/*********************************************************************/
/*                                                                   */
/*                     AgentService Framework                        */
/*                       www.agentservice.it                         */
/*                                                                   */
/* Copyright (C) 2007 l.i.d.o. - DIST, University of Genoa, Italy    */
/* GNU Lesser General Public License                                 */
/*                                                                   */
/* This library is free software; you can redistribute it and/or     */
/* modify it under the terms of the GNU Lesser General Public        */
/* License as published by the Free Software Foundation,             */
/* version 2.1 of the License.                                       */
/*                                                                   */
/* This library is distributed in the hope that it will be useful,   */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of    */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU */
/* Lesser General Public License for more details.                   */
/*                                                                   */
/* You should have received a copy of the GNU Lesser General Public  */
/* License along with this library; if not, write to the             */
/* Free Software Foundation, Inc., 59 Temple Place - Suite 330,      */
/* Boston, MA  02111-1307, USA.                                      */
/*                                                                   */
/*********************************************************************/
using System;

using AgentService.Agent.Knowledge;
using AgentService.Agent.Behaviour;
using AgentService.Platform.AMS;

namespace AgentService.Platform.MTS
{

    /// <summary>
    /// Interface IMTSGateway. Defines the common operation that are
    /// directly accessible from the messaging clients on each agent.
    /// </summary>
    public interface IMTSGateway
    {
        /// <summary>
        /// Checks whether a queue has messages.
        /// </summary>
        /// <param name="aid">agent identifier of the owner of the queue</param>
        /// <returns>true if the queue has messages</returns>
        bool HasMessages(AID aid);

        /// <summary>
        /// Sends a message to an agent.
        /// </summary>
        /// <param name="message">message</param>
        /// <returns>true if the message has been successfully sent</returns>
        bool SendMessage(AgentMessage message);

        /*
        /// <summary>
        /// Receives a message pops it from the queue.
        /// </summary>
        /// <param name="aid">agent identifier of the agent that owns the queue</param>
        /// <returns>the first message available in the queue</returns>
        AgentMessage ReceiveMessage(AID aid);

        /// <summary>
        /// Looks in the queue for a message.
        /// </summary>
        /// <param name="aid">agent identifier of the agent that owns the queue</param>
        /// <returns>the first message available in the queue</returns>
        AgentMessage PeekMessage(AID aid);
        */

        /// <summary>
        /// Retrieves the selected messages from the agent's message queue
        /// </summary>
        /// <param name="aid">agent identifier of the agent that owns the queue</param>
        /// <param name="filter">message filter, set this parameter to null if you do not want to apply a filter</param>
        /// <param name="max">maximum number of messages to retrieve (0 or negative number for all messages)</param>
        /// <param name="bRemove">if true removes the messages from the queue</param>
        /// <returns>the collection of messages retrieved from the queue</returns>
        AgentMessageCollection GetMessages(AID aid, MessageFilter filter, int max, bool bRemove);
        
        /// <summary>
        /// Retrieves the first message satisfying the given conditions from the agent's queue.
        /// </summary>
        /// <param name="aid">agent identifier of the agent that owns the queue</param>
        /// <param name="filter">message filter, set this parameter to null if you do not want to apply a filter</param>
        /// <param name="bRemove">if true removes the messages from the queue</param>
        /// <returns>the collection of messages retrieved from the queue</returns>
        AgentMessage GetMessage(AID aid, MessageFilter filter, bool bRemove);

        /// <summary>
        /// Removes the given message from the queue.
        /// </summary>
        /// <param name="aid">agent identifier of the agent that owns the queue</param>
        /// <param name="message">message to be destroyed</param>
        /// <returns>true if message is successfully removed</returns>
        bool RemoveMessage(AID aid, AgentMessage message);
    }



	/// <summary>
	/// Class MTS. Specific MTS Agent class.
	/// </summary>
	public class MTS : AgentService.Agent.Agent, IMTSGateway
    {
		/// <summary>
		/// Reference to the owning platform.
		/// </summary>
		private AgentService.Platform.IPlatform platform;

		/// <summary>
		/// Constructs an MTS Agent for the given platform.
		/// </summary>
		/// <param name="platform">Reference to the owning platform</param>
		public MTS(AgentService.Platform.IPlatform platform)
		{
			this.platform = platform;
			this.aid = new AID(this.platform.mtsName, this.platform.Description.Name);
		}

		/// <summary>
		/// Registers an agent with the Messaging system 
		/// </summary>
		/// <param name="aid">agent identifier</param>
		/// <returns>false, if the agents is already registered or the queue cannot be created</returns>
		public bool Register(AID aid) 
		{
			return this.platform.Messaging.CreateAgentQueue(aid);
		}
		/// <summary>
		/// Deregister an agent with the Messaging system
		/// </summary>
		/// <param name="aid">agent identifier</param>
		/// <returns>false, if the agent queue is not found or cannot be removed</returns>
		public bool Deregister(AID aid)
		{
			return this.platform.Messaging.RemoveAgentQueue(aid);
		}
		/// <summary>
		/// Checks whether a queue has messages.
		/// </summary>
		/// <param name="aid">agent identifier of the owner of the queue</param>
		/// <returns>true if the queue has messages</returns>
		public bool HasMessages(AID aid)
		{
			bool bReturn = false;

			lock(this) 
			{
				bReturn = this.platform.Messaging.HasMessages(aid);
			}

			return bReturn;
		}

		/// <summary>
		/// Sends a message to an agent.
		/// </summary>
		/// <param name="message">message</param>
		/// <returns>true if the message has been successfully sent</returns>
		public bool SendMessage(AgentMessage message)
		{
			bool bReturn = false;

			lock(this) 
			{
				bReturn = this.platform.Messaging.SendMessage(message);
				if (bReturn == false)
				{
					AgentService.Platform.Modules.IModuleError error = this.platform.Messaging.GetLastError();
				}
			}

			return bReturn;
		}

        /*
		/// <summary>
		/// Receives a message pops it from the queue.
		/// </summary>
		/// <param name="aid">agent identifier of the agent that owns the queue</param>
		/// <returns>the first message available in the queue</returns>
		public AgentMessage ReceiveMessage(AID aid)
		{
			// TODO: Check the new code version

			AgentMessage message = null;
			lock (this) 
			{
				message = this.platform.Messaging.ReceiveMessage(aid);	
			}

			//return null;
			return message;
		}

		/// <summary>
		/// Looks in the queue for a message.
		/// </summary>
		/// <param name="aid">agent identifier of the agent that owns the queue</param>
		/// <returns>the first message available in the queue</returns>
		public AgentMessage PeekMessage(AID aid)
		{
			AgentMessage message = null;
			lock(this) 
			{
                // MOD 2007-09-05 - Christian Vecchiola
                //
                // Changed the implementation of PeekMessage to the new
                // API GetMessage which provides a more consistent way
                // to retrieve messages.
                //
                // OLD CODE:
                //
                // message = this.platform.Messaging.GetMessage(aid,null,false);

				message = this.platform.Messaging.GetMessage(aid,null,false);

                // END MOD
			}

			return message;
		}
        */

		/// <summary>
		/// Retrieves all the messages and removes them from the queue.
		/// </summary>
		/// <param name="aid">agent identifier of the agent that owns the queue</param>
        /// <param name="filter">message filter, set this parameter to null if you do not want to apply any filter</param>
        /// <param name="max">maximum number of messages to retrieve (0 or negative number for unlimited messages)</param>
        /// <param name="bRemove">if true removes the messages from the queue</param>
		/// <returns>the collection of messages retrieved from the queue</returns>
		public AgentMessageCollection GetMessages(AID aid, MessageFilter filter, int max, bool bRemove)
		{
			
			AgentMessageCollection messages = null;
			lock(this) 
			{
				messages = this.platform.Messaging.GetMessages(aid, filter, max, bRemove);	
				return messages;
			}

			
		}

        /// <summary>
        /// Retrieves the first message satisfying the given conditions from the agent's queue.
        /// </summary>
        /// <param name="aid">agent identifier of the agent that owns the queue</param>
        /// <param name="filter">message filter, set this parameter to null if you do not want to apply a filter</param>
        /// <param name="bRemove">if true removes the messages from the queue</param>
        /// <returns>the collection of messages retrieved from the queue</returns>
        public AgentMessage GetMessage(AID aid, MessageFilter filter, bool bRemove)
        {

            AgentMessage message = null;
            lock (this)
            {
                message = this.platform.Messaging.GetMessage(aid, filter, bRemove);
                return message;
            }

        }

		/// <summary>
		/// Removes the given message from the queue.
		/// </summary>
		/// <param name="aid">agent identifier of the agent that owns the queue</param>
		/// <param name="message">message to be destroyed</param>
		/// <returns>true if message is successfully removed</returns>
		public bool RemoveMessage(AID aid,AgentMessage message)
		{
			lock(this)
			{
				return this.platform.Messaging.RemoveMessage(aid, message);
			}
		}

		#region CallBacks
		/// <summary>
		/// Handler of messages directed to the MTS
		/// </summary>
		/// <param name="msg"></param>
		public void DispatchMessage(AgentMessage msg) 
		{
			// ...
		}
		#endregion
	}
}