MQTTnet/Source/MQTTnet/Internal/AsyncEventInvocator.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System;
using System.Threading.Tasks;
using MQTTnet.Implementations;

namespace MQTTnet.Internal
{
    public readonly struct AsyncEventInvocator<TEventArgs>
    {
        readonly Action<TEventArgs> _handler;
        readonly Func<TEventArgs, Task> _asyncHandler;
        
        public AsyncEventInvocator(Action<TEventArgs> handler, Func<TEventArgs, Task> asyncHandler)
        {
            _handler = handler;
            _asyncHandler = asyncHandler;
        }

        public bool WrapsHandler(Action<TEventArgs> handler)
        {
            // Do not use ReferenceEquals! It will not work with delegates.
            return handler == _handler;
        }
        
        public bool WrapsHandler(Func<TEventArgs, Task> handler)
        {
            // Do not use ReferenceEquals! It will not work with delegates.
            return handler == _asyncHandler;
        }
        
        public Task InvokeAsync(TEventArgs eventArgs)
        {
            if (_handler != null)
            {
                _handler.Invoke(eventArgs);
                return CompletedTask.Instance;
            }

            if (_asyncHandler != null)
            {
                return _asyncHandler.Invoke(eventArgs);
            }

            throw new InvalidOperationException();
        }
    }
}