using System.Reflection;
using System.Resources;
using System.Text.RegularExpressions;
using AvParser.UI.Localization;

namespace AvParser.UI.Tests;

/// <summary>
/// Every key the XAML asks for must actually exist.
/// </summary>
/// <remarks>
/// The parity test compares the two resource files against each other, so a key missing from
/// <b>both</b> passes it happily and then renders as <c>!Some.Key!</c> in the running app. That
/// happened during a rename: the XAML was repointed at new key names and the keys themselves were
/// never added. Only a screenshot caught it, which is too late and too manual.
/// </remarks>
public sealed partial class LocalizationCoverageTests
{
    [GeneratedRegex(@"\{l:Loc\s+([A-Za-z0-9_.\-]+)\s*\}", RegexOptions.Compiled)]
    private static partial Regex LocMarkup();

    private static readonly ResourceManager Resources = new(
        "AvParser.UI.Localization.Strings",
        typeof(Localizer).GetTypeInfo().Assembly
    );

    /// <summary>Walks up to the repository root, which the test binary sits several levels below.</summary>
    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.");
    }

    [Fact]
    public void Every_key_used_in_xaml_exists()
    {
        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 LocMarkup().Matches(File.ReadAllText(file)))
            {
                var key = match.Groups[1].Value;

                if (Resources.GetString(key, Localizer.Instance.Culture) is null)
                {
                    missing.Add($"{key} ({Path.GetFileName(file)})");
                }
            }
        }

        missing.ShouldBeEmpty();
    }
}