/*
    * 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.logging.log4j.core.net;
  
  import java.io.BufferedReader;
  import java.io.ByteArrayInputStream;
  import java.io.EOFException;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.ObjectInputStream;
  import java.io.OptionalDataException;
  import java.net.DatagramPacket;
  import java.net.DatagramSocket;
  import java.net.MalformedURLException;
  import java.net.URI;
  import java.net.URL;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.core.AbstractServer;
  import org.apache.logging.log4j.core.LogEvent;
  import org.apache.logging.log4j.core.config.Configuration;
  import org.apache.logging.log4j.core.config.ConfigurationFactory;
  import org.apache.logging.log4j.core.config.XMLConfiguration;
  import org.apache.logging.log4j.core.config.XMLConfigurationFactory;
  
  /**
   * Listens for events over a socket connection.
   */
  public class UDPSocketServer extends AbstractServer implements Runnable {
  
      private final Logger logger;
  
      private static final int MAX_PORT = 65534;
  
      private volatile boolean isActive = true;
  
      private final DatagramSocket server;
  
      // max size so we only have to deal with one packet
      private final int maxBufferSize = 1024 * 65 + 1024;
  
      /**
       * Constructor.
       *
       * @param port
       *            to listen on.
       * @throws IOException
       *             If an error occurs.
       */
      public UDPSocketServer(final int port) throws IOException {
          this.server = new DatagramSocket(port);
          this.logger = LogManager.getLogger(this.getClass().getName() + '.' + port);
      }
  
      /**
       * Main startup for the server.
       *
       * @param args
       *            The command line arguments.
       * @throws Exception
       *             if an error occurs.
       */
      public static void main(final String[] args) throws Exception {
          if (args.length < 1 || args.length > 2) {
              System.err.println("Incorrect number of arguments");
              printUsage();
              return;
          }
          final int port = Integer.parseInt(args[0]);
          if (port <= 0 || port >= MAX_PORT) {
              System.err.println("Invalid port number");
              printUsage();
              return;
          }
          if (args.length == 2 && args[1].length() > 0) {
              ConfigurationFactory.setConfigurationFactory(new ServerConfigurationFactory(args[1]));
          }
          final UDPSocketServer sserver = new UDPSocketServer(port);
          final Thread server = new Thread(sserver);
          server.start();
          final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
         while (true) {
             final String line = reader.readLine();
             if (line == null || line.equalsIgnoreCase("Quit") || line.equalsIgnoreCase("Stop") || line.equalsIgnoreCase("Exit")) {
                 sserver.shutdown();
                 server.join();
                 break;
             }
         }
     }
 
     private static void printUsage() {
         System.out.println("Usage: ServerSocket port configFilePath");
     }
 
     /**
      * Shutdown the server.
      */
     public void shutdown() {
         this.isActive = false;
         Thread.currentThread().interrupt();
     }
 
     /**
      * Accept incoming events and processes them.
      */
     @Override
     public void run() {
         while (isActive) {
             try {
                 final byte[] buf = new byte[maxBufferSize];
                 final DatagramPacket packet = new DatagramPacket(buf, buf.length);
                 server.receive(packet);
                 final ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(packet.getData(), packet.getOffset(), packet.getLength()));
                 final LogEvent event = (LogEvent) ois.readObject();
                 if (event != null) {
                     log(event);
                 }
             } catch (final OptionalDataException opt) {
                 logger.error("OptionalDataException eof=" + opt.eof + " length=" + opt.length, opt);
             } catch (final ClassNotFoundException cnfe) {
                 logger.error("Unable to locate LogEvent class", cnfe);
             } catch (final EOFException eofe) {
                 logger.info("EOF encountered");
             } catch (final IOException ioe) {
                 logger.error("Exception encountered on accept. Ignoring. Stack Trace :", ioe);
             }
         }
     }
 
     /**
      * Factory that creates a Configuration for the server.
      */
     private static class ServerConfigurationFactory extends XMLConfigurationFactory {
 
         private final String path;
 
         public ServerConfigurationFactory(final String path) {
             this.path = path;
         }
 
         @Override
         public Configuration getConfiguration(final String name, final URI configLocation) {
             if (path != null && path.length() > 0) {
                 File file = null;
                 ConfigurationSource source = null;
                 try {
                     file = new File(path);
                     final FileInputStream is = new FileInputStream(file);
                     source = new ConfigurationSource(is, file);
                 } catch (final FileNotFoundException ex) {
                     // Ignore this error
                 }
                 if (source == null) {
                     try {
                         final URL url = new URL(path);
                         source = new ConfigurationSource(url.openStream(), path);
                     } catch (final MalformedURLException mue) {
                         // Ignore this error
                     } catch (final IOException ioe) {
                         // Ignore this error
                     }
                 }
 
                 try {
                     if (source != null) {
                         return new XMLConfiguration(source);
                     }
                 } catch (final Exception ex) {
                     // Ignore this error.
                 }
                 System.err.println("Unable to process configuration at " + path + ", using default.");
             }
             return super.getConfiguration(name, configLocation);
         }
     }
 }