using System.Globalization;

namespace CursorLang.Core.Models;

/// <summary>
/// A keyboard layout in a form convenient for display.
/// </summary>
/// <param name="LocaleId">The locale identifier (the low word of HKL).</param>
/// <param name="ShortName">A short name for the popup at the cursor, "RU" for instance.</param>
/// <param name="DisplayName">The full name, "RU — русский (Россия)" for instance.</param>
public sealed record KeyboardLayout(int LocaleId, string ShortName, string DisplayName)
{
    /// <summary>
    /// Builds the model from a locale identifier. Unknown locales are not an
    /// error: for them we show the identifier itself.
    /// </summary>
    public static KeyboardLayout FromLocaleId(int localeId)
    {
        CultureInfo? culture = TryGetCulture(localeId);
        if (culture is null)
        {
            string fallback = $"0x{localeId:X4}";
            return new KeyboardLayout(localeId, fallback, fallback);
        }

        string shortName = culture.TwoLetterISOLanguageName.ToUpperInvariant();
        return new KeyboardLayout(localeId, shortName, $"{shortName} — {culture.NativeName}");
    }

    private static CultureInfo? TryGetCulture(int localeId)
    {
        try
        {
            return new CultureInfo(localeId);
        }
        catch (CultureNotFoundException)
        {
            return null;
        }
    }
}