using System.Numerics;
using KeepersCompound.LGS;
using KeepersCompound.LGS.Database;
using KeepersCompound.LGS.Database.Chunks;
using Serilog;
using TinyEmbree;

namespace KeepersCompound.Lightmapper;

public class LightMapper
{
    // The objcast element of sunlight is ignored, we just care if it's quadlit
    private struct SunSettings
    {
        public bool Enabled;
        public bool QuadLit;
        public Vector3 Direction;
        public Vector3 Color;
    }
    
    private struct Settings
    {
        public Vector3[] AmbientLight;
        public bool Hdr;
        public SoftnessMode MultiSampling;
        public float MultiSamplingCenterWeight;
        public bool LightmappedWater;
        public SunSettings Sunlight;
        public uint AnimLightCutoff;
        public bool UsePvs;
    }

    private ResourcePathManager.CampaignResources _campaign;
    private string _misPath;
    private DbFile _mission;
    private ObjectHierarchy _hierarchy;
    private Raytracer _scene;
    private Raytracer _sceneNoObj;
    private List<Light> _lights;
    private SurfaceType[] _triangleTypeMap;

    public LightMapper(
        string installPath,
        string campaignName,
        string missionName)
    {
        if (!SetupPathManager(installPath, out var pathManager))
        {
            Log.Error("Failed to configure path manager");
            throw new Exception("Failed to configure path manager");
        }
        
        _campaign = pathManager.GetCampaign(campaignName);
        _misPath = _campaign.GetResourcePath(ResourceType.Mission, missionName);
        _mission = Timing.TimeStage("Parse DB", () => new DbFile(_misPath));
        _hierarchy = Timing.TimeStage("Build Hierarchy", BuildHierarchy);
        _lights = [];

        VerifyRequiredChunksExist();
        
        var (noObjMesh, fullMesh) = Timing.TimeStage("Build Meshes", BuildMeshes);
        _triangleTypeMap = fullMesh.TriangleSurfaceMap;
        _sceneNoObj = Timing.TimeStage("Build RT NoObj Scene", () =>
        {
            var rt = new Raytracer();
            rt.AddMesh(new TriangleMesh(noObjMesh.Vertices, noObjMesh.Indices));
            rt.CommitScene();
            return rt;
        });
        _scene = Timing.TimeStage("Build RT Scene", () =>
        {
            var rt = new Raytracer();
            rt.AddMesh(new TriangleMesh(fullMesh.Vertices, fullMesh.Indices));
            rt.CommitScene();
            return rt;
        });
    }
    
    public void Light(bool pvs)
    {
        // TODO: Throw?
        if (!_mission.TryGetChunk<RendParams>("RENDPARAMS", out var rendParams) ||
            !_mission.TryGetChunk<LmParams>("LM_PARAM", out var lmParams) ||
            !_mission.TryGetChunk<WorldRep>("WREXT", out var worldRep))
        {
            return;
        }

        var sunlightSettings = new SunSettings()
        {
            Enabled = rendParams.useSunlight,
            QuadLit = rendParams.sunlightMode is RendParams.SunlightMode.QuadUnshadowed or RendParams.SunlightMode.QuadObjcastShadows,
            Direction = Vector3.Normalize(rendParams.sunlightDirection),
            Color = Utils.HsbToRgb(rendParams.sunlightHue, rendParams.sunlightSaturation, rendParams.sunlightBrightness),
        };
        
        var ambientLight = rendParams.ambientLightZones.ToList();
        ambientLight.Insert(0, rendParams.ambientLight);
        for (var i = 0; i < ambientLight.Count; i++)
        {
            ambientLight[i] *= 255;
        }

        // TODO: lmParams LightmappedWater doesn't mean the game will actually *use* the lightmapped water hmm
        var settings = new Settings
        {
            Hdr = worldRep.DataHeader.LightmapFormat == 2,
            AmbientLight = [..ambientLight],
            MultiSampling = lmParams.ShadowSoftness,
            MultiSamplingCenterWeight = lmParams.CenterWeight,
            LightmappedWater = lmParams.LightmappedWater,
            Sunlight = sunlightSettings,
            AnimLightCutoff = lmParams.AnimLightCutoff,
            UsePvs = pvs,
        };
        
        Timing.TimeStage("Gather Lights", BuildLightList);
        Timing.TimeStage("Set Light Indices", () => SetCellLightIndices(settings));
        Timing.TimeStage("Trace Scene", () => TraceScene(settings));
        Timing.TimeStage("Update AnimLight Cell Mapping", SetAnimLightCellMaps);

        // We always do object casting, so it's nice to let dromed know that :)
        lmParams.ShadowType = LmParams.LightingMode.Objcast;
        if (rendParams is { useSunlight: true, sunlightMode: RendParams.SunlightMode.SingleUnshadowed })
        {
            rendParams.sunlightMode = RendParams.SunlightMode.SingleObjcastShadows;
        } else if (rendParams is { useSunlight: true, sunlightMode: RendParams.SunlightMode.QuadUnshadowed })
        {
            rendParams.sunlightMode = RendParams.SunlightMode.QuadObjcastShadows;
        }
    }

    public void Save(string missionName)
    {
        var ext = Path.GetExtension(_misPath);
        var dir = Path.GetDirectoryName(_misPath);
        var savePath = Path.Join(dir, missionName + ext);
        Timing.TimeStage("Save DB", () => _mission.Save(savePath));
    }

    private bool VerifyRequiredChunksExist()
    {
        var requiredChunkNames = new []
        {
            "RENDPARAMS",
            "LM_PARAM",
            "WREXT",
            "BRLIST",
            "P$AnimLight",
        };

        var allFound = true;
        foreach (var name in requiredChunkNames)
        {
            if (!_mission.Chunks.ContainsKey(name))
            {
                Log.Warning("Failed to find required chunk: {ChunkName}", name);
                allFound = false;
            }
        }

        return allFound;
    }

    private static bool SetupPathManager(string installPath, out ResourcePathManager pathManager)
    {
        var tmpDir = Directory.CreateTempSubdirectory("KCLightmapper");
        
        pathManager = new ResourcePathManager(tmpDir.FullName);
        return pathManager.TryInit(installPath);
    }

    private ObjectHierarchy BuildHierarchy()
    {
        if (!_mission.TryGetChunk<GamFile>("GAM_FILE", out var gamFile))
        {
            return new ObjectHierarchy(_mission);
        }
        
        var dir = Path.GetDirectoryName(_misPath);
        var options = new EnumerationOptions { MatchCasing = MatchCasing.CaseInsensitive };
        var name = gamFile.fileName;
        var paths = Directory.GetFiles(dir!, name, options);
        if (paths.Length > 0)
        {
            return new ObjectHierarchy(_mission, new DbFile(paths[0]));
        }
        
        Log.Warning("Failed to find GameSys");
        return new ObjectHierarchy(_mission);
    }

    private (Mesh, Mesh) BuildMeshes()
    {
        var meshBuilder = new MeshBuilder();

        // TODO: Should this throw?
        // TODO: Only do object polys if objcast lighting?
        if (!_mission.TryGetChunk<WorldRep>("WREXT", out var worldRep) ||
            !_mission.TryGetChunk<BrList>("BRLIST", out var brList))
        {
            return (meshBuilder.Build(), meshBuilder.Build());
        }

        meshBuilder.AddWorldRepPolys(worldRep);
        var noObjMesh = meshBuilder.Build();
        
        meshBuilder.AddObjectPolys(brList, _hierarchy, _campaign);
        var fullMesh = meshBuilder.Build();
        
        return (noObjMesh, fullMesh);
    }

    private void BuildLightList()
    {
        _lights.Clear();

        // Get the chunks we need
        if (!_mission.TryGetChunk<WorldRep>("WREXT", out var worldRep) ||
            !_mission.TryGetChunk<BrList>("BRLIST", out var brList))
        {
            return;
        }

        worldRep.LightingTable.Reset();
        
        // TODO: Calculate the actual effective radius of infinite lights
        // potentially do the same for all lights and lower their radius if necessary?
        foreach (var brush in brList.Brushes)
        {
            switch (brush.media)
            {
                case BrList.Brush.Media.Light:
                    ProcessBrushLight(worldRep.LightingTable, brush);
                    break;
                case BrList.Brush.Media.Object:
                    ProcessObjectLight(worldRep.LightingTable, brush);
                    break;
            }
        }

        var infinite = 0;
        foreach (var light in _lights)
        {
            if (light.Radius != float.MaxValue)
            {
                continue;
            }

            if (light.ObjId != -1)
            {
                Log.Warning("Infinite light from object {Id}", light.ObjId);
            }
            else
            {
                Log.Warning("Infinite light from brush near {Position}", light.Position);
            }
            infinite++;
        }
        
        if (infinite > 0)
        {
            Log.Warning("Mission contains {Count} infinite lights", infinite);
        }
    }
    
    // TODO: Check if this works (brush is a record type)
    private void ProcessBrushLight(WorldRep.LightTable lightTable, BrList.Brush brush)
    {
        // For some reason the light table index on brush lights is 1 indexed
        brush.brushInfo = (uint)lightTable.LightCount + 1;
        var sz = brush.size;
        
        // Ignore 0 brightness lights
        if (sz.X == 0)
        {
            return;
        }

        var brightness = Math.Min(sz.X, 255.0f);
        var light = new Light
        {
            Position = brush.position,
            Color = Utils.HsbToRgb(sz.Y, sz.Z, brightness),
            Brightness = brightness,
            Radius = float.MaxValue,
            R2 = float.MaxValue,
            LightTableIndex = lightTable.LightCount,
            SpotlightInnerAngle = -1f,
            ObjId = -1,
        };
        
        _lights.Add(light);
        lightTable.AddLight(light.ToLightData(32.0f));
    }

    private void ProcessObjectLight(WorldRep.LightTable lightTable, BrList.Brush brush)
    {
        // TODO: Handle PropSpotlightAndAmbient
        var id = (int)brush.brushInfo;
        var propScale = _hierarchy.GetProperty<PropVector>(id, "P$Scale");
        var propAnimLight = _hierarchy.GetProperty<PropAnimLight>(id, "P$AnimLight", false);
        var propLight = _hierarchy.GetProperty<PropLight>(id, "P$Light", false);
        var propLightColor = _hierarchy.GetProperty<PropLightColor>(id, "P$LightColo");
        var propSpotlight = _hierarchy.GetProperty<PropSpotlight>(id, "P$Spotlight");
        var propSpotAmb = _hierarchy.GetProperty<PropSpotlightAndAmbient>(id, "P$SpotAmb");
        var propModelName = _hierarchy.GetProperty<PropLabel>(id, "P$ModelName");
        var propJointPos = _hierarchy.GetProperty<PropJointPos>(id, "P$JointPos");

        propLightColor ??= new PropLightColor { Hue = 0, Saturation = 0 };
        var joints = propJointPos?.Positions ?? [0, 0, 0, 0, 0, 0];
        
        // Transform data
        var translate = Matrix4x4.CreateTranslation(brush.position);
        var rotate = Matrix4x4.Identity;
        rotate *= Matrix4x4.CreateRotationX(float.DegreesToRadians(brush.angle.X));
        rotate *= Matrix4x4.CreateRotationY(float.DegreesToRadians(brush.angle.Y));
        rotate *= Matrix4x4.CreateRotationZ(float.DegreesToRadians(brush.angle.Z));
        var scale = Matrix4x4.CreateScale(propScale?.value ?? Vector3.One);
        
        var vhotLightPos = Vector3.Zero;
        var vhotLightDir = -Vector3.UnitZ;
        if (propModelName != null)
        {
            var resName = $"{propModelName.value.ToLower()}.bin";
            var modelPath = _campaign.GetResourcePath(ResourceType.Object, resName);
            if (modelPath != null)
            {
                var model = new ModelFile(modelPath);
                model.ApplyJoints(joints);
                
                if (model.TryGetVhot(ModelFile.VhotId.LightPosition, out var vhot))
                {
                    vhotLightPos = vhot.Position - model.Header.Center;
                }
                if (model.TryGetVhot(ModelFile.VhotId.LightDirection, out vhot))
                {
                    vhotLightDir = (vhot.Position - model.Header.Center) - vhotLightPos;
                }
            }
        }
        
        if (propAnimLight != null)
        {
            var lightIndex = lightTable.LightCount;
            propAnimLight.LightTableLightIndex = (ushort)lightIndex;
            
            var light = new Light
            {
                Position = propAnimLight.Offset,
                Color = Utils.HsbToRgb(propLightColor.Hue, propLightColor.Saturation, propAnimLight.MaxBrightness),
                Brightness = propAnimLight.MaxBrightness,
                InnerRadius = propAnimLight.InnerRadius,
                Radius = propAnimLight.Radius,
                R2 = propAnimLight.Radius * propAnimLight.Radius,
                QuadLit = propAnimLight.QuadLit,
                ObjId = id,
                LightTableIndex = propAnimLight.LightTableLightIndex,
                Anim = true,
                Dynamic = propAnimLight.Dynamic,
                SpotlightInnerAngle = -1f,
            };
            
            if (propSpotlight != null)
            {
                light.Spotlight = true;
                light.SpotlightInnerAngle = (float)Math.Cos(float.DegreesToRadians(propSpotlight.InnerAngle));
                light.SpotlightOuterAngle = (float)Math.Cos(float.DegreesToRadians(propSpotlight.OuterAngle));
            }
            
            light.FixRadius();
            light.ApplyTransforms(vhotLightPos, vhotLightDir, translate, rotate, scale);

            _lights.Add(light);
            lightTable.AddLight(light.ToLightData(32.0f), propAnimLight.Dynamic);
        }

        if (propLight != null && propLight.Brightness != 0)
        {
            var light = new Light
            {
                Position = propLight.Offset,
                Color = Utils.HsbToRgb(propLightColor.Hue, propLightColor.Saturation, propLight.Brightness),
                Brightness = propLight.Brightness,
                InnerRadius = propLight.InnerRadius,
                Radius = propLight.Radius,
                R2 = propLight.Radius * propLight.Radius,
                QuadLit = propLight.QuadLit,
                ObjId = id,
                LightTableIndex = lightTable.LightCount,
                SpotlightInnerAngle = -1f,
            };
            
            if (propSpotAmb != null)
            {
                var spot = new Light
                {
                    Position = light.Position,
                    Color = Utils.HsbToRgb(propLightColor.Hue, propLightColor.Saturation, propSpotAmb.SpotBrightness),
                    Brightness = propSpotAmb.SpotBrightness,
                    InnerRadius = light.InnerRadius,
                    Radius = light.Radius,
                    R2 = light.R2,
                    QuadLit = light.QuadLit,
                    Spotlight = true,
                    SpotlightInnerAngle = (float)Math.Cos(float.DegreesToRadians(propSpotAmb.InnerAngle)),
                    SpotlightOuterAngle = (float)Math.Cos(float.DegreesToRadians(propSpotAmb.OuterAngle)),
                    ObjId = light.ObjId,
                    LightTableIndex = light.LightTableIndex,
                };

                light.LightTableIndex++; // Because we're inserting the spotlight part first
                
                spot.FixRadius();
                spot.ApplyTransforms(vhotLightPos, vhotLightDir, translate, rotate, scale);
                
                _lights.Add(spot);
                lightTable.AddLight(spot.ToLightData(32.0f));
            }
            else if (propSpotlight != null)
            {
                light.Spotlight = true;
                light.SpotlightInnerAngle = (float)Math.Cos(float.DegreesToRadians(propSpotlight.InnerAngle));
                light.SpotlightOuterAngle = (float)Math.Cos(float.DegreesToRadians(propSpotlight.OuterAngle));
            }
            
            light.FixRadius();
            light.ApplyTransforms(vhotLightPos, vhotLightDir, translate, rotate, scale);
            
            _lights.Add(light);
            lightTable.AddLight(light.ToLightData(32.0f));
        }
    }

    private void SetCellLightIndices(Settings settings)
    {
        // TODO: Doors aren't blocking lights. Need to do some cell traversal to remove light indices :(
        
        if (!_mission.TryGetChunk<WorldRep>("WREXT", out var worldRep))
            return;
        
        
        var lightVisibleCells = new List<int[]>();
        if (settings.UsePvs)
        {
            lightVisibleCells = Timing.TimeStage("Light PVS", () =>
            {
                var cellCount = worldRep.Cells.Length;
                var aabbs = new MathUtils.Aabb[worldRep.Cells.Length];
                Parallel.For(0, cellCount, i => aabbs[i] = new MathUtils.Aabb(worldRep.Cells[i].Vertices));

                var lightCellMap = new int[_lights.Count];
                Parallel.For(0, _lights.Count, i =>
                {
                    lightCellMap[i] = -1;
                    var light = _lights[i];
                    for (var j = 0; j < cellCount; j++)
                    {
                        if (!MathUtils.Intersects(aabbs[j], light.Position))
                        {
                            continue;
                        }

                        // Half-space contained
                        var cell = worldRep.Cells[j];
                        var contained = true;
                        for (var k = 0; k < cell.PlaneCount; k++)
                        {
                            var plane = cell.Planes[k];
                            if (MathUtils.DistanceFromPlane(plane, light.Position) < -MathUtils.Epsilon)
                            {
                                contained = false;
                                break;
                            }
                        }

                        if (contained)
                        {
                            lightCellMap[i] = j;
                            break;
                        }
                    }
                });
                
                var pvs = new PotentiallyVisibleSet(worldRep.Cells);
                Parallel.ForEach(lightCellMap, i =>
                {
                    if (i != -1) pvs.ComputeVisibility(i);
                });

                var visibleCellMap = new List<int[]>(_lights.Count);
                for (var i = 0; i < _lights.Count; i++)
                {
                    var cellIdx = lightCellMap[i];
                    if (cellIdx == -1)
                    {
                        visibleCellMap.Add([]);
                        continue;
                    }

                    var visibleSet = pvs.GetVisible(lightCellMap[i]);
                    visibleCellMap.Add(visibleSet);
                }

                return visibleCellMap;
            });
        }

        // TODO: Move this functionality to the LGS library
        // We set up light indices in separately from lighting because the actual
        // lighting phase takes a lot of shortcuts that we don't want
        // Parallel.ForEach(worldRep.Cells, cell =>
        Parallel.For(0, worldRep.Cells.Length, i =>
        {
            var cell = worldRep.Cells[i];
            cell.LightIndexCount = 0;
            cell.LightIndices.Clear();
            
            // The first element of the light indices array is used to store how many
            // actual lights are in the list. Which is just LightIndexCount - 1...
            // Odd choice I know
            cell.LightIndexCount++;
            cell.LightIndices.Add(0);
            
            // If we have sunlight, then we just assume the sun has the potential to reach everything (ew)
            // The sun enabled option doesn't actually seem to do anything at runtime, it's purely about if
            // the cell has the sunlight idx on it.
            if (settings.Sunlight.Enabled)
            {
                cell.LightIndexCount++;
                cell.LightIndices.Add(0);
                cell.LightIndices[0]++;
            }

            // The OG lightmapper uses the cell traversal to work out all the cells that
            // are actually visited. We're a lot more coarse and just say if a cell is
            // in range then we potentially affect the lighting in the cell and add it 
            // to the list.
            // There's a soft length limit here of 96 due to the runtime object shadow
            // cache, so we want this to be as minimal as possible. Additionally large
            // lists actually cause performance issues!
            var cellAabb = new MathUtils.Aabb(cell.Vertices);
            for (var j = 0; j < _lights.Count; j++)
            {
                var light = _lights[j];
                if (light.Dynamic || !MathUtils.Intersects(new MathUtils.Sphere(light.Position, light.Radius), cellAabb))
                {
                    continue;
                }
                
                if (settings.UsePvs && !lightVisibleCells[j].Contains(i))
                {
                    continue;
                }
                
                cell.LightIndexCount++;
                cell.LightIndices.Add((ushort)light.LightTableIndex);
                cell.LightIndices[0]++;
            }

            if (cell.LightIndexCount > 97)
            {
                Log.Warning("Cell {Id} sees too many lights ({Count})", i, cell.LightIndices[0]);
            }
        });

        {
            var overLit = 0;
            var maxLights = 0;
            foreach (var cell in worldRep.Cells)
            {
                if (cell.LightIndexCount > 97)
                {
                    overLit++;
                }

                if (cell.LightIndexCount > maxLights)
                {
                    maxLights = cell.LightIndexCount - 1;
                }
            }

            if (overLit > 0)
            {
                Log.Warning("{Count}/{CellCount} cells are overlit. Overlit cells can cause Object/Light Gem lighting issues. Try running with the --pvs flag.", overLit, worldRep.Cells.Length);
            }

            Log.Information("Max cell lights found ({Count}/96)", maxLights);
        }
    }

    private void TraceScene(Settings settings)
    {
        if (!_mission.TryGetChunk<WorldRep>("WREXT", out var worldRep))
        {
            return;
        }
        
        Parallel.ForEach(worldRep.Cells, cell =>
        {
            // Reset cell AnimLight palette
            cell.AnimLightCount = 0;
            cell.AnimLights.Clear();

            var numPolys = cell.PolyCount;
            var numRenderPolys = cell.RenderPolyCount;
            var numPortalPolys = cell.PortalPolyCount;

            // There's nothing to render
            // Portal polys can be render polys (e.g. water) but we're ignoring them for now
            if (numRenderPolys == 0 || numPortalPolys >= numPolys)
            {
                return;
            }

            var solidPolys = numPolys - numPortalPolys;
            var cellIdxOffset = 0;
            for (var polyIdx = 0; polyIdx < numRenderPolys; polyIdx++)
            {
                var poly = cell.Polys[polyIdx];
                var plane = cell.Planes[poly.PlaneId];
                var renderPoly = cell.RenderPolys[polyIdx];
                var info = cell.LightList[polyIdx];
                var lightmap = cell.Lightmaps[polyIdx];

                info.AnimLightBitmask = 0;
                
                // We have to reset the lightmaps for water, but we don't want to do anything else
                var waterPoly = polyIdx >= solidPolys;
                if (!settings.LightmappedWater && waterPoly)
                {
                    lightmap.Reset(Vector3.One * 255f, settings.Hdr);
                    continue;
                }

                var ambientLight = settings.AmbientLight[cell.ZoneInfo.GetAmbientLightZoneIndex()];
                lightmap.Reset(ambientLight, settings.Hdr);

                // Get world position of lightmap (0, 0) (+0.5 so we cast from the center of a pixel)
                var topLeft = cell.Vertices[cell.Indices[cellIdxOffset]];
                topLeft -= renderPoly.TextureVectors.Item1 * (renderPoly.TextureBases.Item1 - info.Bases.Item1 * 0.25f);
                topLeft -= renderPoly.TextureVectors.Item2 * (renderPoly.TextureBases.Item2 - info.Bases.Item2 * 0.25f);

                var xDir = 0.25f * lightmap.Width * renderPoly.TextureVectors.Item1;
                var yDir = 0.25f * lightmap.Height * renderPoly.TextureVectors.Item2;
                var aabb = new MathUtils.Aabb([
                    topLeft,
                    topLeft + xDir,
                    topLeft + yDir,
                    topLeft + xDir + yDir,
                ]);
                
                // Log.Information("Poly plane: {X}x + {Y}y + {Z}z + {D} = 0", plane.Normal.X, plane.Normal.Y, plane.Normal.Z, plane.D);
                var edgePlanes = new Plane[poly.VertexCount];
                for (var i = 0; i < poly.VertexCount; i++)
                {
                    var v0 = cell.Vertices[cell.Indices[cellIdxOffset + i]];
                    var v1 = cell.Vertices[cell.Indices[cellIdxOffset + (i + 1) % poly.VertexCount]];
                
                    var dir = Vector3.Normalize(v1 - v0);
                    var edgePlaneNormal = Vector3.Cross(dir, plane.Normal);
                    var edgePlaneDistance = -Vector3.Dot(edgePlaneNormal, v0);
                    var edgePlane = new Plane(edgePlaneNormal, edgePlaneDistance);
                    edgePlanes[i] = edgePlane;
                    // Log.Information("Edge plane: {X}x + {Y}y + {Z}z + {D} = 0", edgePlane.Normal.X, edgePlane.Normal.Y, edgePlane.Normal.Z, edgePlane.D);
                }

                // Used for clipping points to poly
                var vs = new Vector3[poly.VertexCount];
                for (var i = 0; i < poly.VertexCount; i++)
                {
                    vs[i] = cell.Vertices[cell.Indices[cellIdxOffset + i]];
                }
                var planeMapper = new MathUtils.PlanePointMapper(plane.Normal, vs[0], vs[1]);
                var v2ds = planeMapper.MapTo2d(vs);
                
                // TODO: Only need to generate quadweights if there's any quadlights in the mission
                var (texU, texV) = renderPoly.TextureVectors;
                var (offsets, weights) =
                    GetTraceOffsetsAndWeights(settings.MultiSampling, texU, texV, settings.MultiSamplingCenterWeight);
                var (quadOffsets, quadWeights) = settings.MultiSampling != SoftnessMode.Standard
                    ? (offsets, weights)
                    : GetTraceOffsetsAndWeights(SoftnessMode.HighFourPoint, texU, texV, settings.MultiSamplingCenterWeight);

                for (var y = 0; y < lightmap.Height; y++)
                {
                    for (var x = 0; x < lightmap.Width; x++)
                    {
                        var pos = topLeft;
                        pos += x * 0.25f * renderPoly.TextureVectors.Item1;
                        pos += y * 0.25f * renderPoly.TextureVectors.Item2;
                        
                        // TODO: Handle quad lit lights better. Right now we're computing two sets of points for every
                        // luxel. Maybe it's better to only compute if we encounter a quadlit light?
                        // var tracePoints = GetTracePoints(pos, offsets, renderPoly.Center, plane, edgePlanes);
                        // var quadTracePoints = settings.MultiSampling != SoftnessMode.Standard
                        //     ? tracePoints
                        //     : GetTracePoints(pos, quadOffsets, renderPoly.Center, plane, edgePlanes);
                        var tracePoints = GetTracePoints(pos, offsets, renderPoly.Center, planeMapper, v2ds);
                        var quadTracePoints = settings.MultiSampling != SoftnessMode.Standard
                            ? tracePoints
                            : GetTracePoints(pos, quadOffsets, renderPoly.Center, planeMapper, v2ds);
                        
                        // This is almost perfect now. Any issues seem to be related to Dark not carrying HSB strength correctly
                        if (settings.Sunlight.Enabled) {
                            // Check if plane normal is facing towards the light
                            // If it's not then we're never going to be (directly) lit by this
                            // light.
                            var sunAngle = Vector3.Dot(-settings.Sunlight.Direction, plane.Normal);
                            if (sunAngle > 0)
                            {
                                var strength = 0f;
                                var targetPoints = settings.Sunlight.QuadLit ? quadTracePoints : tracePoints;
                                var targetWeights = settings.Sunlight.QuadLit ? quadWeights : weights;
                                for (var idx = 0; idx < targetPoints.Length; idx++)
                                {
                                    var point = targetPoints[idx];
                                    if (TraceSunRay(point, -settings.Sunlight.Direction))
                                    {
                                        // Sunlight is a simpler lighting algorithm than normal lights so we can just
                                        // do it here
                                        strength += targetWeights[idx] * sunAngle;
                                    }
                                }

                                if (strength != 0f)
                                {
                                    lightmap.AddLight(0, x, y, settings.Sunlight.Color, strength, settings.Hdr);
                                }
                            }
                        }

                        // foreach (var lightIdx in cell.LightIndices)
                        for (var i = 0; i < cell.LightIndexCount; i++)
                        {
                            var lightIdx = cell.LightIndices[i];
                            if (i == 0 || lightIdx == 0)
                            {
                                continue;
                            }
                            
                            var light = _lights[lightIdx - 1];

                            // If the light is behind the plane we'll never be directly lit by this light.
                            // Additionally, if the distance from the plane is more than the light's radius
                            // we know no points on the plane will be lit.
                            var planeDist = MathUtils.DistanceFromPlane(plane, light.Position);
                            if (planeDist <= MathUtils.Epsilon || planeDist > light.Radius)
                            {
                                continue;
                            }

                            // If the poly of the lightmap doesn't intersect the light radius then
                            // none of the lightmap points will so we can discard.
                            if (!MathUtils.Intersects(new MathUtils.Sphere(light.Position, light.Radius), aabb))
                            {
                                continue;
                            }
                            
                            var strength = 0f;
                            var targetPoints = light.QuadLit ? quadTracePoints : tracePoints;
                            var targetWeights = light.QuadLit ? quadWeights : weights;
                            for (var idx = 0; idx < targetPoints.Length; idx++)
                            {
                                var point = targetPoints[idx];
                                
                                // If we're out of range there's no point casting a ray
                                // There's probably a better way to discard the entire lightmap
                                // if we're massively out of range
                                if ((point - light.Position).LengthSquared() > light.R2)
                                {
                                    continue;
                                }
                                
                                if (!TraceOcclusion(_scene, light.Position, point))
                                {
                                    strength += targetWeights[idx] * light.StrengthAtPoint(point, plane, settings.AnimLightCutoff);
                                }
                            }

                            if (strength != 0f)
                            {
                                var layer = 0;

                                // If we're an anim light there's a lot of stuff we need to update
                                // Firstly we need to add the light to the cells anim light palette
                                // Secondly we need to set the appropriate bit of the lightmap's
                                // bitmask. Finally we need to check if the lightmap needs another layer
                                // TODO: Handle too many lights for a layer
                                if (light.Anim)
                                {
                                    // TODO: Don't recalculate this for every point lol
                                    var paletteIdx = cell.AnimLights.IndexOf((ushort)light.LightTableIndex);
                                    if (paletteIdx == -1)
                                    {
                                        paletteIdx = cell.AnimLightCount;
                                        cell.AnimLightCount++;
                                        cell.AnimLights.Add((ushort)light.LightTableIndex);
                                    }
                                    info.AnimLightBitmask |= 1u << paletteIdx;
                                    layer = paletteIdx + 1;
                                }
                                lightmap.AddLight(layer, x, y, light.Color, strength, settings.Hdr);
                            }
                        }
                    }
                }

                cellIdxOffset += poly.VertexCount;
            }
        });
    }
    
    private static (Vector3[], float[]) GetTraceOffsetsAndWeights(
        SoftnessMode mode,
        Vector3 texU,
        Vector3 texV,
        float centerWeight)
    {
        var offsetScale = mode switch
        {
            SoftnessMode.HighFourPoint or SoftnessMode.HighFivePoint or SoftnessMode.HighNinePoint => 4f,
            SoftnessMode.MediumFourPoint or SoftnessMode.MediumFivePoint or SoftnessMode.MediumNinePoint => 8f,
            SoftnessMode.LowFourPoint => 16f,
            _ => 1f,
        };

        var cw = centerWeight;
        var w = 1f - cw;
        texU /= offsetScale;
        texV /= offsetScale;

        return mode switch
        {
            SoftnessMode.LowFourPoint or SoftnessMode.MediumFourPoint or SoftnessMode.HighFourPoint => (
                [-texU - texV, texU - texV, -texU + texV, texU + texV],
                [0.25f, 0.25f, 0.25f, 0.25f]),
            SoftnessMode.MediumFivePoint or SoftnessMode.HighFivePoint => (
                [Vector3.Zero, -texU - texV, texU - texV, -texU + texV, texU + texV],
                [cw, w * 0.25f, w * 0.25f, w * 0.25f, w * 0.25f]),
            SoftnessMode.MediumNinePoint or SoftnessMode.HighNinePoint => (
                [Vector3.Zero, -texU - texV, texU - texV, -texU + texV, texU + texV, -texU, texU, -texV, texV],
                [cw, w * 0.125f, w * 0.125f, w * 0.125f, w * 0.125f, w * 0.125f, w * 0.125f, w * 0.125f, w * 0.125f]),
            _ => (
                [Vector3.Zero],
                [1f]),
        };
    }

    private Vector3[] GetTracePoints(
        Vector3 basePosition,
        Vector3[] offsets,
        Vector3 polyCenter,
        Plane polyPlane,
        Plane[] edgePlanes)
    {
        polyCenter += polyPlane.Normal * 0.25f;
        
        var tracePoints = new Vector3[offsets.Length];
        for (var i = 0; i < offsets.Length; i++)
        {
            var offset = offsets[i];
            var pos = basePosition + offset;

            // If the center can see the target lightmap point then we can just straight use it.
            // Note that the target may actually be on another poly, or floating in space over a ledge.
            if (!TraceOcclusion(_sceneNoObj, polyCenter, pos))
            {
                tracePoints[i] = pos;
                continue;
            }
            
            // If we can't see our target point from the center of the poly
            // then we need to clip the point to slightly inside the poly
            // and retrace to avoid two problems:
            // 1. Darkened spots from lightmap pixels whose center is outside
            //    the polygon but is partially contained in the polygon
            // 2. Darkened spots from linear filtering of points outside the
            //    polygon which have missed
            //
            // TODO: This can cause seams. The ideal solution here is to check if it lies on any other poly, or maybe check if it's "within" any cells.
            foreach (var plane in edgePlanes)
            {
                var distFromPlane = MathUtils.DistanceFromPlane(plane, pos);
                if (distFromPlane >= -MathUtils.Epsilon)
                {
                    // we're inside the plane :)
                    continue;
                }
            
                var u = polyCenter - pos;
                var w = pos - (plane.Normal * -plane.D);
            
                var d = Vector3.Dot(plane.Normal, u);
                var n = -Vector3.Dot(plane.Normal, w);
                var t = n / d;
                
                pos += u * (t + MathUtils.Epsilon);
            }
            
            // After clipping, we can still be in a weird spot. So to fully resolve it we do a cast
            if (TraceOcclusion(_sceneNoObj, polyCenter + polyPlane.Normal * 0.25f, pos))
            {
                var origin = polyCenter + polyPlane.Normal * 0.25f;
                var direction = pos - origin;
                var hitResult = _sceneNoObj.Trace(new Ray
                {
                    Origin = origin,
                    Direction = Vector3.Normalize(direction),
                });
                    
                if (hitResult)
                {
                    pos = hitResult.Position;
                }
            }
            
            tracePoints[i] = pos;
        }
        
        return tracePoints;
    }
    
    private Vector3[] GetTracePoints(
        Vector3 basePosition,
        Vector3[] offsets,
        Vector3 polyCenter,
        MathUtils.PlanePointMapper planeMapper,
        Vector2[] v2ds)
    {
        polyCenter += planeMapper.Normal * 0.25f;
        
        // All of the traces here are done using the no object scene. We just want to find a point in-world, we don't
        // care about if an object is in the way
        var tracePoints = new Vector3[offsets.Length];
        for (var i = 0; i < offsets.Length; i++)
        {
            var offset = offsets[i];
            var pos = basePosition + offset + planeMapper.Normal * MathUtils.Epsilon;

            // If the target lightmap point is in view of the center
            // then we can use it as-is. Using it straight fixes seams and such.
            if (!TraceOcclusion(_sceneNoObj, polyCenter, pos))
            {
                tracePoints[i] = pos;
                continue;
            }
            
            // If we can't see our target point from the center of the poly
            // then we need to clip the point to slightly inside the poly
            // and retrace to avoid two problems:
            // 1. Darkened spots from lightmap pixels whose center is outside
            //    the polygon but is partially contained in the polygon
            // 2. Darkened spots from linear filtering of points outside the
            //    polygon which have missed
            var p2d = planeMapper.MapTo2d(pos);
            p2d = MathUtils.ClipPointToPoly2d(p2d, v2ds);
            pos = planeMapper.MapTo3d(p2d);
            pos += planeMapper.Normal * MathUtils.Epsilon;
            
            // If the clipping fails, just say screw it and cast :(
            if (TraceOcclusion(_sceneNoObj, polyCenter, pos))
            {
                var hitResult = _sceneNoObj.Trace(new Ray
                {
                    Origin = polyCenter,
                    Direction = Vector3.Normalize(pos - polyCenter),
                });
                
                if (hitResult)
                {
                    pos = hitResult.Position;
                }
            }
            
            tracePoints[i] = pos;
        }
        
        return tracePoints;
    }
    
    private static bool TraceOcclusion(Raytracer scene, Vector3 origin, Vector3 target, float epsilon = MathUtils.Epsilon)
    {
        var direction = target - origin;
        var ray = new Ray
        {
            Origin = origin,
            Direction = Vector3.Normalize(direction),
        };
        
        // Epsilon is used here to avoid occlusion when origin lies exactly on a poly
        return scene.IsOccluded(new ShadowRay(ray, direction.Length() - epsilon));
    }

    // TODO: direction should already be normalised here
    private bool TraceSunRay(Vector3 origin, Vector3 direction)
    {
        // Avoid self intersection
        origin += direction * MathUtils.Epsilon;
        
        var hitResult = _scene.Trace(new Ray
        {
            Origin = origin,
            Direction = Vector3.Normalize(direction),
        });

        if (hitResult)
        {
            return _triangleTypeMap[(int)hitResult.PrimId] == SurfaceType.Sky;
        }
        return false;
    }

    private void SetAnimLightCellMaps()
    {
        if (!_mission.TryGetChunk<PropertyChunk<PropAnimLight>>("P$AnimLight", out var animLightChunk) ||
            !_mission.TryGetChunk<WorldRep>("WREXT", out var worldRep))
        {
            return;
        }
        
        // Now that we've set all the per-cell stuff we need to aggregate the cell mappings
        // We can't do this in parallel which is why it's being done afterwards rather than
        // as we go
        var map = new Dictionary<ushort, List<WorldRep.LightTable.AnimCellMap>>();
        for (ushort i = 0; i < worldRep.Cells.Length; i++)
        {
            var cell = worldRep.Cells[i];
            for (ushort j = 0; j < cell.AnimLightCount; j++)
            {
                var animLightIdx = cell.AnimLights[j];
                if (!map.TryGetValue(animLightIdx, out var value))
                {
                    value = [];
                    map[animLightIdx] = value;
                }
                value.Add(new WorldRep.LightTable.AnimCellMap
                {
                    CellIndex = i,
                    LightIndex = j,
                });
            }
        }

        
        foreach (var (lightIdx, animCellMaps) in map)
        {
            // We need to update the object property so it knows its mapping range
            // TODO: Handle nulls
            var light = _lights.Find(l => l.Anim && l.LightTableIndex == lightIdx);
            var prop = animLightChunk.properties.Find(p => p.objectId == light.ObjId);
            prop.LightTableLightIndex = lightIdx;
            prop.LightTableMapIndex = (ushort)worldRep.LightingTable.AnimMapCount;
            prop.CellsReached = (ushort)animCellMaps.Count;

            worldRep.LightingTable.AnimCellMaps.AddRange(animCellMaps);
            worldRep.LightingTable.AnimMapCount += animCellMaps.Count;
        }
    }
}