using System.Numerics;
using System.Reflection;
using AcDream.App.Rendering;
using AcDream.Core.Vfx;

namespace AcDream.App.Tests.Rendering;

public sealed class WorldRenderDiagnosticsTests
{
    [Fact]
    public void GlTripwire_DisabledPerformsNoGlRead()
    {
        var gl = new RecordingGlStateReader();
        var log = new RecordingLog();
        var diagnostics = new WorldRenderDiagnostics(gl, log);

        diagnostics.EmitGlStateTripwireIfChanged(enabled: false);

        Assert.Equal(0, gl.StateCaptureCount);
        Assert.Empty(log.Messages);
    }

    [Fact]
    public void GlTripwire_LogsOnlyChangesAndReportsStableFrameCount()
    {
        var gl = new RecordingGlStateReader
        {
            State = State(depthFunction: 0x201),
        };
        var log = new RecordingLog();
        var diagnostics = new WorldRenderDiagnostics(gl, log);

        diagnostics.EmitGlStateTripwireIfChanged(enabled: true);
        diagnostics.EmitGlStateTripwireIfChanged(enabled: true);
        gl.State = State(depthFunction: 0x203);
        diagnostics.EmitGlStateTripwireIfChanged(enabled: true);

        Assert.Equal(3, gl.StateCaptureCount);
        Assert.Collection(
            log.Messages,
            first =>
            {
                Assert.StartsWith("[gl-state] frame=1 stable=0", first);
                Assert.Contains("dfunc=0x201", first);
            },
            changed =>
            {
                Assert.StartsWith("[gl-state] frame=3 stable=1", changed);
                Assert.Contains("dfunc=0x203", changed);
            });
    }

    [Fact]
    public void ScissorProbe_SequenceAdvancesAcrossSuppressedDuplicates()
    {
        var gl = new RecordingGlStateReader
        {
            Scissor = new RenderGlScissorSnapshot(
                true,
                new IntRenderRectangle(1, 2, 3, 4)),
        };
        var log = new RecordingLog();
        var diagnostics = new WorldRenderDiagnostics(gl, log);

        diagnostics.EmitClipRouteScissorProbe(true, true, new Vector4(-1, -1, 1, 1));
        diagnostics.EmitClipRouteScissorProbe(true, true, new Vector4(-1, -1, 1, 1));
        gl.Scissor = new RenderGlScissorSnapshot(
            true,
            new IntRenderRectangle(5, 6, 7, 8));
        diagnostics.EmitClipRouteScissorProbe(true, true, new Vector4(-1, -1, 1, 1));

        Assert.Equal(3, gl.ScissorCaptureCount);
        Assert.Collection(
            log.Messages,
            first => Assert.StartsWith("[clip-route-scis] n=1", first),
            changed => Assert.StartsWith("[clip-route-scis] n=3", changed));
    }

    [Fact]
    public void Owner_RetainsNoBorrowedFrameProductsOrBroadRuntimeOwners()
    {
        FieldInfo[] fields = typeof(WorldRenderDiagnostics).GetFields(
            BindingFlags.Instance | BindingFlags.NonPublic);

        Type[] forbidden =
        [
            typeof(GameWindow),
            typeof(PortalVisibilityFrame),
            typeof(ClipFrameAssembly),
            typeof(InteriorEntityPartition.Result),
            typeof(AcDream.Core.Physics.PhysicsEngine),
            typeof(CameraController),
            typeof(CellVisibility),
        ];
        foreach (Type type in forbidden)
            Assert.DoesNotContain(fields, field => field.FieldType == type);
        Assert.DoesNotContain(
            fields,
            field => typeof(Delegate).IsAssignableFrom(field.FieldType));
    }

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

        int captureStart = source.IndexOf(
            "public RenderGlStateSnapshot CaptureState()",
            StringComparison.Ordinal);
        int error = source.IndexOf("_gl.GetError()", captureStart, StringComparison.Ordinal);
        int depth = source.IndexOf(
            "_gl.IsEnabled(EnableCap.DepthTest)",
            captureStart,
            StringComparison.Ordinal);

        Assert.True(captureStart >= 0);
        Assert.True(error > captureStart);
        Assert.True(depth > error);
    }

    [Fact]
    public void TerrainDiagnostics_RetryFailedPublicationWithoutLosingSamples()
    {
        var log = new ThrowOnceLog();
        var diagnostics = new WorldRenderDiagnostics(new RecordingGlStateReader(), log);
        var facts = new TerrainRenderDiagnosticFacts(3, 5, 8);

        diagnostics.BeginTerrainDraw();
        diagnostics.EndTerrainDraw();
        Assert.Throws<InvalidOperationException>(() =>
            diagnostics.PublishTerrainDiagnostics(facts));

        diagnostics.BeginTerrainDraw();
        diagnostics.EndTerrainDraw();
        diagnostics.PublishTerrainDiagnostics(facts);

        Assert.Single(log.Messages);
        Assert.Contains("draws=3/frame", log.Messages[0]);
        Assert.Contains("visible=3", log.Messages[0]);
        Assert.Contains("loaded=5", log.Messages[0]);
        Assert.Contains("capacity=8", log.Messages[0]);
    }

    [Fact]
    public void RenderSignature_LogsOnlyChangesAndCarriesStableCount()
    {
        var log = new RecordingLog();
        var diagnostics = new WorldRenderDiagnostics(new RecordingGlStateReader(), log);

        EmitMinimalSignature(diagnostics, "flat");
        EmitMinimalSignature(diagnostics, "flat");
        EmitMinimalSignature(diagnostics, "pview");

        Assert.Collection(
            log.Messages,
            first => Assert.StartsWith("[render-sig] frame=1 stable=0 branch=flat", first),
            changed => Assert.StartsWith("[render-sig] frame=3 stable=1 branch=pview", changed));
    }

    [Fact]
    public void OutStageParticleProbe_IsDisabledWithoutEnumerationAndSuppressesDuplicates()
    {
        var log = new RecordingLog();
        var diagnostics = new WorldRenderDiagnostics(new RecordingGlStateReader(), log);
        var particles = new ParticleSystem(new EmitterDescRegistry());

        diagnostics.EmitOutStageParticles(false, particles, new HashSet<uint>());
        diagnostics.EmitOutStageParticles(true, particles, new HashSet<uint>());
        diagnostics.EmitOutStageParticles(true, particles, new HashSet<uint>());

        Assert.Single(log.Messages);
        Assert.Equal(
            "[outstage-pt] ids=0 attachedEmitters=0 matched=0 unattached=0 matchedIds=[] unmatchedIds=[]",
            log.Messages[0]);
    }

    private static RenderGlStateSnapshot State(int depthFunction) => new(
        DepthTest: true,
        DepthWrite: true,
        DepthFunction: depthFunction,
        Blend: false,
        BlendSource: 1,
        BlendDestination: 0,
        CullFace: true,
        CullMode: 0x405,
        FrontFace: 0x900,
        Scissor: false,
        ScissorBox: new IntRenderRectangle(0, 0, 1280, 720),
        Viewport: new IntRenderRectangle(0, 0, 1280, 720),
        DrawFramebuffer: 0,
        AlphaToCoverage: false,
        Stencil: false,
        ClipBits: 0,
        Error: 0);

    private sealed class RecordingGlStateReader : IRenderGlStateReader
    {
        public RenderGlStateSnapshot State { get; set; } = WorldRenderDiagnosticsTests.State(0x201);
        public RenderGlScissorSnapshot Scissor { get; set; }
        public int StateCaptureCount { get; private set; }
        public int ScissorCaptureCount { get; private set; }

        public RenderGlStateSnapshot CaptureState()
        {
            StateCaptureCount++;
            return State;
        }

        public RenderGlScissorSnapshot CaptureScissor()
        {
            ScissorCaptureCount++;
            return Scissor;
        }
    }

    private sealed class RecordingLog : IRenderFrameDiagnosticLog
    {
        public List<string> Messages { get; } = [];

        public void WriteLine(string message) => Messages.Add(message);
    }

    private sealed class ThrowOnceLog : IRenderFrameDiagnosticLog
    {
        private bool _throw = true;
        public List<string> Messages { get; } = [];

        public void WriteLine(string message)
        {
            if (_throw)
            {
                _throw = false;
                throw new InvalidOperationException("diagnostic sink failed");
            }

            Messages.Add(message);
        }
    }

    private static void EmitMinimalSignature(
        WorldRenderDiagnostics diagnostics,
        string branch) =>
        diagnostics.EmitRenderSignatureIfChanged(
            enabled: true,
            branch: branch,
            clipRoot: null,
            viewerRoot: null,
            playerRoot: null,
            viewerCellId: 0,
            playerCellId: 0,
            playerIndoorGate: false,
            cameraInsideCell: false,
            renderSkyGate: false,
            drawSkyThisFrame: false,
            terrainDrawn: false,
            terrainClipMode: TerrainClipMode.Skip,
            skyDrawn: false,
            depthClear: false,
            outdoorSceneryDrawn: false,
            outdoorPortalDrawn: false,
            outdoorRootObjectCount: 0,
            liveDynamicDrawnCount: 0,
            sceneParticles: "none",
            portalFrame: null,
            clipAssembly: null,
            drawableCells: null,
            partition: null,
            exteriorPortalFrame: null,
            exteriorClipAssembly: null,
            exteriorDrawableCells: null,
            exteriorPartition: null,
            cameraPosition: Vector3.Zero,
            playerPosition: Vector3.Zero);

    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.");
    }
}