#if !NET_4_6
using System;

namespace LinqInternal.Threading
{
    public sealed partial class Disposable : IDisposable
    {
        private int _status;

        [System.Diagnostics.DebuggerNonUserCode]
        ~Disposable()
        {
            try
            {
                // Empty
            }
            finally
            {
                try
                {
                    Dispose(false);
                }
                catch (Exception exception)
                {
                    // Catch'em all - fields may be partially collected.
                    GC.KeepAlive(exception);
                }
            }
        }

        public bool IsDisposed
        {
            [System.Diagnostics.DebuggerNonUserCode]
            get { return _status == -1; }
        }

        [System.Diagnostics.DebuggerNonUserCode]
        public void Dispose()
        {
            try
            {
                Dispose(true);
            }
            finally
            {
                GC.SuppressFinalize(this);
            }
        }

        [System.Diagnostics.DebuggerNonUserCode]
        public void DisposedConditional(Action whenDisposed, Action whenNotDisposed)
        {
            if (_status == -1)
            {
                if (!ReferenceEquals(whenDisposed, null))
                {
                    whenDisposed.Invoke();
                }
            }
            else
            {
                if (!ReferenceEquals(whenNotDisposed, null))
                {
                    if (ThreadingHelper.SpinWaitRelativeSet(ref _status, 1, -1))
                    {
                        try
                        {
                            whenNotDisposed.Invoke();
                        }
                        finally
                        {
                            System.Threading.Interlocked.Decrement(ref _status);
                        }
                    }
                    else
                    {
                        if (!ReferenceEquals(whenDisposed, null))
                        {
                            whenDisposed.Invoke();
                        }
                    }
                }
            }
        }

        [System.Diagnostics.DebuggerNonUserCode]
        public TReturn DisposedConditional<TReturn>(Func<TReturn> whenDisposed, Func<TReturn> whenNotDisposed)
        {
            if (_status == -1)
            {
                if (ReferenceEquals(whenDisposed, null))
                {
                    return default(TReturn);
                }
                else
                {
                    return whenDisposed.Invoke();
                }
            }
            else
            {
                if (ReferenceEquals(whenNotDisposed, null))
                {
                    return default(TReturn);
                }
                else
                {
                    if (ThreadingHelper.SpinWaitRelativeSet(ref _status, 1, -1))
                    {
                        try
                        {
                            return whenNotDisposed.Invoke();
                        }
                        finally
                        {
                            System.Threading.Interlocked.Decrement(ref _status);
                        }
                    }
                    else
                    {
                        if (ReferenceEquals(whenDisposed, null))
                        {
                            return default(TReturn);
                        }
                        else
                        {
                            return whenDisposed.Invoke();
                        }
                    }
                }
            }
        }

        [System.Diagnostics.DebuggerNonUserCode]
        private void Dispose(bool disposeManagedResources)
        {
            GC.KeepAlive(disposeManagedResources);
            if (TakeDisposalExecution())
            {
                try
                {
                    _release.Invoke();
                }
                finally
                {
                    _release = null;
                }
            }
        }

        private bool TakeDisposalExecution()
        {
            return _status != -1 && ThreadingHelper.SpinWaitSetUnless(ref _status, -1, 0, -1);
        }
    }
}
#endif