/**
    * 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.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);
      }
  
      int getSendBufferSize() throws SocketException {
          return ds.getSendBufferSize();
      }
  }