using AcDream.App.Rendering;

namespace AcDream.App.Tests.Rendering;

public sealed class ResourceCleanupGroupTests
{
    [Fact]
    public void CleanupRunsInReverseOrderAndNeverReplaysSuccess()
    {
        var calls = new List<string>();
        var resources = new ResourceCleanupGroup();
        int middleFailures = 1;
        resources.Add("first", () => calls.Add("first"));
        resources.Add("middle", () =>
        {
            calls.Add("middle");
            if (middleFailures-- > 0)
                throw new InvalidOperationException("middle failed");
        });
        resources.Add("last", () => calls.Add("last"));

        Assert.Throws<AggregateException>(resources.RetryCleanup);
        Assert.Equal(["last", "middle", "first"], calls);

        resources.RetryCleanup();
        resources.RetryCleanup();

        Assert.True(resources.IsCleanupComplete);
        Assert.Equal(["last", "middle", "first", "middle"], calls);
    }

    [Fact]
    public void TransferAllLeavesPublishedResourcesUntouched()
    {
        int releaseCalls = 0;
        var resources = new ResourceCleanupGroup();
        resources.Add("published", () => releaseCalls++);

        resources.TransferAll();
        resources.RetryCleanup();

        Assert.True(resources.IsCleanupComplete);
        Assert.Equal(0, releaseCalls);
        Assert.Throws<InvalidOperationException>(() =>
            resources.Add("late", () => { }));
    }

    [Fact]
    public void FailedConstructionRollbackRetainsOnlyUnreleasedOwnership()
    {
        int releases = 0;
        bool releaseFails = true;
        var resources = new ResourceCleanupGroup();
        resources.Add("retryable", () =>
        {
            releases++;
            if (releaseFails)
                throw new InvalidOperationException("release failed");
        });

        ResourceConstructionException failure =
            Assert.Throws<ResourceConstructionException>(() =>
                resources.RollbackConstructionAndThrow(
                    "construction failed",
                    new InvalidOperationException("original failure")));

        Assert.False(failure.IsCleanupComplete);
        Assert.Equal(1, releases);
        releaseFails = false;
        failure.RetryCleanup();
        failure.RetryCleanup();

        Assert.True(failure.IsCleanupComplete);
        Assert.Equal(2, releases);
    }

    /// <summary>
    /// Campaign V slice V4a moved TextRenderer's constructor off raw
    /// VAO/VBO/texture GL names and onto two device-owned resources — a
    /// pipeline and a 1x1 white fill texture — with a catch that disposed
    /// whichever already existed when the other threw.
    ///
    /// Slice V6d removed the white texture: the shader gained an untextured
    /// branch that produces what white-times-colour produced, so the fill needs
    /// no texture at all. That leaves exactly ONE owned resource, which is a
    /// stronger property than correct rollback — with nothing to orphan there is
    /// no partial-construction window to get wrong. This test pins that, so
    /// re-growing a second resource without re-growing the rollback fails here.
    /// </summary>
    [Fact]
    public void TextRendererConstructorOwnsExactlyOneDeviceResource()
    {
        string source = File.ReadAllText(Path.Combine(
            FindRepoRoot(),
            "src",
            "AcDream.App",
            "Rendering",
            "TextRenderer.cs"));

        Assert.Equal(1, CountOccurrences(source, "device.CreatePipeline("));
        Assert.Equal(0, CountOccurrences(source, "device.CreateTexture("));
        Assert.Equal(0, CountOccurrences(source, "device.CreateBuffer("));
        Assert.Equal(0, CountOccurrences(source, "device.CreateSampler("));
        Assert.Equal(0, CountOccurrences(source, "device.RegisterTexture("));

        // And the one resource is released.
        Assert.Contains("public void Dispose() => _pipeline.Dispose();", source, StringComparison.Ordinal);
    }

    private static int CountOccurrences(string source, string needle)
    {
        int count = 0;
        for (int i = source.IndexOf(needle, StringComparison.Ordinal);
             i >= 0;
             i = source.IndexOf(needle, i + needle.Length, StringComparison.Ordinal))
        {
            count++;
        }

        return count;
    }

    private static string FindRepoRoot()
    {
        DirectoryInfo? directory = new(AppContext.BaseDirectory);
        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.");
    }
}