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    * distributed with this work for additional information        *
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    * to you under the Apache License, Version 2.0 (the            *
    * "License"); you may not use this file except in compliance   *
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  package org.apache.james.transport.mailets;
  
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.StringTokenizer;
  
  import javax.mail.MessagingException;
  
  import org.apache.mailet.MailAddress;
  
  /***
   * Implements a Virtual User Table to translate virtual users
   * to real users. This implementation has the same functionality
   * as <code>JDBCVirtualUserTable</code>, but is configured in the
   * JAMES configuration and is thus probably most suitable for smaller
   * and less dynamic mapping requirements.
   * 
   * The configuration is specified in the form:
   * 
   * &lt;mailet match="All" class="XMLVirtualUserTable"&gt;
   *   &lt;mapping&gt;virtualuser@xxx=realuser[@yyy][;anotherrealuser[@zzz]]&lt;/mapping&gt;
   *   &lt;mapping&gt;virtualuser2@*=realuser2[@yyy][;anotherrealuser2[@zzz]]&lt;/mapping&gt;
   *   ...
   * &lt;/mailet&gt;
   * 
   * As many &lt;mapping&gt; elements can be added as necessary. As indicated,
   * wildcards are supported, and multiple recipients can be specified with a 
   * semicolon-separated list. The target domain does not need to be specified if 
   * the real user is local to the server.
   * 
   * Matching is done in the following order:
   * 1. user@domain    - explicit mapping for user@domain
   * 2. user@*         - catchall mapping for user anywhere
   * 3. *@domain       - catchall mapping for anyone at domain
   * 4. null           - no valid mapping
   */
  public class XMLVirtualUserTable extends AbstractVirtualUserTable
  {
    /***
     * Holds the configured mappings
     */
    private Map mappings = new HashMap();
  
    /***
     * Initialize the mailet
     */
    public void init() throws MessagingException {
        String mapping = getInitParameter("mapping");
        
        if(mapping != null) {
            StringTokenizer tokenizer = new StringTokenizer(mapping, ",");
            while(tokenizer.hasMoreTokens()) {
              String mappingItem = tokenizer.nextToken();
              int index = mappingItem.indexOf('=');
              String virtual = mappingItem.substring(0, index).trim().toLowerCase();
              String real = mappingItem.substring(index + 1).trim().toLowerCase();
              mappings.put(virtual, real);
            }
        }
    }
  
    /***
     * Map any virtual recipients to real recipients using the configured mapping.
     * 
     * @param recipientsMap the mapping of virtual to real recipients
     */
    protected void mapRecipients(Map recipientsMap) throws MessagingException {
        Collection recipients = recipientsMap.keySet();  
          
        for (Iterator i = recipients.iterator(); i.hasNext(); ) {
            MailAddress source = (MailAddress)i.next();
            String user = source.getUser().toLowerCase();
            String domain = source.getHost().toLowerCase();
      
            String targetString = getTargetString(user, domain);
            
            if (targetString != null) {
                recipientsMap.put(source, targetString);
           }
       }
   }
 
   /***
    * Returns the real recipient given a virtual username and domain.
    * 
    * @param user the virtual user
    * @param domain the virtual domain
    * @return the real recipient address, or <code>null</code> if no mapping exists
    */
   private String getTargetString(String user, String domain) {
       StringBuffer buf;
       String target;
       
       //Look for exact (user@domain) match
       buf = new StringBuffer().append(user).append("@").append(domain);
       target = (String)mappings.get(buf.toString());
       if (target != null) {
           return target;
       }
       
       //Look for user@* match
       buf = new StringBuffer().append(user).append("@*");
       target = (String)mappings.get(buf.toString());
       if (target != null) {
           return target;
       }
       
       //Look for *@domain match
       buf = new StringBuffer().append("*@").append(domain);
       target = (String)mappings.get(buf.toString());
       if (target != null) {
           return target;
       }
       
       return null;
   }
   
   public String getMailetInfo() {
       return "XML Virtual User Table mailet";
   }
 }