#region
/* -----------------------------------------------------------------------
 * <copyright file="JobQueue.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
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * The views and conclusions contained in the software and
 * documentation are those of the authors and should not be
 * interpreted as representing official policies, either expressed
 * or implied, of GRNET S.A.
 * </copyright>
 * -----------------------------------------------------------------------
 */
#endregion
using System.Collections.Concurrent;
using System.Threading;
using System.Threading.Tasks;

namespace Pithos.Core
{
    using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;

    /// <summary>
    /// TODO: Update summary.
    /// </summary>
    public class JobQueue
    {
        private readonly BlockingCollection<Action> _statusUpdateQueue = new BlockingCollection<Action>();
        private CancellationToken _cancellationToken;
        

        public void Start(CancellationToken token)
        {
            _cancellationToken = token;
            Task.Factory.StartNew(ProcessUpdates, _cancellationToken);
        }

        private void ProcessUpdates()
        {
            foreach (var action in _statusUpdateQueue.GetConsumingEnumerable())
            {
                action();
            }
        }

        public void Add(Action action)
        {
            _statusUpdateQueue.Add(action);
        }

        public void Stop()
        {
            _statusUpdateQueue.CompleteAdding();
        }
       
    }   

    public class JobAgent:Agent<Action>
    {
        protected JobAgent(Action<Agent<Action>>  action)
            :base(action)
        {
            
        }

        public static JobAgent Create()
        {
            return (JobAgent)Start(queue =>
            {
                Action loop = null;
                loop = () =>
                {
                    var job = queue.Receive();
                    job.ContinueWith(t =>
                    {
                        t.IgnoreExceptions();
                        var action = job.Result;
                        action();
                        queue.DoAsync(loop);
                    });
                };
                loop();
            });
        }

    }
}