using System;
using System.Collections.Generic;
using System.Numerics;
using AcDream.App.Rendering.Wb;
using AcDream.Core.World;
using Silk.NET.OpenGL;

namespace AcDream.App.Rendering;

/// <summary>
/// App-layer port of the retail indoor render orchestration:
/// SmartBox::RenderNormalMode -> RenderDeviceD3D::DrawInside ->
/// PView::DrawInside -> ConstructView -> DrawCells.
/// </summary>
public sealed class RetailPViewRenderer
{
    private readonly GL _gl;
    private readonly ClipFrame _clipFrame;
    private readonly EnvCellRenderer _envCells;
    private readonly WbDrawDispatcher _entities;

    private static readonly ClipViewSlice NoClipSlice =
        new(0, new Vector4(-1f, -1f, 1f, 1f), Array.Empty<Vector4>());

    private readonly HashSet<uint> _oneCell = new(1);

    // R-A2: per-building flood grouping, reused across frames (inner lists cleared each frame).
    private readonly Dictionary<uint, List<LoadedCell>> _buildingGroups = new();

    // T2 (BR-4): retail has NO distance constant on the flood-admission chain
    // (DrawBuilding → portal walk → ConstructView: viewconeCheck + side test +
    // GetClip + GetVisible only). The old 48 m seed cap is replaced by the
    // caller's per-building frustum pre-gate on aperture bounds (GameWindow's
    // gather); seeds themselves are unbounded.
    private const float OutdoorBuildingSeedDistance = float.PositiveInfinity;

    public RetailPViewRenderer(
        GL gl,
        ClipFrame clipFrame,
        EnvCellRenderer envCells,
        WbDrawDispatcher entities)
    {
        _gl = gl;
        _clipFrame = clipFrame;
        _envCells = envCells;
        _entities = entities;
    }

    public RetailPViewFrameResult DrawInside(RetailPViewDrawContext ctx)
    {
        ArgumentNullException.ThrowIfNull(ctx);

        var pvFrame = PortalVisibilityBuilder.Build(
            ctx.RootCell,
            ctx.ViewerEyePos,
            ctx.CellLookup,
            ctx.ViewProjection);

        // R-A2: outdoor root — flood each nearby building SEPARATELY from its own entrance and merge
        // the small (~2-cell) per-building views into the frame. Retail reaches building interiors via
        // the terrain BSP -> DrawPortal -> ConstructView(CBldPortal) (decomp:326881/433895/433827); the
        // land root itself has no portals (it floods nothing into buildings). Per-building seeding is
        // robust to the eye's ~36 µm rest jitter where the pre-R-A2 single reverse-portal flood
        // oscillated as the chase eye grazed a doorway (the indoor flap).
        if (ctx.RootCell.IsOutdoorNode && ctx.NearbyBuildingCells is not null)
            MergeNearbyBuildingFloods(ctx, pvFrame);

        var clipAssembly = ClipFrameAssembler.Assemble(_clipFrame, pvFrame);
        UploadClipFrame(ctx.SetTerrainClipUbo);

        // R1: draw EVERY visible cell (retail cell_draw_list), not only the cells the
        // assembler handed a clip-slot. This feeds the Prepare filter + entity partition,
        // so every visible cell's shell has a prepared batch and seals — killing the grey
        // (the old clipAssembly.CellIdToSlot.Keys filter silently dropped slot-less cells).
        // Per-slice trim still applies in DrawEnvCellShells (Task 4 makes it self-contained).
        var drawableCells = new HashSet<uint>(pvFrame.OrderedVisibleCells);
        UseIndoorMembershipOnlyRouting();

        _envCells.PrepareRenderBatches(
            ctx.ViewProjection,
            ctx.CameraWorldPosition,
            filter: drawableCells,
            centerLbX: ctx.RenderCenterLbX,
            centerLbY: ctx.RenderCenterLbY,
            renderRadius: ctx.RenderRadius);

        var partition = InteriorEntityPartition.Partition(drawableCells, ctx.LandblockEntries);
        var result = new RetailPViewFrameResult
        {
            PortalFrame = pvFrame,
            ClipAssembly = clipAssembly,
            DrawableCells = drawableCells,
            Partition = partition,
        };

        ctx.EmitDiagnostics?.Invoke(result);

        // T1 (fused BR-2/3): retail's frame order — static world, then the
        // aperture depth writes, then interior cells WHOLE far→near, then
        // per-cell statics, then ALL dynamics last (retail draws objects after
        // cells: PView::DrawCells Ghidra 0x005a4840; DrawBuilding 0x0059f2a0).
        // The geometric shell chop (gl_ClipDistance crop, 927fd8f/9ce335e) is
        // DELETED — retail never clips cell geometry; aperture exactness comes
        // from the punch/seal depth writes + the z-buffer, and the dynamics-
        // last order is what makes the punch safe (the first BR-2 attempt
        // punched after dynamics and erased the player, reverted 88be519).
        // T3 (BR-5): retail viewconeCheck — meshes are sphere-CULLED per view,
        // never clipped (Ghidra 0x0054c250). Built once per frame from the
        // assembled slices + this frame's view-projection.
        var viewcone = ViewconeCuller.Build(clipAssembly, ctx.ViewProjection);

        // #118: stage assignment for dynamics under an INTERIOR root. Retail
        // draws the OUTSIDE world's objects inside the landscape stage —
        // PView::DrawCells runs LScape::draw FIRST (pc:432719), then the gated
        // full depth clear (pc:432731-432732) and the exit-portal SEALS
        // (pc:432785-432786); DrawBlock draws every landcell's objects via
        // DrawSortCell (0x005a17c0, pc:430124). A dynamic deferred to our
        // single last pass instead z-fails against the seal's true-depth stamp
        // the moment it stands beyond the door plane — the house-exit
        // clip+vanish (pinned by HouseExitWalkReplayTests). So under an
        // interior root: outdoor-classified dynamics draw in the outside
        // stage; an indoor dynamic whose sphere STRADDLES an exit portal
        // draws in BOTH stages (retail's per-overlapped-cell shadow-part
        // draw, DrawBlock pc:430056-430064) so neither body half clips at the
        // plane. Outdoor roots keep ALL dynamics in the last pass — our
        // z-buffered equivalent of retail's painter-ordered outdoor pass (the
        // BR-2 punch-after-dynamics lesson, reverted 88be519).
        _outsideStageDynamics.Clear();
        if (!ctx.RootCell.IsOutdoorNode)
        {
            foreach (var e in partition.Dynamics)
            {
                EntitySphere(e, out var c, out float r);
                if (DynamicDrawsInOutsideStage(e.ParentCellId, c, r, drawableCells, ctx.CellLookup))
                    _outsideStageDynamics.Add(e);
            }
        }

        DrawLandscapeThroughOutsideView(ctx, clipAssembly, partition, viewcone);
        UseIndoorMembershipOnlyRouting();
        DrawExitPortalMasks(ctx, pvFrame, clipAssembly, drawableCells);
        DrawEnvCellShells(pvFrame);
        DrawCellObjectLists(ctx, pvFrame, clipAssembly, drawableCells, partition, viewcone);
        DrawDynamicsLast(ctx, partition, viewcone, ctx.RootCell.IsOutdoorNode);

        return result;
    }

    // R-A2: group the nearby building cells by BuildingId and run one per-building flood per group
    // (retail's per-building ConstructView(CBldPortal)), merging each small view into the frame. The
    // grouping dict is reused across frames; inner lists are cleared each frame so a building that left
    // the near set simply contributes an empty (skipped) group.
    private void MergeNearbyBuildingFloods(RetailPViewDrawContext ctx, PortalVisibilityFrame pvFrame)
    {
        foreach (var group in _buildingGroups.Values)
            group.Clear();

        foreach (var cell in ctx.NearbyBuildingCells!)
        {
            // R-A2 seam fix: a cell without a BuildingId (unstamped, or outdoor-adjacent with an exit
            // portal) must STILL flood — the pre-R-A2 node flood reached it via a reverse portal, so
            // dropping it (the original `continue`) left holes at building/terrain seams. Key it by its
            // own CellId → a singleton per-entrance flood: a cell with an exit portal seeds from it, a
            // cell with none contributes nothing (same as before). BuildingId/CellId key collisions are
            // harmless — BuildFromExterior seeds each exit-portal cell in a group independently.
            uint groupKey = cell.BuildingId ?? cell.CellId;
            if (!_buildingGroups.TryGetValue(groupKey, out var group))
            {
                group = new List<LoadedCell>();
                _buildingGroups[groupKey] = group;
            }
            group.Add(cell);
        }

        foreach (var group in _buildingGroups.Values)
        {
            if (group.Count == 0)
                continue;
            var buildingFrame = PortalVisibilityBuilder.ConstructViewBuilding(
                group, ctx.ViewerEyePos, ctx.CellLookup, ctx.ViewProjection, OutdoorBuildingSeedDistance);
            MergeBuildingFrame(pvFrame, buildingFrame);
        }
    }

    // T2 (BR-4): merge a per-building flood's cells + views into the frame as a
    // UNION. Retail accumulates EVERY clipped portal polygon as a new view_poly
    // on the cell (Render::copy_view appends + view_count++, Ghidra 0x0054dfc0;
    // a cell visible through two apertures holds two views, all consumed
    // downstream). The old first-wins (`ContainsKey -> continue`) dropped the
    // second building flood's views whenever a cell was already in the frame —
    // the multiview-loss-first-wins divergence (a named #109 suspect: per-frame
    // winner flips between apertures). CellView.Add dedups exact/collinear
    // re-emissions (the dac8f6a CanonicalKey), so unioning is convergent.
    // OutsideView is NOT merged — the outdoor root already seeds full-screen
    // terrain, and ConstructViewBuilding (BuildFromExterior) leaves OutsideView
    // empty (it stops at exit portals once inside the building).
    private static void MergeBuildingFrame(PortalVisibilityFrame target, PortalVisibilityFrame src)
    {
        foreach (uint cellId in src.OrderedVisibleCells)
        {
            if (!src.CellViews.TryGetValue(cellId, out var srcView))
                continue;

            if (target.CellViews.TryGetValue(cellId, out var existing))
            {
                foreach (var p in srcView.Polygons)
                    existing.Add(p);
                continue;
            }

            target.CellViews[cellId] = srcView;
            target.OrderedVisibleCells.Add(cellId);
        }
    }

    private void DrawLandscapeThroughOutsideView(
        RetailPViewDrawContext ctx,
        ClipFrameAssembly clipAssembly,
        InteriorEntityPartition.Result partition,
        ViewconeCuller viewcone)
    {
        if (clipAssembly.OutsideViewSlices.Length == 0)
            return;

        int probeSliceIndex = 0;
        foreach (var slice in clipAssembly.OutsideViewSlices)
        {
            _clipFrame.SetTerrainClip(slice.Planes);
            UploadClipFrame(ctx.SetTerrainClipUbo);
            // T3 (BR-5): entities are never hard-clipped — retail viewcone-
            // CHECKS each mesh's sphere against the view (Ghidra 0x0054c250)
            // and draws it whole. The old per-slice entity clip routing
            // (gl_ClipDistance via SetClipRouting) is replaced by the sphere
            // pre-filter below; terrain/sky keep their per-slice plane clip.
            _entities.ClearClipRouting();
            if (AcDream.Core.Rendering.RenderingDiagnostics.ProbeClipRouteEnabled)
                EmitClipRouteProbe(clipAssembly, slice, probeSliceIndex);

            _outdoorStaticScratch.Clear();
            foreach (var e in partition.OutdoorStatic)
            {
                EntitySphere(e, out var c, out float r);
                if (viewcone.SphereVisibleInOutsideSlice(probeSliceIndex, c, r))
                    _outdoorStaticScratch.Add(e);
            }
            // #118: outside-stage dynamics ride the landscape pass like retail's
            // per-landcell DrawSortCell (DrawBlock 0x005a17c0, pc:430124) — drawn
            // BEFORE the depth clear + seals so the seal PROTECTS their pixels in
            // the aperture instead of z-killing them. Same per-slice cone test as
            // the statics above. Empty under outdoor roots (see DrawInside).
            foreach (var e in _outsideStageDynamics)
            {
                EntitySphere(e, out var c, out float r);
                if (viewcone.SphereVisibleInOutsideSlice(probeSliceIndex, c, r))
                    _outdoorStaticScratch.Add(e);
            }
            probeSliceIndex++;
            ctx.DrawLandscapeSlice(new RetailPViewLandscapeSliceContext(slice, _outdoorStaticScratch));
        }

        // T1: retail clears the FULL depth buffer ONCE between the outside
        // stage and the interior stage (PView::DrawCells, Ghidra 0x005a4840 —
        // Clear gated on portalsDrawnCount; exact gate semantics is a plan
        // open question, staged as "any outside slice drawn"), then re-stamps
        // every outside-leading portal's TRUE depth (the seals,
        // DrawExitPortalMasks). Replaces the old per-slice scissored AABB
        // clear (wrong shape, no seal after it).
        if (clipAssembly.OutsideViewSlices.Length > 0)
            ctx.ClearDepthForInterior?.Invoke();

        UseIndoorMembershipOnlyRouting();
    }

    // §4 flap [clip-route] probe state (2026-06-10, throwaway): print-on-change signature +
    // monotonic sequence so held-flap vs healthy frames diff cleanly in one capture.
    private string? _lastClipRouteSig;
    private long _clipRouteSeq;
    private readonly List<uint> _clipRouteCellKeys = new();

    // §4 flap apparatus (2026-06-10): the decisive probe between the surviving suspects
    // (handoff 2026-06-09 §1). Emits the EXACT clip inputs the landscape pass draws under:
    // the outside slice's slot + NDC AABB + planes (CPU side), the region-SSBO bytes decoded
    // at that slot (what mesh_modern.vert reads for routed instances), the terrain-UBO head
    // (what terrain/sky gate against), and the CellIdToSlot routing table. Fires AFTER
    // SetTerrainClip + UploadClipFrame + SetClipRouting, BEFORE DrawLandscapeSlice — so the
    // printed bytes are exactly what this slice's draws consume.
    private void EmitClipRouteProbe(ClipFrameAssembly clipAssembly, ClipViewSlice slice, int sliceIndex)
    {
        var sb = new System.Text.StringBuilder(256);
        sb.Append(System.FormattableString.Invariant(
            $"slice={sliceIndex}/{clipAssembly.OutsideViewSlices.Length} slot={slice.Slot}"));
        sb.Append(System.FormattableString.Invariant(
            $" ndc=({slice.NdcAabb.X:F3},{slice.NdcAabb.Y:F3},{slice.NdcAabb.Z:F3},{slice.NdcAabb.W:F3})"));
        sb.Append(System.FormattableString.Invariant($" planes={slice.Planes.Length}["));
        for (int i = 0; i < slice.Planes.Length; i++)
        {
            var p = slice.Planes[i];
            if (i > 0) sb.Append(' ');
            sb.Append(System.FormattableString.Invariant($"({p.X:F3},{p.Y:F3},{p.Z:F3},{p.W:F3})"));
        }

        // CellIdToSlot sorted by cell id so dictionary enumeration order can't fake a change.
        sb.Append("] cells={");
        _clipRouteCellKeys.Clear();
        foreach (uint key in clipAssembly.CellIdToSlot.Keys)
            _clipRouteCellKeys.Add(key);
        _clipRouteCellKeys.Sort();
        for (int i = 0; i < _clipRouteCellKeys.Count; i++)
        {
            if (i > 0) sb.Append(',');
            sb.Append(System.FormattableString.Invariant(
                $"0x{_clipRouteCellKeys[i]:X8}:{clipAssembly.CellIdToSlot[_clipRouteCellKeys[i]]}"));
        }
        sb.Append('}');

        // Region-SSBO content decoded at the routed slot, from the packed bytes UploadClipFrame
        // just uploaded — slot stride 144: count uint at +0, planes[8] at +16.
        var rb = _clipFrame.RegionBytesForTest;
        int off = slice.Slot * ClipFrame.CellClipStrideBytes;
        if (off >= 0 && off + ClipFrame.CellClipStrideBytes <= rb.Length)
        {
            uint ssboCount = System.BitConverter.ToUInt32(rb.Slice(off, 4));
            sb.Append(System.FormattableString.Invariant($" ssbo[{slice.Slot}]: n={ssboCount}"));
            int planeN = (int)System.Math.Min(ssboCount, (uint)ClipFrame.MaxPlanes);
            for (int i = 0; i < planeN; i++)
            {
                int po = off + ClipFrame.CellClipPlanesOffset + i * 16;
                float px = System.BitConverter.ToSingle(rb.Slice(po, 4));
                float py = System.BitConverter.ToSingle(rb.Slice(po + 4, 4));
                float pz = System.BitConverter.ToSingle(rb.Slice(po + 8, 4));
                float pw = System.BitConverter.ToSingle(rb.Slice(po + 12, 4));
                sb.Append(System.FormattableString.Invariant($" ({px:F3},{py:F3},{pz:F3},{pw:F3})"));
            }
        }
        else
        {
            sb.Append(System.FormattableString.Invariant(
                $" ssbo[{slice.Slot}]: OUT-OF-RANGE len={rb.Length}"));
        }

        // Terrain-UBO head as uploaded (std140: int count at +0, planes[8] at +16).
        var tb = _clipFrame.TerrainBytesForTest;
        int uboCount = System.BitConverter.ToInt32(tb.Slice(0, 4));
        float u0 = System.BitConverter.ToSingle(tb.Slice(16, 4));
        float u1 = System.BitConverter.ToSingle(tb.Slice(20, 4));
        float u2 = System.BitConverter.ToSingle(tb.Slice(24, 4));
        float u3 = System.BitConverter.ToSingle(tb.Slice(28, 4));
        sb.Append(System.FormattableString.Invariant(
            $" ubo: n={uboCount} p0=({u0:F3},{u1:F3},{u2:F3},{u3:F3})"));

        string sig = sb.ToString();
        _clipRouteSeq++;
        if (sig == _lastClipRouteSig)
            return;
        _lastClipRouteSig = sig;
        Console.WriteLine($"[clip-route] n={_clipRouteSeq} {sig}");
    }

    private void DrawExitPortalMasks(
        IRetailPViewCellDrawCallbacks ctx,
        PortalVisibilityFrame pvFrame,
        ClipFrameAssembly clipAssembly,
        HashSet<uint> drawableCells)
    {
        if (ctx.DrawExitPortalMasks is null)
            return;

        for (int i = pvFrame.OrderedVisibleCells.Count - 1; i >= 0; i--)
        {
            uint cellId = pvFrame.OrderedVisibleCells[i];
            if (!drawableCells.Contains(cellId))
                continue;

            foreach (var slice in GetCellSlicesOrNoClip(clipAssembly, cellId))
                ctx.DrawExitPortalMasks(new RetailPViewCellSliceContext(cellId, slice, Array.Empty<WorldEntity>()));
        }
    }

    private void DrawEnvCellShells(PortalVisibilityFrame pvFrame)
    {
        // T1 (fused BR-2/3): retail DrawCells Loop 2 — every visible cell's
        // shell drawn WHOLE, reverse cell_draw_list (far→near), drawn once.
        // Retail NEVER clips cell geometry: the production path is the
        // prebuilt mesh (DrawEnvCell use_built_mesh, pc:427905; the
        // planeMask=0xffffffff legacy submit means skip-all-edges), and
        // aperture exactness comes from the punch/seal depth writes + the
        // z-buffer + this order. The former gl_ClipDistance chop
        // (927fd8f/9ce335e, #114) is deleted with this rewrite.
        // Per-cell opaque+transparent keeps the far→near transparent
        // compositing the per-cell loop already provided.
        UseIndoorMembershipOnlyRouting();
        foreach (var entry in IndoorDrawPlan.ShellPass(pvFrame))
        {
            _oneCell.Clear();
            _oneCell.Add(entry.CellId);
            _envCells.Render(WbRenderPass.Opaque, _oneCell);
            _envCells.Render(WbRenderPass.Transparent, _oneCell);
        }
    }

    // T1: the frame's single LAST entity pass — ALL server-spawned dynamics
    // (player, NPCs, doors, items), indoor or out, drawn after the static
    // world + punches + interior cells. Depth-tested, never hard-clipped
    // (retail draws objects per cell AFTER cells and viewcone-culls them —
    // PView::DrawCells epilogue Ghidra 0x005a4840; the sphere-vs-view cull is
    // T3). Drawing dynamics last is what makes the aperture punch safe.
    // T3 (BR-5): each dynamic is viewcone-culled like retail — sphere vs its
    // cell's views; outdoor/unresolved vs the outside views (pass-all under
    // the outdoor root's full-screen outside view). A dynamic in a NON-flooded
    // room culls HERE — retail never reaches an object whose cell is not in
    // the draw list; the partition keeps routing it so the CULL (not the
    // visibility set) drops it, exactly retail's shape.
    private void DrawDynamicsLast(
        IRetailPViewCellDrawContext ctx,
        InteriorEntityPartition.Result partition,
        ViewconeCuller viewcone,
        bool rootIsOutdoor)
    {
        if (partition.Dynamics.Count == 0)
            return;

        _dynamicsScratch.Clear();
        foreach (var e in partition.Dynamics)
        {
            EntitySphere(e, out var c, out float r);
            bool indoor = InteriorEntityPartition.IsIndoorCellId(e.ParentCellId);
            // #118: under an interior root, outdoor-classified dynamics drew in
            // the outside stage (pre-clear, seal-protected) — retail draws them
            // via LScape::draw's per-landcell DrawSortCell, never in the
            // post-seal cell-object epilogue (PView::DrawCells pc:432719 vs
            // pc:432878). Drawing them here instead z-fails them against the
            // seal. Indoor dynamics (incl. exit-portal straddlers, which drew
            // in BOTH stages) stay — this pass is retail's loop C.
            if (!rootIsOutdoor && !indoor)
                continue;
            bool visible = indoor
                ? viewcone.SphereVisibleInCell(e.ParentCellId!.Value, c, r)
                : viewcone.SphereVisibleOutside(c, r);
            if (visible)
                _dynamicsScratch.Add(e);
        }

        if (_dynamicsScratch.Count == 0)
            return;

        UseIndoorMembershipOnlyRouting();
        DrawEntityBucket(ctx, _dynamicsScratch, visibleCellIds: null);

        // #121: dynamics' attached emitters (portal swirls, creature effects)
        // gate through the SAME cone-surviving owner set as their meshes —
        // retail draws emitters with the owner object. Before this callback,
        // dynamics' emitters fell through EVERY particle filter under the pview
        // path (the landscape slice carries outdoor statics + #118 outside-
        // stage dynamics; the cell callback carries cell statics; T4 deleted
        // the old clipRoot==null global pass from normal frames) — all world
        // portals went invisible. Outside-stage dynamics are excluded here:
        // their emitters already drew in the landscape slice (alpha-blended
        // particles must not double-draw, unlike the depth-idempotent meshes).
        if (ctx.DrawDynamicsParticles is not null)
        {
            _dynamicsParticleScratch.Clear();
            foreach (var e in _dynamicsScratch)
                if (!_outsideStageDynamics.Contains(e))
                    _dynamicsParticleScratch.Add(e);
            if (_dynamicsParticleScratch.Count > 0)
                ctx.DrawDynamicsParticles(_dynamicsParticleScratch);
        }
    }

    private void DrawCellObjectLists(
        IRetailPViewCellDrawContext ctx,
        PortalVisibilityFrame pvFrame,
        ClipFrameAssembly clipAssembly,
        HashSet<uint> drawableCells,
        InteriorEntityPartition.Result partition,
        ViewconeCuller viewcone)
    {
        // T1: per-cell STATIC object lists only (dat-baked 0x40 statics) —
        // dynamics moved to DrawDynamicsLast. Far→near with the cells, after
        // the shells (retail DrawCells epilogue: PortalList = cell's views →
        // DrawObjCell, Ghidra 0x005a4840). T3 (BR-5): each static's sphere is
        // tested against ITS CELL's views (retail viewconeCheck) — the
        // statics-through-walls fix: a static whose sphere is outside every
        // view of its cell no longer paints through the wall (the cottage
        // phantom staircase's draw path).
        for (int i = pvFrame.OrderedVisibleCells.Count - 1; i >= 0; i--)
        {
            uint cellId = pvFrame.OrderedVisibleCells[i];
            if (!drawableCells.Contains(cellId))
                continue;

            if (!partition.ByCell.TryGetValue(cellId, out var bucket) || bucket.Count == 0)
                continue;

            _cellStaticScratch.Clear();
            foreach (var e in bucket)
            {
                EntitySphere(e, out var c, out float r);
                if (viewcone.SphereVisibleInCell(cellId, c, r))
                    _cellStaticScratch.Add(e);
            }

            // BR-2 phantom-site probe (T3-updated): post-viewcone survivors.
            if (AcDream.Core.Rendering.RenderingDiagnostics.ProbePhantomEnabled)
                EmitPhantomObjsProbe(cellId, _cellStaticScratch.Count);

            if (_cellStaticScratch.Count > 0)
            {
                _oneCell.Clear();
                _oneCell.Add(cellId);
                UseIndoorMembershipOnlyRouting();
                DrawEntityBucket(ctx, _cellStaticScratch, _oneCell);
            }

            // T3 (BR-5): particles gate through the SAME viewcone as their
            // owners — the callback receives the cone-surviving entity set, so
            // an emitter attached to a culled static no longer draws through
            // the wall (the candle-flames-through-walls fix). Consumed
            // synchronously within this iteration (scratch list reuse).
            foreach (var slice in GetCellSlicesOrNoClip(clipAssembly, cellId))
                ctx.DrawCellParticles?.Invoke(new RetailPViewCellSliceContext(cellId, slice, _cellStaticScratch));
        }
    }

    // T3 scratch lists (render thread only; cleared per use).
    private readonly List<WorldEntity> _outdoorStaticScratch = new();
    private readonly List<WorldEntity> _cellStaticScratch = new();
    private readonly List<WorldEntity> _dynamicsScratch = new();
    // #118: dynamics assigned to the OUTSIDE stage this frame (interior roots
    // only) — outdoor-classified + exit-portal straddlers. Cleared per frame.
    private readonly List<WorldEntity> _outsideStageDynamics = new();
    // #121: cone-surviving dynamics whose emitters draw in the dynamics
    // particle pass (survivors minus outside-stage). Cleared per use.
    private readonly List<WorldEntity> _dynamicsParticleScratch = new();

    /// <summary>
    /// #118 stage assignment for a dynamic under an INTERIOR root: does it draw
    /// in the OUTSIDE (landscape) stage — before the gated depth clear and the
    /// exit-portal seals — like retail's per-landcell object draw
    /// (LScape::draw → DrawBlock 0x005a17c0 → DrawSortCell pc:430124, run at
    /// the top of PView::DrawCells pc:432719)?
    ///
    /// True for outdoor-classified dynamics (their fragments lie beyond the
    /// door plane and would z-fail the seal in the last pass), and for INDOOR
    /// dynamics whose sphere straddles an exit-portal plane of their flood-
    /// visible cell — retail draws an object once per overlapped shadow cell
    /// (DrawBlock pc:430056-430064), so a threshold-straddling body draws in
    /// both stages and neither half clips at the plane. Pure — also driven
    /// headlessly by HouseExitWalkReplayTests as the ordering contract.
    /// </summary>
    public static bool DynamicDrawsInOutsideStage(
        uint? parentCellId,
        Vector3 sphereCenter,
        float sphereRadius,
        HashSet<uint> drawableCells,
        Func<uint, LoadedCell?> cellLookup)
    {
        if (!InteriorEntityPartition.IsIndoorCellId(parentCellId))
            return true;

        uint cellId = parentCellId!.Value;
        if (!drawableCells.Contains(cellId))
            return false;   // not in the flood — the last-pass cone cull owns it
        var cell = cellLookup(cellId);
        if (cell is null)
            return false;

        var localC = Vector3.Transform(sphereCenter, cell.InverseWorldTransform);
        int n = Math.Min(cell.Portals.Count, cell.ClipPlanes.Count);
        for (int i = 0; i < n; i++)
        {
            if (cell.Portals[i].OtherCellId != 0xFFFF)
                continue;
            var plane = cell.ClipPlanes[i];
            if (plane.Normal.LengthSquared() < 1e-8f)
                continue;
            float dist = Vector3.Dot(plane.Normal, localC) + plane.D;
            if (MathF.Abs(dist) < sphereRadius)
                return true;   // sphere straddles the exit-portal plane
        }
        return false;
    }

    // Conservative bounding sphere from the entity's cached AABB — the same
    // bounds source the dispatcher's frustum cull uses.
    private static void EntitySphere(WorldEntity e, out Vector3 center, out float radius)
    {
        if (e.AabbDirty)
            e.RefreshAabb();
        center = (e.AabbMin + e.AabbMax) * 0.5f;
        radius = (e.AabbMax - e.AabbMin).Length() * 0.5f;
    }

    // BR-2 phantom-site probe state: print-on-change per cell so the log stays
    // diffable while the condition persists. Throwaway apparatus — strip when
    // the #113 phantom residual closes. (The [phantom-shell] half died with
    // the T1 chop deletion — shells draw whole, there is no slice state left
    // to report.)
    private readonly Dictionary<uint, int> _phantomObjsSig = new();

    private void EmitPhantomObjsProbe(uint cellId, int bucketCount)
    {
        if (_phantomObjsSig.TryGetValue(cellId, out var prev) && prev == bucketCount) return;
        _phantomObjsSig[cellId] = bucketCount;
        Console.WriteLine($"[phantom-objs] cell=0x{cellId:X8} entities={bucketCount} (drawn unclipped, no viewcone)");
    }

    private static ClipViewSlice[] GetCellSlicesOrNoClip(
        ClipFrameAssembly clipAssembly,
        uint cellId)
    {
        if (clipAssembly.CellIdToViewSlices.TryGetValue(cellId, out var slices)
            && slices.Length > 0)
            return slices;

        return new[] { NoClipSlice };
    }

    private void UseIndoorMembershipOnlyRouting()
    {
        // T1: NOTHING in the world passes hard-clips geometry anymore — retail
        // viewcone-CHECKS meshes (sphere vs view planes, T3) and never clips
        // cell shells (DrawEnvCell draws the whole prebuilt mesh, pc:427905).
        // This clears any clip routing left by the landscape slices.
        _envCells.SetClipRouting(null);
        _entities.ClearClipRouting();
    }

    private void DrawEntityBucket(
        IRetailPViewCellDrawContext ctx,
        IReadOnlyList<WorldEntity> bucket,
        HashSet<uint>? visibleCellIds)
    {
        uint lbId = ctx.PlayerLandblockId ?? 0u;
        var entry = (lbId, Vector3.Zero, Vector3.Zero,
            (IReadOnlyList<WorldEntity>)bucket,
            (IReadOnlyDictionary<uint, WorldEntity>?)null);

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

    private void RestoreNoClip(Action<uint> setTerrainClipUbo)
    {
        _clipFrame.Reset();
        UploadClipFrame(setTerrainClipUbo);
        UseIndoorMembershipOnlyRouting();
    }

    private void UploadClipFrame(Action<uint> setTerrainClipUbo)
    {
        _clipFrame.UploadShared(_gl);
        _entities.SetClipRegionSsbo(_clipFrame.RegionSsbo);
        _envCells.SetClipRegionSsbo(_clipFrame.RegionSsbo);
        setTerrainClipUbo(_clipFrame.TerrainUbo);
    }
}

public interface IRetailPViewCellDrawCallbacks
{
    public Action<RetailPViewCellSliceContext>? DrawExitPortalMasks { get; }
    public Action<RetailPViewCellSliceContext>? DrawCellParticles { get; }
}

public interface IRetailPViewCellDrawContext : IRetailPViewCellDrawCallbacks
{
    public ICamera Camera { get; }
    public FrustumPlanes? Frustum { get; }
    public uint? PlayerLandblockId { get; }
    public HashSet<uint>? AnimatedEntityIds { get; }

    /// <summary>#121: draw the Scene-pass emitters attached to the frame's
    /// cone-surviving dynamics (portal swirls, creature effects). Invoked once
    /// per frame after the last entity pass with the survivor list.</summary>
    public Action<IReadOnlyList<WorldEntity>>? DrawDynamicsParticles { get; }
}

public sealed class RetailPViewDrawContext : IRetailPViewCellDrawContext
{
    public required LoadedCell RootCell { get; init; }

    /// <summary>R-A2: nearby building cells (BuildingId-tagged) flooded per-building when the root is the
    /// outdoor node. Null for interior roots. Grouped by BuildingId inside <see cref="DrawInside"/>.</summary>
    public IReadOnlyList<LoadedCell>? NearbyBuildingCells { get; init; }

    public required Vector3 ViewerEyePos { get; init; }
    public required Matrix4x4 ViewProjection { get; init; }
    public required Func<uint, LoadedCell?> CellLookup { get; init; }
    public required ICamera Camera { get; init; }
    public required Vector3 CameraWorldPosition { get; init; }
    public required FrustumPlanes? Frustum { get; init; }
    public required uint? PlayerLandblockId { get; init; }
    public required HashSet<uint>? AnimatedEntityIds { get; init; }
    public required int RenderCenterLbX { get; init; }
    public required int RenderCenterLbY { get; init; }
    public required int RenderRadius { get; init; }
    public required IEnumerable<(uint LandblockId, Vector3 AabbMin, Vector3 AabbMax,
        IReadOnlyList<WorldEntity> Entities,
        IReadOnlyDictionary<uint, WorldEntity>? AnimatedById)> LandblockEntries { get; init; }
    public required Action<uint> SetTerrainClipUbo { get; init; }
    public required Action<RetailPViewLandscapeSliceContext> DrawLandscapeSlice { get; init; }
    /// <summary>T1: one full-buffer depth clear between the outside stage and the
    /// interior stage (retail PView::DrawCells, Ghidra 0x005a4840). Null for outdoor
    /// roots — outdoors the interiors must depth-test against terrain + exteriors and
    /// appear only through punched apertures.</summary>
    public Action? ClearDepthForInterior { get; init; }
    public Action<RetailPViewCellSliceContext>? DrawExitPortalMasks { get; init; }
    public Action<RetailPViewCellSliceContext>? DrawCellParticles { get; init; }
    public Action<IReadOnlyList<WorldEntity>>? DrawDynamicsParticles { get; init; }
    public Action<RetailPViewFrameResult>? EmitDiagnostics { get; init; }
}

public sealed class RetailPViewFrameResult
{
    public required PortalVisibilityFrame PortalFrame { get; init; }
    public required ClipFrameAssembly ClipAssembly { get; init; }
    public required HashSet<uint> DrawableCells { get; init; }
    public required InteriorEntityPartition.Result Partition { get; init; }
}

public readonly record struct RetailPViewLandscapeSliceContext(
    ClipViewSlice Slice,
    IReadOnlyList<WorldEntity> OutdoorEntities);

public readonly record struct RetailPViewCellSliceContext(
    uint CellId,
    ClipViewSlice Slice,
    IReadOnlyList<WorldEntity> CellEntities);