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


public class HTMLAppletViewer extends Frame implements AppletContext {

  Applet theApplet = null;
  AppletTag theTag = null;
  ParamAppletStub theStub = null;
  Panel appletPanel = new Panel();
  TextField thePage = new TextField(40);
  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);
  URL documentBase = null;

  public static void main(String[] args) {

    HTMLAppletViewer hav = new HTMLAppletViewer();
    System.setSecurityManager(new SimpleSecurityManager());
    hav.show();

  }

  public HTMLAppletViewer() {

    super("HTML Applet Viewer");
    init();

  }

  public 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(thePage);
    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);
    resize(400, 250);

  }

  public void readPage(String s) {

     // is the name a URL?
    try {
      documentBase = new URL(s);
      theTag = parsePage(documentBase.openStream());
      if (theTag != null) {
        System.out.println(theTag);
        loadApplet();
      }
    }
    catch(MalformedURLException e) {
    }
    catch(IOException e) {
    }


  }

  public AppletTag parsePage(InputStream in) throws IOException {

    String at = null;
    int c;
    while ((c = in.read()) != -1) {
      if (c != '<') continue;
      c = in.read();
      if (c == ' ') continue; // just a < sign
      String tag = scanTag(c, in);
      if (tag.toUpperCase().startsWith("<APPLET ")) at = tag;
      if (tag.toUpperCase().startsWith("<PARAM ") && at != null) at += tag;
      if (tag.toUpperCase().startsWith("</APPLET") && at != null) {
        at += tag;
        break;
      }      
    }
    return new AppletTag(at);

  }

  String scanTag(int c, InputStream in) throws IOException {

    StringBuffer sb = new StringBuffer("<" + (char) c);
    while ((c = in.read()) != -1) {
      sb.append((char) c);
      if (c == '>') break;
    }

    return sb.toString();

  }


  public void loadApplet() {

    Class c = null;
    removeApplet();
    URLClassLoader ucl;

    if (theTag != null) {
      try {
        if (theTag.codebase() != null) ucl = new URLClassLoader(theTag.codebase());
        else ucl = new URLClassLoader(documentBase);
        c = ucl.loadClass(theTag.code());
        theApplet = (Applet) c.newInstance();
        theStub = new ParamAppletStub(this, theTag.params(), documentBase, theTag.codebase()); 
        theApplet.setStub(theStub);
        theApplet.resize(theTag.height(), theTag.width());
        appletPanel.add("Center", theApplet);
        theApplets.addElement(theApplet);
        theApplet.init();
        theStub.activate();
        theApplet.start();
        validate();
      }
      catch (Exception e) {
        showStatus(e.toString());
      }

    }
  }


  public void removeApplet() {

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

  public void reload() {

    if (theTag != null) {
      loadApplet();
    }

  }

  public void restart() {

   if (theApplet != null) {
      theApplet.stop();
      theApplet.start();
    }

  }

  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) {
      readPage(thePage.getText());
      return true;
    }
    else if (e.target == removeButton) {
      removeApplet();
      return true;
    }
    else if (e.target == thePage) {
      loadApplet();
      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);
  }

}