using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using MSNPSharp;



namespace MessengerBot

{

    /// <summary>

    /// This class encapsulates a session with a user.

    /// </summary>

    public sealed class Session

    {

        /// <summary>

        /// This is the backing field for the <see cref="Bot"/> property.

        /// </summary>

        private readonly Bot _Bot;



        /// <summary>

        /// This is the backing field for the <see cref="Conversation"/> property.

        /// </summary>

        private readonly Conversation _Conversation;



        /// <summary>

        /// This field holds a collection of system state objects for the registered systems.

        /// </summary>

        private readonly List<Tuple<ISystem, object>> _SystemState = new List<Tuple<ISystem, object>>();



        /// <summary>

        /// Initializes a new instance of the <see cref="Session"/> class.

        /// </summary>

        /// <param name="bot">

        /// The bot that manages this <see cref="Session"/>.

        /// </param>

        /// <param name="conversation">

        /// The <see cref="Conversation"/> object this <see cref="Session"/> will encapsulate.

        /// </param>

        /// <exception cref="ArgumentNullException">

        /// <para><paramref name="bot"/> is <c>null</c>.</para>

        /// <para>- or -</para>

        /// <para><paramref name="conversation"/> is <c>null</c>.</para>

        /// </exception>

        public Session(Bot bot, Conversation conversation)

        {

            if (bot == null)

                throw new ArgumentNullException("bot");

            if (conversation == null)

                throw new ArgumentNullException("conversation");



            _Bot = bot;

            _Conversation = conversation;



            _Conversation.ContactJoined += ContactJoined;

            _Conversation.ContactLeft += ContactLeft;

            _Conversation.ConversationEnded += ConversationEnded;

            _Conversation.EmoticonDefinitionReceived += EmoticonDefinitionReceived;

            _Conversation.ExceptionOccurred += ExceptionOccurred;

            _Conversation.MSNObjectDataTransferCompleted += MSNObjectDataTransferCompleted;

            _Conversation.NudgeReceived += NudgeReceived;

            _Conversation.RemoteOwnerChanged += RemoteOwnerChanged;

            _Conversation.ServerErrorReceived += ServerErrorReceived;

            _Conversation.SessionClosed += SessionClosed;

            _Conversation.SessionEstablished += SessionEstablished;

            _Conversation.TextMessageReceived += TextMessageReceived;

            _Conversation.UserTyping += UserTyping;

            _Conversation.WinkReceived += WinkReceived;

        }



        /// <summary>

        /// Gets the <see cref="Bot"/> that manages this <see cref="Session"/>.

        /// </summary>

        public Bot Bot

        {

            get

            {

                return _Bot;

            }

        }



        /// <summary>

        /// Gets the <see cref="Conversation"/> that this <see cref="Session"/> encapsulates.

        /// </summary>

        public Conversation Conversation

        {

            get

            {

                return _Conversation;

            }

        }



        /// <summary>

        /// Event, WinkReceived.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.WinkEventArgs"/> instance containing the event data.</param>

        private void WinkReceived(object sender, WinkEventArgs e)

        {

        }



        /// <summary>

        /// Event, UserTyping.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ContactEventArgs"/> instance containing the event data.</param>

        private void UserTyping(object sender, ContactEventArgs e)

        {

        }



        /// <summary>

        /// Event, TextMessageReceived.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.TextMessageEventArgs"/> instance containing the event data.</param>

        private void TextMessageReceived(object sender, TextMessageEventArgs e)

        {

            foreach (var systemState in _SystemState)

                systemState.Item1.MessageReceived(Bot, this, systemState.Item2, e.Message.Text);



            // TODO: Handle quotes

            string[] parts = e.Message.Text.Split(

                new[]

                {

                    ' '

                }, StringSplitOptions.RemoveEmptyEntries);

            string[] arguments;

            ICommand command = CommandParser.GetCommand(_Bot.Commands, parts, out arguments);

            if (command != null)

            {

                _Conversation.SendTypingMessage();



                Type commandType = command.GetType();

                ICommandBasedSystem ownerSystem = (from system in _Bot.Configuration.Systems.OfType<ICommandBasedSystem>()

                                                   where system.GetCommands().Contains(commandType)

                                                   select system).FirstOrDefault();

                Debug.Assert(ownerSystem != null, "ownerSystem should not be null here");



                try

                {

                    command.Execute(ownerSystem, this, arguments);

                }

                catch (CommandException ex)

                {

                    _Conversation.SendTextMessage(new TextMessage("Error: " + ex.Message));

                    _Conversation.SendTextMessage(new TextMessage("If you need assistance, use the command 'help'"));

                }

                catch (Exception ex)

                {

                    _Conversation.SendTextMessage(new TextMessage("An exception occured :("));

                    _Conversation.SendTextMessage(new TextMessage(ex.GetType().FullName + ": " + ex.Message));

                    _Conversation.SendTextMessage(new TextMessage(ex.StackTrace));

                }

            }

            else

                _Conversation.SendTextMessage(new TextMessage("Unknown command, use the command 'help' for help"));

        }



        /// <summary>

        /// Event, SessionEstablished.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>

        private void SessionEstablished(object sender, EventArgs e)

        {

            _SystemState.Clear();

            foreach (ISystem system in Bot.Configuration.Systems)

            {

                object state = system.SessionStarted(Bot, this);

                _SystemState.Add(Tuple.Create(system, state));

            }

        }



        /// <summary>

        /// Event, SessionClosed.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>

        private void SessionClosed(object sender, EventArgs e)

        {

            foreach (var systemState in _SystemState)

                systemState.Item1.SessionEnded(Bot, this, systemState.Item2);

            _SystemState.Clear();

        }



        /// <summary>

        /// Event, ServerErrorReceived.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.MSNErrorEventArgs"/> instance containing the event data.</param>

        private void ServerErrorReceived(object sender, MSNErrorEventArgs e)

        {

        }



        /// <summary>

        /// Event, RemoteOwnerChanged.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ConversationRemoteOwnerChangedEventArgs"/> instance containing the event data.</param>

        private void RemoteOwnerChanged(object sender, ConversationRemoteOwnerChangedEventArgs e)

        {

        }



        /// <summary>

        /// Event, NudgeReceived.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ContactEventArgs"/> instance containing the event data.</param>

        private void NudgeReceived(object sender, ContactEventArgs e)

        {

        }



        /// <summary>

        /// Event, MSNObjectDataTransferCompleted.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ConversationMSNObjectDataTransferCompletedEventArgs"/> instance containing the event data.</param>

        private void MSNObjectDataTransferCompleted(object sender, ConversationMSNObjectDataTransferCompletedEventArgs e)

        {

        }



        /// <summary>

        /// Event, ExceptionOccurred.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ExceptionEventArgs"/> instance containing the event data.</param>

        private void ExceptionOccurred(object sender, ExceptionEventArgs e)

        {

        }



        /// <summary>

        /// Event, EmoticonDefinitionReceived.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.EmoticonDefinitionEventArgs"/> instance containing the event data.</param>

        private void EmoticonDefinitionReceived(object sender, EmoticonDefinitionEventArgs e)

        {

        }



        /// <summary>

        /// Event, ConversationEnded.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ConversationEndEventArgs"/> instance containing the event data.</param>

        private void ConversationEnded(object sender, ConversationEndEventArgs e)

        {

        }



        /// <summary>

        /// Event, ContactLeft.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ContactConversationEventArgs"/> instance containing the event data.</param>

        private void ContactLeft(object sender, ContactConversationEventArgs e)

        {

        }



        /// <summary>

        /// Event, ContactJoined.

        /// </summary>

        /// <param name="sender">The sender.</param>

        /// <param name="e">The <see cref="MSNPSharp.ContactConversationEventArgs"/> instance containing the event data.</param>

        private void ContactJoined(object sender, ContactConversationEventArgs e)

        {

        }

    }

}