using MrGameEng.Graphics;
using Xunit;

namespace MrGameEng.Graphics.Tests;

public class SortKeyTests
{
    [Fact]
    public void LayerDominatesDepthAndTexture()
    {
        var lowLayer = SpriteSortKey.Make(0, 1000f, textureKey: 5);
        var highLayer = SpriteSortKey.Make(1, -1000f, textureKey: 1);

        Assert.True(lowLayer < highLayer);
    }

    [Fact]
    public void DepthDominatesTexture_WithinLayer()
    {
        var behind = SpriteSortKey.Make(3, -5f, textureKey: 999);
        var inFront = SpriteSortKey.Make(3, 5f, textureKey: 1);

        Assert.True(behind < inFront);
    }

    [Theory]
    [InlineData(-100f, -1f)]
    [InlineData(-1f, 0f)]
    [InlineData(0f, 1f)]
    [InlineData(1f, 100f)]
    [InlineData(-0.5f, 0.5f)]
    public void DepthBits_PreserveFloatOrder(float smaller, float larger)
    {
        Assert.True(
            SpriteSortKey.DepthToSortableBits(smaller) < SpriteSortKey.DepthToSortableBits(larger)
        );
    }

    [Fact]
    public void EqualLayerAndDepth_GroupByTexture()
    {
        var a1 = SpriteSortKey.Make(2, 1f, textureKey: 7);
        var b = SpriteSortKey.Make(2, 1f, textureKey: 9);
        var a2 = SpriteSortKey.Make(2, 1f, textureKey: 7);

        Assert.Equal(a1, a2);
        Assert.NotEqual(a1, b);
    }
}