/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    * 
    *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.apache.log4j.net;
  
  import java.io.IOException;
  import java.net.DatagramPacket;
  import java.net.InetAddress;
  import java.net.MulticastSocket;
  import java.net.UnknownHostException;
  import java.util.HashMap;
  import java.util.Hashtable;
  import java.util.Map;
  
  import org.apache.log4j.AppenderSkeleton;
  import org.apache.log4j.helpers.Constants;
  import org.apache.log4j.spi.LoggingEvent;
  import org.apache.log4j.helpers.LogLog;
  import org.apache.log4j.xml.XMLLayout;
  
  
  /**
   *  Multicast-based Appender.  Works in conjunction with the MulticastReceiver, which expects
   *  a LoggingEvent encoded using XMLLayout. 
   * 
   *  Sends log information as a multicast datagrams.
   *
   *  <p>Messages are not sent as LoggingEvent objects but as text after
   *  applying XMLLayout.
   *
   *  <p>The port and remoteHost properties can be set in configuration properties.
   *  By setting the remoteHost to a broadcast address any number of clients can
   *  listen for log messages.
   *
   *  <p>This was inspired and really extended/copied from {@link SocketAppender}.  Please
   *  see the docs for the proper credit to the authors of that class.
   *
   *  @author  <a href="mailto:kbrown@versatilesolutions.com">Kevin Brown</a>
   *  @author Scott Deboy &lt;sdeboy@apache.org&gt;
   * 
   */
  public class MulticastAppender extends AppenderSkeleton implements PortBased {
    /**
       The default port number for the multicast packets. (9991).
    */
    static final int DEFAULT_PORT = 9991;
  
    /**
     * The MulticastDNS zone advertised by a MulticastAppender
     * the MulticastAppender also adds a 'multicastAddress' property with the multicast address value as a string
     */
    public static final String ZONE = "_log4j_xml_mcast_appender.local.";
  
    /**
       We remember host name as String in addition to the resolved
       InetAddress so that it can be returned via getOption().
    */
    String hostname;
    String remoteHost;
    String application;
    int timeToLive;
    InetAddress address;
    int port = DEFAULT_PORT;
    MulticastSocket outSocket;
    private String encoding;
  
    private boolean locationInfo = false;
    private boolean advertiseViaMulticastDNS;
    private ZeroConfSupport zeroConf;
  
    public MulticastAppender() {
       super(false);
    }
  
    /**
       Open the multicast sender for the <b>RemoteHost</b> and <b>Port</b>.
    */
    public void activateOptions() {
      try {
        hostname = InetAddress.getLocalHost().getHostName();
      } catch (UnknownHostException uhe) {
        try {
          hostname = InetAddress.getLocalHost().getHostAddress();
        } catch (UnknownHostException uhe2) {
          hostname = "unknown";
       }
     }
 
     //allow system property of application to be primary
     if (application == null) {
       application = System.getProperty(Constants.APPLICATION_KEY);
     } else {
       if (System.getProperty(Constants.APPLICATION_KEY) != null) {
         application = application + "-" + System.getProperty(Constants.APPLICATION_KEY);
       }
     }
 
     if(remoteHost != null) {
       address = getAddressByName(remoteHost);
     } else {
       String err = "The RemoteHost property is required for MulticastAppender named "+ name;
       LogLog.error(err);
       throw new IllegalStateException(err);
     }
 
     if (layout == null) {
         layout = new XMLLayout();
     }
       
     if (advertiseViaMulticastDNS) {
         Map properties = new HashMap();
         properties.put("multicastAddress", remoteHost);
         zeroConf = new ZeroConfSupport(ZONE, port, getName(), properties);
         zeroConf.advertise();
     }
     connect();
     super.activateOptions();
   }
 
   /**
      Close this appender.
      <p>This will mark the appender as closed and
      call then {@link #cleanUp} method.
   */
   public synchronized void close() {
     if (closed) {
       return;
     }
 
     this.closed = true;
     if (advertiseViaMulticastDNS) {
         zeroConf.unadvertise();
     }
     cleanUp();
   }
 
   /**
      Close the Socket and release the underlying
      connector thread if it has been created
    */
   public void cleanUp() {
     if (outSocket != null) {
       try {
         outSocket.close();
       } catch (Exception e) {
         LogLog.error("Could not close outSocket.", e);
       }
 
       outSocket = null;
     }
   }
 
   void connect() {
     if (this.address == null) {
       return;
     }
 
     try {
       // First, close the previous connection if any.
       cleanUp();
       outSocket = new MulticastSocket();
       outSocket.setTimeToLive(timeToLive);
     } catch (IOException e) {
       LogLog.error("Error in connect method of MulticastAppender named "+name, e);
     }
   }
 
   public void append(LoggingEvent event) {
     if (event == null) {
       return;
     }
 
     if(locationInfo) {
 	   event.getLocationInformation();
 	}
 
     if (outSocket != null) {
         event.setProperty(Constants.HOSTNAME_KEY, hostname);
 
         if (application != null) {
           event.setProperty(Constants.APPLICATION_KEY, application);
         }
       
 		if(locationInfo) {
 		   event.getLocationInformation();
 		}
 
 
       try {
         StringBuffer buf = new StringBuffer(layout.format(event));
 
         byte[] payload;
         if(encoding == null) {
           payload = buf.toString().getBytes();
         } else {
           payload = buf.toString().getBytes(encoding);
         }
 
         DatagramPacket dp =
            new DatagramPacket(payload, payload.length, address, port);
         outSocket.send(dp);
       } catch (IOException e) {
         outSocket = null;
         LogLog.warn("Detected problem with Multicast connection: " + e);
       }
     }
   }
 
   InetAddress getAddressByName(String host) {
     try {
       return InetAddress.getByName(host);
     } catch (Exception e) {
       LogLog.error("Could not find address of [" + host + "].", e);
       return null;
     }
   }
 
   /**
      The <b>RemoteHost</b> option takes a string value which should be
      the host name or ipaddress to send the multicast packets.
    */
   public void setRemoteHost(String host) {
     remoteHost = host;
   }
 
   /**
      Returns value of the <b>RemoteHost</b> option.
    */
   public String getRemoteHost() {
     return remoteHost;
   }
 
   /**
   The <b>LocationInfo</b> option takes a boolean value. If true,
   the information sent to the remote host will include location
   information. By default no location information is sent to the server.
    */
   public void setLocationInfo(boolean locationInfo) {
 	  this.locationInfo = locationInfo;
   }
 
   /**
    * Returns value of the <b>LocationInfo</b> option.
    */
   public boolean getLocationInfo() {
 	  return locationInfo;
   }
 
   /**
       The <b>Encoding</b> option specifies how the bytes are encoded.  If this option is not specified, 
       the System encoding is used.
     */
    public void setEncoding(String encoding) {
      this.encoding = encoding;
    }
 
    /**
       Returns value of the <b>Encoding</b> option.
     */
    public String getEncoding() {
      return encoding;
    }
   /**
      The <b>App</b> option takes a string value which should be the name of the application getting logged.
      If property was already set (via system property), don't set here.
    */
   public void setApplication(String app) {
     this.application = app;
   }
 
   /**
      Returns value of the <b>App</b> option.
    */
   public String getApplication() {
     return application;
   }
 
   /**
      The <b>Time to live</b> option takes a positive integer representing
      the time to live value.
    */
   public void setTimeToLive(int timeToLive) {
     this.timeToLive = timeToLive;
   }
 
   /**
      Returns value of the <b>Time to Live</b> option.
    */
   public int getTimeToLive() {
     return timeToLive;
   }
 
   /**
      The <b>Port</b> option takes a positive integer representing
      the port where multicast packets will be sent.
    */
   public void setPort(int port) {
     this.port = port;
   }
 
   /**
      Returns value of the <b>Port</b> option.
    */
   public int getPort() {
     return port;
   }
 
   /* (non-Javadoc)
    * @see org.apache.log4j.net.NetworkBased#isActive()
    */
   public boolean isActive() {
     // TODO handle active/inactive
     return true;
   }
 
     /**
      * Gets whether appender requires a layout.
      * @return false
      */
   public boolean requiresLayout() {
       return true;
   }
 
   public boolean isAdvertiseViaMulticastDNS() {
       return advertiseViaMulticastDNS;
   }
 
   public void setAdvertiseViaMulticastDNS(boolean advertiseViaMulticastDNS) {
       this.advertiseViaMulticastDNS = advertiseViaMulticastDNS;
   }
 }