using System.Globalization;
using Avalonia;
using Avalonia.Data.Converters;
using Avalonia.Media;
using Material.Icons;

namespace ClaudeDo.Ui.Converters;

/// <summary>
/// Converts an icon key to its geometry: "Sun" → the "Icon.Sun" StreamGeometry resource,
/// "mdi:RocketLaunch" → the Material Design Icons path of that <see cref="MaterialIconKind"/>.
/// </summary>
public class IconKeyConverter : IValueConverter
{
    /// <summary>Key prefix marking a Material Design Icons kind.</summary>
    public const string MdiPrefix = "mdi:";

    public static IconKeyConverter Instance { get; } = new();

    private static readonly Dictionary<string, Geometry?> MdiCache = new();

    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
    {
        if (value is not string key || string.IsNullOrEmpty(key))
            return null;

        if (key.StartsWith(MdiPrefix, StringComparison.Ordinal))
            return MdiGeometry(key[MdiPrefix.Length..]);

        var resourceKey = $"Icon.{key}";
        if (Application.Current?.TryGetResource(resourceKey, null, out var res) == true)
            return res as StreamGeometry;
        return null;
    }

    /// <summary>Parses (and caches) the geometry for an MDI kind name; null for unknown names.</summary>
    private static Geometry? MdiGeometry(string name)
    {
        if (MdiCache.TryGetValue(name, out var cached))
            return cached;
        var geometry = Enum.TryParse<MaterialIconKind>(name, out var kind)
            ? StreamGeometry.Parse(MaterialIconDataProvider.GetData(kind))
            : null;
        MdiCache[name] = geometry;
        return geometry;
    }

    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
        => throw new NotSupportedException();
}