using AcDream.Core.Items;

namespace AcDream.App.World;

/// <summary>
/// Owns the network side effect of replacing retail's current ground object.
/// Presentation controllers observe the same state but do not own session
/// lifecycle messages.
/// </summary>
public sealed class ExternalContainerLifecycleController : IDisposable
{
    private readonly ExternalContainerState _state;
    private readonly ClientObjectTable _objects;
    private readonly Action<uint> _sendNoLongerViewingContents;
    private bool _disposed;

    public ExternalContainerLifecycleController(
        ExternalContainerState state,
        ClientObjectTable objects,
        Action<uint> sendNoLongerViewingContents)
    {
        _state = state ?? throw new ArgumentNullException(nameof(state));
        _objects = objects ?? throw new ArgumentNullException(nameof(objects));
        _sendNoLongerViewingContents = sendNoLongerViewingContents
            ?? throw new ArgumentNullException(nameof(sendNoLongerViewingContents));
        _state.Changed += OnChanged;
    }

    private void OnChanged(ExternalContainerTransition transition)
    {
        // ClientUISystem::SetGroundObject @ 0x00564510 always queues the old
        // root's contents tree for destruction when the ground object changes.
        if (transition.PreviousContainerId != 0u)
            _objects.StopViewingContentsTree(transition.PreviousContainerId);

        // SetGroundObject(new, notifyServer:true) emits this while the new
        // request is still pending, not after ViewContents arrives. The
        // authored close/range path instead sends Use(root) and waits for
        // event 0x0052.
        if (transition.Kind == ExternalContainerTransitionKind.ReplacementRequested
            && transition.PreviousContainerId != 0u)
        {
            _sendNoLongerViewingContents(transition.PreviousContainerId);
        }
    }

    public void Dispose()
    {
        if (_disposed) return;
        _disposed = true;
        _state.Changed -= OnChanged;
    }
}