Windows vs IANA Timezone Hell

// Dangerous: Windows-specific timezone names
TimeZoneInfo pstZone = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time");
DateTime meetingTime = new DateTime(2024, 3, 15, 14, 0, 0);
DateTime utcTime = TimeZoneInfo.ConvertTimeToUtc(meetingTime, pstZone);

// This breaks on non-Windows systems!
// Linux/Mac don't have "Pacific Standard Time"
// They use "America/Los_Angeles" instead

// Sending calendar invites with Windows timezone names
var invite = new CalendarInvite
{
    StartTime = meetingTime,
    TimeZone = "Pacific Standard Time", // ❌ Windows-only
    Subject = "Board Meeting"
};

// Safe: Use IANA timezone IDs with fallback mapping
public class CrossPlatformTimeZone
{
    private static readonly Dictionary<string, string> WindowsToIana = new()
    {
        { "Pacific Standard Time", "America/Los_Angeles" },
        { "Eastern Standard Time", "America/New_York" },
        { "GMT Standard Time", "Europe/London" }
    };

    public static TimeZoneInfo GetTimeZone(string ianaId)
    {
        try
        {
            // Try IANA ID first (works on .NET Core/5+)
            return TimeZoneInfo.FindSystemTimeZoneById(ianaId);
        }
        catch (TimeZoneNotFoundException)
        {
            // Fallback to Windows mapping on .NET Framework
            var windowsId = IanaToWindows(ianaId);
            return TimeZoneInfo.FindSystemTimeZoneById(windowsId);
        }
    }

    // Always store and transmit IANA timezone IDs
    var meetingTimeZone = GetTimeZone("America/Los_Angeles");
    var meetingTime = new DateTimeOffset(2024, 3, 15, 14, 0, 0, 
                                        meetingTimeZone.GetUtcOffset(DateTime.Now));

    // Calendar invite with IANA timezone
    var invite = new CalendarInvite
    {
        StartTime = meetingTime.ToUniversalTime(),
        TimeZoneId = "America/Los_Angeles", // ✅ Cross-platform
        Subject = "Board Meeting"
    };
}