/*

 *   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 java.util.ArrayList;

import java.util.List;

import javax.mail.Address;

import javax.mail.Authenticator;

import javax.mail.Message;

import javax.mail.MessagingException;

import javax.mail.PasswordAuthentication;

import javax.mail.internet.InternetAddress;

import org.sonews.config.Config;

import org.sonews.storage.Article;

import org.sonews.storage.Headers;

import org.sonews.storage.StorageBackendException;

import org.sonews.storage.StorageManager;

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

      final String password = 

        Config.inst().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)

      {

        to = msg.getReplyTo();

      }

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

      {

        Log.msg("Skipping message because no recipient!", false);

        return false;

      }

      else

      {

        boolean      posted     = false;

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

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

        {

          if (toa instanceof InternetAddress)

          {

            List<String> groups = StorageManager.current()

              .getGroupsForList((InternetAddress)toa);

            newsgroups.addAll(groups);

          }

        }

        if (newsgroups.size() > 0)

        {

          StringBuilder groups = new StringBuilder();

          for(int n = 0; n < newsgroups.size(); n++)

          {

            groups.append(newsgroups.get(n));

            if(n + 1 != newsgroups.size())

            {

              groups.append(',');

            }

          }

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

          // Create new Article object

          Article article = new Article(msg);

          article.setGroup(groups.toString());

          article.removeHeader(Headers.REPLY_TO);

          article.removeHeader(Headers.TO);

          // Write article to database

          if(!StorageManager.current().isArticleExisting(article.getMessageID()))

          {

            StorageManager.current().addArticle(article);

            Stats.getInstance().mailGatewayed(

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

          }

          else

          {

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

          }

          posted = true;

        }

        else

        {

          StringBuilder buf = new StringBuilder();

          for(Address toa : to)

          {

            buf.append(' ');

            buf.append(toa.toString());

          }

          Log.msg("No group for" + buf.toString(), false);

        }

        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, StorageBackendException

  {

    // 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 = StorageManager.current().getListForGroup(groupname);

      if(listAddress != null)

      {

        listAddresses.add(listAddress);

      }

    }

    for(String listAddress : listAddresses)

    {

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

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

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

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

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

      String smtpFrom = Config.inst().get(

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

      // TODO: Make Article cloneable()

      String group = article.getHeader(Headers.NEWSGROUPS)[0];

      article.getMessageID(); // Make sure an ID is existing

      article.removeHeader(Headers.NEWSGROUPS);

      article.removeHeader(Headers.PATH);

      article.removeHeader(Headers.LINES);

      article.removeHeader(Headers.BYTES);

      article.setHeader("To", listAddress);

      article.setHeader("Reply-To", listAddress);

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

      {

        rewriteSenderAddress(article); // Set the SENDER address

      }

      SMTPTransport smtpTransport = new SMTPTransport(smtpHost, smtpPort);

      smtpTransport.send(article, smtpFrom, listAddress);

      smtpTransport.close();

      Stats.getInstance().mailGatewayed(group);

      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(Article msg)

    throws MessagingException

  {

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

    if(mlAddress != null)

    {

      msg.setHeader(Headers.SENDER, mlAddress);

    }

    else

    {

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

    }

  }

}