import java.applet.*;
import java.net.*;
import java.io.*;
import java.util.*;
import java.awt.*;

public class ReloadApplet extends Applet implements Runnable {
  static long   last_reload = 0;
  Thread        reload_thread;
  
  private long getLastModified () {
    URL                 doc_url = getDocumentBase ();
    Socket              s = null;
    DataInputStream     in;
    PrintStream         out;
    String              line;
    long                last_modified = 0;

    try {
      s = new Socket (doc_url.getHost (), doc_url.getPort ());
      in = new DataInputStream (s.getInputStream ());
      out = new PrintStream (s.getOutputStream ());
      out.println ("HEAD " + doc_url.getFile () + " HTTP/1.0");
      out.println (""); out.flush ();
      while (true) {
        if ((line = in.readLine ()) == null)
          break;
        if (line.substring (0, 15).equalsIgnoreCase ("last-modified: ")) {
          last_modified = Date.parse (line.substring (15));
          break;
        }
      }
    }
    catch (IOException e) { System.out.println (e.toString ()); }
    finally { if (s != null) s.close (); }
    return last_modified;
  }

  public void run () {
    while (true) {
      try { Thread.sleep (10000); }
      catch (InterruptedException e) {}
      if (getLastModified () > last_reload)
        getAppletContext ().showDocument (getDocumentBase ());
    }
  }
  
  public void start () {
    last_reload = getLastModified ();
    reload_thread = new Thread (this);
    reload_thread.start ();
  }
  
  public void stop () {
    reload_thread.stop ();
  }

  public void addNotify () {}
  public void show () {}
}