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

namespace AcDream.App.Tests.Rendering.Wb;

public class InstanceGroupClearTests
{
    // #193 (regression from #188, 2026-07-09): WbDrawDispatcher's InstanceGroup holds
    // five per-instance parallel lists — Matrices, Slots, LightSets, IndoorFlags,
    // Opacities — appended in lockstep (one entry per drawn instance) every frame. The
    // per-frame reset must clear ALL of them. #188 added Opacities but left it out of
    // the inline clear loop, so it grew one float per instance per frame forever; as
    // List<float>'s backing array doubled it produced ~128 MB / ~512 MB LOH float[]
    // arrays and leaked ~1 GB/min -> OOM after ~50 min of play. This test pins that
    // every parallel list is reset, so a newly-added list can't silently drift again.
    [Fact]
    public void ClearPerInstanceData_ClearsEveryParallelPerInstanceList()
    {
        var grp = new WbDrawDispatcher.InstanceGroup();
        grp.Matrices.Add(Matrix4x4.Identity);
        grp.Slots.Add(1u);
        grp.LightSets.Add(-1);
        grp.IndoorFlags.Add(0u);
        grp.Opacities.Add(1.0f);

        grp.ClearPerInstanceData();

        Assert.Empty(grp.Matrices);
        Assert.Empty(grp.Slots);
        Assert.Empty(grp.LightSets);
        Assert.Empty(grp.IndoorFlags);
        Assert.Empty(grp.Opacities); // #193 — the list that leaked
    }
}