using System.Reflection;
using AcDream.App.Composition;
using AcDream.App.Rendering;

namespace AcDream.App.Tests.Composition;

public sealed class FrameRootCompositionTests
{
    [Fact]
    public void RuntimeBindingsReleaseInReverseAndRetryOnlyFailedEdges()
    {
        var calls = new List<string>();
        var bindings = new FrameRootRuntimeBindings();
        bindings.Adopt("first", new RetryBinding("first", calls, 0));
        bindings.Adopt("second", new RetryBinding("second", calls, 1));

        Assert.Throws<AggregateException>(bindings.Dispose);
        Assert.Equal(["second", "first"], calls);

        bindings.Dispose();
        bindings.Dispose();

        Assert.Equal(["second", "first", "second"], calls);
        Assert.Throws<ObjectDisposedException>(() =>
            bindings.Adopt("late", new RetryBinding("late", calls, 0)));
    }

    [Fact]
    public void ProductionPhasePublishesOnlyAfterBothRootsExist()
    {
        string source = File.ReadAllText(Path.Combine(
            FindRepoRoot(),
            "src",
            "AcDream.App",
            "Composition",
            "FrameRootComposition.cs"));

        AssertAppearsInOrder(
            source,
            "new RenderFrameResourceController(",
            "new WorldSceneRenderer(",
            "new RenderFrameOrchestrator(",
            "new RetailLiveFrameCoordinator(",
            "new UpdateFrameOrchestrator(",
            "d.FrameGraphs.PublishOwned(",
            "_publication.PublishFrameRoots(result);",
            "graphLease.Transfer();",
            "bindingsLease.Transfer();");
    }

    [Fact]
    public void GameWindowRetainsOnlyThePhaseBoundaryAndFrameHandoffs()
    {
        string source = File.ReadAllText(Path.Combine(
            FindRepoRoot(),
            "src",
            "AcDream.App",
            "Rendering",
            "GameWindow.cs"));

        Assert.Contains("new FrameRootCompositionPhase(", source);
        Assert.DoesNotContain("new AcDream.App.Rendering.WorldSceneRenderer(", source);
        Assert.DoesNotContain("new AcDream.App.Update.UpdateFrameOrchestrator(", source);
        Assert.DoesNotContain("CaptureWorldLifecycleResourceSnapshot", source);
        Assert.DoesNotContain("_frameGraphs.Publish(", source);
    }

    [Fact]
    public void FramePhaseAndSnapshotSourceRetainNoWindowOwner()
    {
        Assert.DoesNotContain(
            typeof(FrameRootCompositionPhase).GetFields(
                BindingFlags.Instance | BindingFlags.NonPublic),
            field => field.FieldType == typeof(GameWindow));

        string snapshots = File.ReadAllText(Path.Combine(
            FindRepoRoot(),
            "src",
            "AcDream.App",
            "Diagnostics",
            "WorldLifecycleResourceSnapshotSource.cs"));
        Assert.DoesNotContain("GameWindow", snapshots, StringComparison.Ordinal);
        Assert.Contains("_liveEntities.PendingTeardownCount", snapshots);
        Assert.Contains("GpuMemoryTracker.AllocatedBytes", snapshots);
        Assert.Contains("_frameProfiler.LastReport", snapshots);
    }

    private sealed class RetryBinding(
        string name,
        List<string> calls,
        int failures) : IDisposable
    {
        private int _failures = failures;

        public void Dispose()
        {
            calls.Add(name);
            if (_failures-- > 0)
                throw new InvalidOperationException("retry");
        }
    }

    private static void AssertAppearsInOrder(string source, params string[] values)
    {
        int cursor = 0;
        foreach (string value in values)
        {
            int found = source.IndexOf(value, cursor, StringComparison.Ordinal);
            Assert.True(found >= 0, $"Missing expected source fragment: {value}");
            cursor = found + value.Length;
        }
    }

    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.");
    }
}