/*
    * 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
    *
    *      https://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.commons.net.examples.unix;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.io.InterruptedIOException;
  import java.net.InetAddress;
  import java.net.SocketException;
  import java.nio.charset.Charset;
  import java.time.Duration;
  
  import org.apache.commons.net.chargen.CharGenTCPClient;
  import org.apache.commons.net.chargen.CharGenUDPClient;
  
  /**
   * This is an example program demonstrating how to use the CharGenTCPClient and CharGenUDPClient classes. This program connects to the default chargen service
   * port of a specified server, then reads 100 lines from of generated output, writing each line to standard output, and then closes the connection. The UDP
   * invocation of the program sends 50 datagrams, printing the reply to each. The default is to use the TCP port. Use the -udp flag to use the UDP port.
   * <p>
   * Usage: chargen [-udp] <hostname>
   */
  public final class chargen {
  
      public static void chargenTCP(final String host) throws IOException {
          int lines = 100;
          String line;
          final CharGenTCPClient client = new CharGenTCPClient();
  
          // We want to timeout if a response takes longer than 60 seconds
          client.setDefaultTimeout(60000);
          client.connect(host);
          try (BufferedReader chargenInput = new BufferedReader(new InputStreamReader(client.getInputStream(), Charset.defaultCharset()))) {
  
              // We assume the chargen service outputs lines, but it really doesn't
              // have to, so this code might actually not work if no newlines are
              // present.
              while (lines-- > 0) {
                  if ((line = chargenInput.readLine()) == null) {
                      break;
                  }
                  System.out.println(line);
              }
          }
          client.disconnect();
      }
  
      public static void chargenUDP(final String host) throws IOException {
          int packets = 50;
          byte[] data;
          final InetAddress address;
  
          address = InetAddress.getByName(host);
          try (CharGenUDPClient client = new CharGenUDPClient()) {
  
              client.open();
              // If we don't receive a return packet within 5 seconds, assume
              // the packet is lost.
              client.setSoTimeout(Duration.ofSeconds(5));
  
              while (packets-- > 0) {
                  client.send(address);
  
                  try {
                      data = client.receive();
                  } catch (final SocketException e) {
                      // Here we catch both SocketException and InterruptedIOException,
                      // because even though the JDK 1.1 docs claim that
                      // InterruptedIOException is thrown on a timeout, it seems
                      // SocketException is also thrown.
                      // We timed out and assume the packet is lost.
                      System.err.println("SocketException: Timed out and dropped packet");
                      continue;
                  } catch (final InterruptedIOException e) {
                      // We timed out and assume the packet is lost.
                      System.err.println("InterruptedIOException: Timed out and dropped packet");
                      continue;
                  }
                  System.out.write(data);
                  System.out.flush();
              }
  
          }
     }
 
     public static void main(final String[] args) {
 
         if (args.length == 1) {
             try {
                 chargenTCP(args[0]);
             } catch (final IOException e) {
                 e.printStackTrace();
                 System.exit(1);
             }
         } else if (args.length == 2 && args[0].equals("-udp")) {
             try {
                 chargenUDP(args[1]);
             } catch (final IOException e) {
                 e.printStackTrace();
                 System.exit(1);
             }
         } else {
             System.err.println("Usage: chargen [-udp] <hostname>");
             System.exit(1);
         }
 
     }
 
 }