// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using Microsoft.Extensions.Logging;

#nullable enable

namespace Microsoft.AspNetCore.Connections
{
    internal static class ConnectionCompletion
    {
        public static Task FireOnCompletedAsync(ILogger logger, Stack<KeyValuePair<Func<object, Task>, object>>? onCompleted)
        {
            if (onCompleted == null || onCompleted.Count == 0)
            {
                return Task.CompletedTask;
            }

            return CompleteAsyncMayAwait(logger, onCompleted);
        }

        private static Task CompleteAsyncMayAwait(ILogger logger, Stack<KeyValuePair<Func<object, Task>, object>> onCompleted)
        {
            while (onCompleted.TryPop(out var entry))
            {
                try
                {
                    var task = entry.Key.Invoke(entry.Value);
                    if (!task.IsCompletedSuccessfully)
                    {
                        return CompleteAsyncAwaited(task, logger, onCompleted);
                    }
                }
                catch (Exception ex)
                {
                    logger.LogError(ex, "An error occurred running an IConnectionCompleteFeature.OnCompleted callback.");
                }
            }

            return Task.CompletedTask;
        }

        private static async Task CompleteAsyncAwaited(Task currentTask, ILogger logger, Stack<KeyValuePair<Func<object, Task>, object>> onCompleted)
        {
            try
            {
                await currentTask;
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "An error occurred running an IConnectionCompleteFeature.OnCompleted callback.");
            }

            while (onCompleted.TryPop(out var entry))
            {
                try
                {
                    await entry.Key.Invoke(entry.Value);
                }
                catch (Exception ex)
                {
                    logger.LogError(ex, "An error occurred running an IConnectionCompleteFeature.OnCompleted callback.");
                }
            }
        }
    }
}
