// Copyright (c) Microsoft Corporation. All rights reserved. See License.txt in the project root for license information.

using System.Threading;

namespace System.Web.Mvc.Async
{
    internal sealed class SimpleAsyncResult : IAsyncResult
    {
        private readonly object _asyncState;
        private bool _completedSynchronously;
        private volatile bool _isCompleted;

        public SimpleAsyncResult(object asyncState)
        {
            _asyncState = asyncState;
        }

        public object AsyncState
        {
            get { return _asyncState; }
        }

        // ASP.NET IAsyncResult objects should never expose a WaitHandle due to potential deadlocking
        public WaitHandle AsyncWaitHandle
        {
            get { return null; }
        }

        public bool CompletedSynchronously
        {
            get { return _completedSynchronously; }
        }

        public bool IsCompleted
        {
            get { return _isCompleted; }
        }

        // Proper order of execution:
        // 1. Set the CompletedSynchronously property to the correct value
        // 2. Set the IsCompleted flag
        // 3. Execute the callback
        // 4. Signal the WaitHandle (which we don't have)
        public void MarkCompleted(bool completedSynchronously, AsyncCallback callback)
        {
            _completedSynchronously = completedSynchronously;
            _isCompleted = true;

            if (callback != null)
            {
                callback(this);
            }
        }
    }
}
