using System.Collections.Generic;
using System.Numerics;
using AcDream.Core.Physics;
using Xunit;

namespace AcDream.Core.Tests.Physics;

public class CellTransitFindTransitCellsSphereTests
{
    private static CellPhysics MakeCellWithPortalAtRightWall(
        Matrix4x4 worldTransform, uint otherCellId, ushort flags)
    {
        // Portal poly at local x=2.5 (right wall), normal +X.
        var portalPolyA = new ResolvedPolygon
        {
            Vertices  = new[]
            {
                new Vector3(2.5f, -2.5f,  0f),
                new Vector3(2.5f,  2.5f,  0f),
                new Vector3(2.5f,  2.5f,  5f),
                new Vector3(2.5f, -2.5f,  5f),
            },
            Plane     = new Plane(new Vector3(1, 0, 0), -2.5f),  // x = 2.5
            NumPoints = 4,
            SidesType = DatReaderWriter.Enums.CullMode.None,
        };

        Matrix4x4.Invert(worldTransform, out var inv);
        return new CellPhysics
        {
            WorldTransform = worldTransform,
            InverseWorldTransform = inv,
            Resolved = new Dictionary<ushort, ResolvedPolygon>(),
            PortalPolygons = new Dictionary<ushort, ResolvedPolygon> { [10] = portalPolyA },
            Portals = new[]
            {
                new PortalInfo(otherCellId: (ushort)otherCellId, polygonId: 10, flags: flags),
            },
        };
    }

    [Fact]
    public void SphereInsideCellA_NearPortal_AddsCellB()
    {
        var cellA = MakeCellWithPortalAtRightWall(Matrix4x4.Identity, otherCellId: 0x0101, flags: 0);

        var cellBT = Matrix4x4.CreateTranslation(new Vector3(5f, 0f, 0f));
        Matrix4x4.Invert(cellBT, out var cellBInv);
        var cellB = new CellPhysics
        {
            WorldTransform = cellBT,
            InverseWorldTransform = cellBInv,
            Resolved = new Dictionary<ushort, ResolvedPolygon>(),
        };

        var cache = new PhysicsDataCache();
        cache.RegisterCellStructForTest(0xA9B40100u, cellA);
        cache.RegisterCellStructForTest(0xA9B40101u, cellB);

        // Sphere center near portal (local x=2.0, radius=0.5 → reaches x=2.5 = portal plane).
        var worldSphereCenter = new Vector3(2.0f, 0f, 2.5f);

        var candidates = new HashSet<uint>();
        CellTransit.FindTransitCellsSphere(
            cache, cellA, currentCellId: 0xA9B40100u,
            worldSphereCenter, sphereRadius: 0.5f, candidates, out bool exitOutside);

        Assert.Contains(0xA9B40101u, candidates);
        Assert.False(exitOutside);
    }

    [Fact]
    public void SphereInsideCellA_FarFromPortal_DoesNotAddCellB()
    {
        var cellA = MakeCellWithPortalAtRightWall(Matrix4x4.Identity, otherCellId: 0x0101, flags: 0);

        var cache = new PhysicsDataCache();
        cache.RegisterCellStructForTest(0xA9B40100u, cellA);

        // Sphere far from portal (local x=-1.0, reach to x=-0.5 — nowhere near portal at x=2.5).
        var worldSphereCenter = new Vector3(-1.0f, 0f, 2.5f);

        var candidates = new HashSet<uint>();
        CellTransit.FindTransitCellsSphere(
            cache, cellA, currentCellId: 0xA9B40100u,
            worldSphereCenter, sphereRadius: 0.5f, candidates, out bool exitOutside);

        Assert.DoesNotContain(0xA9B40101u, candidates);
    }

    [Fact]
    public void ExitPortal_SphereStraddlesPortalPlane_FlagsCheckOutside()
    {
        var exitCell = MakeCellWithPortalAtRightWall(Matrix4x4.Identity, otherCellId: 0xFFFF, flags: 0);

        var cache = new PhysicsDataCache();
        cache.RegisterCellStructForTest(0xA9B40100u, exitCell);

        var worldSphereCenter = new Vector3(2.0f, 0f, 2.5f);
        var candidates = new HashSet<uint>();

        CellTransit.FindTransitCellsSphere(
            cache, exitCell, currentCellId: 0xA9B40100u,
            worldSphereCenter, sphereRadius: 0.5f, candidates, out bool exitOutside);

        Assert.True(exitOutside);
    }
}