using System.Text.RegularExpressions;
using Avalonia;
using Avalonia.Headless.XUnit;
using Avalonia.Styling;

namespace AvParser.UI.HeadlessTests;

/// <summary>
/// Every resource key the XAML asks for must actually resolve.
/// </summary>
/// <remarks>
/// A <c>DynamicResource</c> naming a key that does not exist fails silently: the property simply
/// keeps its default, so a background never paints and a brush is transparent. That shipped twice —
/// most recently as a viewer overlay you could see straight through, caught only by looking at a
/// screenshot. Both themes are checked, because a key can exist in one dictionary and not the other.
/// </remarks>
public partial class ResourceKeyTests
{
    [GeneratedRegex(@"\{(?:Dynamic|Static)Resource\s+([A-Za-z0-9_.]+)\s*\}", RegexOptions.Compiled)]
    private static partial Regex ResourceMarkup();

    /// <summary>Keys defined inside a view's own <c>Resources</c> block rather than in a theme.</summary>
    private static readonly HashSet<string> Local = new(StringComparer.Ordinal) { "LocalizedOptionTemplate" };

    private static DirectoryInfo RepositoryRoot()
    {
        var directory = new DirectoryInfo(AppContext.BaseDirectory);

        while (directory is not null && !File.Exists(Path.Combine(directory.FullName, "AvParser.slnx")))
        {
            directory = directory.Parent;
        }

        return directory ?? throw new InvalidOperationException("Could not find the repository root.");
    }

    [AvaloniaTheory]
    [InlineData("Light")]
    [InlineData("Dark")]
    public void Every_resource_key_used_in_xaml_resolves(string theme)
    {
        var application = Application.Current.ShouldNotBeNull();
        application.RequestedThemeVariant = theme == "Light" ? ThemeVariant.Light : ThemeVariant.Dark;

        var views = Path.Combine(RepositoryRoot().FullName, "src", "AvParser.UI");
        var files = Directory.GetFiles(views, "*.axaml", SearchOption.AllDirectories);

        files.ShouldNotBeEmpty();

        var missing = new SortedSet<string>(StringComparer.Ordinal);

        foreach (var file in files)
        {
            foreach (Match match in ResourceMarkup().Matches(File.ReadAllText(file)))
            {
                var key = match.Groups[1].Value;

                if (Local.Contains(key))
                {
                    continue;
                }

                if (!application.TryGetResource(key, application.ActualThemeVariant, out _))
                {
                    missing.Add($"{key} ({Path.GetFileName(file)})");
                }
            }
        }

        missing.ShouldBeEmpty();
    }
}