/*
 *                 Sun Public License Notice
 * 
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 * 
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Nokia. Portions Copyright 2003-2004 Nokia.
 * All Rights Reserved.
 */

package org.netbeans.modules.enode;

import java.util.ArrayList;
import java.util.List;
import java.util.Iterator;

import org.openide.ErrorManager;
import org.openide.util.WeakListener;
import org.openide.util.RequestProcessor;

import org.netbeans.api.enode.ExtensibleNode;
import org.netbeans.api.registry.*;

/**
 * Object that helps the ExtensibleNode to keep track of
 * its icon. 
 * @author David Strupl
 */
public class ExtensibleNodeIcons {
    
    /**
     * Our node.
     */
    private ExtensibleNode enode;
    
    /**
     * We hold a reference to the listener for preventing
     * the garbage collection.
     */
    private Listener listener;
    
    /**
     * Prevent the listeners to be attached more than once.
     */
    private boolean listenersAttached = false;
    
    
    /**
     * Just remember the parameter enode.
     */
    public ExtensibleNodeIcons(ExtensibleNode enode) {
        this.enode = enode;
    }
    
    /** Reads actions from a context. Also adds a listener
     * to the context.
     * @param name of the context.
     * @return array of actions
     */
    public String getIconBase() {
        ArrayList arr = new ArrayList ();
        String paths[] = enode.getPaths();
        for (int i = 0; i < paths.length; i++) {
            String path = ExtensibleNode.E_NODE_ICONS + paths[i];
            try {
                Context con = Context.getDefault().getSubcontext(path);
                if (con == null) {
                    con = Context.getDefault().createSubcontext(path);
                }
                if (!listenersAttached) {
                    ContextListener l1 = getContextListener(con);
                    con.addContextListener(l1);
                }
                List objects = con.getOrderedObjects();
                Iterator it = objects.iterator();
                while (it.hasNext()) {
                    Object obj = it.next();
                    if (obj instanceof String) {
                        arr.add(obj);
                    }
                }
            } catch (ContextException ce) {
                ErrorManager.getDefault().getInstance("org.netbeans.modules.enode").notify(ErrorManager.INFORMATIONAL, ce); // NOI18N
            }
        }
        listenersAttached = true;
        if (arr.isEmpty()) {
            return null;
        }
        return (String)arr.get(0);
    }

    /**
     * Lazy initialization of the listener variable. This method
     * will return a weak listener according to the type argument.
     * In both cases the weak listener references the object hold
     * by the  listener  variable.
     * @param type ObjectChangeListener or NamespaceChangeListener
     */
    private ContextListener getContextListener(Object source) {
        if (listener == null) {
            listener = new Listener();
        }
        return (ContextListener)WeakListener.create(ContextListener.class, listener, source);
    }
    
    /**
     * If something has changed on the system file system, force
     * the icon reload.
     */
    private void changeIcon() {
        RequestProcessor.getDefault().post(new Runnable() {
            public void run() {
                String iBase = getIconBase();
                if (iBase != null) {
                    enode.setIconBase(iBase);
                }
            }
        });
    }
    
    /**
     * Whatever happens in the selected context this listener only calls
     * changeIcon. 
     */
    private class Listener implements ContextListener {
        public void attributeChanged(AttributeEvent evt) {
            changeIcon();
        }
        
        public void bindingChanged(BindingEvent evt) {
            changeIcon();
        }
        
        public void subcontextChanged(SubcontextEvent evt) {
            changeIcon();
        }
    }
}