// ManuelResetEventSlim.cs
//
// Copyright (c) 2008 Jérémie "Garuma" Laval
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//
//

#if NET_4_0 || MOBILE

using System;

namespace System.Threading
{
	[System.Diagnostics.DebuggerDisplayAttribute ("Set = {IsSet}")]
	public class ManualResetEventSlim : IDisposable
	{
		const int isSet    = 1;
		const int isNotSet = 0;
		const int defaultSpinCount = 100;

		int state;
		readonly int spinCount;

		ManualResetEvent handle;
		internal AtomicBooleanValue disposed;
		bool used;

		readonly static Watch sw = Watch.StartNew ();

		public ManualResetEventSlim () : this (false, defaultSpinCount)
		{
		}

		public ManualResetEventSlim (bool initialState) : this (initialState, defaultSpinCount)
		{
		}

		public ManualResetEventSlim (bool initialState, int spinCount)
		{
			if (spinCount < 0)
				throw new ArgumentOutOfRangeException ("spinCount is less than 0", "spinCount");

			this.state = initialState ? isSet : isNotSet;
			this.spinCount = spinCount;
		}

		public bool IsSet {
			get {
				return state == isSet;
			}
		}

		public int SpinCount {
			get {
				return spinCount;
			}
		}

		public void Reset ()
		{
			state = isNotSet;
			if (handle != null) {
				used = true;
				Thread.MemoryBarrier ();
				var tmpHandle = handle;
				if (tmpHandle != null)
					tmpHandle.Reset ();
				Thread.MemoryBarrier ();
				used = false;
			}
		}

		public void Set ()
		{
			state = isSet;
			if (handle != null) {
				used = true;
				Thread.MemoryBarrier ();
				var tmpHandle = handle;
				if (tmpHandle != null)
					tmpHandle.Set ();
				Thread.MemoryBarrier ();
				used = false;
			}
		}

		public void Wait ()
		{
			Wait (CancellationToken.None);
		}

		public bool Wait (int millisecondsTimeout)
		{
			return Wait (millisecondsTimeout, CancellationToken.None);
		}

		public bool Wait (TimeSpan timeout)
		{
			return Wait (CheckTimeout (timeout), CancellationToken.None);
		}

		public void Wait (CancellationToken cancellationToken)
		{
			Wait (Timeout.Infinite, cancellationToken);
		}

		public bool Wait (int millisecondsTimeout, CancellationToken cancellationToken)
		{
			if (millisecondsTimeout < -1)
				throw new ArgumentOutOfRangeException ("millisecondsTimeout",
				                                       "millisecondsTimeout is a negative number other than -1");
			ThrowIfDisposed ();

			long start = millisecondsTimeout == -1 ? 0 : sw.ElapsedMilliseconds;
			SpinWait wait = new SpinWait ();

			while (state == isNotSet) {
				cancellationToken.ThrowIfCancellationRequested ();

				if (millisecondsTimeout > -1 && (sw.ElapsedMilliseconds - start) > millisecondsTimeout)
					return false;

				if (wait.Count < spinCount) {
					wait.SpinOnce ();
				} else {
					int waitTime = millisecondsTimeout == -1 ? -1 : Math.Max (millisecondsTimeout - (int)(sw.ElapsedMilliseconds - start) , 1);
					ThrowIfDisposed ();
					WaitHandle handle = WaitHandle;
					if (state == isSet)
						return true;
					ThrowIfDisposed ();

					if (cancellationToken.CanBeCanceled)
						if (WaitHandle.WaitAny (new[] { handle, cancellationToken.WaitHandle }, waitTime, false) == 0)
							return true;
					else
						if (handle.WaitOne (waitTime, false))
							return true;
				}
			}

			return true;
		}

		public bool Wait (TimeSpan timeout, CancellationToken cancellationToken)
		{
			return Wait (CheckTimeout (timeout), cancellationToken);
		}

		public WaitHandle WaitHandle {
			get {
				if (handle != null) {
					if (state == isSet)
						handle.Set ();

					return handle;
				}

				var result = LazyInitializer.EnsureInitialized (ref handle,
				                                                () => new ManualResetEvent (state == isSet ? true : false));
				if (state == isSet)
					result.Set ();

				return result;
			}
		}

		public void Dispose ()
		{
			Dispose (true);
		}

		protected virtual void Dispose (bool disposing)
		{
			if (!disposed.TryRelaxedSet ())
				return;
			if (handle != null) {
				var tmpHandle = Interlocked.Exchange (ref handle, null);
				if (used) {
					// A tiny wait (just a few cycles normally) before releasing
					SpinWait wait = new SpinWait ();
					while (used)
						wait.SpinOnce ();
				}
				tmpHandle.Dispose ();
			}
		}

		void ThrowIfDisposed ()
		{
			if (disposed.Value)
				throw new ObjectDisposedException ("ManualResetEventSlim");
		}

		static int CheckTimeout (TimeSpan timeout)
		{
			try {
				return checked ((int)timeout.TotalMilliseconds);
			} catch (System.OverflowException) {
				throw new ArgumentOutOfRangeException ("timeout");
			}
		}
	}
}
#endif