/*
 * 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.spi.LoggingEvent;
import org.apache.log4j.Layout;
import org.apache.log4j.helpers.SyslogWriter;
import org.apache.log4j.helpers.SyslogQuietWriter;

// Contributors: Yves Bossel 
//               Christopher Taylor 

/**
    Use SyslogAppender to send log messages to a remote syslog daemon.

    @author Ceki Gülcü
    @author Anders Kristensen
 */
public class SyslogAppender extends AppenderSkeleton {
  // The following constants are extracted from a syslog.h file
  // copyrighted by the Regents of the University of California
  // I hope nobody at Berkley gets offended.

  /** Kernel messages */
  final static public int LOG_KERN     = 0;
  /** Random user-level messages */
  final static public int LOG_USER     = 1<<3;
  /** Mail system */
  final static public int LOG_MAIL     = 2<<3;
  /** System daemons */
  final static public int LOG_DAEMON   = 3<<3;
  /** security/authorization messages */
  final static public int LOG_AUTH     = 4<<3;
  /** messages generated internally by syslogd */
  final static public int LOG_SYSLOG   = 5<<3;

  /** line printer subsystem */
  final static public int LOG_LPR      = 6<<3;
  /** network news subsystem */
  final static public int LOG_NEWS     = 7<<3;
  /** UUCP subsystem */
  final static public int LOG_UUCP     = 8<<3;
  /** clock daemon */
  final static public int LOG_CRON     = 9<<3;
  /** security/authorization  messages (private) */
  final static public int LOG_AUTHPRIV = 10<<3;
  /** ftp daemon */
  final static public int LOG_FTP      = 11<<3;

  // other codes through 15 reserved for system use
  /** reserved for local use */
  final static public int LOG_LOCAL0 = 16<<3;
  /** reserved for local use */
  final static public int LOG_LOCAL1 = 17<<3;
  /** reserved for local use */
  final static public int LOG_LOCAL2 = 18<<3;
  /** reserved for local use */
  final static public int LOG_LOCAL3 = 19<<3;
  /** reserved for local use */
  final static public int LOG_LOCAL4 = 20<<3;
  /** reserved for local use */
  final static public int LOG_LOCAL5 = 21<<3;
  /** reserved for local use */
  final static public int LOG_LOCAL6 = 22<<3;
  /** reserved for local use*/
  final static public int LOG_LOCAL7 = 23<<3;

  protected static final int SYSLOG_HOST_OI = 0;
  protected static final int FACILITY_OI = 1;

  static final String TAB = "    ";

  // Have LOG_USER as default
  int syslogFacility = LOG_USER;
  String facilityStr;
  boolean facilityPrinting = false;

  //SyslogTracerPrintWriter stp;
  SyslogQuietWriter sqw;
  String syslogHost;

  public
  SyslogAppender() {
    this.initSyslogFacilityStr();
  }

  public
  SyslogAppender(Layout layout, int syslogFacility) {
    this.layout = layout;
    this.syslogFacility = syslogFacility;
    this.initSyslogFacilityStr();
  }

  public
  SyslogAppender(Layout layout, String syslogHost, int syslogFacility) {
    this(layout, syslogFacility);
    setSyslogHost(syslogHost);
  }

  /**
     Release any resources held by this SyslogAppender.

     @since 0.8.4
   */
  synchronized
  public
  void close() {
    closed = true;
    // A SyslogWriter is UDP based and needs no opening. Hence, it
    // can't be closed. We just unset the variables here.
    sqw = null;
  }

  private
  void initSyslogFacilityStr() {
    facilityStr = getFacilityString(this.syslogFacility);

    if (facilityStr == null) {
      System.err.println("\"" + syslogFacility +
                  "\" is an unknown syslog facility. Defaulting to \"USER\".");
      this.syslogFacility = LOG_USER;
      facilityStr = "user:";
    } else {
      facilityStr += ":";
    }
  }

  /**
     Returns the specified syslog facility as a lower-case String,
     e.g. "kern", "user", etc.
  */
  public
  static
  String getFacilityString(int syslogFacility) {
    switch(syslogFacility) {
    case LOG_KERN:      return "kern";
    case LOG_USER:      return "user";
    case LOG_MAIL:      return "mail";
    case LOG_DAEMON:    return "daemon";
    case LOG_AUTH:      return "auth";
    case LOG_SYSLOG:    return "syslog";
    case LOG_LPR:       return "lpr";
    case LOG_NEWS:      return "news";
    case LOG_UUCP:      return "uucp";
    case LOG_CRON:      return "cron";
    case LOG_AUTHPRIV:  return "authpriv";
    case LOG_FTP:       return "ftp";
    case LOG_LOCAL0:    return "local0";
    case LOG_LOCAL1:    return "local1";
    case LOG_LOCAL2:    return "local2";
    case LOG_LOCAL3:    return "local3";
    case LOG_LOCAL4:    return "local4";
    case LOG_LOCAL5:    return "local5";
    case LOG_LOCAL6:    return "local6";
    case LOG_LOCAL7:    return "local7";
    default:            return null;
    }
  }

  /**
     Returns the integer value corresponding to the named syslog
     facility, or -1 if it couldn't be recognized.

     @param facilityName one of the strings KERN, USER, MAIL, DAEMON,
            AUTH, SYSLOG, LPR, NEWS, UUCP, CRON, AUTHPRIV, FTP, LOCAL0,
            LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
            The matching is case-insensitive.

     @since 1.1
  */
  public
  static
  int getFacility(String facilityName) {
    if(facilityName != null) {
      facilityName = facilityName.trim();
    }
    if("KERN".equalsIgnoreCase(facilityName)) {
      return LOG_KERN;
    } else if("USER".equalsIgnoreCase(facilityName)) {
      return LOG_USER;
    } else if("MAIL".equalsIgnoreCase(facilityName)) {
      return LOG_MAIL;
    } else if("DAEMON".equalsIgnoreCase(facilityName)) {
      return LOG_DAEMON;
    } else if("AUTH".equalsIgnoreCase(facilityName)) {
      return LOG_AUTH;
    } else if("SYSLOG".equalsIgnoreCase(facilityName)) {
      return LOG_SYSLOG;
    } else if("LPR".equalsIgnoreCase(facilityName)) {
      return LOG_LPR;
    } else if("NEWS".equalsIgnoreCase(facilityName)) {
      return LOG_NEWS;
    } else if("UUCP".equalsIgnoreCase(facilityName)) {
      return LOG_UUCP;
    } else if("CRON".equalsIgnoreCase(facilityName)) {
      return LOG_CRON;
    } else if("AUTHPRIV".equalsIgnoreCase(facilityName)) {
      return LOG_AUTHPRIV;
    } else if("FTP".equalsIgnoreCase(facilityName)) {
      return LOG_FTP;
    } else if("LOCAL0".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL0;
    } else if("LOCAL1".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL1;
    } else if("LOCAL2".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL2;
    } else if("LOCAL3".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL3;
    } else if("LOCAL4".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL4;
    } else if("LOCAL5".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL5;
    } else if("LOCAL6".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL6;
    } else if("LOCAL7".equalsIgnoreCase(facilityName)) {
      return LOG_LOCAL7;
    } else {
      return -1;
    }
  }

  public
  void append(LoggingEvent event) {

    if(!isAsSevereAsThreshold(event.getLevel()))
      return;

    // We must not attempt to append if sqw is null.
    if(sqw == null) {
      errorHandler.error("No syslog host is set for SyslogAppedender named \""+
			this.name+"\".");
      return;
    }

    String buffer = (facilityPrinting? facilityStr : "") +
                          layout.format(event);

    sqw.setLevel(event.getLevel().getSyslogEquivalent());
    sqw.write(buffer);

    String[] s = event.getThrowableStrRep();
    if (s != null) {
      int len = s.length;
      if(len > 0) {
	sqw.write(s[0]);

	for(int i = 1; i < len; i++) {
	    sqw.write(TAB+s[i].substring(1));
	}
      }

    }
  }

  /**
     This method returns immediately as options are activated when they
     are set.
  */
  public
  void activateOptions() {
  }

  /**
     The SyslogAppender requires a layout. Hence, this method returns
     true.

     @since 0.8.4 */
  public
  boolean requiresLayout() {
    return true;
  }

  /**
    The SyslogHost option is the name of the the syslog host
    where log output should go.

    WARNING If the SyslogHost is not set, then this appender
    will fail.
   */
  public
  void setSyslogHost(String syslogHost) {
    this.sqw = new SyslogQuietWriter(new SyslogWriter(syslogHost),
				     syslogFacility, errorHandler);
    //this.stp = new SyslogTracerPrintWriter(sqw);
    this.syslogHost = syslogHost;
  }

  /**
     Returns the value of the SyslogHost option.
   */
  public
  String getSyslogHost() {
    return syslogHost;
  }

  /**
     Set the syslog facility. This is the Facility option.

     
The facilityName parameter must be one of the
     strings KERN, USER, MAIL, DAEMON, AUTH, SYSLOG, LPR, NEWS, UUCP,
     CRON, AUTHPRIV, FTP, LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4,
     LOCAL5, LOCAL6, LOCAL7. Case is unimportant.

     @since 0.8.1 */
  public
  void setFacility(String facilityName) {
    if(facilityName == null)
      return;

    syslogFacility = getFacility(facilityName);
    if (syslogFacility == -1) {
      System.err.println("["+facilityName +
                  "] is an unknown syslog facility. Defaulting to [USER].");
      syslogFacility = LOG_USER;
    }

    this.initSyslogFacilityStr();

    // If there is already a sqw, make it use the new facility.
    if(sqw != null) {
      sqw.setSyslogFacility(this.syslogFacility);
    }
  }

  /**
     Returns the value of the Facility option.
   */
  public
  String getFacility() {
    return getFacilityString(syslogFacility);
  }

  /**
    If the FacilityPrinting option is set to true, the printed
    message will include the facility name of the application. It is
    false by default.
   */
  public
  void setFacilityPrinting(boolean on) {
    facilityPrinting = on;
  }

  /**
     Returns the value of the FacilityPrinting option.
   */
  public
  boolean getFacilityPrinting() {
    return facilityPrinting;
  }
}