/****************************************************************
    * Licensed to the Apache Software Foundation (ASF) under one   *
    * or more contributor license agreements.  See the NOTICE file *
    * 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   *
    *                                                              *
   *   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.pop3server;
  
  import org.apache.james.util.stream.ExtraDotOutputStream;
  import org.apache.james.util.watchdog.BytesWrittenResetOutputStream;
  import org.apache.mailet.Mail;
  
  import javax.mail.MessagingException;
  import javax.mail.internet.MimeMessage;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.OutputStream;
  import java.util.Enumeration;
  
  /**
    * Handles TOP command
    */
  public class TopCmdHandler implements CommandHandler {
  
      /**
       * @see org.apache.james.pop3server.CommandHandler#onCommand(POP3Session)
       */
      public void onCommand(POP3Session session) {
          doTOP(session,session.getCommandArgument());
      }
  
      /**
       * Handler method called upon receipt of a TOP command.
       * This command retrieves the top N lines of a specified
       * message in the mailbox.
       *
       * The expected command format is
       *  TOP [mail message number] [number of lines to return]
       *
       * @param arguments the first argument parsed by the parseCommand method
       */
      private void doTOP(POP3Session session,String arguments) {
          String responseString = null;
          
          if (arguments == null) {
              responseString = POP3Handler.ERR_RESPONSE + " Usage: TOP [mail number] [Line number]";
              session.writeResponse(responseString);
              return;
          }
          
          String argument = "";
          String argument1 = "";
          int pos = arguments.indexOf(" ");
          if (pos > 0) {
              argument = arguments.substring(0,pos);
              argument1 = arguments.substring(pos+1);
          }
  
          if (session.getHandlerState() == POP3Handler.TRANSACTION) {
              int num = 0;
              int lines = 0;
              try {
                  num = Integer.parseInt(argument);
                  lines = Integer.parseInt(argument1);
              } catch (NumberFormatException nfe) {
                  responseString = POP3Handler.ERR_RESPONSE + " Usage: TOP [mail number] [Line number]";
                  session.writeResponse(responseString);
                  return;
              }
              try {
                  Mail mc = (Mail) session.getUserMailbox().get(num);
                  if (mc != POP3Handler.DELETED) {
                      responseString = POP3Handler.OK_RESPONSE + " Message follows";
                      session.writeResponse(responseString);
                      try {
                          for (Enumeration e = mc.getMessage().getAllHeaderLines(); e.hasMoreElements(); ) {
                              session.writeResponse(e.nextElement().toString());
                          }
                          session.writeResponse("");
                          ExtraDotOutputStream edouts =
                                  new ExtraDotOutputStream(session.getOutputStream());
                          OutputStream nouts = new BytesWrittenResetOutputStream(edouts,
                                                                   session.getWatchdog(),
                                                                   session.getConfigurationData().getResetLength());
                         writeMessageContentTo(mc.getMessage(),nouts,lines);
                         nouts.flush();
                         edouts.checkCRLFTerminator();
                         edouts.flush();
                     } finally {
                         session.writeResponse(".");
                     }
                 } else {
                     StringBuffer responseBuffer =
                         new StringBuffer(64)
                                 .append(POP3Handler.ERR_RESPONSE)
                                 .append(" Message (")
                                 .append(num)
                                 .append(") already deleted.");
                     responseString = responseBuffer.toString();
                     session.writeResponse(responseString);
                 }
             } catch (IOException ioe) {
                 responseString = POP3Handler.ERR_RESPONSE + " Error while retrieving message.";
                 session.writeResponse(responseString);
             } catch (MessagingException me) {
                 responseString = POP3Handler.ERR_RESPONSE + " Error while retrieving message.";
                 session.writeResponse(responseString);
             } catch (IndexOutOfBoundsException iob) {
                 StringBuffer exceptionBuffer =
                     new StringBuffer(64)
                             .append(POP3Handler.ERR_RESPONSE)
                             .append(" Message (")
                             .append(num)
                             .append(") does not exist.");
                 responseString = exceptionBuffer.toString();
                 session.writeResponse(responseString);
             }
         } else {
             responseString = POP3Handler.ERR_RESPONSE;
             session.writeResponse(responseString);
         }
     }
 
 
     /**
      * Writes the content of the message, up to a total number of lines, out to 
      * an OutputStream.
      *
      * @param out the OutputStream to which to write the content
      * @param lines the number of lines to write to the stream
      *
      * @throws MessagingException if the MimeMessage is not set for this MailImpl
      * @throws IOException if an error occurs while reading or writing from the stream
      */
     public void writeMessageContentTo(MimeMessage message, OutputStream out, int lines)
         throws IOException, MessagingException {
         String line;
         BufferedReader br;
         if (message != null) {
             br = new BufferedReader(new InputStreamReader(message.getRawInputStream()));
             try {
                 while (lines-- > 0) {
                     if ((line = br.readLine()) == null) {
                         break;
                     }
                     line += "\r\n";
                     out.write(line.getBytes());
                 }
             } finally {
                 br.close();
             }
         } else {
             throw new MessagingException("No message set for this MailImpl.");
         }
     }
 
 }