import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import java.util.*;

public class Proxy extends JFrame implements Runnable {

   private Thread thread = new Thread(this);
   private ServerSocket ss;
   private Socket clientSocket, serverSocket;
   private BufferedReader inFromClient, inFromServer;
   private PrintWriter outToClient, outToServer;

   private static int defaultPort = 9999;
   private JTextArea textAreaFromClient = new JTextArea(), textAreaFromServer = new JTextArea();

   public static void main(String args[]) {
      if(args.length != 0) defaultPort = Integer.parseInt(args[0]);
      new Proxy();
   }

   public Proxy() {
      addWindowListener(new L1());
      getContentPane().setLayout(new BorderLayout());

      JPanel panelAreas = new JPanel();
      panelAreas.setLayout(new GridLayout(1, 2));
      panelAreas.add(new JScrollPane(textAreaFromClient));
      panelAreas.add(new JScrollPane(textAreaFromServer));
      getContentPane().add(BorderLayout.CENTER, panelAreas);


      JPanel panelButtons = new JPanel();
      panelButtons.setLayout(new FlowLayout());
      JButton buttonClearClient = new JButton("Clear Client");
      buttonClearClient.addActionListener(new L2());
      panelButtons.add(buttonClearClient);
      JButton buttonClearServer = new JButton("Clear Server");
      buttonClearServer.addActionListener(new L3());
      panelButtons.add(buttonClearServer);
      getContentPane().add(BorderLayout.SOUTH, panelButtons);

      setLocation(0, 0);
      setSize(640, 480);
      show();

      try {
         ss = new ServerSocket(defaultPort);
      } catch (IOException e) {
         System.out.println("COULD NOT LISTEN ON PORT: " + defaultPort);
         System.exit(1);
      }

      thread.start();
   }

   public void run() {
      while(true) {
         try {
	      clientSocket = ss.accept();
         } catch(IOException e) {
            System.out.println("ACCEPT FAILED");
         }
         handleClient();
      }
   }

   private void handleClient() {
      System.out.println("HANDLING INCOMING CLIENT REQUEST");

      try {
         inFromClient = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
         outToClient = new PrintWriter(clientSocket.getOutputStream(), true);
      } catch(Exception e) {
         System.out.println("ERROR IN GETTING STREAMS FROM CLIENT SOCKET");
      }

      String firstLine = receive(inFromClient);
      textAreaFromClient.append(firstLine + "\n");

      String address = getAdress(firstLine);
      int port = getPort(firstLine);

      try {
         System.out.println("CONNECTING TO: " + address + " AT PORT: " + port);
         serverSocket = new Socket(address, port);
      } catch(UnknownHostException uhe) {
         System.out.println("UNKNOWN HOST\n");
      } catch(IOException ioe) {
         System.out.println("I/O EXCEPTION\n");
      }

      try {
         inFromServer = new BufferedReader(new InputStreamReader(serverSocket.getInputStream()));
         outToServer = new PrintWriter(serverSocket.getOutputStream(), true);
      } catch(Exception e) {
         System.out.println("ERROR IN GETTING STREAMS FROM SERVER SOCKET");
      }

      send(outToServer, firstLine);

      new MiddleHandler(inFromClient, outToServer, textAreaFromClient);
      new MiddleHandler(inFromServer, outToClient, textAreaFromServer);
   }

   private String receive(BufferedReader in) {
      String inputLine = null; 
      try {
         inputLine = in.readLine();
      } catch(Exception e) {
         System.out.println("ERROR IN RECEIVE");
      }
      return inputLine;
   }

   private void send(PrintWriter out, String line) {
      try {
         out.println(line);
      } catch(Exception e) {
         System.out.println("ERROR IN SEND");
      }
   }

   private String getAdress(String line) {
      // GET http://www.dn.se/ HTTP/1.0
      line = line + "/";
      StringTokenizer st = new StringTokenizer(line, "/");
      if(st.hasMoreTokens()) st.nextToken();
      if(st.hasMoreTokens()) return st.nextToken(); else return "ERROR";
   }

   private int getPort(String line) {
      line = ":" + line + ":";
      String stringTmp = "";
      int port = 80;

      StringTokenizer st1 = new StringTokenizer(line, ":");
      if(st1.hasMoreTokens()) st1.nextToken();
      if(st1.hasMoreTokens()) st1.nextToken();
      if(st1.hasMoreTokens()) {
         StringTokenizer st2 = new StringTokenizer(st1.nextToken(), "/");
         if(st2.hasMoreTokens()) port = Integer.parseInt(st2.nextToken());
      }

      return port;
   }

   class MiddleHandler extends Thread {
      BufferedReader in;
      PrintWriter out;
      JTextArea textArea;

      public MiddleHandler(BufferedReader in, PrintWriter out, JTextArea textArea) {
         this.in = in;
         this.out = out;
         this.textArea = textArea;
         start();
      }

      public void run() {
         try {
            String inputLine;
            while((inputLine = receive(in)) != null) {
               textArea.append(inputLine + "\n");
               send(out, inputLine);
            }
         } catch(Exception e) {
            System.out.println("CLOSING HANDLER");
         }
      }
   }

   class L1 extends WindowAdapter {
      public void windowClosing(WindowEvent we) {
         dispose();
      }

      public void windowClosed(WindowEvent we) {
         System.exit(1);
      }
   }

   class L2 implements ActionListener {
      public void actionPerformed(ActionEvent we) {
         textAreaFromClient.setText("");
      }
   }

   class L3 implements ActionListener {
      public void actionPerformed(ActionEvent we) {
         textAreaFromServer.setText("");
      }
   }
}