/**
    * 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.core.net;
  
  import java.io.IOException;
  import java.io.OutputStream;
  import java.net.SocketException;
  import java.net.UnknownHostException;
  import java.nio.charset.Charset;
  
  import ch.qos.logback.core.AppenderBase;
  import ch.qos.logback.core.CoreConstants;
  import ch.qos.logback.core.Layout;
  
  /**
   * Base class for SyslogAppender.
   * 
   * @author Ceki Gülcü
   * 
   * @param <E>
   */
  public abstract class SyslogAppenderBase<E> extends AppenderBase<E> {
  
      final static String SYSLOG_LAYOUT_URL = CoreConstants.CODES_URL + "#syslog_layout";
      final static int MAX_MESSAGE_SIZE_LIMIT = 65000;
  
      Layout<E> layout;
      String facilityStr;
      String syslogHost;
      protected String suffixPattern;
      SyslogOutputStream sos;
      int port = SyslogConstants.SYSLOG_PORT;
      int maxMessageSize;
      Charset charset;
  
      public void start() {
          int errorCount = 0;
          if (facilityStr == null) {
              addError("The Facility option is mandatory");
              errorCount++;
          }
  
          if (charset == null) {
              // Using defaultCharset() preserves the previous behavior when String.getBytes()
              // was
              // called without arguments
              charset = Charset.defaultCharset();
          }
  
          try {
              sos = createOutputStream();
  
              final int systemDatagramSize = sos.getSendBufferSize();
              if (maxMessageSize == 0) {
                  maxMessageSize = Math.min(systemDatagramSize, MAX_MESSAGE_SIZE_LIMIT);
                  addInfo("Defaulting maxMessageSize to [" + maxMessageSize + "]");
              } else if (maxMessageSize > systemDatagramSize) {
                  addWarn("maxMessageSize of [" + maxMessageSize
                          + "] is larger than the system defined datagram size of [" + systemDatagramSize + "].");
                  addWarn("This may result in dropped logs.");
              }
          } catch (UnknownHostException e) {
              addError("Could not create SyslogWriter", e);
              errorCount++;
          } catch (SocketException e) {
              addWarn("Failed to bind to a random datagram socket. Will try to reconnect later.", e);
          }
  
          if (layout == null) {
              layout = buildLayout();
          }
  
          if (errorCount == 0) {
              super.start();
          }
      }
  
      abstract public SyslogOutputStream createOutputStream() throws UnknownHostException, SocketException;
  
      abstract public Layout<E> buildLayout();
  
      abstract public int getSeverityForEvent(Object eventObject);
  
      @Override
      protected void append(E eventObject) {
          if (!isStarted()) {
              return;
          }
 
         try {
             String msg = layout.doLayout(eventObject);
             if (msg == null) {
                 return;
             }
             if (msg.length() > maxMessageSize) {
                 msg = msg.substring(0, maxMessageSize);
             }
             sos.write(msg.getBytes(charset));
             sos.flush();
             postProcess(eventObject, sos);
         } catch (IOException ioe) {
             addError("Failed to send diagram to " + syslogHost, ioe);
         }
     }
 
     protected void postProcess(Object event, OutputStream sw) {
 
     }
 
     /**
      * Returns the integer value corresponding to the named syslog facility.
      * 
      * @throws IllegalArgumentException if the facility string is not recognized
      */
     static public int facilityStringToint(String facilityStr) {
         if ("KERN".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_KERN;
         } else if ("USER".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_USER;
         } else if ("MAIL".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_MAIL;
         } else if ("DAEMON".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_DAEMON;
         } else if ("AUTH".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_AUTH;
         } else if ("SYSLOG".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_SYSLOG;
         } else if ("LPR".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LPR;
         } else if ("NEWS".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_NEWS;
         } else if ("UUCP".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_UUCP;
         } else if ("CRON".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_CRON;
         } else if ("AUTHPRIV".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_AUTHPRIV;
         } else if ("FTP".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_FTP;
         } else if ("NTP".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_NTP;
         } else if ("AUDIT".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_AUDIT;
         } else if ("ALERT".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_ALERT;
         } else if ("CLOCK".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_CLOCK;
         } else if ("LOCAL0".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL0;
         } else if ("LOCAL1".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL1;
         } else if ("LOCAL2".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL2;
         } else if ("LOCAL3".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL3;
         } else if ("LOCAL4".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL4;
         } else if ("LOCAL5".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL5;
         } else if ("LOCAL6".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL6;
         } else if ("LOCAL7".equalsIgnoreCase(facilityStr)) {
             return SyslogConstants.LOG_LOCAL7;
         } else {
             throw new IllegalArgumentException(facilityStr + " is not a valid syslog facility string");
         }
     }
 
     /**
      * Returns the value of the <b>SyslogHost</b> option.
      */
     public String getSyslogHost() {
         return syslogHost;
     }
 
     /**
      * The <b>SyslogHost</b> option is the name of the syslog host where log
      * output should go.
      * 
      * <b>WARNING</b> If the SyslogHost is not set, then this appender will fail.
      */
     public void setSyslogHost(String syslogHost) {
         this.syslogHost = syslogHost;
     }
 
     /**
      * Returns the string value of the <b>Facility</b> option.
      * 
      * See {@link #setFacility} for the set of allowed values.
      */
     public String getFacility() {
         return facilityStr;
     }
 
     /**
      * The <b>Facility</b> option must be set one of the strings KERN, USER, MAIL,
      * DAEMON, AUTH, SYSLOG, LPR, NEWS, UUCP, CRON, AUTHPRIV, FTP, NTP, AUDIT,
      * ALERT, CLOCK, LOCAL0, LOCAL1, LOCAL2, LOCAL3, LOCAL4, LOCAL5, LOCAL6, LOCAL7.
      * Case is not important.
      * 
      * <p>
      * See {@link ch.qos.logback.core.net.SyslogConstants SyslogConstants} and RFC
      * 3164 for more information about the <b>Facility</b> option.
      */
     public void setFacility(String facilityStr) {
         if (facilityStr != null) {
             facilityStr = facilityStr.trim();
         }
         this.facilityStr = facilityStr;
     }
 
     /**
      * 
      * @return
      */
     public int getPort() {
         return port;
     }
 
     /**
      * The port number on the syslog server to connect to. Normally, you would not
      * want to change the default value, that is 514.
      */
     public void setPort(int port) {
         this.port = port;
     }
 
     public int getMaxMessageSize() {
         return maxMessageSize;
     }
 
     /**
      * Maximum size for the syslog message (in characters); messages longer than
      * this are truncated. The default value is 65400 (which is near the maximum for
      * syslog-over-UDP). Note that the value is characters; the number of bytes may
      * vary if non-ASCII characters are present.
      */
     public void setMaxMessageSize(int maxMessageSize) {
         this.maxMessageSize = maxMessageSize;
     }
 
     public Layout<E> getLayout() {
         return layout;
     }
 
     public void setLayout(Layout<E> layout) {
         addWarn("The layout of a SyslogAppender cannot be set directly. See also " + SYSLOG_LAYOUT_URL);
     }
 
     @Override
     public void stop() {
         if (sos != null) {
             sos.close();
         }
         super.stop();
     }
 
     /**
      * See {@link #setSuffixPattern #setSuffixPattern(String)}.
      * 
      * @return
      */
     public String getSuffixPattern() {
         return suffixPattern;
     }
 
     /**
      * The <b>suffixPattern</b> option specifies the format of the non-standardized
      * part of the message sent to the syslog server.
      * 
      * @param suffixPattern
      */
     public void setSuffixPattern(String suffixPattern) {
         this.suffixPattern = suffixPattern;
     }
 
     /**
      * Returns the Charset used to encode String messages into byte sequences when
      * writing to syslog.
      */
     public Charset getCharset() {
         return charset;
     }
 
     /**
      * The Charset to use when encoding messages into byte sequences.
      *
      * @param charset
      */
     public void setCharset(Charset charset) {
         this.charset = charset;
     }
 }