using System.Collections.Generic;
using System.Numerics;
using AcDream.App.Rendering.Wb;
using DatReaderWriter.DBObjs;
using DatReaderWriter.Types;
using Xunit;

namespace AcDream.App.Tests.Rendering.Wb;

public class BuildingLoaderTests
{
    // Helper: build a minimal LandBlockInfo with one BuildingInfo per supplied tuple.
    // OtherCellId values are 16-bit cell-local ids (low word of full cell id).
    private static LandBlockInfo MakeInfo(params (uint modelId, uint[] portalOtherCellIds)[] buildings)
    {
        var bls = new List<BuildingInfo>();
        foreach (var (modelId, portals) in buildings)
        {
            var portalList = new List<BuildingPortal>();
            foreach (var ocid in portals)
            {
                portalList.Add(new BuildingPortal
                {
                    OtherCellId  = (ushort)(ocid & 0xFFFFu),
                    Flags        = 0,
                    OtherPortalId = 0,
                    StabList     = new List<ushort>(),
                });
            }
            bls.Add(new BuildingInfo
            {
                ModelId  = modelId,
                Frame    = new Frame { Origin = Vector3.Zero, Orientation = Quaternion.Identity },
                Portals  = portalList,
            });
        }
        return new LandBlockInfo
        {
            Objects   = new List<Stab>(),
            Buildings = bls,
        };
    }

    [Fact]
    public void Empty_NoBuildings_EmptyRegistry()
    {
        var info = new LandBlockInfo { Objects = new List<Stab>(), Buildings = new List<BuildingInfo>() };
        var reg = BuildingLoader.Build(info, landblockId: 0xA9B40000u, cellsByCellId: new Dictionary<uint, AcDream.App.Rendering.LoadedCell>());
        Assert.Equal(0, reg.Count);
    }

    [Fact]
    public void OneBuilding_OnePortal_MapsToOneCell()
    {
        // Building points to cell 0x0150 in landblock 0xA9B40000 → full cell id 0xA9B40150
        var info = MakeInfo((modelId: 0x02000123u, portalOtherCellIds: new[] { 0x0150u }));
        // Pass an empty cell dict — loader seeds from BuildingInfo.Portals only
        var reg = BuildingLoader.Build(info, landblockId: 0xA9B40000u, cellsByCellId: new Dictionary<uint, AcDream.App.Rendering.LoadedCell>());
        Assert.Equal(1, reg.Count);
        var building = System.Linq.Enumerable.First(reg.All());
        Assert.Contains(0xA9B40150u, building.EnvCellIds);
    }

    [Fact]
    public void OneBuilding_MultiplePortals_MapsToMultipleCells()
    {
        var info = MakeInfo((0x02000123u, new[] { 0x0150u, 0x0151u, 0x0152u }));
        var reg = BuildingLoader.Build(info, 0xA9B40000u, new Dictionary<uint, AcDream.App.Rendering.LoadedCell>());
        var building = System.Linq.Enumerable.First(reg.All());
        Assert.Equal(3, building.EnvCellIds.Count);
        Assert.Contains(0xA9B40150u, building.EnvCellIds);
        Assert.Contains(0xA9B40151u, building.EnvCellIds);
        Assert.Contains(0xA9B40152u, building.EnvCellIds);
    }

    [Fact]
    public void TwoBuildings_AllocateSequentialIds()
    {
        var info = MakeInfo(
            (0x02000001u, new[] { 0x0150u }),
            (0x02000002u, new[] { 0x0160u }));
        var reg = BuildingLoader.Build(info, 0xA9B40000u, new Dictionary<uint, AcDream.App.Rendering.LoadedCell>());
        Assert.Equal(2, reg.Count);
        var ids = new SortedSet<uint>();
        foreach (var b in reg.All()) ids.Add(b.BuildingId);
        Assert.Equal(new SortedSet<uint> { 1, 2 }, ids);  // sequential 1, 2
    }

    [Fact]
    public void Build_StampsLoadedCellBuildingId()
    {
        // Fixture: minimal LoadedCell instances representing 2 cottage cells.
        var cell150 = new AcDream.App.Rendering.LoadedCell
        {
            CellId = 0xA9B40150u,
            Portals = new List<AcDream.App.Rendering.CellPortalInfo>(),
            PortalPolygons = new List<Vector3[]>(),
            WorldTransform = Matrix4x4.Identity,
            InverseWorldTransform = Matrix4x4.Identity,
            LocalBoundsMin = new Vector3(-5, -5, -5),
            LocalBoundsMax = new Vector3(5, 5, 5),
            ClipPlanes = new List<AcDream.App.Rendering.PortalClipPlane>(),
        };
        var cell151 = new AcDream.App.Rendering.LoadedCell
        {
            CellId = 0xA9B40151u,
            Portals = new List<AcDream.App.Rendering.CellPortalInfo>(),
            PortalPolygons = new List<Vector3[]>(),
            WorldTransform = Matrix4x4.Identity,
            InverseWorldTransform = Matrix4x4.Identity,
            LocalBoundsMin = new Vector3(-5, -5, -5),
            LocalBoundsMax = new Vector3(5, 5, 5),
            ClipPlanes = new List<AcDream.App.Rendering.PortalClipPlane>(),
        };
        var cells = new Dictionary<uint, AcDream.App.Rendering.LoadedCell>
        {
            { 0xA9B40150u, cell150 },
            { 0xA9B40151u, cell151 },
        };

        var info = MakeInfo((0x02000123u, new[] { 0x0150u, 0x0151u }));
        var reg = BuildingLoader.Build(info, 0xA9B40000u, cells);

        Assert.Equal(1, reg.Count);
        var b = System.Linq.Enumerable.First(reg.All());
        // Both cells stamped with the building id:
        Assert.Equal(b.BuildingId, cell150.BuildingId);
        Assert.Equal(b.BuildingId, cell151.BuildingId);
    }
}