using System.Numerics;
using AcDream.App.Rendering;
using Xunit;

namespace AcDream.App.Tests.Rendering;

public sealed class ViewconeCullerReuseTests
{
    [Fact]
    public void ReusedCuller_ReplacesPriorCellAndOutsideState()
    {
        const uint firstCell = 0xA9B40100;
        const uint secondCell = 0xA9B40101;
        var clipFrame = ClipFrame.NoClip();
        var assemblyScratch = new ClipFrameAssembly();
        var culler = new ViewconeCuller();

        var first = Frame(firstCell, includeOutside: true);
        ClipFrameAssembly firstAssembly = ClipFrameAssembler.Assemble(
            clipFrame,
            first,
            assemblyScratch);
        Assert.Same(culler, ViewconeCuller.Build(firstAssembly, Matrix4x4.Identity, culler));
        Assert.True(culler.SphereVisibleInCell(firstCell, Vector3.Zero, 0f));
        Assert.True(culler.SphereVisibleOutside(Vector3.Zero, 0f));

        var second = Frame(secondCell, includeOutside: false);
        ClipFrameAssembly secondAssembly = ClipFrameAssembler.Assemble(
            clipFrame,
            second,
            assemblyScratch);
        Assert.Same(culler, ViewconeCuller.Build(secondAssembly, Matrix4x4.Identity, culler));

        Assert.False(culler.SphereVisibleInCell(firstCell, Vector3.Zero, 0f));
        Assert.True(culler.SphereVisibleInCell(secondCell, Vector3.Zero, 0f));
        Assert.False(culler.SphereVisibleInCell(secondCell, new Vector3(2f, 0f, 0f), 0f));
        Assert.False(culler.SphereVisibleOutside(Vector3.Zero, 0f));
    }

    private static PortalVisibilityFrame Frame(uint cellId, bool includeOutside)
    {
        var result = new PortalVisibilityFrame();
        var cellView = new CellView();
        cellView.Add(Square(0.5f));
        result.CellViews.Add(cellId, cellView);
        result.OrderedVisibleCells.Add(cellId);
        if (includeOutside)
            result.OutsideView.Add(Square(0.5f));
        return result;
    }

    private static ViewPolygon Square(float half)
        => new(new[]
        {
            new Vector2(-half, -half),
            new Vector2(half, -half),
            new Vector2(half, half),
            new Vector2(-half, half),
        });
}