/*
 * Copyright (C) The Apache Software Foundation. All rights reserved.
 *
 * This software is published under the terms of the Apache Software
 * License version 1.1, a copy of which has been included with this
 * distribution in the LICENSE.txt file.  */

package org.apache.log4j.net;

import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.Level;
import org.apache.log4j.helpers.CyclicBuffer;
import org.apache.log4j.helpers.OptionConverter;
import org.apache.log4j.helpers.LogLog;
import org.apache.log4j.spi.LoggingEvent;
import org.apache.log4j.spi.ErrorCode;
import org.apache.log4j.spi.TriggeringEventEvaluator;
import java.util.Properties;
import java.util.Date;

import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import javax.mail.Multipart;
import javax.mail.internet.MimeMultipart;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.AddressException;

/**
   Send an e-mail when a specific logging event occurs, typically on
   errors or fatal errors.

   
The number of logging events delivered in this e-mail depend on
   the value of BufferSize option. The
   SMTPAppender keeps only the last
   BufferSize logging events in its cyclic buffer. This
   keeps memory requirements at a reasonable level while still
   delivering useful application context.

   @author Ceki Gülcü
   @since 1.0 */
public class SMTPAppender extends AppenderSkeleton {
  private String to;
  private String from;
  private String subject;
  private String smtpHost;
  private int bufferSize = 512;
  private boolean locationInfo = false;

  protected CyclicBuffer cb = new CyclicBuffer(bufferSize);
  protected Message msg;

  protected TriggeringEventEvaluator evaluator;



  /**
     The default constructor will instantiate the appender with a
     {@link TriggeringEventEvaluator} that will trigger on events with
     level ERROR or higher.*/
  public
  SMTPAppender() {
    this(new DefaultEvaluator());
  }


  /**
     Use evaluator passed as parameter as the {@link
     TriggeringEventEvaluator} for this SMTPAppender.  */
  public
  SMTPAppender(TriggeringEventEvaluator evaluator) {
    this.evaluator = evaluator;
  }


  /**
     Activate the specified options, such as the smtp host, the
     recipient, from, etc. */
  public
  void activateOptions() {
    Properties props = new Properties (System.getProperties());
    if (smtpHost != null)
      props.put("mail.smtp.host", smtpHost);


    Session session = Session.getInstance(props, null);
    //session.setDebug(true);
    msg = new MimeMessage(session);

     try {
       if (from != null)
	 msg.setFrom(getAddress(from));
       else
	 msg.setFrom();

       msg.setRecipients(Message.RecipientType.TO, parseAddress(to));
       if(subject != null)
	 msg.setSubject(subject);
     } catch(MessagingException e) {
       LogLog.error("Could not activate SMTPAppender options.", e );
     }
  }

  /**
     Perform SMTPAppender specific appending actions, mainly adding
     the event to a cyclic buffer and checking if the event triggers
     an e-mail to be sent. */
  public
  void append(LoggingEvent event) {

    if(!checkEntryConditions()) {
      return;
    }

    event.getThreadName();
    event.getNDC();
    if(locationInfo) {
      event.getLocationInformation();
    }
    cb.add(event);
    if(evaluator.isTriggeringEvent(event)) {
      sendBuffer();
    }
  }

 /**
     This method determines if there is a sense in attempting to append.

     
It checks whether there is a set output target and also if
     there is a set layout. If these checks fail, then the boolean
     value false is returned. */
  protected
  boolean checkEntryConditions() {
    if(this.msg == null) {
      errorHandler.error("Message object not configured.");
      return false;
    }

    if(this.evaluator == null) {
      errorHandler.error("No TriggeringEventEvaluator is set for appender ["+
			 name+"].");
      return false;
    }


    if(this.layout == null) {
      errorHandler.error("No layout set for appender named ["+name+"].");
      return false;
    }
    return true;
  }


  synchronized
  public
  void close() {
    this.closed = true;
  }

  InternetAddress getAddress(String addressStr) {
    try {
      return new InternetAddress(addressStr);
    } catch(AddressException e) {
      errorHandler.error("Could not parse address ["+addressStr+"].", e,
			 ErrorCode.ADDRESS_PARSE_FAILURE);
      return null;
    }
  }

  InternetAddress[] parseAddress(String addressStr) {
    try {
      return InternetAddress.parse(addressStr, true);
    } catch(AddressException e) {
      errorHandler.error("Could not parse address ["+addressStr+"].", e,
			 ErrorCode.ADDRESS_PARSE_FAILURE);
      return null;
    }
  }

  /**
     Returns value of the To option.
   */
  public
  String getTo() {
    return to;
  }


  /**
     The SMTPAppender requires a {@link
     org.apache.log4j.Layout layout}.  */
  public
  boolean requiresLayout() {
    return true;
  }

  /**
     Send the contents of the cyclic buffer as an e-mail message.
   */
  protected
  void sendBuffer() {

    // Note: this code already owns the monitor for this
    // appender. This frees us from needing to synchronize on 'cb'.
    try {
      MimeBodyPart part = new MimeBodyPart();

      StringBuffer sbuf = new StringBuffer();
      String t = layout.getHeader();
      if(t != null)
	sbuf.append(t);
      int len =  cb.length();
      for(int i = 0; i < len; i++) {
	//sbuf.append(MimeUtility.encodeText(layout.format(cb.get())));
	LoggingEvent event = cb.get();
	sbuf.append(layout.format(event));
	if(layout.ignoresThrowable()) {
	  String[] s = event.getThrowableStrRep();
	  if (s != null) {
	    for(int j = 0; j < s.length; j++) {
	      sbuf.append(s[j]);
	    }
	  }
	}
      }
      t = layout.getFooter();
      if(t != null)
	sbuf.append(t);
      part.setContent(sbuf.toString(), layout.getContentType());

      Multipart mp = new MimeMultipart();
      mp.addBodyPart(part);
      msg.setContent(mp);

      msg.setSentDate(new Date());
      Transport.send(msg);
    } catch(Exception e) {
      LogLog.error("Error occured while sending e-mail notification.", e);
    }
  }



  /**
     Returns value of the EvaluatorClass option.
   */
  public
  String getEvaluatorClass() {
    return evaluator == null ? null : evaluator.getClass().getName();
  }

  /**
     Returns value of the From option.
   */
  public
  String getFrom() {
    return from;
  }

  /**
     Returns value of the Subject option.
   */
  public
  String getSubject() {
    return subject;
  }

  /**
     The From option takes a string value which should be a
     e-mail address of the sender.
   */
  public
  void setFrom(String from) {
    this.from = from;
  }

  /**
     The Subject option takes a string value which should be a
     the subject of the e-mail message.
   */
  public
  void setSubject(String subject) {
    this.subject = subject;
  }


  /**
     The BufferSize option takes a positive integer
     representing the maximum number of logging events to collect in a
     cyclic buffer. When the BufferSize is reached,
     oldest events are deleted as new events are added to the
     buffer. By default the size of the cyclic buffer is 512 events.
   */
  public
  void setBufferSize(int bufferSize) {
    this.bufferSize = bufferSize;
    cb.resize(bufferSize);
  }

  /**
     The SMTPHost option takes a string value which should be a
     the host name of the SMTP server that will send the e-mail message.
   */
  public
  void setSMTPHost(String smtpHost) {
    this.smtpHost = smtpHost;
  }

  /**
     Returns value of the SMTPHost option.
   */
  public
  String getSMTPHost() {
    return smtpHost;
  }

  /**
     The To option takes a string value which should be a
     comma separated list of e-mail address of the recipients.
   */
  public
  void setTo(String to) {
    this.to = to;
  }



  /**
     Returns value of the BufferSize option.
   */
  public
  int getBufferSize() {
    return bufferSize;
  }

  /**
     The EvaluatorClass option takes a string value
     representing the name of the class implementing the {@link
     TriggeringEventEvaluator} interface. A corresponding object will
     be instantiated and assigned as the triggering event evaluator
     for the SMTPAppender.
   */
  public
  void setEvaluatorClass(String value) {
      evaluator = (TriggeringEventEvaluator)
                OptionConverter.instantiateByClassName(value,
					   TriggeringEventEvaluator.class,
						       evaluator);
  }


  /**
     The LocationInfo option takes a boolean value. By
     default, it is set to false which means there will be no effort
     to extract the location information related to the event. As a
     result, the layout that formats the events as they are sent out
     in an e-mail is likely to place the wrong location information
     (if present in the format).

     
Location information extraction is comparatively very slow and
     should be avoided unless performance is not a concern.
   */
  public
  void setLocationInfo(boolean locationInfo) {
    this.locationInfo = locationInfo;
  }

  /**
     Returns value of the LocationInfo option.
   */
  public
  boolean getLocationInfo() {
    return locationInfo;
  }
}

class DefaultEvaluator implements TriggeringEventEvaluator {
  /**
     Is this event the e-mail triggering event?

     
This method returns true, if the event level
     has ERROR level or higher. Otherwise it returns
     false. */
  public
  boolean isTriggeringEvent(LoggingEvent event) {
    return event.level.isGreaterOrEqual(Level.ERROR);
  }
}