standard Time
• E. Africa Standard Time
• Iran Standard Time
• Arabian Standard Time
• Azerbaijan Standard Time
• Russia TZ 3 Standard Time
• Mauritius Standard Time
• Georgian Standard Time
• Caucasus Standard Time
• Afghanistan Standard Time
• West Asia Standard Time
• Russia TZ 4 Standard Time
• Pakistan Standard Time
• India Standard Time
• Sri Lanka Standard Time
• Nepal Standard Time
• Central Asia Standard Time
• Bangladesh Standard Time
• Russia TZ 5 Standard Time
• Myanmar Standard Time
• SE Asia Standard Time
• Russia TZ 6 Standard Time
• China Standard Time
• Russia TZ 7 Standard Time
• Malay Peninsula Standard Time
• W. Australia Standard Time
• Taipei Standard Time
• Ulaanbaatar Standard Time
• Tokyo Standard Time
• Korea Standard Time
• Russia TZ 8 Standard Time
• Cen. Australia Standard Time
• AUS Central Standard Time
• E. Australia Standard Time
• AUS Eastern Standard Time
• West Pacific Standard Time
• Tasmania Standard Time
• Magadan Standard Time
• Russia TZ 9 Standard Time
• Russia TZ 10 Standard Time
• Central Pacific Standard Time
• Russia TZ 11 Standard Time
• New Zealand Standard Time
• UTC+12
• Fiji Standard Time
• Kamchatka Standard Time
• Tonga Standard Time
• Samoa Standard Time
• Line Islands Standard Time

Unfortunately I am unsure which formal naming standard / naming conventions was used for the above listed values

UPDATE

I have, since I posted this answer, adopted the use of Jon Skeet's Nodatime library, which is an excellent library for working with datetime concepts. I highly recommend it over struggling with BCL date, time and timespan classes!