namespace AcDream.App.Rendering.Wb;

/// <summary>
/// Reports the physical outcome when a mesh-reference callback cannot provide
/// the normal strong exception guarantee. <see cref="MutationCommitted"/> lets
/// a transactional owner reconcile its marker without guessing whether a
/// throwing backend already changed the reference count.
/// </summary>
public sealed class MeshReferenceMutationException : Exception
{
    public MeshReferenceMutationException(
        string message,
        bool mutationCommitted,
        Exception innerException)
        : base(message, innerException)
    {
        MutationCommitted = mutationCommitted;
    }

    public bool MutationCommitted { get; }
}

/// <summary>
/// Mockable interface over <see cref="WbMeshAdapter"/> so adapters that
/// drive ref-count lifecycle (e.g. LandblockSpawnAdapter, EntitySpawnAdapter)
/// can be unit-tested without a real WB pipeline behind them.
/// </summary>
public interface IWbMeshAdapter
{
    /// <summary>
    /// Acquires one logical reference. A normal exception guarantees that no
    /// reference was acquired; <see cref="MeshReferenceMutationException"/>
    /// explicitly reports the exceptional backend case where it was committed.
    /// </summary>
    void IncrementRefCount(ulong id);

    /// <summary>
    /// Releases one logical reference under the same committed-outcome contract
    /// as <see cref="IncrementRefCount"/>.
    /// </summary>
    void DecrementRefCount(ulong id);

    /// <summary>
    /// Pins render data whose CPU preparation is owned by a specialized
    /// pipeline (for example synthetic EnvCell geometry). Unlike ordinary
    /// registration, production implementations must not start a generic
    /// GfxObj decode for this id.
    /// </summary>
    void PinPreparedRenderData(ulong id) => IncrementRefCount(id);

    /// <summary>
    /// True once the mesh has crossed the render-thread upload barrier and is
    /// available to draw. The default keeps lifecycle-only test doubles
    /// source-compatible; production adapters override it.
    /// </summary>
    bool IsRenderDataReady(ulong id) => true;
}