using System.Numerics;
using AcDream.App.Rendering.Gpu;
using AcDream.App.Rendering.Scene;
using AcDream.App.Rendering.Sky;
using AcDream.App.Rendering.Wb;
using AcDream.App.Rendering.Walk;
using AcDream.Core.Rendering;
using AcDream.Core.Vfx;
using AcDream.Core.World;

namespace AcDream.App.Rendering;

internal interface IEnvCellImmediateDrawSink
{
    void DrawImmediate(
        uint cellId,
        EnvCellTransparentRoute route,
        bool detailSurfaceActive);
}

// S3 chunk 4 fix round 2 (L2): RetailPViewFramebufferSize / IRetailPViewFramebufferSource
// / SilkRetailPViewFramebufferSource are deleted — their only consumer was
// the RHI surface's NDC-to-pixel scissor conversion, and that scissor
// mechanism itself is deleted in the same round (no producer of a narrowed
// rectangle remains anywhere in the walk).

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;
}

/// <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>
/// <summary>
/// Campaign V slice V6j: backend-neutral. The order it implements is retail's and
/// is written once; the four places it touches graphics state directly are owned
/// by <see cref="IWorldPassSurface"/>.
/// </summary>
internal sealed partial class RetailPViewPassExecutor : IEnvCellImmediateDrawSink
{
    private readonly IWorldPassSurface _surface;
    private readonly IRenderFrameGlState _frameGlState;
    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 HashSet<uint> _noSceneParticleEntityIds = [];
    private readonly EnvCellAlphaDrawSource _envCellClipAlphaSource;
    private readonly EnvCellAlphaDrawSource _envCellBlendAlphaSource;

    internal delegate void RenderImmediateEnvCellRoute(
        uint cellId,
        EnvCellTransparentRoute route,
        bool detailSurfaceActive);

    public RetailPViewPassExecutor(
        IWorldPassSurface surface,
        IRenderFrameGlState frameGlState,
        ClipFrame clipFrame,
        TerrainModernRenderer? terrain,
        EnvCellRenderer envCells,
        WbDrawDispatcher entities,
        SkyRenderer? sky,
        ParticleSystem? particles,
        ParticleRenderer? particleRenderer,
        PortalDepthMaskRenderer? portalDepthMask,
        RetailAlphaQueue alpha,
        WorldRenderDiagnostics diagnostics,
        TerrainDrawDiagnosticsController terrainDiagnostics)
    {
        _surface = surface ?? throw new ArgumentNullException(nameof(surface));
        _frameGlState = frameGlState
            ?? throw new ArgumentNullException(nameof(frameGlState));
        _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));
        _envCellClipAlphaSource = new EnvCellAlphaDrawSource(
            _envCells.RenderTransparentOrdered,
            EnvCellTransparentRoute.Clip);
        _envCellBlendAlphaSource = new EnvCellAlphaDrawSource(
            _envCells.RenderTransparentOrdered,
            EnvCellTransparentRoute.Alpha);
    }

    public void BeginFrame()
    {
        // Campaign OVERHAUL S2 chunk 6: no per-frame particle-owner
        // classification to reset any more — particle draws are cell-scoped
        // and read live from ParticleSystem's own retained cell index.
    }

    /// <summary>Campaign FW3.2b-2: the shared dispatcher, for
    /// <see cref="RetailPViewRenderer"/>'s <c>WalkFrameDriver</c>
    /// construction — the driver's ctor takes a <see cref="WbDrawDispatcher"/>
    /// directly (it calls <c>SubmitOrderedStream</c> itself; see that
    /// class's own doc comment).</summary>
    internal WbDrawDispatcher Dispatcher => _entities;

    /// <summary>Campaign FW3.2b-2: forwards to
    /// <see cref="WbDrawDispatcher.RequireWalkSubmission"/> — the frame/
    /// encoder pair the walk driver submits its stream flushes into.</summary>
    internal (IGpuFrame Frame, IGpuPassEncoder Encoder) RequireWalkSubmission() =>
        _entities.RequireWalkSubmission();

    /// <summary>Campaign FW3.2b-2: forwards to
    /// <see cref="WbDrawDispatcher.WalkAttachmentExtent"/> — the real
    /// viewport size for <c>WalkProductionFrameContext</c>.</summary>
    internal (int Width, int Height)? WalkAttachmentExtent =>
        _entities.WalkAttachmentExtent;

    public void AbortFrame()
    {
        List<Exception>? failures = null;
        TryAbort(_frameGlState.RestoreFrameDefaults);
        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 BeginWalkClipFrame(
        bool outdoorRoot,
        ClipFrameAssembly reuseAssembly) =>
        ClipFrameAssembler.BeginWalkFrame(_clipFrame, outdoorRoot, reuseAssembly);

    public void PrepareClipFrame() =>
        _surface.PrepareClipFrame();

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

    /// <summary>
    /// S4-c2 fix round 1 (M6, contract C4): retail <c>DrawEnvCell</c>
    /// @0x0059f1c2 installs the environment detail surface (may be null)
    /// before <c>DrawMesh</c> @0x0059f212 and clears it @0x0059f21a — detail
    /// ON makes eligible subsets take Row 1 (immediate, WITH detail —
    /// <see cref="EnvCellRenderer.TransparentDetailEnabled"/>'s own doc
    /// comment); detail OFF still routes each real subset by the exact
    /// <c>TextureBatchData.RetailSurfaceMask</c> retained on
    /// <c>ObjectRenderBatch</c>. A pure Base1ClipMap mask 0x08 reaches CLIP;
    /// alpha-family 0x02 reaches ALPHA; a table-Immediate mask stays at the
    /// cell turn. The queue coalesces only to one token per (cell,list), the
    /// accepted AP-238 granularity residual.
    /// </summary>
    internal void SubmitOrDrawTransparentCellShell(uint cellId)
    {
        bool detailSurfaceActive = _envCells.TransparentDetailEnabled;
        EnvCellTransparentRoute routes = _envCells.GetTransparentRoutes(
            cellId,
            detailSurfaceActive);
        DispatchTransparentCellShell(
            cellId,
            routes,
            detailSurfaceActive,
            _alpha,
            _envCellClipAlphaSource,
            _envCellBlendAlphaSource,
            this);
    }

    private readonly List<uint> _singleCellListScratch = new(1);

    private void DrawImmediateEnvCellRoute(
        uint cellId,
        EnvCellTransparentRoute route,
        bool detailSurfaceActive)
    {
        _singleCellListScratch.Clear();
        _singleCellListScratch.Add(cellId);
        _envCells.RenderTransparentOrdered(
            _singleCellListScratch,
            route,
            detailSurfaceActive);
    }

    void IEnvCellImmediateDrawSink.DrawImmediate(
        uint cellId,
        EnvCellTransparentRoute route,
        bool detailSurfaceActive) =>
        DrawImmediateEnvCellRoute(cellId, route, detailSurfaceActive);

    /// <summary>
    /// Production dispatch for one cell after <see cref="EnvCellRenderer"/>
    /// scanned its real transparent batches. Separate source identities keep
    /// CLIP and ALPHA replay filters attached to their tokens. Immediate
    /// subsets draw at the cell turn; each deferred list receives at most one
    /// token for this cell.
    /// </summary>
    internal static void DispatchTransparentCellShell(
        uint cellId,
        EnvCellTransparentRoute routes,
        bool detailSurfaceActive,
        RetailAlphaQueue queue,
        EnvCellAlphaDrawSource clipSource,
        EnvCellAlphaDrawSource alphaSource,
        IEnvCellImmediateDrawSink renderImmediate)
    {
        if ((routes & EnvCellTransparentRoute.Immediate) != 0)
        {
            renderImmediate.DrawImmediate(
                cellId,
                EnvCellTransparentRoute.Immediate,
                detailSurfaceActive);
        }

        if ((routes & EnvCellTransparentRoute.Clip) != 0)
        {
            int token = clipSource.AddPendingCellId(cellId);
            queue.TryAppend(RetailAlphaList.Clip, clipSource, token, overrideClipmap: true);
        }

        if ((routes & EnvCellTransparentRoute.Alpha) != 0)
        {
            int token = alphaSource.AddPendingCellId(cellId);
            queue.TryAppend(RetailAlphaList.Alpha, alphaSource, token, overrideClipmap: false);
        }
    }


    /// <summary>Delegate adapter retained for focused route/allocation tests;
    /// production calls the interface overload above with <c>this</c>, so no
    /// per-cell delegate conversion or retained callback enters the owner.</summary>
    internal static void DispatchTransparentCellShell(
        uint cellId,
        EnvCellTransparentRoute routes,
        bool detailSurfaceActive,
        RetailAlphaQueue queue,
        EnvCellAlphaDrawSource clipSource,
        EnvCellAlphaDrawSource alphaSource,
        RenderImmediateEnvCellRoute renderImmediate)
    {
        if ((routes & EnvCellTransparentRoute.Immediate) != 0)
        {
            renderImmediate(
                cellId,
                EnvCellTransparentRoute.Immediate,
                detailSurfaceActive);
        }

        if ((routes & EnvCellTransparentRoute.Clip) != 0)
        {
            int token = clipSource.AddPendingCellId(cellId);
            queue.TryAppend(RetailAlphaList.Clip, clipSource, token, overrideClipmap: true);
        }

        if ((routes & EnvCellTransparentRoute.Alpha) != 0)
        {
            int token = alphaSource.AddPendingCellId(cellId);
            queue.TryAppend(RetailAlphaList.Alpha, alphaSource, token, overrideClipmap: false);
        }
    }

    /// <summary>
    /// The queue-facing half of <see cref="SubmitOrDrawTransparentCellShell"/>:
    /// retains the cell ids submitted to one fixed list in append order and replays
    /// a drained slice through <see cref="EnvCellRenderer.RenderTransparentOrdered"/>
    /// (production wiring) — one token per cell, never per subset (M6's
    /// documented granularity residual). <see cref="IRetailAlphaDrawSource.PrepareAlphaDraws"/>'s
    /// "only adjacent same-source entries batch" invariant means a particle
    /// or ordinary GfxObj instance appended BETWEEN two cell tokens keeps
    /// its own position in the combined drain — this source never
    /// re-orders across another entry. Depends on a delegate rather than
    /// the concrete <see cref="EnvCellRenderer"/> type (marked
    /// <see langword="internal"/>, not <see langword="private"/>) so
    /// <c>EnvCellAlphaDrawSourceTests</c> can pin the queue mechanics
    /// without standing up a GPU-backed renderer.
    /// </summary>
    internal delegate void RenderEnvCellsByRoute(
        IReadOnlyList<uint> cellIds,
        EnvCellTransparentRoute route,
        bool detailSurfaceActive);

    internal sealed class EnvCellAlphaDrawSource(
        RenderEnvCellsByRoute renderTransparentOrdered,
        EnvCellTransparentRoute route)
        : IRetailAlphaDrawSource
    {
        private readonly List<uint> _pendingCellIds = new();
        private readonly List<uint> _preparedCellIds = new();
        private readonly List<uint> _drawScratch = new();

        /// <summary>Returns this cell's token — its index into
        /// <see cref="_pendingCellIds"/> at the moment it was added.</summary>
        internal int AddPendingCellId(uint cellId)
        {
            int token = _pendingCellIds.Count;
            _pendingCellIds.Add(cellId);
            return token;
        }

        public void PrepareAlphaDraws(ReadOnlySpan<int> tokens)
        {
            _preparedCellIds.Clear();
            for (int i = 0; i < tokens.Length; i++)
                _preparedCellIds.Add(_pendingCellIds[tokens[i]]);
        }

        public void DrawPreparedAlphaBatch(int firstPreparedDraw, int drawCount)
        {
            if (drawCount <= 0)
                return;
            _drawScratch.Clear();
            for (int i = 0; i < drawCount; i++)
                _drawScratch.Add(_preparedCellIds[firstPreparedDraw + i]);
            renderTransparentOrdered(_drawScratch, route, detailSurfaceActive: false);
        }

        public void ResetAlphaSubmissions()
        {
            _pendingCellIds.Clear();
            _preparedCellIds.Clear();
            _drawScratch.Clear();
        }

        internal int PendingCount => _pendingCellIds.Count;
    }

    /// <summary>
    /// S3 chunk 1 fix round 2 (§11.6 H1): retail draws the weather pass
    /// EXACTLY ONCE per frame — <c>GameSky::Draw</c> @0x00506ff0 with
    /// <c>arg2==1</c> runs AFTER <c>LScape::draw</c>'s landblock loop
    /// finishes (@0x00506396), not once per active landscape view. This call
    /// is UNCLIPPED and sets no scissor — S3 chunk 4 (§10.2) deleted the
    /// former per-outside-view-slice loop (the walk's own screen-space
    /// terrain-clip writer, its per-frame clip-routing reset call, and the
    /// old <c>DrawLandscapeSliceLate</c> leaf, one call per active landscape
    /// view) that used to run before this
    /// call and re-submit the rain mesh once per doorway aperture; this is
    /// now the ONLY weather call site, matching retail's ONE unclipped
    /// <c>GameSky::Draw(sky,1)</c>.
    /// <para>
    /// S3 chunk 4 (§10.2): the rain PARTICLE emitters
    /// (<c>ParticleRenderPass.SkyPostScene</c>) moved here too, as ONE
    /// unclipped submission — retail inserts emitters into one unclipped
    /// alpha list (no per-doorway <c>clipSlot</c>), the same rule as the
    /// mesh draw above.
    /// </para>
    /// <para>
    /// Gated exactly as before —
    /// <see cref="ShouldDrawWeatherOnce(bool,bool,uint)"/>, retail's
    /// <c>SmartBox::is_player_outside</c> @0x00451e80 check ANDed with the
    /// two render toggles — via <c>_sky?.RenderWeather(...)</c> (null-
    /// conditional, matching every other <c>_sky?.RenderSky(...)</c> call
    /// site in this codebase): a missing sky asset silently skips the GL
    /// draw.
    /// </para>
    /// <para>
    /// S3 chunk 4 (O3): the transcript "OC" print that used to live here
    /// moved to <c>WalkFrameDriver.OnWeatherTurn</c>, fired by
    /// <c>RetailFrameWalk.DrawLandscape</c> at Collect time (retail's real
    /// turn — between the landscape and the flood for an interior root, at
    /// the end of the walk for an outdoor root) instead of wherever the GPU
    /// draw happens to run at Replay.
    /// </para>
    /// <para>
    /// S3 chunk 4 fix round 1 (K2): the caller (<see
    /// cref="RetailPViewRenderer.DrawLandscapeDynamicsPhase"/>) now gates
    /// this call on <c>WalkFrameDriver.WeatherTurnFired</c> — the walk's own
    /// record of "a Landscape turn ran with the weather gate open" — rather
    /// than re-deriving the gate independently, so this method's own
    /// <see cref="ShouldDrawWeatherOnce(bool,bool,uint)"/> check is a
    /// provably redundant safety net (the caller reads the same
    /// <paramref name="frame"/>'s toggles the flag was computed from).
    /// </para>
    /// <para>
    /// S3 chunk 4 fix round 1 (K8): the weather MESH draws before the rain
    /// PARTICLE emitters below purely as this method's own call order —
    /// retail's single <c>GameSky::Draw(sky,1)</c> call imposes no ordering
    /// between acdream's two substitutes (the mesh and the particle
    /// system), so this order is a bookkeeping choice, not a retail fact.
    /// </para>
    /// </summary>
    public void DrawWeatherOnce(RetailPViewFrameInput frame)
    {
        if (!ShouldDrawWeatherOnce(frame.RenderSky, frame.RenderWeather, frame.PlayerCellId))
            return;

        _sky?.RenderWeather(
            frame.Camera,
            frame.CameraWorldPosition,
            frame.DayFraction,
            frame.ActiveDayGroup,
            frame.SkyKeyframe,
            frame.EnvironOverrideActive);

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

    /// <summary>
    /// S3 chunk 1 fix round 2 (§11.6 H1): the weather pass's gate, extracted
    /// as a pure predicate — retail's <c>SmartBox::is_player_outside</c>
    /// @0x00451e80 check, <c>(player objcell_id &amp; 0xFFFF) &lt; 0x100</c>,
    /// ANDed with the two render toggles. Internal (not private) so a test
    /// can pin "no weather while the player stands indoors" and "no weather
    /// with either toggle off" without a live GL/DAT <see cref="SkyRenderer"/>
    /// — <see cref="DrawWeatherOnce"/> itself still needs one to actually
    /// draw, but this predicate alone decides whether it would even try (and
    /// therefore whether the OC print fires).
    /// </summary>
    internal static bool ShouldDrawWeatherOnce(
        bool renderSky, bool renderWeather, uint playerCellId)
        => renderSky && renderWeather && (playerCellId & 0xFFFFu) < 0x100u;

    public void DrawLandscapeStaticParticles(
        RetailPViewFrameInput frame,
        uint cellId)
    {
        // One unclipped submission per cell per frame. Retail never clips a
        // particle to a portal view — its polys join the one alpha list during
        // the owner cell's walk turn and the depth test at the flush decides
        // occlusion (FlushAlphaList @0x0059D2E0). The former per-slice call
        // with the slice's clip slot both hardware-cut effects at aperture
        // boundaries and double-submitted owners visible in two slices.
        // Retail CPhysicsObj::add_particle_shadow_to_cell (0x00514a70): an
        // emitter owns one shadow in its OWN current cell, so this is a cell
        // lookup, not an owner union — a hidden/suspended owner's emitter
        // still draws here.
        if (_particles is not null && _particleRenderer is not null)
        {
            _particleRenderer.DrawForCell(
                frame.Camera,
                frame.CameraWorldPosition,
                ParticleRenderPass.Scene,
                cellId,
                clipSlot: 0);
        }
    }

    public void ClearInteriorDepth()
    {
        _surface.ClearInteriorDepth();
    }

    /// <summary>Returns the number of exit-seal fans ATTEMPTED this turn —
    /// S4-c1 fix round 1 F2 corrected this from "matches what reached the
    /// GPU": retail increments <c>portalsDrawnCount</c> BEFORE
    /// <c>polyClipFinish</c> runs (0x59BD70-0x59BD74 precedes 0x59BDB0), so
    /// the counter records guard-passing ATTEMPTS, not successful GPU fans.
    /// A portal whose polygon has fewer than 3 vertices is counted here even
    /// though the GPU renderer's own internal <c>&lt;3</c> guard
    /// (<c>DrawDepthFan</c>) draws nothing for it
    /// (RetailPViewPassExecutorTests.DrawExitPortalMask_CountsAnUnclippableTwoVertexPolygon_ButDrawsNothing
    /// pins exactly this).</summary>
    public int DrawExitPortalMask(
        RetailPViewFrameInput frame,
        uint cellId,
        ReadOnlySpan<Vector4> clipPlanes) =>
        DrawPortalDepthWrite(
            cellId,
            clipPlanes,
            frame,
            forceFarZ: frame.RootCell.IsOutdoorNode);

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

        // Retail draws an unattached emitter once, during its owner CELL's
        // walk turn, with NO portal-view clip (CPhysicsObj::ShouldDrawParticles
        // @0x0050FE60 gates by cell in-view + distance; occlusion is the depth
        // test at FlushAlphaList @0x0059D2E0). Outdoor-cell emitters submit in
        // the landscape stage, interior-cell emitters in the final world stage.
        // The former once-per-OutsideView-slice submission with that slice's
        // hardware clip slot made effects vanish by view direction (zero
        // outside slices in view = zero submissions) — invented behavior.
        _particleRenderer.DrawForOwners(
            frame.Camera,
            frame.CameraWorldPosition,
            ParticleRenderPass.Scene,
            _noSceneParticleEntityIds,
            includeUnattached: true,
            clipSlot: 0,
            unattachedCellScope: outdoorCells
                ? UnattachedEmitterCellScope.OutdoorCells
                : UnattachedEmitterCellScope.InteriorCells);
    }

    /// <summary><c>PView::DrawCells</c> @0x005a4840's own
    /// <c>FlushAlphaList(0f)</c> @0x005a4872 (OH1 contract §7 site 3).</summary>
    public void FlushLandscapeAlpha() =>
        _alpha.Flush(RetailAlphaFlushSite.LandscapeFlush, 0f);

    /// <summary><c>RenderDeviceD3D::DrawBuilding</c> @0x0059f2a0's own
    /// <c>FlushAlphaList(0f)</c> @0x0059f30b (OH1 contract §7 site 1) — the
    /// building alpha barrier. Distinct call from <see cref="FlushLandscapeAlpha"/>
    /// even though both drain under the same 0f threshold (S4-c2: the two
    /// sites were sharing one undifferentiated call before the two-list
    /// FIFO cutover, when no site label existed to distinguish them).</summary>
    internal void FlushBuildingAlpha() =>
        _alpha.Flush(RetailAlphaFlushSite.DrawBuilding, 0f);

    /// <summary><c>RenderDeviceD3D::DrawBlock</c> @0x005a17c0's (per-land-cell
    /// loop head @0x005a18d0) own <c>FlushAlphaList(::flush)</c> @0x005a1a07,
    /// the immutable global 0.75f pressure valve (OH1 contract §7 site
    /// 2).</summary>
    internal void FlushSortCellExitAlpha() =>
        _alpha.Flush(RetailAlphaFlushSite.SortCellExit, 0.75f);

    public void DrawCellParticles(
        RetailPViewFrameInput frame,
        uint cellId)
    {
        if (_particles is null || _particleRenderer is null)
            return;

        // Retail never clips cell particles to a portal view: the owner
        // cell's walls own occlusion via the depth test at the alpha flush.
        // CPhysicsObj::add_particle_shadow_to_cell (0x00514a70) draws an
        // emitter in its OWN current cell, so this is a cell lookup, not an
        // owner union — a hidden/suspended owner's emitter still draws here.
        _particleRenderer.DrawForCell(
            frame.Camera,
            frame.CameraWorldPosition,
            ParticleRenderPass.Scene,
            cellId,
            clipSlot: 0);
    }

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

    /// <summary>Retail <c>D3DPolyRender::DrawPortalPolyInternal</c>
    /// @0x0059BC90. Main interior roots stamp true depth (seal); outdoor and
    /// look-in apertures stamp far depth (punch). The renderer owns that
    /// choice. Returns the number of portals ATTEMPTED (not necessarily
    /// drawn) this turn — S4-c1 fix round 1 F2 retired the ">=3 vertices"
    /// pre-filter that used to gate the count: every portal with
    /// <c>OtherCellId == 0xFFFF</c> that survives the ±12 boundary guard
    /// (<see cref="WalkVisibilityMath.IsRejectedByPortalPolygonBoundaryGuard"/>)
    /// is counted here, BEFORE the vertex-count check that decides whether
    /// its fan actually draws — matching retail's own count-BEFORE-clip
    /// order (0x59BD70-0x59BD74 precedes 0x59BDB0). This is the same
    /// enumeration <c>WalkFrameDriver.OnInteriorFloodDrawTurn</c> counts
    /// through <c>DrawExitSeals</c>'s return value.</summary>
    private int DrawPortalDepthWrite(
        uint cellId,
        ReadOnlySpan<Vector4> clipPlanes,
        RetailPViewFrameInput frame,
        bool forceFarZ,
        int? onlyPortalIndex = null)
    {
        if (_portalDepthMask is null)
            return 0;
        LoadedCell? cell = frame.Cells.Find(cellId);
        if (cell is null)
            return 0;

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

            // S4-c1 C1 (fix round 1 F1): DrawPortalPolyInternal's
            // degenerate-input guard
            // (WalkVisibilityMath.IsRejectedByPortalPolygonBoundaryGuard's
            // own doc comment) — tested on the LOCAL portal-polygon
            // vertices, BEFORE the world-transform loop below. A hit drops
            // the whole polygon: no transform, no fan submission, no
            // `submitted` increment (retail's reject -> transform -> clip
            // -> count order). No length pre-filter runs before this any
            // more (fix round 1 F2 — see the count comment below).
            if (WalkVisibilityMath.IsRejectedByPortalPolygonBoundaryGuard(localVertices))
                continue;

            int count = Math.Min(localVertices.Length, world.Length);
            for (int vertex = 0; vertex < count; vertex++)
            {
                // FW3.3: fans draw at the dat aperture verbatim (the
                // ShellDrawLiftZ retirement — shells draw unlifted too).
                world[vertex] = Vector3.Transform(
                    localVertices[vertex],
                    cell.WorldTransform);
            }

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

            // S4-c1 fix round 1 F2: retail increments portalsDrawnCount
            // (0x59BD70-0x59BD74) BEFORE polyClipFinish runs (0x59BDB0) —
            // the counter records accepted ATTEMPTS, not successful GPU
            // fans (oh1-depth-lifecycle.md's arbitration table). A polygon
            // with fewer than 3 vertices is counted here even though
            // DrawDepthFan below draws nothing — its own `< 3` guard is
            // this port's stand-in for retail's post-clip `var_4 >= 3`
            // check. Round 0 counted AFTER that guard (a `< 3` continue
            // ahead of both the boundary guard and this increment), which
            // silently dropped the count for such a polygon — never
            // observed on authored dat data (every real portal polygon has
            // >= 3 vertices) but wrong order all the same.
            submitted++;

            _portalDepthMask.DrawDepthFan(
                world[..count],
                frame.ViewProjection,
                clipPlanes,
                forceFarZ);
        }
        return submitted;
    }

    // S3 chunk 4 fix round 1 (K4): the sky's own doorway-scissor bracket and
    // the EnableClipDistances wrapper around it are deleted — their only
    // caller was DrawWalkSky's per-outside-view-slice loop
    // (RetailPViewPassExecutor.WalkLeaf.cs), itself deleted by the same fix
    // (retail draws the sky ONCE, unclipped, exactly like the terrain and
    // the weather — see DrawWalkSky's own doc comment).
    //
    // S3 chunk 4 fix round 2 (L2): round 1's own comment here asserted that
    // the interior depth clear still had a live scissor to end at that
    // point — a mechanism that no longer existed ANYWHERE by then (K4 had
    // already deleted the sky's own scissor bracket, the last production
    // producer of a narrowed rectangle). The interface's own scissor
    // begin/end pair and their RhiWorldPassSurface bodies are deleted outright
    // in this round; the interior depth clear no longer ends anything
    // because nothing narrows a rectangle any more — the pass encoder sets
    // the full-attachment scissor once, at pass begin
    // (VulkanGpuPassEncoder.cs:87), and it stays that way for the life of
    // the pass.
    //
    // S3 review fix round 1 (F3): round 2's own comment above claimed "the
    // KEEP clips (exit seals, punch fans) bracket their own draws with
    // Enable/DisableClipDistances below" — FALSE. Neither
    // DrawExitPortalMask/DrawPortalDepthWrite nor
    // RetailPViewPassExecutor.WalkLeaf.cs's DrawWalkPunchFan ever called
    // Enable/DisableClipDistances; every one of this file's six
    // DisableClipDistances() call sites sat around the UNCLIPPED particle
    // draws (DrawWeatherOnce, DrawLandscapeStaticParticles x2,
    // DrawUnattachedSceneParticles, DrawCellParticles x2) — bodies that were
    // already no-ops on the only backend
    // (RhiWorldPassSurface.EnableClipDistances/DisableClipDistances, see
    // WorldPassSurface.cs). A no-op call bracketing an unclipped draw is not
    // a clip bracket at all; it asserted a mechanism this file never had.
    // Deleted outright with this correction, along with the private
    // DisableClipDistances() wrapper (a method that does nothing on the
    // only backend is a false mechanism too). IWorldPassSurface.
    // EnableClipDistances/DisableClipDistances stay on the INTERFACE —
    // WorldScenePassExecutor (the separate flat-world path) still calls
    // them — only this file's now-pointless use of them is gone.
}