/*
    * 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 events over a socket connection.
   * 
   * @param <T>
   *            The kind of input stream read
   */
  public class UdpSocketServer<T extends InputStream> extends AbstractSocketServer<T> {
  
      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);
      }
  
      /**
       * 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.
      * 
      * @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<ObjectInputStream> socketServer = UdpSocketServer.createSerializedSocketServer(port);
         final Thread server = new Log4jThread(socketServer);
         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")) {
                 socketServer.shutdown();
                 server.join();
                 break;
             }
         }
     }
 
     private static void printUsage() {
         System.out.println("Usage: ServerSocket port configFilePath");
     }
 
     /**
      * 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();
     }
 }