namespace LiteCharms.Features.Extensions;

public static class Timezones
{
    public static TimeZoneInfo SouthAfricanTimeZone => TimeZoneInfo.FindSystemTimeZoneById("South Africa Standard Time");

    public static string? LocaliseDateTime(this DateTime dateTime, TimeSpan offset) => offset.Hours > 0
        ? $"{dateTime:yyyy-MM-ddTHH:mm:ss.fff}+{offset.Hours:00}:{offset.Minutes:00}"
        : $"{dateTime:yyyy-MM-ddTHH:mm:ss.fff}{offset.Hours:00}:{offset.Minutes:00}";

    public static string? LocaliseDateTimeOffset(this DateTimeOffset dateTime, TimeSpan offset) => LocaliseDateTime(dateTime.DateTime, offset);

    public static DateTimeOffset ToDateTimeWithTimeZone(this DateTime source, TimeZoneInfo? timezone = null)
    {
        DateTime sourceDateAdjusted = source.Kind != DateTimeKind.Utc
            ? new(source.Ticks, DateTimeKind.Utc)
            : source;

        var localised = timezone is null
            ? new DateTimeOffset(sourceDateAdjusted.Ticks, SouthAfricanTimeZone.BaseUtcOffset).LocaliseDateTimeOffset(SouthAfricanTimeZone.BaseUtcOffset)
            : new DateTimeOffset(sourceDateAdjusted.Ticks, timezone!.BaseUtcOffset).LocaliseDateTimeOffset(timezone.BaseUtcOffset);

        return DateTimeOffset.Parse(localised!, CultureInfo.InvariantCulture);
    }

    public static DateTime UtcNow(this TimeZoneInfo timezone) => ToDateTimeWithTimeZone(DateTime.Now, timezone).UtcDateTime;
}