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    * Licensed to the Apache Software Foundation (ASF) under one   *
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    * distributed with this work for additional information        *
    * regarding copyright ownership.  The ASF licenses this file   *
    * to you under the Apache License, Version 2.0 (the            *
    * "License"); you may not use this file except in compliance   *
    * with the License.  You may obtain a copy of the License at   *
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   * software distributed under the License is distributed on an  *
   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
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   * specific language governing permissions and limitations      *
   * under the License.                                           *
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  package org.apache.james.transport.mailets;
  
  import java.util.ArrayList;
  import java.util.Collection;
  
  import javax.mail.MessagingException;
  import javax.mail.internet.MimeMessage;
  
  import org.apache.avalon.framework.service.ServiceException;
  import org.apache.avalon.framework.service.ServiceManager;
  import org.apache.james.Constants;
  import org.apache.james.api.user.UsersRepository;
  import org.apache.james.api.user.UsersStore;
  import org.apache.james.api.vut.ErrorMappingException;
  import org.apache.james.api.vut.VirtualUserTable;
  import org.apache.mailet.MailAddress;
  
  /**
   * Receives a Mail from JamesSpoolManager and takes care of delivery of the
   * message to local inboxes.
   * 
   * Available configurations are:
   * 
   * <enableAliases>true</enableAliases>: specify wether the user aliases should
   * be looked up or not. Default is false.
   * 
   * <enableForwarding>true</enableForwarding>: enable the forwarding. Default to
   * false.
   * 
   * <usersRepository>LocalAdmins</usersRepository>: specific users repository
   * name. Default to empty. If empty does lookup the default userRepository.
   */
  public class UsersRepositoryAliasingForwarding extends AbstractVirtualUserTableMailet {
  
      /**
       * The user repository for this mail server. Contains all the users with
       * inboxes on this server.
       */
      private UsersRepository usersRepository;
  
      /**
       * Return a string describing this mailet.
       * 
       * @return a string describing this mailet
       */
      public String getMailetInfo() {
          return "Local User Aliasing and Forwarding Mailet";
      }
  
      /**
       * Return null when the mail should be GHOSTed, the username string when it
       * should be changed due to the ignoreUser configuration.
       * 
       * @param sender
       * @param recipient
       * @param message
       * @throws MessagingException
       */
      public Collection processMail(MailAddress sender, MailAddress recipient,
              MimeMessage message) throws MessagingException {
          if (recipient == null) {
              throw new IllegalArgumentException(
                      "Recipient for mail to be spooled cannot be null.");
          }
          if (message == null) {
              throw new IllegalArgumentException(
                      "Mail message to be spooled cannot be null.");
          }
  
          if (usersRepository instanceof VirtualUserTable) {
              Collection mappings;
              try {
                  mappings = ((VirtualUserTable) usersRepository).getMappings(recipient.getUser(), recipient.getHost());
              } catch (ErrorMappingException e) {
                  StringBuffer errorBuffer = new StringBuffer(128)
                      .append("A problem as occoured trying to alias and forward user ")
                      .append(recipient)
                      .append(": ")
                     .append(e.getMessage());
                     throw new MessagingException(errorBuffer.toString());
             }
             
             if (mappings != null) {
                 return handleMappings(mappings, sender, recipient, message);
             }
         } else {
             StringBuffer errorBuffer = new StringBuffer(128)
                 .append("Warning: the repository ")
                 .append(usersRepository.getClass().getName())
                 .append(" does not implement VirtualUserTable interface).");
             getMailetContext().log(errorBuffer.toString());
         }
         String realName = usersRepository.getRealName(recipient.getUser());
         if (realName != null) {
             ArrayList ret = new ArrayList();
             ret.add(new MailAddress(realName, recipient.getHost()));
             return ret;
         } else {
             ArrayList ret = new ArrayList();
             ret.add(recipient);
             return ret;
         }
     }
 
     /**
      * @see org.apache.mailet.GenericMailet#init()
      */
     public void init() throws MessagingException {
         super.init();
         ServiceManager compMgr = (ServiceManager) getMailetContext()
                 .getAttribute(Constants.AVALON_COMPONENT_MANAGER);
 
         try {
             String userRep = getInitParameter("usersRepository");
             if (userRep == null || userRep.length() == 0) {
                 try {
                     usersRepository = (UsersRepository) compMgr
                             .lookup(UsersRepository.ROLE);
                 } catch (ServiceException e) {
                     log("Failed to retrieve UsersRepository component:"
                             + e.getMessage());
                 }
             } else {
                 UsersStore usersStore = (UsersStore) compMgr.lookup(UsersStore.ROLE);
                 usersRepository = usersStore.getRepository(userRep);
             }
 
         } catch (ServiceException cnfe) {
             log("Failed to retrieve UsersStore component:" + cnfe.getMessage());
         }
 
     }
 
 }