/*

 *   SONEWS News Server

 *   see AUTHORS for the list of contributors

 *

 *   This program is free software: you can redistribute it and/or modify

 *   it under the terms of the GNU General Public License as published by

 *   the Free Software Foundation, either version 3 of the License, or

 *   (at your option) any later version.

 *

 *   This program 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 General Public License for more details.

 *

 *   You should have received a copy of the GNU General Public License

 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

package org.sonews.daemon;

import org.sonews.config.Config;

import org.sonews.util.Log;

import org.sonews.util.Stats;

import java.io.IOException;

import java.net.InetSocketAddress;

import java.net.Socket;

import java.nio.channels.SocketChannel;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.ListIterator;

import java.util.Map;

/**

 * Daemon thread collecting all NNTPConnection instances. The thread

 * checks periodically if there are stale/timed out connections and

 * removes and purges them properly.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public final class Connections extends AbstractDaemon

{

  private static final Connections instance = new Connections();

  /**

   * @return Active Connections instance.

   */

  public static Connections getInstance()

  {

    return Connections.instance;

  }

  private final List<NNTPConnection> connections 

    = new ArrayList<NNTPConnection>();

  private final Map<SocketChannel, NNTPConnection> connByChannel 

    = new HashMap<SocketChannel, NNTPConnection>();

  private Connections()

  {

    setName("Connections");

  }

  /**

   * Adds the given NNTPConnection to the Connections management.

   * @param conn

   * @see org.sonews.daemon.NNTPConnection

   */

  public void add(final NNTPConnection conn)

  {

    synchronized(this.connections)

    {

      this.connections.add(conn);

      this.connByChannel.put(conn.getSocketChannel(), conn);

    }

  }

  /**

   * @param channel

   * @return NNTPConnection instance that is associated with the given

   * SocketChannel.

   */

  public NNTPConnection get(final SocketChannel channel)

  {

    synchronized(this.connections)

    {

      return this.connByChannel.get(channel);

    }

  }

  int getConnectionCount(String remote)

  {

    int cnt = 0;

    synchronized(this.connections)

    {

      for(NNTPConnection conn : this.connections)

      {

        assert conn != null;

        assert conn.getSocketChannel() != null;

        Socket socket = conn.getSocketChannel().socket();

        if(socket != null)

        {

          InetSocketAddress sockAddr = (InetSocketAddress)socket.getRemoteSocketAddress();

          if(sockAddr != null)

          {

            if(sockAddr.getHostName().equals(remote))

            {

              cnt++;

            }

          }

        } // if(socket != null)

      }

    }

    return cnt;

  }

  /**

   * Run loops. Checks periodically for timed out connections and purged them

   * from the lists.

   */

  @Override

  public void run()

  {

    while(isRunning())

    {

      int timeoutMillis = 1000 * Config.inst().get(Config.TIMEOUT, 180);

      synchronized (this.connections)

      {

        final ListIterator<NNTPConnection> iter = this.connections.listIterator();

        NNTPConnection conn;

        while (iter.hasNext())

        {

          conn = iter.next();

          if((System.currentTimeMillis() - conn.getLastActivity()) > timeoutMillis

              && conn.getBuffers().isOutputBufferEmpty())

          {

            // A connection timeout has occurred so purge the connection

            iter.remove();

            // Close and remove the channel

            SocketChannel channel = conn.getSocketChannel();

            connByChannel.remove(channel);

            try

            {

              assert channel != null;

              assert channel.socket() != null;

              // Close the channel; implicitely cancels all selectionkeys

              channel.close();

              Log.get().info("Disconnected: " + channel.socket().getRemoteSocketAddress() +

                " (timeout)");

            }

            catch(IOException ex)

            {

              Log.get().warning("Connections.run(): " + ex);

            }

            // Recycle the used buffers

            conn.getBuffers().recycleBuffers();

            Stats.getInstance().clientDisconnect();

          }

        }

      }

      try

      {

        Thread.sleep(10000); // Sleep ten seconds

      }

      catch(InterruptedException ex)

      {

        Log.get().warning("Connections Thread was interrupted: " + ex.getMessage());

      }

    }

  }

}