using OpenTK.Mathematics;
using VoxelEngine.World.Persistence;
using Xunit;

namespace VoxelEngine.Tests.Persistence;

public class InMemoryChunkModificationStoreTests
{
    [Fact]
    public void NewStore_HasNoDiffs()
    {
        var s = new InMemoryChunkModificationStore();
        Assert.False(s.HasDiff(new Vector3i(0, 0, 0)));
        Assert.False(s.TryGetDiff(new Vector3i(0, 0, 0), out _));
    }

    [Fact]
    public void RecordEdit_StoresAndIsRetrievable()
    {
        var s = new InMemoryChunkModificationStore();
        Vector3i pos = new(1, 2, 3);
        s.RecordEdit(pos, 42, 7);

        Assert.True(s.HasDiff(pos));
        Assert.True(s.TryGetDiff(pos, out var diff));
        Assert.Single(diff!);
        Assert.Equal((ushort)7, diff![42]);
    }

    [Fact]
    public void RecordEdit_OverwritesSameLocalIndex()
    {
        var s = new InMemoryChunkModificationStore();
        Vector3i pos = new(0, 0, 0);
        s.RecordEdit(pos, 10, 1);
        s.RecordEdit(pos, 10, 2);

        Assert.True(s.TryGetDiff(pos, out var diff));
        Assert.Single(diff!);
        Assert.Equal((ushort)2, diff![10]);
    }

    [Fact]
    public void RecordEdit_MultipleChunks_AreIndependent()
    {
        var s = new InMemoryChunkModificationStore();
        s.RecordEdit(new Vector3i(0, 0, 0), 0, 1);
        s.RecordEdit(new Vector3i(1, 0, 0), 0, 2);

        Assert.True(s.TryGetDiff(new Vector3i(0, 0, 0), out var a));
        Assert.True(s.TryGetDiff(new Vector3i(1, 0, 0), out var b));
        Assert.Equal((ushort)1, a![0]);
        Assert.Equal((ushort)2, b![0]);
    }

    [Fact]
    public void ClearDiff_RemovesChunk()
    {
        var s = new InMemoryChunkModificationStore();
        Vector3i pos = new(5, 5, 5);
        s.RecordEdit(pos, 0, 1);
        s.ClearDiff(pos);
        Assert.False(s.HasDiff(pos));
    }
}