/*
 *                 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 Sun Microsystems, Inc. Portions Copyright 1997-2000 Sun
 * Microsystems, Inc. All Rights Reserved.
 */

package org.netbeans.modules.web.core.jsploader;

import java.beans.*;
import java.util.Map;
import java.util.TreeMap;
import java.io.IOException;

import org.w3c.dom.*;
import org.xml.sax.*;

import org.openide.nodes.Node;
import org.openide.loaders.DataObject;
import org.openide.loaders.XMLDataObject;
import org.openide.filesystems.FileChangeAdapter;
import org.openide.filesystems.FileEvent;
import org.openide.filesystems.FileRenameEvent;
import org.openide.ErrorManager;

/** Support for providing information about web.xml files. The information 
 *  extracted is a Map containing entries of (taglib-uri, taglib-location)
 *  about tag libraries used by the web application. Used by syntax coloring
 *  and code completion.
 *
 * @author  Petr Jiricka
 * @version 
 */
public class WebXMLSupport implements Node.Cookie {
    
    public static final String PROP_TAGLIBRARYMAP = "tagLibraryMap";    // NOI18N

    protected DataObject dobj;
    protected Map tagLibraryMap;
    private transient PropertyChangeSupport pcs;
    
    /** Creates new WebXMLSupport */
    public WebXMLSupport(DataObject dobj) {
        this.dobj = dobj;
        dobj.getPrimaryFile().addFileChangeListener(
            new FileChangeAdapter() {
            
                public void fileChanged(FileEvent fe) {
                    invalidate();
                }
                
                public void fileDeleted(FileEvent fe) {
                    invalidate();
                }
                
                public void fileRenamed(FileRenameEvent fe) {
                    invalidate();
                }
            }
        );
          
    }
    
    /** Returns tag library information represented by this web.xml object
    * as a map of (String taglib-uri ; String taglib-location).*/
    public Map getTagLibraryMap() {
        if (tagLibraryMap == null) {
            synchronized (this) {
                if (tagLibraryMap == null)
                    tagLibraryMap = createTagLibraryMap();
            }
        }
        return tagLibraryMap;
    }
    
    private Map createTagLibraryMap() {
        Map map = new TreeMap();
        try {
            Document webxml = XMLDataObject.parse(dobj.getPrimaryFile().getURL(), 
                new ErrorHandler() {
                    public void error(SAXParseException exception) throws SAXException {
                    }

                    public void fatalError(SAXParseException exception) throws SAXException {
                        throw exception;
                    }

                    public void warning(SAXParseException exception) throws SAXException {
                    }
                }, true);
                 
            NodeList nList =  webxml.getElementsByTagName("taglib");    // NOI18N
            if (nList.getLength() != 0) {
                for(int i = 0; i < nList.getLength(); i++) {
                    Element e = (Element) nList.item(i);
                    NodeList list = e.getChildNodes();
                    String tagLoc = null;
                    String uri = null;
                    for(int j = 0; j < list.getLength(); j++) {
                        org.w3c.dom.Node em = list.item(j);
                        String tname = em.getNodeName();
                        if (tname.equals("taglib-location")) {  // NOI18N
                            Text t = (Text) em.getFirstChild();
                            if (t != null) {
                                tagLoc = t.getData();
                                if (tagLoc != null) {
                                    tagLoc = tagLoc.trim();
                                    if (!tagLoc.startsWith("/"))    // NOI18N
                                        tagLoc = "/WEB-INF/" + tagLoc;  // NOI18N
                                }
                            }
                        }
                        if (tname.equals("taglib-uri")) {   // NOI18N
                            Text t = (Text) em.getFirstChild();
                            if (t != null) {
                                uri =  t.getData();
                                if (uri != null) {
                                    uri = uri.trim();
                                }
                            }
                        }
                    }
                    if ((tagLoc != null) && (uri != null))
                        map.put(uri, tagLoc);
                }
            }
        }
        catch (IOException e) {
            ErrorManager.getDefault ().notify (ErrorManager.INFORMATIONAL, e);
        }
        catch (SAXException e) { 
            if (Boolean.getBoolean("netbeans.debug.exceptions")) { // NOI18N
                // only report the error in netbeans.debug.exceptions mode, as this is a usual 
                // and common exception, which does not imply a bug or an unusual condition
                ErrorManager.getDefault ().notify (ErrorManager.INFORMATIONAL, e);
            }
        }
        return map;
    }
    
    private synchronized void invalidate() {
        tagLibraryMap = null;
        fireWebXMLChange();
    }
    
    public void addPropertyChangeListener(PropertyChangeListener pcl) {
        if (pcs == null)
            pcs = new PropertyChangeSupport(this);
        pcs.addPropertyChangeListener(pcl);
    }
    
    public void removePropertyChangeListener(PropertyChangeListener pcl) {
        if (pcs == null)
            return;
        pcs.removePropertyChangeListener(pcl);
    }
    
    void fireWebXMLChange() {
        if (pcs != null)
            pcs.firePropertyChange(PROP_TAGLIBRARYMAP, null, null);
    }
    
    private static final Map association = new java.util.WeakHashMap(); // Map
    /** Returns WebXMLSupport attached to DataObject dobj. If no support is attached,
    * creates a new one and attaches it to the object. 
    * @param dobj web.xml object for which the support should be created
    */
    public static WebXMLSupport getWebXMLSupport(DataObject dobj) {
        WebXMLSupport sup = (WebXMLSupport)association.get(dobj);
        if (sup == null) {
            sup = new WebXMLSupport(dobj);
            association.put(dobj, sup);
        }
        return sup;
    }

}