namespace AcDream.App.Rendering;

internal interface IRetryableResourceCleanup
{
    bool IsCleanupComplete { get; }
    void RetryCleanup();
}

internal sealed class GlResourceConstructionException : AggregateException,
    IRetryableResourceCleanup
{
    private readonly IRetryableResourceCleanup _cleanup;

    public GlResourceConstructionException(
        string message,
        IRetryableResourceCleanup cleanup,
        IEnumerable<Exception> failures)
        : base(message, failures)
    {
        _cleanup = cleanup ?? throw new ArgumentNullException(nameof(cleanup));
    }

    public bool IsCleanupComplete => _cleanup.IsCleanupComplete;

    public void RetryCleanup() => _cleanup.RetryCleanup();
}

/// <summary>
/// Lifetime root for cleanup work that could not finish before a throwing GL
/// factory returned control. The original exception remains the retry owner;
/// this ledger prevents it and its exact pending names from becoming local-only.
/// </summary>
internal sealed class GlConstructionCleanupLedger : IDisposable
{
    private readonly List<IRetryableResourceCleanup> _pending = [];
    private bool _disposing;

    public bool IsComplete => _pending.Count == 0;

    public bool RetainFrom(Exception failure)
    {
        ArgumentNullException.ThrowIfNull(failure);
        bool retained = false;
        Visit(failure);
        return retained;

        void Visit(Exception current)
        {
            if (current is IRetryableResourceCleanup cleanup)
            {
                if (!cleanup.IsCleanupComplete && !_pending.Contains(cleanup))
                    _pending.Add(cleanup);
                retained = true;
            }

            if (current is AggregateException aggregate)
            {
                foreach (Exception inner in aggregate.InnerExceptions)
                    Visit(inner);
            }
            else if (current.InnerException is { } inner)
            {
                Visit(inner);
            }
        }
    }

    public void Dispose()
    {
        if (_disposing || _pending.Count == 0)
            return;

        _disposing = true;
        List<Exception>? failures = null;
        try
        {
            for (int i = _pending.Count - 1; i >= 0; i--)
            {
                IRetryableResourceCleanup cleanup = _pending[i];
                try
                {
                    cleanup.RetryCleanup();
                    if (cleanup.IsCleanupComplete)
                        _pending.RemoveAt(i);
                }
                catch (Exception failure)
                {
                    (failures ??= []).Add(failure);
                }
            }
        }
        finally
        {
            _disposing = false;
        }

        if (failures is not null)
            throw new AggregateException(
                "One or more failed GL construction transactions remain pending.",
                failures);
    }
}