/**
    * 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.core.net;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.net.DatagramPacket;
  import java.net.DatagramSocket;
  import java.net.InetAddress;
  import java.net.SocketException;
  import java.net.UnknownHostException;
  
  /**
   * SyslogOutputStream is a wrapper around the {@link DatagramSocket} class so that it
   * behaves like an {@link OutputStream}.
   */
  public class SyslogOutputStream extends OutputStream {
  
    /**
     * The maximum length after which we discard the existing string buffer and
     * start anew.
     */
    private static final int MAX_LEN = 1024;
  
    private InetAddress address;
    private DatagramSocket ds;
    private ByteArrayOutputStream baos = new ByteArrayOutputStream();
    final private int port;
  
    public SyslogOutputStream(String syslogHost, int port) throws UnknownHostException,
        SocketException {
      this.address = InetAddress.getByName(syslogHost);
      this.port = port;
      this.ds = new DatagramSocket();
    }
  
    public void write(byte[] byteArray, int offset, int len) throws IOException {
      baos.write(byteArray, offset, len);
    }
  
    public void flush() throws IOException {
      byte[] bytes = baos.toByteArray();
      DatagramPacket packet = new DatagramPacket(bytes, bytes.length, address,
          port);
  
      // clean up for next round
      if (baos.size() > MAX_LEN) {
        baos = new ByteArrayOutputStream();
      } else {
        baos.reset();
      }
      
      // after a failure, it can happen that bytes.length is zero
      // in that case, there is no point in sending out an empty message/
      if(bytes.length == 0) {
        return;
      }
      if (this.ds != null) {
        ds.send(packet);
      }
    
    }
  
    public void close() {
      address = null;
      ds = null;
    }
  
    public int getPort() {
      return port;
    }
  
    @Override
    public void write(int b) throws IOException {
      baos.write(b);
    }
  
  }