/*********************************************************************/
/*                                                                   */
/*                     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 System.ServiceModel;
using AgentService.Platform.AMS;



namespace AgentService.Platform.MTS
{
    /// <summary>
    /// Interface IMsgService. This interface defines the
    /// methods and the services that are offered to users
    /// and within behavior objects to interact with the
    /// messaging system.
    /// </summary>
    public interface IMsgService
    {
        /// <summary>
        /// Raises when a proposal for a new conversation is received.
        /// </summary>
        event ConversationDelegate OnIncomingConversation;

        /// <summary>
        /// Open a bidirectional conversation with an agents.
        /// </summary>
        /// <param name="to">agent identifier of the agent to talk to</param>
        /// <returns>identifier of the new conversation</returns>
        IConversation OpenConversation(AID to);

        /// <summary>
        /// Open a bidirectiona conversation, using the ontology service to represent message content and to validate it.
        /// </summary>
        /// <param name="to">agent identifier of the agent to talk to</param>
        /// <param name="onto">the ontology used to represent the message content</param>
        /// <returns>identifier of the new conversation</returns>
        IOntologicalConversation OpenConversation(AID to, AgentService.Ontology.Ontology onto);

        /// <summary>
        /// Checks whether the agent's queue has messages.
        /// </summary>
        /// <returns>true if the queue has messages</returns>
        bool HasMessages();

        /// <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 and pops it from the queue.
        /// </summary>
        /// <returns>the first message available in the queue</returns>
        AgentMessage ReceiveMessage();

        /// <summary>
        /// Receives all the messages that satisfy the condition of the given filter.  
        /// </summary>
        /// <param name="filter">Specifies the selection criteria</param>
        /// <param name="blocking">If true the call is blocking</param>
        /// <returns>A collection of filtered messages retrieved from the agent's queue</returns>
        AgentMessageCollection ReceiveMessage(MessageFilter filter, bool blocking);

        /// <summary>
        /// Looks in the agent's queue for a message.
        /// </summary>
        /// <returns>the first message available in the queue</returns>
        AgentMessage PeekMessage();

        /// <summary>
        /// Retrieves all the messages and removes them from the queue.
        /// </summary>
        /// <param name="bRemove">if true messages are removed from the queue</param>
        /// <returns>the collection of messages retrieved from the queue</returns>
        AgentMessageCollection GetAllMessages(bool bRemove);

        /// <summary>
        /// Waits until a new message arrives in the agent's queue and pops it.
        /// </summary>
        /// <returns>The new message arrived</returns>
        AgentMessage WaitForMessage();

        /// <summary>
        /// Removes the given message from the queue.
        /// </summary>
        /// <param name="message">message to be destroyed</param>
        /// <returns>true if message is successfully removed</returns>
        bool RemoveMessage(AgentMessage message);
    }
}