using System.Collections;
using System.Globalization;
using System.IO;
using System.Reflection;
using System.Resources;
using System.Text.RegularExpressions;
using CursorLang.Core.Services;

namespace CursorLang.Settings.Tests.Views;

/// <summary>
/// The settings window markup against the resource strings.
/// </summary>
/// <remarks>
/// The resources live in Core and the markup lives here, so the check that the two
/// agree has to live here too. What the resources say among themselves — that every
/// key is translated, that the placeholders match — is checked by StringsTests, next
/// to the resources.
///
/// The markup is read as an embedded copy rather than off disk: a test that walks up
/// the folder tree looking for a .xaml file breaks the moment anything moves.
/// </remarks>
public sealed partial class MarkupStringsTests
{
    private static readonly ResourceManager Resources =
        new("CursorLang.Core.Resources.Strings", typeof(LocalizationService).Assembly);

    /// <summary>
    /// Every key the settings window markup asks for has to exist in the
    /// resources: otherwise the user sees the key itself in its place.
    /// </summary>
    [Fact]
    public void Every_key_from_the_settings_window_markup_exists_in_the_resources()
    {
        HashSet<string> known = [.. NeutralKeys()];
        List<string> missing = [];

        foreach (Match match in LocalizationBinding().Matches(ReadSettingsWindowMarkup()))
        {
            string key = match.Groups["key"].Value;
            if (!known.Contains(key))
            {
                missing.Add(key);
            }
        }

        Assert.Empty(missing);
    }

    /// <summary>The markup does ask for strings — otherwise the check above means nothing.</summary>
    [Fact]
    public void The_settings_window_markup_asks_for_resource_strings()
    {
        Assert.NotEmpty(LocalizationBinding().Matches(ReadSettingsWindowMarkup()));
    }

    private static IEnumerable<string> NeutralKeys()
    {
        ResourceSet set = Resources.GetResourceSet(CultureInfo.InvariantCulture, true, true)!;

        foreach (DictionaryEntry entry in set)
        {
            yield return (string)entry.Key;
        }
    }

    private static string ReadSettingsWindowMarkup()
    {
        using Stream stream = Assembly.GetExecutingAssembly().GetManifestResourceStream("MainWindow.xaml")
            ?? throw new InvalidOperationException("The settings window markup is not embedded in the test assembly");

        using var reader = new StreamReader(stream);
        return reader.ReadToEnd();
    }

    [GeneratedRegex(@"Localization\[(?<key>\w+)\]")]
    private static partial Regex LocalizationBinding();
}