/************************************************************************
    * Copyright (c) 2000-2006 The Apache Software Foundation.             *
    * All rights reserved.                                                *
    * ------------------------------------------------------------------- *
    * Licensed 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:                                *
    *                                                                     *
    *     http://www.apache.org/licenses/LICENSE-2.0                      *
   *                                                                     *
   * Unless required by applicable law or agreed to in writing, software *
   * distributed under the License is distributed on an "AS IS" BASIS,   *
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or     *
   * implied.  See the License for the specific language governing       *
   * permissions and limitations under the License.                      *
   ***********************************************************************/
  
  package org.apache.james.transport.mailets;
  
  import org.apache.james.core.MailImpl;
  import org.apache.james.util.XMLResources;
  import org.apache.mailet.GenericMailet;
  import org.apache.mailet.Mail;
  import org.apache.mailet.MailAddress;
  import org.apache.oro.text.regex.MatchResult;
  import org.apache.oro.text.regex.Pattern;
  import org.apache.oro.text.regex.Perl5Compiler;
  import org.apache.oro.text.regex.Perl5Matcher;
  
  import javax.mail.MessagingException;
  import javax.mail.internet.ParseException;
  
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.StringTokenizer;
  
  /***
   * Provides an abstraction of common functionality needed for implementing
   * a Virtual User Table. Override the <code>mapRecipients</code> method to
   * map virtual recipients to real recipients.
   */
  public abstract class AbstractVirtualUserTable extends GenericMailet
  {
      static private final String MARKER = "org.apache.james.transport.mailets.AbstractVirtualUserTable.mapped";
  
      /***
       * Checks the recipient list of the email for user mappings.  Maps recipients as
       * appropriate, modifying the recipient list of the mail and sends mail to any new
       * non-local recipients.
       *
       * @param mail the mail to process
       */
      public void service(Mail mail) throws MessagingException
      {
          if (mail.getAttribute(MARKER) != null) {
              mail.removeAttribute(MARKER);
              return;
          }
  
          Collection recipientsToRemove = new HashSet();
          Collection recipientsToAddLocal = new ArrayList();
          Collection recipientsToAddForward = new ArrayList();
  
          Collection recipients = mail.getRecipients();
          Map recipientsMap = new HashMap(recipients.size());
  
          for (Iterator iter = recipients.iterator(); iter.hasNext(); ) {
              MailAddress address = (MailAddress)iter.next();
  
              // Assume all addresses are non-virtual at start
              recipientsMap.put(address, null);
          }
  
          mapRecipients(recipientsMap);
  
          for (Iterator iter = recipientsMap.keySet().iterator(); iter.hasNext(); ) {
              MailAddress source = (MailAddress)iter.next();
              String targetString = (String)recipientsMap.get(source);
  
              // Only non-null mappings are translated
              if(targetString != null) {
                  if (targetString.startsWith("error:")) {
                      //Mark this source address as an address to remove from the recipient list
                      recipientsToRemove.add(source);
                      processDSN(mail, source, targetString);
                  } else {
                      StringTokenizer tokenizer = new StringTokenizer(targetString, getSeparator(targetString));
  
                      while (tokenizer.hasMoreTokens()) {
                          String targetAddress = tokenizer.nextToken().trim();
  
                          // log("Attempting to map from " + source + " to " + targetAddress);
  
                          if (targetAddress.startsWith("regex:")) {
                              targetAddress = regexMap(mail, source, targetAddress);
                             if (targetAddress == null) continue;
                         }
 
                         try {
                             MailAddress target = (targetAddress.indexOf('@') < 0) ? new MailAddress(targetAddress, "localhost")
                                 : new MailAddress(targetAddress);
 
                             //Mark this source address as an address to remove from the recipient list
                             recipientsToRemove.add(source);
 
                             // We need to separate local and remote
                             // recipients.  This is explained below.
                             if (getMailetContext().isLocalServer(target.getHost())) {
                                 recipientsToAddLocal.add(target);
                             } else {
                                 recipientsToAddForward.add(target);
                             }
 
                             StringBuffer buf = new StringBuffer().append("Translating virtual user ")
                                                                  .append(source)
                                                                  .append(" to ")
                                                                  .append(target);
                             log(buf.toString());
 
                         } catch (ParseException pe) {
                             //Don't map this address... there's an invalid address mapping here
                             StringBuffer exceptionBuffer =
                                 new StringBuffer(128)
                                 .append("There is an invalid map from ")
                                 .append(source)
                                 .append(" to ")
                                 .append(targetAddress);
                             log(exceptionBuffer.toString());
                             continue;
                         }
                     }
                 }
             }
         }
 
         // Remove mapped recipients
         recipients.removeAll(recipientsToRemove);
 
         // Add mapped recipients that are local
         recipients.addAll(recipientsToAddLocal);
 
         // We consider an address that we map to be, by definition, a
         // local address.  Therefore if we mapped to a remote address,
         // then we want to make sure that the mail can be relayed.
         // However, the original e-mail would typically be subjected to
         // relay testing.  By posting a new mail back through the
         // system, we have a locally generated mail, which will not be
         // subjected to relay testing.
 
         // Forward to mapped recipients that are remote
         if (recipientsToAddForward.size() != 0) {
             // Can't use this ... some mappings could lead to an infinite loop
             // getMailetContext().sendMail(mail.getSender(), recipientsToAddForward, mail.getMessage());
 
             // duplicates the Mail object, to be able to modify the new mail keeping the original untouched
             MailImpl newMail = new MailImpl(mail,newName(mail));
             try {
                 try {
                     newMail.setRemoteAddr(java.net.InetAddress.getLocalHost().getHostAddress());
                     newMail.setRemoteHost(java.net.InetAddress.getLocalHost().getHostName());
                 } catch (java.net.UnknownHostException _) {
                     newMail.setRemoteAddr("127.0.0.1");
                     newMail.setRemoteHost("localhost");
                 }
                 newMail.setRecipients(recipientsToAddForward);
                 newMail.setAttribute(MARKER, Boolean.TRUE);
                 getMailetContext().sendMail(newMail);
             } finally {
                 newMail.dispose();
             }
         }
 
         // If there are no recipients left, Ghost the message
         if (recipients.size() == 0) {
             mail.setState(Mail.GHOST);
         }
     }
 
     /***
      * Override to map virtual recipients to real recipients, both local and non-local.
      * Each key in the provided map corresponds to a potential virtual recipient, stored as
      * a <code>MailAddress</code> object.
      * 
      * Translate virtual recipients to real recipients by mapping a string containing the
      * address of the real recipient as a value to a key. Leave the value <code>null<code>
      * if no mapping should be performed. Multiple recipients may be specified by delineating
      * the mapped string with commas, semi-colons or colons.
      * 
      * @param recipientsMap the mapping of virtual to real recipients, as 
      *    <code>MailAddress</code>es to <code>String</code>s.
      */
     protected abstract void mapRecipients(Map recipientsMap) throws MessagingException;
   
     /***
      * Sends the message for DSN processing
      *
      * @param mail the Mail instance being processed
      * @param address the MailAddress causing the DSN
      * @param error a String in the form "error:<code> <msg>"
      */
     private void processDSN(Mail mail, MailAddress address, String error) {
         // parse "error:<code> <msg>"
       int msgPos = error.indexOf(' ');
       try {
           Integer code = Integer.valueOf(error.substring("error:".length(),msgPos));
       } catch (NumberFormatException e) {
           log("Cannot send DSN.  Exception parsing DSN code from: " + error, e);
           return;
       }
       String msg = error.substring(msgPos + 1);
       // process bounce for "source" address
       try {
           getMailetContext().bounce(mail, error);
       }
       catch (MessagingException me) {
           log("Cannot send DSN.  Exception during DSN processing: ", me);
       }
   }
 
   /***
    * Processes regex virtual user mapping
    *
    * If a mapped target string begins with the prefix regex:, it must be
    * formatted as regex:<regular-expression>:<parameterized-string>,
    * e.g., regex:(.*)@(.*):${1}@tld
    *
    * @param mail the Mail instance being processed
    * @param address the MailAddress to be mapped
    * @param targetString a String specifying the mapping
    */
   private String regexMap(Mail mail, MailAddress address, String targetString) {
       String result = null;
 
       try {
           int msgPos = targetString.indexOf(':', "regex:".length() + 1);
 
           // log("regex: targetString = " + targetString);
           // log("regex: msgPos = " + msgPos);
           // log("regex: compile " + targetString.substring("regex:".length(), msgPos));
           // log("regex: address = " + address.toString());
           // log("regex: replace = " + targetString.substring(msgPos + 1));
 
           Pattern pattern = new Perl5Compiler().compile(targetString.substring("regex:".length(), msgPos));
           Perl5Matcher matcher = new Perl5Matcher();
 
           if (matcher.matches(address.toString(), pattern)) {
               MatchResult match = matcher.getMatch();
               Map parameters = new HashMap(match.groups());
               for (int i = 1; i < match.groups(); i++) {
                   parameters.put(Integer.toString(i), match.group(i));
               }
               result = XMLResources.replaceParameters(targetString.substring(msgPos + 1), parameters);
           }
       }
       catch (Exception e) {
           log("Exception during regexMap processing: ", e);
       }
 
       // log("regex: result = " + result);
       return result;
   }
 
   /***
    * Returns the character used to delineate multiple addresses.
    * 
    * @param targetString the string to parse
    * @return the character to tokenize on
    */
   private String getSeparator(String targetString) {
       return (targetString.indexOf(',') > -1 ? "," : (targetString.indexOf(';') > -1 ? ";" : (targetString.indexOf("regex:") > -1? "" : ":" )));
   }
 
   private static final java.util.Random random = new java.util.Random();  // Used to generate new mail names
 
   /***
    * Create a unique new primary key name.
    *
    * @param mail the mail to use as the basis for the new mail name
    * @return a new name
    */
   private String newName(Mail mail) throws MessagingException {
       String oldName = mail.getName();
 
         // Checking if the original mail name is too long, perhaps because of a
         // loop caused by a configuration error.
         // it could cause a "null pointer exception" in AvalonMailRepository much
         // harder to understand.
       if (oldName.length() > 76) {
           int count = 0;
           int index = 0;
           while ((index = oldName.indexOf('!', index + 1)) >= 0) {
               count++;
           }
             // It looks like a configuration loop. It's better to stop.
           if (count > 7) {
               throw new MessagingException("Unable to create a new message name: too long.  Possible loop in config.xml.");
           }
           else {
               oldName = oldName.substring(0, 76);
           }
       }
 
       StringBuffer nameBuffer =
                                new StringBuffer(64)
                                .append(oldName)
                                .append("-!")
                                .append(random.nextInt(1048576));
       return nameBuffer.toString();
   }
 }