/*
    * 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.EOFException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.ObjectInputStream;
  import java.io.OptionalDataException;
  import java.net.ServerSocket;
  import java.net.Socket;
  import java.nio.charset.Charset;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  
  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 TcpSocketServer<T extends InputStream> extends AbstractSocketServer<T> {
  
      /**
       * Thread that processes the events.
       */
      private class SocketHandler extends Thread {
  
          private final T inputStream;
  
          private volatile boolean shutdown = false;
  
          public SocketHandler(final Socket socket) throws IOException {
              this.inputStream = logEventInput.wrapStream(socket.getInputStream());
          }
  
          @Override
          public void run() {
              logger.entry();
              boolean closed = false;
              try {
                  try {
                      while (!shutdown) {
                          logEventInput.logEvents(inputStream, TcpSocketServer.this);
                      }
                  } catch (final EOFException e) {
                      closed = true;
                  } catch (final OptionalDataException e) {
                      logger.error("OptionalDataException eof=" + e.eof + " length=" + e.length, e);
                  } catch (final IOException e) {
                      logger.error("IOException encountered while reading from socket", e);
                  }
                  if (!closed) {
                      try {
                          inputStream.close();
                      } catch (final Exception ex) {
                          // Ignore the exception;
                      }
                  }
              } finally {
                  handlers.remove(Long.valueOf(getId()));
              }
              logger.exit();
          }
  
          public void shutdown() {
              this.shutdown = true;
              interrupt();
          }
      }
  
      private final ConcurrentMap<Long, SocketHandler> handlers = new ConcurrentHashMap<>();
  
      private final ServerSocket serverSocket;
  
      /**
       * Constructor.
       * 
       * @param port
      *        to listen.
      * @param logEventInput
      *        the log even input
      * @throws IOException
      *         if an I/O error occurs when opening the socket.
      */
     public TcpSocketServer(final int port, final LogEventBridge<T> logEventInput) throws IOException {
         this(port, logEventInput, new ServerSocket(port));
     }
 
     /**
      * Constructor.
      * 
      * @param port
      *        to listen.
      * @param logEventInput
      *        the log even input
      * @param serverSocket
      *        the socket server
      * @throws IOException
      *         if an I/O error occurs when opening the socket.
      */
     public TcpSocketServer(final int port, final LogEventBridge<T> logEventInput, final ServerSocket serverSocket)
             throws IOException {
         super(port, logEventInput);
         this.serverSocket = serverSocket;
     }
 
     /**
      * 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 TcpSocketServer<InputStream> createJsonSocketServer(final int port) throws IOException {
         LOGGER.entry("createJsonSocketServer", port);
         final TcpSocketServer<InputStream> socketServer = new TcpSocketServer<>(port, new JsonInputStreamLogEventBridge());
         return LOGGER.exit(socketServer);
     }
 
     /**
      * 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 TcpSocketServer<ObjectInputStream> createSerializedSocketServer(final int port) throws IOException {
         LOGGER.entry(port);
         final TcpSocketServer<ObjectInputStream> socketServer = new TcpSocketServer<>(port, new ObjectInputStreamLogEventBridge());
         return LOGGER.exit(socketServer);
     }
 
     /**
      * 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 TcpSocketServer<InputStream> createXmlSocketServer(final int port) throws IOException {
         LOGGER.entry(port);
         final TcpSocketServer<InputStream> socketServer = new TcpSocketServer<>(port, new XmlInputStreamLogEventBridge());
         return LOGGER.exit(socketServer);
     }
 
     /**
      * 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 TcpSocketServer<ObjectInputStream> socketServer = TcpSocketServer.createSerializedSocketServer(port);
         final Thread serverThread = new Log4jThread(socketServer);
         serverThread.start();
         final Charset enc = Charset.defaultCharset();
         final BufferedReader reader = new BufferedReader(new InputStreamReader(System.in, enc));
         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 static void printUsage() {
         System.out.println("Usage: ServerSocket port configFilePath");
     }
 
     /**
      * Accept incoming events and processes them.
      */
     @Override
     public void run() {
         logger.entry();
         while (isActive()) {
             if (serverSocket.isClosed()) {
                 return;
             }
             try {
                 // Accept incoming connections.
                 logger.debug("Socket accept()...");
                 final Socket clientSocket = serverSocket.accept();
                 logger.debug("Socket accepted: {}", clientSocket);
                 clientSocket.setSoLinger(true, 0);
 
                 // accept() will block until a client connects to the server.
                 // If execution reaches this point, then it means that a client
                 // socket has been accepted.
 
                 final SocketHandler handler = new SocketHandler(clientSocket);
                 handlers.put(Long.valueOf(handler.getId()), handler);
                 handler.start();
             } catch (final IOException e) {
                 if (serverSocket.isClosed()) {
                     // OK we're done.
                     logger.exit();
                     return;
                 }
                 logger.error("Exception encountered on accept. Ignoring. Stack Trace :", e);
             }
         }
         for (final Map.Entry<Long, SocketHandler> entry : handlers.entrySet()) {
             final SocketHandler handler = entry.getValue();
             handler.shutdown();
             try {
                 handler.join();
             } catch (final InterruptedException ie) {
                 // Ignore the exception
             }
         }
         logger.exit();
     }
 
     /**
      * Shutdown the server.
      * 
      * @throws IOException if the server socket could not be closed
      */
     public void shutdown() throws IOException {
         logger.entry();
         setActive(false);
         Thread.currentThread().interrupt();
         serverSocket.close();
         logger.exit();
     }
 }