/*

  *   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 java.util.regex.Matcher;

 import java.util.regex.Pattern;

 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.Group;

 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 to 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);

     }

   }

   /**

    * Chunks out the email address of the full List-Post header field.

    * @param listPostValue

    * @return The matching email address or null

    */

   private static String chunkListPost(String listPostValue)

   {

     // listPostValue is of form "<mailto:dev@openoffice.org>"

     Pattern mailPattern = Pattern.compile("(\\w+[-|.])*\\w+@(\\w+.)+\\w+");

     Matcher mailMatcher = mailPattern.matcher(listPostValue);

     if(mailMatcher.find())

     {

       return listPostValue.substring(mailMatcher.start(), mailMatcher.end());

     }

     else

     {

       return null;

     }

   }

   /**

    * This method inspects the header of the given message, trying

    * to find the most appropriate recipient.

    * @param msg

    * @param fallback If this is false only List-Post and X-List-Post headers

    *                 are examined.

    * @return null or fitting group name for the given message.

    */

   private static List<String> getGroupFor(final Message msg, final boolean fallback)

     throws MessagingException, StorageBackendException

   {

     List<String> groups = null;

     // Is there a List-Post header?

     String[]        listPost = msg.getHeader(Headers.LIST_POST);

     InternetAddress listPostAddr;

     if(listPost == null || listPost.length == 0 || "".equals(listPost[0]))

     {

       // Is there a X-List-Post header?

       listPost = msg.getHeader(Headers.X_LIST_POST);

     }

     if(listPost != null && listPost.length > 0 

       && !"".equals(listPost[0]) && chunkListPost(listPost[0]) != null)

     {

       // listPost[0] is of form "<mailto:dev@openoffice.org>"

       listPost[0]  = chunkListPost(listPost[0]);

       listPostAddr = new InternetAddress(listPost[0], false);

       groups = StorageManager.current().getGroupsForList(listPostAddr.getAddress());

     }

     else if(fallback)

     {

       Log.get().info("Using fallback recipient discovery for: " + msg.getSubject());

       groups = new ArrayList<String>();

       // Fallback to TO/CC/BCC addresses

       Address[] to = msg.getAllRecipients();

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

       {

         if(toa instanceof InternetAddress)

         {

           List<String> g = StorageManager.current()

             .getGroupsForList(((InternetAddress)toa).getAddress());

           groups.addAll(g);

         }

       }

     }

     return groups;

   }

   /**

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

    * appropriate newsgroup.

    * If the message already exists in the storage, this message checks

    * if it must be posted in an additional group. This can happen for

    * crosspostings in different mailing lists.

    * @param msg

    */

   public static boolean toGroup(final Message msg)

   {

     if(msg == null)

 	{

       throw new IllegalArgumentException("Argument 'msg' must not be null!");

     }

     try

     {

       // Create new Article object

       Article article = new Article(msg);

       boolean posted  = false;

       // Check if this mail is already existing the storage

       boolean updateReq = 

         StorageManager.current().isArticleExisting(article.getMessageID());

       List<String> newsgroups = getGroupFor(msg, !updateReq);

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

       if(updateReq)

       {

         // Check for duplicate entries of the same group

         Article oldArticle = StorageManager.current().getArticle(article.getMessageID());

         if(oldArticle != null)

 		{

           List<Group> oldGroups = oldArticle.getGroups();

           for(Group oldGroup : oldGroups)

           {

             if(!newsgroups.contains(oldGroup.getName()))

             {

               oldgroups.add(oldGroup.getName());

             }

           }

 		}

       }

       if(newsgroups.size() > 0)

       {

         newsgroups.addAll(oldgroups);

         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.get().info("Posting to group " + groups.toString());

         article.setGroup(groups.toString());

         //article.removeHeader(Headers.REPLY_TO);

         //article.removeHeader(Headers.TO);

         // Write article to database

         if(updateReq)

         {

           Log.get().info("Updating " + article.getMessageID()

             + " with additional groups");

           StorageManager.current().delete(article.getMessageID());

           StorageManager.current().addArticle(article);

         }

         else

         {

           Log.get().info("Gatewaying " + article.getMessageID() + " to "

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

           StorageManager.current().addArticle(article);

           Stats.getInstance().mailGatewayed(

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

         }

         posted = true;

       }

       else

       {

         StringBuilder buf = new StringBuilder();

         for (Address toa : msg.getAllRecipients())

         {

           buf.append(' ');

           buf.append(toa.toString());

         }

         buf.append(" " + article.getHeader(Headers.LIST_POST)[0]);

         Log.get().warning("No group for" + buf.toString());

       }

       return posted;

     }

     catch(Exception ex)

     {

       ex.printStackTrace();

       return false;

     }

   }

   /**

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

    * This method MAY be called several times by PostCommand for the same

    * article.

    */

   public static void toList(Article article, String group)

     throws IOException, MessagingException, StorageBackendException

   {

     // Get mailing lists for the group of this article

     List<String> rcptAddresses = StorageManager.current().getListsForGroup(group);

     if(rcptAddresses == null || rcptAddresses.size() == 0)

     {

       Log.get().warning("No ML-address for " + group + " found.");

       return;

     }

     for(String rcptAddress : rcptAddresses)

     {

       // 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()

       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", rcptAddress);

       //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, rcptAddress);

       smtpTransport.close();

       Stats.getInstance().mailGatewayed(group);

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

         + " was delivered to " + rcptAddress + ".");

     }

   }

   /**

    * 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!");

     }

   }

 }