/**
 * 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();
  }
}
