namespace JdeScoping.DataSync.Services;

/// <summary>
/// Converts parameter values to JDE-specific formats with timezone support.
/// </summary>
public class ParameterFormatConverter
{
    private readonly TimeZoneInfo _timezone;

    /// <summary>
    /// Initializes a new instance of the <see cref="ParameterFormatConverter"/> class.
    /// </summary>
    /// <param name="timezone">
    /// The timezone to use for conversions.
    /// Accepts "UTC", "LOCAL", or a valid timezone ID (e.g., "Eastern Standard Time").
    /// </param>
    public ParameterFormatConverter(string timezone)
    {
        _timezone = timezone.ToUpperInvariant() switch
        {
            "UTC" => TimeZoneInfo.Utc,
            "LOCAL" => TimeZoneInfo.Local,
            _ => TimeZoneInfo.FindSystemTimeZoneById(timezone)
        };
    }

    /// <summary>
    /// Converts a DateTime value to the specified format.
    /// </summary>
    /// <param name="value">The DateTime value to convert.</param>
    /// <param name="format">
    /// The format to convert to. Supported formats:
    /// - "jdejulian": JDE Julian date (CYYDDD format)
    /// - "jdetime": JDE time (HHMMSS as integer)
    /// - null: Returns the timezone-adjusted DateTime
    /// </param>
    /// <returns>The converted value.</returns>
    /// <exception cref="ArgumentException">Thrown when an unknown format is specified.</exception>
    public object Convert(DateTime value, string? format)
    {
        var adjusted = TimeZoneInfo.ConvertTime(value, _timezone);

        return format?.ToLowerInvariant() switch
        {
            "jdejulian" => ToJdeJulianDate(adjusted),
            "jdetime" => ToJdeTime(adjusted),
            null => adjusted,
            _ => throw new ArgumentException($"Unknown format: {format}")
        };
    }

    /// <summary>
    /// Converts a DateTime to JDE Julian date format (CYYDDD).
    /// </summary>
    /// <param name="date">The date to convert.</param>
    /// <returns>
    /// The JDE Julian date as an integer where:
    /// - C is the century bit (0 for 1900s, 1 for 2000s)
    /// - YY is the two-digit year
    /// - DDD is the day of year (001-366)
    /// </returns>
    public static int ToJdeJulianDate(DateTime date)
    {
        int century = date.Year >= 2000 ? 1 : 0;
        int year = date.Year % 100;
        int dayOfYear = date.DayOfYear;
        return century * 100000 + year * 1000 + dayOfYear;
    }

    /// <summary>
    /// Converts a DateTime to JDE time format (HHMMSS).
    /// </summary>
    /// <param name="time">The time to convert.</param>
    /// <returns>The JDE time as an integer in HHMMSS format.</returns>
    public static int ToJdeTime(DateTime time)
    {
        return time.Hour * 10000 + time.Minute * 100 + time.Second;
    }
}