// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Threading;
 
namespace System.Net.Mime
{
    internal sealed class MultiAsyncResult : LazyAsyncResult
    {
        private readonly object _context;
        private int _outstanding;
 
        internal MultiAsyncResult(object context, AsyncCallback? callback, object? state) : base(context, state, callback)
        {
            _context = context;
        }
 
        internal object Context => _context;
 
        internal void Enter() => Increment();
 
        internal void Leave() => Decrement();
 
        internal void Leave(object result)
        {
            Result = result;
            Decrement();
        }
 
        private void Decrement()
        {
            if (Interlocked.Decrement(ref _outstanding) == -1)
            {
                InvokeCallback(Result);
            }
        }
 
        private void Increment() => Interlocked.Increment(ref _outstanding);
 
        internal void CompleteSequence() => Decrement();
 
        internal static object? End(IAsyncResult result)
        {
            MultiAsyncResult thisPtr = (MultiAsyncResult)result;
            thisPtr.InternalWaitForCompletion();
            return thisPtr.Result;
        }
    }
}