using System.Globalization;
using System.Resources;

namespace SharepointToolbox.Web.Localization;

/// <summary>
/// Singleton string lookup backed by Strings.resx / Strings.fr.resx.
/// Web version: no INotifyPropertyChanged — culture switching is per-request.
/// </summary>
public class TranslationSource
{
    public static readonly TranslationSource Instance = new();

    // Construct the ResourceManager with the explicit manifest base name rather
    // than Strings.ResourceManager: the generated designer carries a stale base
    // name ("SharepointToolbox.Strings") from before the project was renamed to
    // *.Web, so its lookups throw MissingManifestResourceException. The embedded
    // resource is "SharepointToolbox.Web.Localization.Strings".
    private ResourceManager _resourceManager =
        new ResourceManager("SharepointToolbox.Web.Localization.Strings", typeof(TranslationSource).Assembly);
    private CultureInfo _currentCulture = CultureInfo.CurrentUICulture;

    private TranslationSource() { }

    public string this[string key] =>
        _resourceManager.GetString(key, _currentCulture) ?? $"[{key}]";

    public CultureInfo CurrentCulture
    {
        get => _currentCulture;
        set
        {
            if (Equals(_currentCulture, value)) return;
            _currentCulture = value;
        }
    }

    public void SetCulture(string lang)
    {
        CurrentCulture = lang switch
        {
            "fr" => new CultureInfo("fr"),
            _    => CultureInfo.InvariantCulture
        };
    }
}