using Microsoft.Xna.Framework;
using MrGameEng.Graphics;
using Xunit;

namespace MrGameEng.Graphics.Tests;

public class CullingTests
{
    [Fact]
    public void BoundingCircle_UnrotatedTopLeftOrigin_CenterIsRegionCenter()
    {
        var transform = Transform2D.At(new Vector2(100f, 200f));

        var (center, radius) = CullingMath.SpriteBoundingCircle(transform, 32f, 32f, Vector2.Zero);

        Assert.Equal(new Vector2(116f, 216f), center);
        Assert.Equal(0.5f * MathF.Sqrt(32f * 32f * 2f), radius, 3);
    }

    [Fact]
    public void BoundingCircle_CenterOrigin_CenterIsPosition()
    {
        var transform = Transform2D.At(new Vector2(50f, 50f));

        var (center, _) = CullingMath.SpriteBoundingCircle(transform, 64f, 32f, new Vector2(32f, 16f));

        Assert.Equal(new Vector2(50f, 50f), center);
    }

    [Fact]
    public void BoundingCircle_Scale_GrowsRadius()
    {
        var transform = new Transform2D(Vector2.Zero, scale: new Vector2(2f, 2f));

        var (_, radius) = CullingMath.SpriteBoundingCircle(transform, 10f, 10f, Vector2.Zero);

        Assert.Equal(0.5f * MathF.Sqrt(800f), radius, 3);
    }

    [Theory]
    [InlineData(50f, 50f, true)]    // inside
    [InlineData(-4f, 50f, true)]    // touching from the left (radius 5)
    [InlineData(-20f, 50f, false)]  // far left
    [InlineData(50f, 130f, false)]  // far below
    public void CircleIntersectsRect_DetectsOverlap(float x, float y, bool expected)
    {
        var rect = new RectF(0f, 0f, 100f, 100f);

        Assert.Equal(expected, CullingMath.CircleIntersectsRect(new Vector2(x, y), 5f, rect));
    }
}