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


public class URLAppletViewer extends Frame implements AppletContext {

  Applet theApplet = null;
  SimpleAppletStub theStub = null;
  Panel appletPanel = new Panel();
  TextField appletName = new TextField(35);
  Button loadButton = new Button("Load");
  Button removeButton = new Button("Remove");
  Button reloadButton = new Button("Reload");
  Button restartButton = new Button("Restart");
  Vector theApplets = new Vector();
  TextField status = new TextField(33);

  public static void main(String[] args) {

    URLAppletViewer uav = new URLAppletViewer();
    uav.show();
    System.setSecurityManager(new SimpleSecurityManager());

  }

  public URLAppletViewer() {

    super("URL Applet Viewer");
    init();
    resize(400, 250);

  }

  protected void init() {

    Panel p1 = new Panel();
    p1.setLayout(new GridLayout(3, 1)); 
    Panel p0 = new Panel();
    p0.setLayout(new FlowLayout(FlowLayout.LEFT));
    p0.add(new Label("URL: "));
    p0.add(appletName);
    p1.add(p0);
    Panel p2 = new Panel();
    p2.add(loadButton);
    p2.add(removeButton);
    p2.add(reloadButton);
    p2.add(restartButton);
    p1.add(p2);
    Panel p4 = new Panel();
    p4.setLayout(new FlowLayout(FlowLayout.LEFT));
    p4.add(new Label("Status: "));
    status.setEditable(false);
    p4.add(status);
    p1.add(p4);
    add("South", p1);
    appletPanel.setLayout(new BorderLayout());
    add("Center", appletPanel);
 
  }


  public void loadApplet(String name) {

    removeApplet();
    // is the name a URL?
    try {
      URL u = new URL(name);
      loadApplet(u);
      return;
    }
    catch(MalformedURLException e) {
    }

    removeApplet();
    if (name != null && !name.equals("")) {
       try {
         Class c = Class.forName(name); 
         theApplet = (Applet) c.newInstance(); 
         appletPanel.add("Center", theApplet);
         theApplets.addElement(theApplet);
         theApplet.init();
         theApplet.start();
         validate();
       }
       catch (Exception e) {
         showStatus(e.toString());
       }
    }

  }

  public void loadApplet(URL u) {

    Class c = null;
    removeApplet();

    try {
      URLClassLoader ucl = new URLClassLoader(u);
      String appletname = u.getFile();
      appletname = appletname.substring(appletname.lastIndexOf('/')+1);
      showStatus("Loading " + appletname);
      c = ucl.loadClass(appletname);
      theApplet = (Applet) c.newInstance();
      theStub = new SimpleAppletStub(this); 
      theApplet.setStub(theStub);
      appletPanel.add("Center", theApplet);
      theApplets.addElement(theApplet);
      theApplet.init();
      theStub.activate();
      theApplet.start();
      validate();
      repaint();
    }
    catch (Exception e) {
      showStatus(e.toString());
    }

  }


  public void removeApplet() {

    if (theApplet != null) {
      theApplet.stop();
      theApplet.destroy();
      theApplets.removeElement(theApplet);
      appletPanel.remove(theApplet);
      theApplet = null;
      validate();
      repaint();
    }

  }


  public void reload() {

    String name = appletName.getText();

    if (theApplet != null) {
      Class c = theApplet.getClass();
      name = c.getName();
      removeApplet();
      loadApplet(name);
    }

  }


  public void restart() {
   if (theApplet != null) {
      theApplet.stop();
      theApplet.start();
    }
    else loadApplet(appletName.getText());
  }

  public boolean action(Event e, Object what) {

    if (e.target == restartButton) {
      restart();
      return true;
    }
    else if (e.target == reloadButton) {
      reload();
      return true;
    }
    else if (e.target == loadButton) {
      loadApplet(appletName.getText());
      return true;
    }
    else if (e.target == removeButton) {
      removeApplet();
      return true;
    }
    else if (e.target == appletName) {
      loadApplet(appletName.getText());
      return true;
    }

    return false;

  }


  public Image getImage(URL u) {
    return Toolkit.getDefaultToolkit().getImage(u);
  }

  public AudioClip getAudioClip(URL u) {
    return new NullAudioClip();
  }

  public Applet getApplet(String s) {
    return null;
  }

  public Enumeration getApplets() {
    return (Enumeration) theApplets;
  }

  public void showDocument(URL url) {};

  public void showDocument(URL url, String target) {};

  public void showStatus(String s) {
    status.setText(s);
  }

}