using OpenTK.Mathematics;
using VoxelEngine.Rendering;
using Xunit;

namespace VoxelEngine.Tests;

public class FrustumTests
{
    // Camera at the origin, default yaw -90° → looks down -Z.
    private static Frustum MakeFrustum()
    {
        var cam = new Camera(new Vector3(0, 0, 0), 16f / 9f);
        return Frustum.FromViewProjection(cam.GetViewMatrix() * cam.GetProjectionMatrix());
    }

    [Fact]
    public void AABBInFront_IsVisible()
    {
        var f = MakeFrustum();
        Assert.True(f.Intersects(new Vector3(-2, -2, -22), new Vector3(2, 2, -18)));
    }

    [Fact]
    public void AABBBehindCamera_IsCulled()
    {
        var f = MakeFrustum();
        Assert.False(f.Intersects(new Vector3(-2, -2, 18), new Vector3(2, 2, 22)));
    }

    [Fact]
    public void AABBStraddlingCamera_Intersects()
    {
        var f = MakeFrustum();
        Assert.True(f.Intersects(new Vector3(-2, -2, -5), new Vector3(2, 2, 5)));
    }

    [Fact]
    public void AABBFarToTheSide_IsCulled()
    {
        var f = MakeFrustum();
        // Far along +X at a depth in front of the camera — outside horizontal FOV.
        Assert.False(f.Intersects(new Vector3(1000, -2, -5), new Vector3(1004, 2, -1)));
    }
}