/**
    * Logback: the reliable, generic, fast and flexible logging framework.
    * Copyright (C) 1999-2015, 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.SimpleDateFormat;
  import java.util.Calendar;
  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 simpleMonthFormat;
      SimpleDateFormat simpleTimeFormat;
      private final Calendar calendar = Calendar.getInstance(Locale.US);
  
      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
              simpleMonthFormat = new SimpleDateFormat("MMM", Locale.US);
              simpleTimeFormat = new SimpleDateFormat("HH:mm:ss", 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) {
              // Since the formatted output is only precise to the second, we can use the same
              // cached string if the
             // current
             // second is the same (stripping off the milliseconds).
             if ((now / 1000) != lastTimestamp) {
                 lastTimestamp = now / 1000;
                 Date nowDate = new Date(now);
                 calendar.setTime(nowDate);
                 timesmapStr = String.format("%s %2d %s", simpleMonthFormat.format(nowDate),
                         calendar.get(Calendar.DAY_OF_MONTH), simpleTimeFormat.format(nowDate));
             }
             return timesmapStr;
         }
     }
 }