using System.Numerics;
using AcDream.App.Rendering.Scene;
using AcDream.App.Rendering.Sky;
using AcDream.App.Rendering.Wb;
using AcDream.Core.Rendering;
using AcDream.Core.Vfx;
using AcDream.Core.World;
using Silk.NET.OpenGL;
using Silk.NET.Windowing;

namespace AcDream.App.Rendering;

internal readonly record struct RetailPViewFramebufferSize(int Width, int Height);

internal interface IRetailPViewFramebufferSource
{
    RetailPViewFramebufferSize Capture();
}

internal sealed class SilkRetailPViewFramebufferSource(IWindow window) :
    IRetailPViewFramebufferSource
{
    private readonly IWindow _window = window
        ?? throw new ArgumentNullException(nameof(window));

    public RetailPViewFramebufferSize Capture()
    {
        var size = _window.FramebufferSize;
        return new RetailPViewFramebufferSize(size.X, size.Y);
    }
}

internal sealed class RetailPViewCellSource : IRetailPViewCellSource
{
    private readonly CellVisibility _cells;

    public RetailPViewCellSource(CellVisibility cells) =>
        _cells = cells ?? throw new ArgumentNullException(nameof(cells));

    public LoadedCell? Find(uint cellId) =>
        _cells.TryGetCell(cellId, out LoadedCell? cell) ? cell : null;
}

internal sealed class RetailPViewParticleClassifications
{
    private readonly HashSet<uint> _outdoor = [];
    private readonly HashSet<uint> _visible = [];
    private readonly HashSet<uint> _dynamics = [];

    public IReadOnlySet<uint> Outdoor => _outdoor;
    public HashSet<uint> Visible => _visible;
    public HashSet<uint> Dynamics => _dynamics;

    public void BeginFrame()
    {
        _outdoor.Clear();
        _visible.Clear();
        _dynamics.Clear();
    }

    public void ReplaceOutdoor(IReadOnlyList<WorldEntity> owners)
    {
        _outdoor.Clear();
        foreach (WorldEntity owner in owners)
            _outdoor.Add(owner.Id);
    }
}

/// <summary>
/// Concrete GL implementation of the named passes ordered by
/// <see cref="RetailPViewRenderer"/>. It owns reusable pass-local particle
/// classifications but borrows every renderer and world source.
/// The order it implements is retail <c>PView::DrawCells @ 0x005A4840</c>:
/// landscape, delayed-alpha flush, optional interior depth clear, exit masks,
/// cell shells/objects, then surviving dynamics. Landscape sky/terrain/weather
/// placement follows <c>LScape::draw @ 0x00506330</c>.
/// </summary>
internal interface IOutdoorSceneParticleOwnerSource
{
    IReadOnlySet<uint> OutdoorSceneParticleEntityIds { get; }
}

internal readonly record struct RenderFrameEntityDrawRequest(
    RenderFrameView View,
    RenderFrameCandidateRoute Route,
    int RouteIndex,
    uint CellId,
    uint TupleLandblockId);

internal interface IRenderFrameEntityPassExecutor
{
    void BeginEntityFrame(in RenderFrameView view);

    bool DrawEntityRoute(
        ICamera camera,
        in RenderFrameView view,
        RenderFrameCandidateRoute route,
        int routeIndex,
        uint cellId,
        uint tupleLandblockId);

    void CompleteEntityFrame(in RenderFrameView view);

    void AbortEntityFrame();
}

internal sealed class RetailPViewPassExecutor :
    IRetailPViewPassExecutor,
    IRenderFrameEntityPassExecutor,
    IOutdoorSceneParticleOwnerSource
{
    private readonly GL _gl;
    private readonly IRenderFrameGlState _frameGlState;
    private readonly IRetailPViewFramebufferSource _framebuffer;
    private readonly ClipFrame _clipFrame;
    private readonly TerrainModernRenderer? _terrain;
    private readonly EnvCellRenderer _envCells;
    private readonly WbDrawDispatcher _entities;
    private readonly SkyRenderer? _sky;
    private readonly ParticleSystem? _particles;
    private readonly ParticleRenderer? _particleRenderer;
    private readonly PortalDepthMaskRenderer? _portalDepthMask;
    private readonly RetailAlphaQueue _alpha;
    private readonly WorldRenderDiagnostics _diagnostics;
    private readonly TerrainDrawDiagnosticsController _terrainDiagnostics;
    private readonly RetailPViewParticleClassifications _particleClassifications = new();
    private readonly HashSet<uint> _noSceneParticleEntityIds = [];

    /// <summary>
    /// Borrowed until the next late landscape pass. The outdoor-root post-world
    /// particle pass consumes this synchronously before another PView frame.
    /// </summary>
    public IReadOnlySet<uint> OutdoorSceneParticleEntityIds =>
        _particleClassifications.Outdoor;

    public RetailPViewPassExecutor(
        GL gl,
        IRenderFrameGlState frameGlState,
        IRetailPViewFramebufferSource framebuffer,
        ClipFrame clipFrame,
        TerrainModernRenderer? terrain,
        EnvCellRenderer envCells,
        WbDrawDispatcher entities,
        SkyRenderer? sky,
        ParticleSystem? particles,
        ParticleRenderer? particleRenderer,
        PortalDepthMaskRenderer? portalDepthMask,
        RetailAlphaQueue alpha,
        WorldRenderDiagnostics diagnostics,
        TerrainDrawDiagnosticsController terrainDiagnostics)
    {
        _gl = gl ?? throw new ArgumentNullException(nameof(gl));
        _frameGlState = frameGlState
            ?? throw new ArgumentNullException(nameof(frameGlState));
        _framebuffer = framebuffer
            ?? throw new ArgumentNullException(nameof(framebuffer));
        _clipFrame = clipFrame ?? throw new ArgumentNullException(nameof(clipFrame));
        _terrain = terrain;
        _envCells = envCells ?? throw new ArgumentNullException(nameof(envCells));
        _entities = entities ?? throw new ArgumentNullException(nameof(entities));
        _sky = sky;
        _particles = particles;
        _particleRenderer = particleRenderer;
        _portalDepthMask = portalDepthMask;
        _alpha = alpha ?? throw new ArgumentNullException(nameof(alpha));
        _diagnostics = diagnostics ?? throw new ArgumentNullException(nameof(diagnostics));
        _terrainDiagnostics = terrainDiagnostics
            ?? throw new ArgumentNullException(nameof(terrainDiagnostics));
    }

    public void BeginFrame()
    {
        _particleClassifications.BeginFrame();
    }

    public void BeginEntityFrame(in RenderFrameView view) =>
        _entities.BeginPackedProductionFrame(in view);

    public bool DrawEntityRoute(
        ICamera camera,
        in RenderFrameView view,
        RenderFrameCandidateRoute route,
        int routeIndex,
        uint cellId,
        uint tupleLandblockId) =>
        _entities.DrawPackedProductionRoute(
            camera,
            in view,
            route,
            routeIndex,
            cellId,
            tupleLandblockId);

    public void CompleteEntityFrame(in RenderFrameView view) =>
        _entities.CompletePackedProductionFrame(in view);

    public void AbortEntityFrame() =>
        _entities.AbortPackedProductionFrame();

    public void AbortFrame()
    {
        List<Exception>? failures = null;
        TryAbort(_frameGlState.RestoreFrameDefaults);
        TryAbort(_particleClassifications.BeginFrame);
        TryAbort(_noSceneParticleEntityIds.Clear);
        if (failures is { Count: > 0 })
            throw new AggregateException("Retail PView pass abort failed.", failures);

        void TryAbort(Action operation)
        {
            try
            {
                operation();
            }
            catch (Exception error)
            {
                (failures ??= []).Add(error);
            }
        }
    }

    public ClipFrameAssembly AssembleClipFrame(
        PortalVisibilityFrame portalFrame,
        ClipFrameAssembly reuseAssembly) =>
        ClipFrameAssembler.Assemble(_clipFrame, portalFrame, reuseAssembly);

    public void PrepareClipFrame(int terrainUploadCount)
    {
        // Allocate every terrain record before issuing the first draw. BufferData
        // must not replace the arena while an earlier slice can reference it.
        _clipFrame.ReserveTerrainUploads(_gl, terrainUploadCount);
        _clipFrame.UploadRegions(_gl);
        _entities.SetClipRegionSsbo(_clipFrame.RegionSsbo);
        _envCells.SetClipRegionSsbo(_clipFrame.RegionSsbo);
        UploadTerrainClip();
    }

    public void SetTerrainClip(ReadOnlySpan<Vector4> planes)
    {
        _clipFrame.SetTerrainClip(planes);
        UploadTerrainClip();
    }

    public void ClearClipRouting() => _entities.ClearClipRouting();

    public void UseIndoorMembershipOnlyRouting()
    {
        // Retail viewcone-checks meshes and draws whole cell shells. This clears
        // any terrain-slice routing before the indoor membership passes.
        _envCells.SetClipRouting(null);
        _entities.ClearClipRouting();
    }

    public void PrepareCellBatches(
        RetailPViewFrameInput frame,
        HashSet<uint> visibleCellIds) =>
        _envCells.PrepareRenderBatches(
            frame.ViewProjection,
            frame.CameraWorldPosition,
            filter: visibleCellIds,
            centerLbX: frame.RenderCenterLbX,
            centerLbY: frame.RenderCenterLbY,
            renderRadius: frame.RenderRadius);

    public void DrawOpaqueCellShells(HashSet<uint> cellIds) =>
        _envCells.Render(WbRenderPass.Opaque, cellIds);

    public bool CellHasTransparentShell(uint cellId) =>
        _envCells.CellHasTransparent(cellId);

    public void DrawTransparentCellShells(HashSet<uint> cellIds) =>
        _envCells.Render(WbRenderPass.Transparent, cellIds);

    public void DrawTransparentCellShellsOrdered(IReadOnlyList<uint> cellIds) =>
        _envCells.RenderTransparentOrdered(cellIds);

    public void DrawEntityBucket(
        RetailPViewFrameInput frame,
        IReadOnlyList<WorldEntity> entities,
        HashSet<uint>? visibleCellIds)
    {
        uint landblockId = frame.PlayerLandblockId ?? 0u;
        var entry = (
            landblockId,
            Vector3.Zero,
            Vector3.Zero,
            entities,
            (IReadOnlyDictionary<uint, WorldEntity>?)null);

        _entities.Draw(
            frame.Camera,
            new[] { entry },
            frame.Frustum,
            neverCullLandblockId: frame.PlayerLandblockId,
            visibleCellIds: visibleCellIds,
            animatedEntityIds: frame.AnimatedEntityIds);
    }

    public void EmitClipRouteProbe(
        ClipFrameAssembly clipAssembly,
        ClipViewSlice slice,
        int sliceIndex) =>
        _diagnostics.EmitClipRouteProbe(
            RenderingDiagnostics.ProbeClipRouteEnabled,
            _clipFrame,
            clipAssembly,
            slice,
            sliceIndex);

    public void EmitOutStageOwner(
        WorldEntity entity,
        Vector3 sphereCenter,
        float sphereRadius,
        int sliceIndex,
        bool passed) =>
        _diagnostics.EmitOutStageOwner(
            RenderingDiagnostics.ProbeOutStageEnabled,
            RenderingDiagnostics.DumpEntitySourceIds,
            entity,
            sphereCenter,
            sphereRadius,
            sliceIndex,
            passed);

    public void EmitOutStageRouting(
        int sliceIndex,
        IReadOnlyList<WorldEntity> entities,
        ViewconeCuller viewcone) =>
        _diagnostics.EmitOutStageRouting(
            RenderingDiagnostics.ProbeOutStageEnabled,
            sliceIndex,
            entities,
            viewcone);

    public void EmitPhantomObjects(uint cellId, int survivorCount) =>
        _diagnostics.EmitPhantomObjects(
            RenderingDiagnostics.ProbePhantomEnabled,
            cellId,
            survivorCount);

    public void DrawLandscapeSlice(
        RetailPViewFrameInput frame,
        RetailPViewLandscapeSliceContext context)
    {
        ClipViewSlice slice = context.Slice;
        bool scissor = BeginDoorwayScissor(slice.NdcAabb);
        _diagnostics.EmitClipRouteScissorProbe(
            RenderingDiagnostics.ProbeClipRouteEnabled,
            scissor,
            slice.NdcAabb);

        _clipFrame.BindTerrainClip(_gl);
        EnableClipDistances();
        if (frame.RenderSky)
        {
            _sky?.RenderSky(
                frame.Camera,
                frame.CameraWorldPosition,
                frame.DayFraction,
                frame.ActiveDayGroup,
                frame.SkyKeyframe,
                frame.EnvironOverrideActive);
        }

        DisableClipDistances();
        if (frame.RenderSky && _particles is not null && _particleRenderer is not null)
        {
            _particleRenderer.Draw(
                frame.Camera,
                frame.CameraWorldPosition,
                ParticleRenderPass.SkyPreScene);
        }

        EnableClipDistances();
        _terrainDiagnostics.Begin();
        _terrain?.Draw(
            frame.Camera,
            frame.Frustum,
            neverCullLandblockId: frame.PlayerLandblockId,
            clipPlanes: slice.Planes,
            ndcClipAabb: slice.NdcAabb);
        _terrainDiagnostics.Complete();

        DisableClipDistances();
        if (context.EntityDraw is RenderFrameEntityDrawRequest request)
        {
            RenderFrameView drawView = request.View;
            _entities.DrawPackedProductionRoute(
                frame.Camera,
                in drawView,
                request.Route,
                request.RouteIndex,
                request.CellId,
                request.TupleLandblockId);
        }
        else if (context.OutdoorEntities.Count > 0)
        {
            var sceneryEntry = (
                frame.PlayerLandblockId ?? 0u,
                Vector3.Zero,
                Vector3.Zero,
                context.OutdoorEntities,
                (IReadOnlyDictionary<uint, WorldEntity>?)null);
            _entities.Draw(
                frame.Camera,
                new[] { sceneryEntry },
                frame.Frustum,
                neverCullLandblockId: frame.PlayerLandblockId,
                visibleCellIds: null,
                animatedEntityIds: frame.AnimatedEntityIds);
        }

        if (scissor)
            _gl.Disable(EnableCap.ScissorTest);
        DisableClipDistances();
    }

    public void DrawLandscapeSliceLate(
        RetailPViewFrameInput frame,
        RetailPViewLandscapeLateSliceContext context)
    {
        ClipViewSlice slice = context.Slice;
        bool scissor = BeginDoorwayScissor(slice.NdcAabb);
        _clipFrame.BindTerrainClip(_gl);

        DisableClipDistances();
        if (context.EntityDraw is RenderFrameEntityDrawRequest request)
        {
            RenderFrameView drawView = request.View;
            _entities.DrawPackedProductionRoute(
                frame.Camera,
                in drawView,
                request.Route,
                request.RouteIndex,
                request.CellId,
                request.TupleLandblockId);
        }
        else if (context.Dynamics.Count > 0)
        {
            var dynamicsEntry = (
                frame.PlayerLandblockId ?? 0u,
                Vector3.Zero,
                Vector3.Zero,
                context.Dynamics,
                (IReadOnlyDictionary<uint, WorldEntity>?)null);
            _entities.Draw(
                frame.Camera,
                new[] { dynamicsEntry },
                frame.Frustum,
                neverCullLandblockId: frame.PlayerLandblockId,
                visibleCellIds: null,
                animatedEntityIds: frame.AnimatedEntityIds);
        }

        _particleClassifications.ReplaceOutdoor(context.ParticleOwners);

        _diagnostics.EmitOutStageParticles(
            RenderingDiagnostics.ProbeOutStageEnabled,
            _particles,
            _particleClassifications.Outdoor);

        if (!frame.RootCell.IsOutdoorNode
            && _particleClassifications.Outdoor.Count > 0
            && _particles is not null
            && _particleRenderer is not null)
        {
            _particleRenderer.DrawForOwners(
                frame.Camera,
                frame.CameraWorldPosition,
                ParticleRenderPass.Scene,
                _particleClassifications.Outdoor);
        }

        EnableClipDistances();
        if (frame.RenderSky && frame.RenderWeather)
        {
            _sky?.RenderWeather(
                frame.Camera,
                frame.CameraWorldPosition,
                frame.DayFraction,
                frame.ActiveDayGroup,
                frame.SkyKeyframe,
                frame.EnvironOverrideActive);
            DisableClipDistances();
            if (_particles is not null && _particleRenderer is not null)
            {
                _particleRenderer.Draw(
                    frame.Camera,
                    frame.CameraWorldPosition,
                    ParticleRenderPass.SkyPostScene);
            }
        }
        else
        {
            DisableClipDistances();
        }

        if (scissor)
            _gl.Disable(EnableCap.ScissorTest);
        DisableClipDistances();
    }

    public void ClearInteriorDepth()
    {
        _gl.Disable(EnableCap.ScissorTest);
        _gl.DepthMask(true);
        _gl.Clear(ClearBufferMask.DepthBufferBit);
    }

    public void DrawExitPortalMask(
        RetailPViewFrameInput frame,
        RetailPViewCellSliceContext context) =>
        DrawPortalDepthWrite(context, frame, forceFarZ: frame.RootCell.IsOutdoorNode);

    public void DrawLookInPortalPunch(
        RetailPViewFrameInput frame,
        RetailPViewCellSliceContext context) =>
        DrawPortalDepthWrite(context, frame, forceFarZ: true);

    public void DrawUnattachedSceneParticles(RetailPViewFrameInput frame)
    {
        if (_particles is null || _particleRenderer is null)
            return;

        DisableClipDistances();
        _particleRenderer.DrawForOwners(
            frame.Camera,
            frame.CameraWorldPosition,
            ParticleRenderPass.Scene,
            _noSceneParticleEntityIds,
            includeUnattached: true);
    }

    public void FlushLandscapeAlpha() => _alpha.Flush();

    public void DrawCellParticles(
        RetailPViewFrameInput frame,
        RetailPViewCellSliceContext context)
    {
        if (_particles is null
            || _particleRenderer is null
            || context.CellEntities.Count == 0)
        {
            return;
        }

        HashSet<uint> visible = _particleClassifications.Visible;
        visible.Clear();
        foreach (WorldEntity entity in context.CellEntities)
            visible.Add(entity.Id);
        if (visible.Count == 0)
            return;

        DisableClipDistances();
        _particleRenderer.DrawForOwners(
            frame.Camera,
            frame.CameraWorldPosition,
            ParticleRenderPass.Scene,
            visible);
        DisableClipDistances();
    }

    public void DrawDynamicsParticles(
        RetailPViewFrameInput frame,
        IReadOnlyList<WorldEntity> survivors)
    {
        if (_particles is null || _particleRenderer is null || survivors.Count == 0)
            return;

        HashSet<uint> dynamics = _particleClassifications.Dynamics;
        dynamics.Clear();
        foreach (WorldEntity entity in survivors)
            dynamics.Add(entity.Id);
        if (dynamics.Count == 0)
            return;

        DisableClipDistances();
        _particleRenderer.DrawForOwners(
            frame.Camera,
            frame.CameraWorldPosition,
            ParticleRenderPass.Scene,
            dynamics);
        DisableClipDistances();
    }

    public void EmitDiagnostics(
        RetailPViewFrameInput frame,
        RetailPViewFrameResult result) =>
        _diagnostics.EmitRetailPViewDiagnostics(
            RenderingDiagnostics.ProbeViewerEnabled,
            RenderingDiagnostics.ProbeVisibilityEnabled,
            RenderingDiagnostics.ProbeFlapEnabled,
            result,
            frame.RootCell,
            frame.ViewerCellId,
            frame.PlayerCellId,
            frame.CameraWorldPosition,
            frame.PlayerViewPosition,
            frame.CameraView,
            frame.CameraCellResolution);

    private void UploadTerrainClip()
    {
        TerrainClipBufferBinding binding = _clipFrame.UploadTerrainClip(_gl);
        _terrain?.SetClipUbo(binding);
    }

    private void DrawPortalDepthWrite(
        RetailPViewCellSliceContext context,
        RetailPViewFrameInput frame,
        bool forceFarZ)
    {
        // Retail D3DPolyRender::DrawPortalPolyInternal @ 0x0059BC90.
        // Main interior roots stamp true depth (seal); outdoor and look-in
        // apertures stamp far depth (punch). The renderer owns that choice.
        if (_portalDepthMask is null)
            return;
        LoadedCell? cell = frame.Cells.Find(context.CellId);
        if (cell is null)
            return;

        Span<Vector3> world = stackalloc Vector3[32];
        for (int index = 0; index < cell.Portals.Count; index++)
        {
            if (cell.Portals[index].OtherCellId != 0xFFFF)
                continue;
            if (index >= cell.PortalPolygons.Count)
                break;
            Vector3[] localVertices = cell.PortalPolygons[index];
            if (localVertices.Length < 3)
                continue;

            int count = Math.Min(localVertices.Length, world.Length);
            for (int vertex = 0; vertex < count; vertex++)
            {
                world[vertex] = Vector3.Transform(
                    localVertices[vertex],
                    cell.WorldTransform);
                world[vertex].Z += PortalVisibilityBuilder.ShellDrawLiftZ;
            }

            _diagnostics.EmitSeamMask(
                RenderingDiagnostics.ProbeSeamDrawEnabled,
                RenderingDiagnostics.SeamDrawTargetCells,
                context.CellId,
                index,
                forceFarZ,
                world[..count]);

            _portalDepthMask.DrawDepthFan(
                world[..count],
                frame.ViewProjection,
                context.Slice.Planes,
                forceFarZ);
        }
    }

    private bool BeginDoorwayScissor(Vector4 ndcAabb)
    {
        RetailPViewFramebufferSize framebuffer = _framebuffer.Capture();
        var box = NdcScissorRect.ToPixels(
            ndcAabb,
            framebuffer.Width,
            framebuffer.Height);
        _gl.Enable(EnableCap.ScissorTest);
        _gl.Scissor(box.X, box.Y, (uint)box.Width, (uint)box.Height);
        return true;
    }

    private void EnableClipDistances()
    {
        for (int index = 0; index < ClipFrame.MaxPlanes; index++)
            _gl.Enable(EnableCap.ClipDistance0 + index);
    }

    private void DisableClipDistances()
    {
        for (int index = 0; index < ClipFrame.MaxPlanes; index++)
            _gl.Disable(EnableCap.ClipDistance0 + index);
    }
}