/*
    * 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.server;
  
  import java.io.BufferedReader;
  import java.io.ByteArrayInputStream;
  import java.io.EOFException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.ObjectInputStream;
  import java.io.OptionalDataException;
  import java.net.DatagramPacket;
  import java.net.DatagramSocket;
  
  import org.apache.logging.log4j.core.config.ConfigurationFactory;
  import org.apache.logging.log4j.core.util.Log4jThread;
  
  /**
   * Listens for Log4j events on a datagram socket and passes them on to Log4j. 
   * 
   * @param <T>
   *            The kind of input stream read
   * @see #main(String[])
   */
  public class UdpSocketServer<T extends InputStream> extends AbstractSocketServer<T> {
  
      /**
       * Creates a socket server that reads JSON log events.
       * 
       * @param port
       *            the port to listen
       * @return a new a socket server
       * @throws IOException
       *             if an I/O error occurs when opening the socket.
       */
      public static UdpSocketServer<InputStream> createJsonSocketServer(final int port) throws IOException {
          return new UdpSocketServer<>(port, new JsonInputStreamLogEventBridge());
      }
  
      /**
       * Creates a socket server that reads serialized log events.
       * 
       * @param port
       *            the port to listen
       * @return a new a socket server
       * @throws IOException
       *             if an I/O error occurs when opening the socket.
       */
      public static UdpSocketServer<ObjectInputStream> createSerializedSocketServer(final int port) throws IOException {
          return new UdpSocketServer<>(port, new ObjectInputStreamLogEventBridge());
      }
  
      /**
       * Creates a socket server that reads XML log events.
       * 
       * @param port
       *            the port to listen
       * @return a new a socket server
       * @throws IOException
       *             if an I/O error occurs when opening the socket.
       */
      public static UdpSocketServer<InputStream> createXmlSocketServer(final int port) throws IOException {
          return new UdpSocketServer<>(port, new XmlInputStreamLogEventBridge());
      }
  
      /**
       * Main startup for the server. Run with "--help" for to print command line help on the console.
       * 
       * @param args
       *            The command line arguments.
       * @throws Exception
       *             if an error occurs.
       */
      public static void main(final String[] args) throws Exception {
          final CommandLineArguments cla = parseCommandLine(args, UdpSocketServer.class, new CommandLineArguments());
          if (cla.isHelp()) {
              return;
          }
          if (cla.getConfigLocation() != null) {
              ConfigurationFactory.setConfigurationFactory(new ServerConfigurationFactory(cla.getConfigLocation()));
          }
          final UdpSocketServer<ObjectInputStream> socketServer = UdpSocketServer
                  .createSerializedSocketServer(cla.getPort());
          final Thread serverThread = new Log4jThread(socketServer);
         serverThread.start();
         if (cla.isInteractive()) {
             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")) {
                     socketServer.shutdown();
                     serverThread.join();
                     break;
                 }
             }
         }
     }
 
     private final DatagramSocket datagramSocket;
 
     // max size so we only have to deal with one packet
     private final int maxBufferSize = 1024 * 65 + 1024;
 
     /**
      * Constructor.
      * 
      * @param port
      *            to listen on.
      * @param logEventInput
      * @throws IOException
      *             If an error occurs.
      */
     public UdpSocketServer(final int port, final LogEventBridge<T> logEventInput) throws IOException {
         super(port, logEventInput);
         this.datagramSocket = new DatagramSocket(port);
     }
 
     /**
      * Accept incoming events and processes them.
      */
     @Override
     public void run() {
         while (isActive()) {
             if (datagramSocket.isClosed()) {
                 // OK we're done.
                 return;
             }
             try {
                 final byte[] buf = new byte[maxBufferSize];
                 final DatagramPacket packet = new DatagramPacket(buf, buf.length);
                 datagramSocket.receive(packet);
                 final ByteArrayInputStream bais = new ByteArrayInputStream(packet.getData(), packet.getOffset(), packet.getLength());
                 logEventInput.logEvents(logEventInput.wrapStream(bais), this);
             } catch (final OptionalDataException e) {
                 if (datagramSocket.isClosed()) {
                     // OK we're done.
                     return;
                 }
                 logger.error("OptionalDataException eof=" + e.eof + " length=" + e.length, e);
             } catch (final EOFException e) {
                 if (datagramSocket.isClosed()) {
                     // OK we're done.
                     return;
                 }
                 logger.info("EOF encountered");
             } catch (final IOException e) {
                 if (datagramSocket.isClosed()) {
                     // OK we're done.
                     return;
                 }
                 logger.error("Exception encountered on accept. Ignoring. Stack Trace :", e);
             }
         }
     }
 
     /**
      * Shutdown the server.
      */
     public void shutdown() {
         this.setActive(false);
         Thread.currentThread().interrupt();
         datagramSocket.close();
     }
 }