/*
    * 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 org.apache.log4j.AppenderSkeleton;
  import org.apache.log4j.helpers.LogLog;
  import org.apache.log4j.spi.LoggingEvent;
  
  import java.io.IOException;
  import java.io.PrintWriter;
  import java.io.InterruptedIOException;
  import java.net.ServerSocket;
  import java.net.Socket;
  import java.util.Enumeration;
  import java.util.Iterator;
  import java.util.Vector;
  
  /**
    <p>The TelnetAppender is a log4j appender that specializes in
    writing to a read-only socket.  The output is provided in a
    telnet-friendly way so that a log can be monitored over TCP/IP.
    Clients using telnet connect to the socket and receive log data.
    This is handy for remote monitoring, especially when monitoring a
    servlet.
  
    <p>Here is a list of the available configuration options:
  
    <table border=1>
     <tr>
     <th>Name</th>
     <th>Requirement</th>
     <th>Description</th>
     <th>Sample Value</th>
     </tr>
  
     <tr>
     <td>Port</td>
     <td>optional</td>
     <td>This parameter determines the port to use for announcing log events.  The default port is 23 (telnet).</td>
     <td>5875</td>
     </table>
  
     @author <a HREF="mailto:jay@v-wave.com">Jay Funnell</a>
  */
  
  public class TelnetAppender extends AppenderSkeleton {
  
    private SocketHandler sh;
    private int port = 23;
  
    /** 
        This appender requires a layout to format the text to the
        attached client(s). */
    public boolean requiresLayout() {
      return true;
    }
  
    /** all of the options have been set, create the socket handler and
        wait for connections. */
    public void activateOptions() {
      try {
        sh = new SocketHandler(port);
        sh.start();
      }
      catch(InterruptedIOException e) {
        Thread.currentThread().interrupt();
        e.printStackTrace();
      } catch(IOException e) {
        e.printStackTrace();
      } catch(RuntimeException e) {
        e.printStackTrace();
      }
      super.activateOptions();
    }
  
    public
    int getPort() {
      return port;
    }
  
    public
    void setPort(int port) {
      this.port = port;
    }
 
 
   /** shuts down the appender. */
   public void close() {
     if (sh != null) {
         sh.close();
         try {
             sh.join();
         } catch(InterruptedException ex) {
             Thread.currentThread().interrupt();
         }
     }
   }
 
   /** Handles a log event.  For this appender, that means writing the
     message to each connected client.  */
   protected void append(LoggingEvent event) {
       if(sh != null) {
         sh.send(layout.format(event));
         if(layout.ignoresThrowable()) {
             String[] s = event.getThrowableStrRep();
             if (s != null) {
                 StringBuffer buf = new StringBuffer();
                 for(int i = 0; i < s.length; i++) {
                     buf.append(s[i]);
                     buf.append("\r\n");
                 }
                 sh.send(buf.toString());
             }
         }
       }
   }
 
   //---------------------------------------------------------- SocketHandler:
 
   /** The SocketHandler class is used to accept connections from
       clients.  It is threaded so that clients can connect/disconnect
       asynchronously. */
   protected class SocketHandler extends Thread {
 
     private Vector writers = new Vector();
     private Vector connections = new Vector();
     private ServerSocket serverSocket;
     private int MAX_CONNECTIONS = 20;
 
     public void finalize() {
         close();
     }
       
     /** 
     * make sure we close all network connections when this handler is destroyed.
     * @since 1.2.15 
     */
     public void close() {
       synchronized(this) {
         for(Enumeration e = connections.elements();e.hasMoreElements();) {
             try {
                 ((Socket)e.nextElement()).close();
             } catch(InterruptedIOException ex) {
                 Thread.currentThread().interrupt();
             } catch(IOException ex) {
             } catch(RuntimeException ex) {
             }
         }
       }
 
       try {
         serverSocket.close();
       } catch(InterruptedIOException ex) {
           Thread.currentThread().interrupt();
       } catch(IOException ex) {
       } catch(RuntimeException ex) {
       }
     }
 
     /** sends a message to each of the clients in telnet-friendly output. */
     public synchronized void send(final String message) {
       Iterator ce = connections.iterator();
       for(Iterator e = writers.iterator();e.hasNext();) {
         ce.next();
         PrintWriter writer = (PrintWriter)e.next();
         writer.print(message);
         if(writer.checkError()) {
           ce.remove();
           e.remove();
         }
       }
     }
 
     /** 
 	Continually accepts client connections.  Client connections
         are refused when MAX_CONNECTIONS is reached. 
     */
     public void run() {
       while(!serverSocket.isClosed()) {
         try {
           Socket newClient = serverSocket.accept();
           PrintWriter pw = new PrintWriter(newClient.getOutputStream());
           if(connections.size() < MAX_CONNECTIONS) {
             synchronized(this) {
                 connections.addElement(newClient);
                 writers.addElement(pw);
                 pw.print("TelnetAppender v1.0 (" + connections.size()
 		            + " active connections)\r\n\r\n");
                 pw.flush();
             }
           } else {
             pw.print("Too many connections.\r\n");
             pw.flush();
             newClient.close();
           }
         } catch(Exception e) {
           if (e instanceof InterruptedIOException || e instanceof InterruptedException) {
               Thread.currentThread().interrupt();
           }
           if (!serverSocket.isClosed()) {
             LogLog.error("Encountered error while in SocketHandler loop.", e);
           }
           break;
         }
       }
 
       try {
           serverSocket.close();
       } catch(InterruptedIOException ex) {
           Thread.currentThread().interrupt();
       } catch(IOException ex) {
       }
     }
 
     public SocketHandler(int port) throws IOException {
       serverSocket = new ServerSocket(port);
       setName("TelnetAppender-" + getName() + "-" + port);
     }
 
   }
 }