// Copyright (c) 1995, 1996 Regents of the University of California.
// All rights reserved.
//
// This software was developed by the Arcadia project
// at the University of California, Irvine.
//
// Redistribution and use in source and binary forms are permitted
// provided that the above copyright notice and this paragraph are
// duplicated in all such forms and that any documentation,
// advertising materials, and other materials related to such
// distribution and use acknowledge that the software was developed
// by the University of California, Irvine.  The name of the
// University may not be used to endorse or promote products derived
// from this software without specific prior written permission.
// THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
// WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

// File: Preloader.java
// Classes: Preloader
// Original Author: Jason Robbins
// $Id: Preloader.java,v 1.2 2000/09/19 21:08:38 dougo Exp $

// Modified by : Kedar Patankar
// Last Modified 12 Oct 1997

package edu.neu.ccs.demeter.tools.apstudio.util;

import java.util.Vector;
import java.util.Enumeration;


/**
 * Load a set of java classes from an http server and display a
 * progress dialog when it is happening. This is very useful for large
 * applets that use many classes if the browser does not support
 * sending .zip files.
 * @see Package
 * @see Progress
 */

public class Preloader {
  /** List of classes to load. */
  private Vector _classes;
  
  /** Progress dialog box */
  private Progress _progress;

  /** Load a Vector of classes by name. Put up a progress dialog box
   * while the user is waiting.
   * @param classNames Fully qualified names of the classes to load.   */
  public static void loadClasses(Vector classNames) {
    Preloader p = new Preloader(classNames);
  }

  /** Define a new Preloader object to load the given classes.
   * @param classes The classes to load */
  public Preloader(Vector classes) {
    _classes = classes;
    _progress = new Progress("Loading Classes", classes.size());
    _progress.show();
    loadClasses();
  }

  /**
   * Static method to load all classes listed in the given set of
   * Package objects. 
   * @param packages A Vector of Package objects.
   * @see Package   */
  public static void loadPackages(Vector packages) {
    Vector allClassNames = new Vector(packages.size() * 10);
    Enumeration packs = packages.elements();
    while (packs.hasMoreElements()) {
      String packName = (String) packs.nextElement();
      Package p = null;
      try {
	Class packClass = Class.forName(packName); 
	p = (Package) packClass.newInstance();
      }
      catch (java.lang.ClassNotFoundException ignore) { }
      catch (java.lang.IllegalAccessException ignore) { }
      catch (java.lang.InstantiationException ignore) { }
      
 //     if (p instanceof Package) {
	Vector classNames = p.classNames();
	Enumeration cls = classNames.elements();
	while (cls.hasMoreElements()) {
	  String name = (String) cls.nextElement();
	  allClassNames.addElement(name);
	}
//      }
    }
    loadClasses(allClassNames);
  }
  
  /** Load all the classes stored in _classes. */
  private void loadClasses() {
    Enumeration cls = _classes.elements();
    while (cls.hasMoreElements()) {
      String className = (String) cls.nextElement();
      _progress.setMessage(className);
      try { Class.forName(className); }
      catch (java.lang.ClassNotFoundException ignore) { };
      _progress.advance();
      if (_progress.canceled()) {
	_progress.setVisible(false);
	_progress.dispose();
	return;
      }
    }
    _progress.setVisible(false);
    _progress.dispose();
  }

  /** A main() to test out this code. It loads all classes in the
   * <a href="http://www.ics.uci.edu/~jrobbins/GraphEditingFramework.html">
   * UCI graph editing framework </a>   */
  public static void main(String argv[]) {
    Vector v = new Vector();
    v.addElement("uci.graphedit.PackageGraphEdit");
    Preloader.loadPackages(v);
    System.out.println("done");
  }
    
} /* end class Preloader */