using System.Linq;
using AcDream.App.Streaming;
using AcDream.Core.World;
using DatReaderWriter.DBObjs;
using Xunit;

namespace AcDream.Core.Tests.Streaming;

public class GpuWorldStateTwoTierTests
{
    private static LoadedLandblock MakeStubLandblock(uint canonicalId, params WorldEntity[] entities)
        => new(canonicalId, new LandBlock(), entities);

    private static WorldEntity MakeStubEntity(uint id)
        => new()
        {
            Id = id,
            SourceGfxObjOrSetupId = 0x01000001u,
            Position = System.Numerics.Vector3.Zero,
            Rotation = System.Numerics.Quaternion.Identity,
            MeshRefs = System.Array.Empty<MeshRef>(),
        };

    [Fact]
    public void RemoveEntitiesFromLandblock_KeepsLandblockButDropsEntities()
    {
        var state = new GpuWorldState();
        var lb = MakeStubLandblock(0xAAAAFFFFu,
            MakeStubEntity(1),
            MakeStubEntity(2));
        state.AddLandblock(lb);
        Assert.Equal(2, state.Entities.Count);

        state.RemoveEntitiesFromLandblock(0xAAAAFFFFu);

        Assert.Empty(state.Entities);
        Assert.True(state.IsLoaded(0xAAAAFFFFu));   // landblock still resident
    }

    [Fact]
    public void AddEntitiesToExistingLandblock_MergesIntoExistingRecord()
    {
        var state = new GpuWorldState();
        var lb = MakeStubLandblock(0xAAAAFFFFu, MakeStubEntity(1));
        state.AddLandblock(lb);

        state.AddEntitiesToExistingLandblock(0xAAAAFFFFu, new[]
        {
            MakeStubEntity(2),
            MakeStubEntity(3),
        });

        Assert.Equal(3, state.Entities.Count);
    }

    [Fact]
    public void AddEntitiesToExistingLandblock_LandblockNotYetLoaded_ParksInPending()
    {
        var state = new GpuWorldState();

        // Landblock not loaded yet.
        state.AddEntitiesToExistingLandblock(0xAAAAFFFFu, new[]
        {
            MakeStubEntity(1),
            MakeStubEntity(2),
        });

        // Nothing in the flat view yet.
        Assert.Empty(state.Entities);
        Assert.Equal(2, state.PendingLiveEntityCount);

        // Now load the landblock — pending entities should merge in.
        state.AddLandblock(MakeStubLandblock(0xAAAAFFFFu));
        Assert.Equal(2, state.Entities.Count);
    }
}