using System.Runtime.CompilerServices;
using System.Xml.Linq;

namespace AcDream.Launcher.Core.Tests;

// Campaign LA plan §LA3 review finding F5: AcDream.Launcher.Core's entire
// premise (spec §LA3, SessionConfigDocument.cs's "PINNED CONTRACT" remarks)
// is being the BCL-plus-Platform-only assembly the external Avalonia
// launcher (LA4) can reference without pulling in any game-solution
// dependency. That contract is what this guard enforces — the csproj must
// declare exactly one ProjectReference (AcDream.Platform) and zero
// PackageReference entries, forever, in the same spirit as Platform's,
// Runtime's, and Headless's dependency-boundary guards.
public sealed class LauncherCoreDependencyBoundaryTests
{
    [Fact]
    public void LauncherCoreProjectReferencesOnlyPlatformAndDeclaresNoPackages()
    {
        string repositoryRoot = FindRepositoryRoot();
        string projectPath = Path.Combine(
            repositoryRoot,
            "src",
            "AcDream.Launcher.Core",
            "AcDream.Launcher.Core.csproj");
        var project = XDocument.Load(projectPath);

        var projectReferences = project.Descendants("ProjectReference")
            .Select(element => element.Attribute("Include")?.Value)
            // The csproj is authored with Windows-style "..\Foo\Foo.csproj"
            // separators; Path.GetFileName only recognizes the platform's
            // own separator, so on Linux it would return the whole
            // relative path unchanged instead of just the filename.
            // Normalizing to '/' first keeps this assertion
            // platform-agnostic (this project's tests run under both
            // native Windows and WSL — see Campaign LA plan §LA3 review
            // finding F5's acceptance).
            .Select(include => include is null
                ? null
                : Path.GetFileName(include.Replace('\\', '/')))
            .ToList();

        Assert.Equal(["AcDream.Platform.csproj"], projectReferences);
        Assert.Empty(project.Descendants("PackageReference"));
    }

    private static string FindRepositoryRoot(
        [CallerFilePath] string sourcePath = "")
    {
        string[] starts =
        {
            Path.GetDirectoryName(sourcePath) ?? string.Empty,
            Directory.GetCurrentDirectory(),
            AppContext.BaseDirectory,
        };
        foreach (string start in starts)
        {
            if (string.IsNullOrEmpty(start))
            {
                continue;
            }

            var directory = new DirectoryInfo(start);
            while (directory is not null)
            {
                if (File.Exists(Path.Combine(
                        directory.FullName,
                        "AcDream.slnx")))
                {
                    return directory.FullName;
                }

                directory = directory.Parent;
            }
        }

        throw new DirectoryNotFoundException(
            "Could not find AcDream.slnx above the source, working, or output directory.");
    }
}