/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2011, QOS.ch. All rights reserved.
    *
    * This program and the accompanying materials are dual-licensed under
    * either the terms of the Eclipse Public License v1.0 as published by
    * the Eclipse Foundation
    *
    *   or (per the licensee's choosing)
   *
   * under the terms of the GNU Lesser General Public License version 2.1
   * as published by the Free Software Foundation.
   */
  package ch.qos.logback.classic.pattern;
  
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  import java.text.DateFormatSymbols;
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.Locale;
  
  import ch.qos.logback.classic.spi.ILoggingEvent;
  import ch.qos.logback.classic.util.LevelToSyslogSeverity;
  import ch.qos.logback.core.net.SyslogAppenderBase;
  
  public class SyslogStartConverter extends ClassicConverter {
  
    long lastTimestamp = -1;
    String timesmapStr = null;
    SimpleDateFormat simpleFormat;
    String localHostName;
    int facility;
  
    public void start() {
      int errorCount = 0;
      
      String facilityStr = getFirstOption();
      if (facilityStr == null) {
        addError("was expecting a facility string as an option");
        return;
      }
  
      facility = SyslogAppenderBase.facilityStringToint(facilityStr);
    
      localHostName = getLocalHostname();
      try {
        // hours should be in 0-23, see also http://jira.qos.ch/browse/LBCLASSIC-48
        simpleFormat = new SimpleDateFormat("MMM dd HH:mm:ss", new DateFormatSymbols(Locale.US));
      } catch (IllegalArgumentException e) {
        addError("Could not instantiate SimpleDateFormat", e);
        errorCount++;
      }
  
      if(errorCount == 0) {
        super.start();
      }
    }
  
    public String convert(ILoggingEvent event) {
      StringBuilder sb = new StringBuilder();
  
      int pri = facility + LevelToSyslogSeverity.convert(event);
    
      sb.append("<");
      sb.append(pri);
      sb.append(">");
      sb.append(computeTimeStampString(event.getTimeStamp()));
      sb.append(' ');
      sb.append(localHostName);
      sb.append(' ');
  
      return sb.toString();
    }
  
    /**
     * This method gets the network name of the machine we are running on.
     * Returns "UNKNOWN_LOCALHOST" in the unlikely case where the host name 
     * cannot be found.
     * @return String the name of the local host
     */
    public String getLocalHostname() {
      try {
        InetAddress addr = InetAddress.getLocalHost();
        return addr.getHostName();
      } catch (UnknownHostException uhe) {
        addError("Could not determine local host name", uhe);
        return "UNKNOWN_LOCALHOST";
      }
    }
  
    String computeTimeStampString(long now) {
      synchronized (this) {
        if (now != lastTimestamp) {
          lastTimestamp = now;
          timesmapStr = simpleFormat.format(new Date(now));
        }
        return timesmapStr;
      }
   }  
 }