/*

 *   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.mlgw;

import java.io.IOException;

import org.sonews.daemon.Config;

import org.sonews.daemon.storage.Article;

import org.sonews.util.io.ArticleInputStream;

import org.sonews.daemon.storage.Database;

import java.sql.SQLException;

import java.util.ArrayList;

import java.util.List;

import java.util.Properties;

import javax.mail.Address;

import javax.mail.Authenticator;

import javax.mail.Message;

import javax.mail.MessagingException;

import javax.mail.PasswordAuthentication;

import javax.mail.Session;

import javax.mail.Transport;

import javax.mail.internet.InternetAddress;

import javax.mail.internet.MimeMessage;

import org.sonews.daemon.storage.Headers;

import org.sonews.util.Log;

import org.sonews.util.Stats;

/**

 * Dispatches messages from mailing list or newsserver or vice versa.

 * @author Christian Lins

 * @since sonews/0.5.0

 */

public class Dispatcher 

{

  static class PasswordAuthenticator extends Authenticator

  {

    @Override

    public PasswordAuthentication getPasswordAuthentication()

    {

      final String username = 

        Config.getInstance().get(Config.MLSEND_USER, "user");

      final String password = 

        Config.getInstance().get(Config.MLSEND_PASSWORD, "mysecret");

      return new PasswordAuthentication(username, password);

    }

  }

  /**

   * Posts a message that was received from a mailing list to the 

   * appropriate newsgroup.

   * @param msg

   */

  public static boolean toGroup(final Message msg)

  {

    try

    {

      Address[] to = msg.getAllRecipients(); // includes TO/CC/BCC

      if(to == null || to.length <= 0)

      {

        Log.msg("Skipping message because no receipient!", true);

        return false;

      }

      else

      {

        boolean posted = false;

        for(Address toa : to) // Address can have '<' '>' around

        {

          if(!(toa instanceof InternetAddress))

          {

            continue;

          }

          String group = Database.getInstance()

            .getGroupForList((InternetAddress)toa);

          if(group != null)

          {

            Log.msg("Posting to group " + group, true);

            // Create new Article object

            Article article = new Article(msg);

            article.setGroup(group);

            // Write article to database

            if(!Database.getInstance().isArticleExisting(article.getMessageID()))

            {

              Database.getInstance().addArticle(article);

              Stats.getInstance().mailGatewayed(

                article.getHeader(Headers.NEWSGROUPS)[0]);

            }

            else

            {

              Log.msg("Article " + article.getMessageID() + " already existing.", true);

              // TODO: It may be possible that a ML mail is posted to several

              // ML addresses...

            }

            posted = true;

          }

          else

          {

            Log.msg("No group for " + toa, true);

          }

        } // end for

        return posted;

      }

    }

    catch(Exception ex)

    {

      ex.printStackTrace();

      return false;

    }

  }

  /**

   * Mails a message received through NNTP to the appropriate mailing list.

   */

  public static void toList(Article article)

    throws IOException, MessagingException, SQLException

  {

    // Get mailing lists for the group of this article

    List<String> listAddresses = new ArrayList<String>();

    String[]     groupnames    = article.getHeader(Headers.NEWSGROUPS)[0].split(",");

    for(String groupname : groupnames)

    {

      String listAddress = Database.getInstance().getListForGroup(groupname);

      if(listAddress != null)

      {

        listAddresses.add(listAddress);

      }

    }

    for(String listAddress : listAddresses)

    {

      // Compose message and send it via given SMTP-Host

      String smtpHost = Config.getInstance().get(Config.MLSEND_HOST, "localhost");

      int    smtpPort = Config.getInstance().get(Config.MLSEND_PORT, 25);

      String smtpUser = Config.getInstance().get(Config.MLSEND_USER, "user");

      String smtpPw   = Config.getInstance().get(Config.MLSEND_PASSWORD, "mysecret");

      Properties props    = System.getProperties();

      props.put("mail.smtp.localhost", 

        Config.getInstance().get(Config.HOSTNAME, "localhost"));

      props.put("mail.smtp.from",  // Used for MAIL FROM command

        Config.getInstance().get(

          Config.MLSEND_ADDRESS, article.getHeader(Headers.FROM)[0]));

      props.put("mail.smtp.host", smtpHost);

      props.put("mail.smtp.port", smtpPort);

      props.put("mail.smtp.auth", "true");

      Address[] address = new Address[1];

      address[0] = new InternetAddress(listAddress);

      ArticleInputStream in = new ArticleInputStream(article);

      Session session = Session.getDefaultInstance(props, new PasswordAuthenticator());

      MimeMessage msg = new MimeMessage(session, in);

      msg.setRecipient(Message.RecipientType.TO, address[0]);

      msg.setReplyTo(address);

      msg.removeHeader(Headers.NEWSGROUPS);

      msg.removeHeader(Headers.PATH);

      msg.removeHeader(Headers.LINES);

      msg.removeHeader(Headers.BYTES);

      if(Config.getInstance().get(Config.MLSEND_RW_SENDER, false))

      {

        rewriteSenderAddress(msg); // Set the SENDER address

      }

      if(Config.getInstance().get(Config.MLSEND_RW_FROM, false))

      {

        rewriteFromAddress(msg);   // Set the FROM address

      }

      msg.saveChanges();

      // Send the mail

      Transport transport = session.getTransport("smtp");

      transport.connect(smtpHost, smtpPort, smtpUser, smtpPw);

      transport.sendMessage(msg, msg.getAllRecipients());

      transport.close();

      Stats.getInstance().mailGatewayed(article.getHeader(Headers.NEWSGROUPS)[0]);

      Log.msg("MLGateway: Mail " + article.getHeader("Subject")[0] 

        + " was delivered to " + listAddress + ".", true);

    }

  }

  /**

   * Sets the SENDER header of the given MimeMessage. This might be necessary

   * for moderated groups that does not allow the "normal" FROM sender.

   * @param msg

   * @throws javax.mail.MessagingException

   */

  private static void rewriteSenderAddress(MimeMessage msg)

    throws MessagingException

  {

    String mlAddress = Config.getInstance().get(Config.MLSEND_ADDRESS, null);

    if(mlAddress != null)

    {

      msg.setSender(new InternetAddress(mlAddress));

    }

    else

    {

      throw new MessagingException("Cannot rewrite SENDER header!");

    }

  }

  /**

   * Sets the FROM header of the given MimeMessage. This might be necessary

   * for moderated groups that does not allow the "normal" FROM sender.

   * @param msg

   * @throws javax.mail.MessagingException

   */

  private static void rewriteFromAddress(MimeMessage msg)

    throws MessagingException

  {

    Address[] froms  = msg.getFrom();

    String mlAddress = Config.getInstance().get(Config.MLSEND_ADDRESS, null);

    if(froms.length > 0 && froms[0] instanceof InternetAddress 

      && mlAddress != null)

    {

      InternetAddress from = (InternetAddress)froms[0];

      from.setAddress(mlAddress);

      msg.setFrom(from);

    }

    else

    {

      throw new MessagingException("Cannot rewrite FROM header!");

    }    

  }

}