/// Version 1.0.0
/// Last modified 24.5.2014
///
/// Copyright (C) 2014 Ilkka Rautiainen
///
/// Halyri-system is a prototype emergency call system. Its purpose is to
/// demonstrate the use of the advanced capabilities available in the current
/// generation smartphones in facilitating the emergency service dispatcher's
/// capability to determine the nature of the emergency and to dispatch help.
///
/// For more information, see the README file of this package.
///
/// The MIT License (MIT)
///
/// Permission is hereby granted, free of charge, to any person obtaining a copy
/// of this software and associated documentation files (the "Software"), to
/// deal in the Software without restriction, including without limitation the
/// rights to use, copy, modify, merge, publish, distribute, sublicense,
/// and/or sell copies of the Software, and to permit persons to whom the
/// Software is furnished to do so, subject to the following conditions:
///
/// The above copyright notice and this permission notice shall be included in
/// all copies or substantial portions of the Software.
///
/// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
/// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
/// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
/// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
/// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
/// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
/// IN THE SOFTWARE.
///

using System;
using System.Windows.Threading;
using System.ServiceModel;
using System.Diagnostics;
using System.Windows;

namespace Hake_WPF.Network
{
    /// <author>Ilkka Rautiainen</author>
    /// <summary>
    /// The class is used for sending keep-alive messages to the server.
    /// </summary>
    class Pinger
    {
        private int keepaliveIntervalSeconds;
        private Connection connection;
        private DispatcherTimer dispatcherTimer;

        /// <summary>
        /// The function creates the pinger.
        /// </summary>
        /// <param name="interval">The interval of keep-alive messages in seconds.</param>
        /// <param name="connection">The connection.</param>
        public Pinger(int interval, Connection connection)
        {
            this.keepaliveIntervalSeconds = interval;
            this.connection = connection;
        }

        /// <summary>
        /// The function starts the pinger by creating a new timer and an event handler.
        /// The keep-alive message interval is entered here.
        /// </summary>
        public void StartPinger()
        {
            dispatcherTimer = new DispatcherTimer();
            dispatcherTimer.Tick += new EventHandler(SendKeepalive);
            dispatcherTimer.Interval = new TimeSpan(0, 0, keepaliveIntervalSeconds);
            dispatcherTimer.Start();
        }

        /// <summary>
        /// The function stops the pinger by removing the event handler.
        /// </summary>
        private void StopPinger()
        {
            dispatcherTimer.Tick -= SendKeepalive;
        }

        /// <summary>
        /// The function sends the keep-alive message on regular intervals.
        /// If the connection is lost, stops the pinger and shows
        /// a message box to the user.
        /// </summary>
        private async void SendKeepalive(object sender, EventArgs e)
        {
            try
            {
                await connection.PingAsync(keepaliveIntervalSeconds);
            }
            catch (CommunicationException ex)
            {
                StopPinger();
                MessageBox.Show("Connection to server lost");
                Debug.WriteLine(ex.ToString());
            }
        }
    }
}