#region
/* -----------------------------------------------------------------------
 * <copyright file="IdleBatch.cs" company="GRNet">
 * 
 * Copyright 2011-2012 GRNET S.A. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 *   1. Redistributions of source code must retain the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer in the documentation and/or other materials
 *      provided with the distribution.
 *
 *
 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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 * POSSIBILITY OF SUCH DAMAGE.
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 * The views and conclusions contained in the software and
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 * or implied, of GRNET S.A.
 * </copyright>
 * -----------------------------------------------------------------------
 */
#endregion

using System.Reflection;
using System.Threading;
using System.Threading.Tasks.Dataflow;
using System;
using log4net;

namespace Pithos.Core.Agents
{

    /// <summary>
    /// Calls a callback function if an idle timeout expires after the last post
    /// </summary>
    public class IdleBatch<T>
    {
        private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        readonly Timer _triggerTimer;

        private readonly BatchBlock<T> _batchBlock;
        private readonly TransformBlock<T, T> _timerBlock;
        private readonly ActionBlock<T[]> _processBlock;

        private readonly int _timeOut;

        public IdleBatch(int idleTimeout, Action<T[]> action)
        {
            _timeOut = idleTimeout;
            _timerBlock = new TransformBlock<T, T>(t =>
            {
                _triggerTimer.Change(_timeOut, Timeout.Infinite);
                return t;
            });
            _batchBlock = new BatchBlock<T>(9999);
            _processBlock = new ActionBlock<T[]>(action);

            _timerBlock.LinkTo(_batchBlock);
            _batchBlock.LinkTo(_processBlock);

            _timerBlock.Completion.ContinueWith(_ => _batchBlock.Complete());
            _batchBlock.Completion.ContinueWith(_ => _processBlock.Complete());

            _triggerTimer = new Timer(_ => _batchBlock.TriggerBatch());
        }

        public void Post(T input)
        {
            _timerBlock.Post(input);
        }

        public void ForceTrigger()
        {
            _batchBlock.TriggerBatch();
            _timerBlock.Complete();
            _processBlock.Completion.Wait();
        }
    }

}