/**
 * Copyright © 2002 The JA-SIG Collaborative.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the JA-SIG Collaborative
 *    (http://www.jasig.org/)."
 *
 * THIS SOFTWARE IS PROVIDED BY THE JA-SIG COLLABORATIVE "AS IS" AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE JA-SIG COLLABORATIVE OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */


package org.jasig.portal.layout;

import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Enumeration;
import java.util.Random;
import java.util.Set;
import java.util.Vector;

import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.sax.SAXResult;

import org.apache.xpath.XPathAPI;
import org.jasig.portal.IUserLayoutStore;
import org.jasig.portal.PortalException;
import org.jasig.portal.UserProfile;
import org.jasig.portal.EntityIdentifier;
import org.jasig.portal.security.IPerson;
import org.jasig.portal.security.IAuthorizationPrincipal;
import org.jasig.portal.services.AuthorizationService;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.jasig.portal.utils.DocumentFactory;
import org.jasig.portal.utils.IPortalDocument;
import org.jasig.portal.utils.XSLT;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xml.sax.ContentHandler;

/**
 * An implementation of a user layout manager that uses 2.0-release store implementations.
 *
 * @author <a href="mailto:pkharchenko@interactivebusiness.com">Peter Kharchenko</a>
 * @version $Revision: 1.32 $
 */
public class SimpleUserLayoutManager implements IUserLayoutManager {
    private static final Log log = LogFactory.getLog(SimpleUserLayoutManager.class);
    
    protected final IPerson owner;
    protected final UserProfile profile;
    protected IUserLayoutStore store=null;
    protected Set listeners=new HashSet();

    protected IUserLayout userLayout = null;
    protected Document userLayoutDocument=null;
    protected Document markedUserLayout=null;

    protected static Random rnd=new Random();
    protected String cacheKey="initialKey";
    protected String rootNodeId;

    private boolean dirtyState=false;

    // marking mode variables
    private String markingMode=null; // null means markings are turned off
    private String markingNode;

    // The names for marking nodes
    private static final String ADD_COMMAND = "add";
    private static final String MOVE_COMMAND = "move";

    // marking stylesheet
    private static final String MARKING_XSLT_URI="/org/jasig/portal/layout/MarkUserLayout.xsl";


    public SimpleUserLayoutManager(IPerson owner, UserProfile profile, IUserLayoutStore store) throws PortalException {
        if(owner==null) {
            throw new PortalException("A non-null owner needs to be specified.");
        }

        if(profile==null) {
            throw new PortalException("A non-null profile needs to be specified.");
        }

        this.owner=owner;
        this.profile=profile;
        this.rootNodeId = null;
        this.setLayoutStore(store);
        this.loadUserLayout();
        this.markingMode=null;
        this.markingNode=null;
    }

    public IUserLayout getUserLayout() throws PortalException {
        // Temporary until we use IUserLayout for real
        return new SimpleLayout(String.valueOf(profile.getLayoutId()), this.userLayoutDocument);
    }

    public void setUserLayout(IUserLayout userLayout) throws PortalException {
        // Temporary until we use IUserLayout for real
        Document doc = DocumentFactory.getNewDocument();
        try {
            userLayout.writeTo(doc);
        } catch (PortalException pe) {
        }
        this.userLayoutDocument=doc;
        this.markedUserLayout=null;
        this.updateCacheKey();
    }

    private void setUserLayoutDOM(Document doc) {
        this.userLayoutDocument=doc;
        this.markedUserLayout=null;
        this.updateCacheKey();
    }

    public Document getUserLayoutDOM() {
        return this.userLayoutDocument;
    }

    public void getUserLayout(ContentHandler ch) throws PortalException {
        Document ulm=this.getUserLayoutDOM();
        if(ulm==null) {
            throw new PortalException("User layout has not been initialized");
        } else {
            getUserLayout(ulm,ch);
        }
    }

    public void getUserLayout(String nodeId, ContentHandler ch) throws PortalException {
        Document ulm=this.getUserLayoutDOM();

        if(ulm==null) {
            throw new PortalException("User layout has not been initialized");
        } else {
            Node rootNode=ulm.getElementById(nodeId);

            if(rootNode==null) {
                throw new PortalException("A requested root node (with id=\""+nodeId+"\") is not in the user layout.");
            } else {
                getUserLayout(rootNode,ch);
            }
        }
    }

    protected void getUserLayout(Node n,ContentHandler ch) throws PortalException {
        // do a DOM2SAX transformation, invoking marking transformation if necessary
        try {
            if(markingMode!=null) {
                Hashtable stylesheetParams=new Hashtable(1);
                stylesheetParams.put("operation",markingMode);
                if(markingNode!=null) {
                    stylesheetParams.put("targetId",markingNode);
                }
                XSLT xslt = XSLT.getTransformer(this);
                xslt.setXML(n); 
                xslt.setTarget(ch);
                xslt.setStylesheetParameters(stylesheetParams);
                xslt.setXSL(MARKING_XSLT_URI);
                xslt.transform();
            } else {
                Transformer emptyt=TransformerFactory.newInstance().newTransformer();
                emptyt.transform(new DOMSource(n), new SAXResult(ch));
            }
        } catch (Exception e) {
            throw new PortalException("Encountered an exception trying to output user layout",e);
        }
    }


    public void setLayoutStore(IUserLayoutStore store) {
        this.store=store;
    }

    protected IUserLayoutStore getLayoutStore() {
        return this.store;
    }


    public void loadUserLayout() throws PortalException {
        if(this.getLayoutStore()==null) {
            throw new PortalException("Store implementation has not been set.");
        } else {
            try {
                Document uli=this.getLayoutStore().getUserLayout(this.owner,this.profile);
                if(uli!=null) {
                    this.setUserLayoutDOM(uli);
                    clearDirtyFlag();
                    // inform listeners
                    for(Iterator i=listeners.iterator();i.hasNext();) {
                        LayoutEventListener lel=(LayoutEventListener)i.next();
                        lel.layoutLoaded();
                    }
                    updateCacheKey();
                } else {
                    throw new PortalException("Null user layout returned for ownerId=\""+owner.getID()+"\", profileId=\""+profile.getProfileId()+"\", layoutId=\""+profile.getLayoutId()+"\"");
                }
            } catch (PortalException pe) {
                throw pe;
            } catch (Exception e) {
                throw new PortalException("Exception encountered while reading a layout for userId="+this.owner.getID()+", profileId="+this.profile.getProfileId(),e);
            }
        }
    }

    public void saveUserLayout() throws PortalException{
        if(isLayoutDirty()) {
            Document ulm=this.getUserLayoutDOM();
            if(ulm==null) {
                throw new PortalException("UserLayout has not been initialized.");
            } else {
                if(this.getLayoutStore()==null) {
                    throw new PortalException("Store implementation has not been set.");
                } else {
                    try {
                        this.getLayoutStore().setUserLayout(this.owner,this.profile,ulm,true);
                        // inform listeners
                        for(Iterator i=listeners.iterator();i.hasNext();) {
                            LayoutEventListener lel=(LayoutEventListener)i.next();
                            lel.layoutSaved();
                        }
                    } catch (PortalException pe) {
                        throw pe;
                    } catch (Exception e) {
                        throw new PortalException("Exception encountered while trying to save a layout for userId="+this.owner.getID()+", profileId="+this.profile.getProfileId(),e);
                    }
                }
            }
        }
    }

    public IUserLayoutNodeDescription getNode(String nodeId) throws PortalException {
        Document ulm=this.getUserLayoutDOM();
        if(ulm==null) {
            throw new PortalException("UserLayout has not been initialized.");
        }

        // find an element with a given id
        Element element = (Element) ulm.getElementById(nodeId);

        if(element==null) {
            throw new PortalException("Element with ID=\""+nodeId+"\" doesn't exist.");
        }
        return UserLayoutNodeDescription.createUserLayoutNodeDescription(element);
    }

    /**
     * Returns the depth of a node in the layout tree.
     *
     * @param nodeId a <code>String</code> value
     * @return a depth value
     * @exception PortalException if an error occurs
     */
    public int getDepth(String nodeId) throws PortalException {
        int depth = 0;
        for (String parentId = getParentId(nodeId); parentId != null; parentId = getParentId(parentId), depth++);
        return depth;
    }

    public IUserLayoutNodeDescription addNode(IUserLayoutNodeDescription node, String parentId, String nextSiblingId) throws PortalException {
        boolean isChannel=false;
        IUserLayoutNodeDescription parent=this.getNode(parentId);
        if(canAddNode(node,parent,nextSiblingId)) {
            // assign new Id

            if(this.getLayoutStore()==null) {
                throw new PortalException("Store implementation has not been set.");
            } else {
                try {
                    if(node instanceof IUserLayoutChannelDescription) {
                        isChannel=true;
                        node.setId(this.getLayoutStore().generateNewChannelSubscribeId(owner));
                    } else {
                        node.setId(this.getLayoutStore().generateNewFolderId(owner));
                    }
                } catch (PortalException pe) {
                    throw pe;
                } catch (Exception e) {
                    throw new PortalException("Exception encountered while generating new usre layout node Id for userId="+this.owner.getID());
                }
            }

            Document ulm=this.getUserLayoutDOM();
            Element childElement=node.getXML(ulm);
            
            // If channel is editable, check if user has permission to edit this channel
            if (node instanceof IUserLayoutChannelDescription) {
              if (childElement.getAttribute("editable") == "true") {
                EntityIdentifier ei = owner.getEntityIdentifier();
                IAuthorizationPrincipal ap = AuthorizationService.instance().newPrincipal(ei.getKey(),ei.getType());
                // Remove edit option if user doesn't have access 
                if (!ap.canEdit(Integer.parseInt(childElement.getAttribute("chanID")))) {
                  childElement.setAttribute("editable", "false");
                }
              }
            }

            Element parentElement=(Element)ulm.getElementById(parentId);
            if(nextSiblingId==null) {
                parentElement.appendChild(childElement);
            } else {
                Node nextSibling=ulm.getElementById(nextSiblingId);
                parentElement.insertBefore(childElement,nextSibling);
            }
            markLayoutDirty();
            // register element id
            if (ulm instanceof IPortalDocument) {
                ((IPortalDocument)ulm).putIdentifier(
                    node.getId(),childElement);
            } else {
                StringBuffer msg = new StringBuffer(128);
                msg.append("SimpleUserLayoutManager::addNode() : ");
                msg.append("User Layout does not implement IPortalDocument, ");
                msg.append("so element caching cannot be performed.");
                log.error( msg.toString());
            }

            this.updateCacheKey();
            this.clearMarkings();

            // inform the listeners
            LayoutEvent ev=new LayoutEvent(this,node);
            for(Iterator i=listeners.iterator();i.hasNext();) {
                LayoutEventListener lel=(LayoutEventListener)i.next();
                if(isChannel) {
                  lel.channelAdded(ev);
                } else {
                    lel.folderAdded(ev);
                }
            }
            return node;
        }
        return null;
    }

    public void clearMarkings() {
        markingMode=null;
        markingNode=null;
    }

    public boolean moveNode(String nodeId, String parentId, String nextSiblingId) throws PortalException  {

        IUserLayoutNodeDescription parent=this.getNode(parentId);
        IUserLayoutNodeDescription node=this.getNode(nodeId);
        String oldParentNodeId=getParentId(nodeId);
        if(canMoveNode(node,parent,nextSiblingId)) {
            // must be a folder
            Document ulm=this.getUserLayoutDOM();
            Element childElement=(Element)ulm.getElementById(nodeId);
            Element parentElement=(Element)ulm.getElementById(parentId);
            if(nextSiblingId==null) {
                parentElement.appendChild(childElement);
            } else {
                Node nextSibling=ulm.getElementById(nextSiblingId);
                parentElement.insertBefore(childElement,nextSibling);
            }
            markLayoutDirty();
            clearMarkings();
            updateCacheKey();

            // inform the listeners
            boolean isChannel=false;
            if(node instanceof IUserLayoutChannelDescription) {
                isChannel=true;
            }
            LayoutMoveEvent ev=new LayoutMoveEvent(this,node,oldParentNodeId);
            for(Iterator i=listeners.iterator();i.hasNext();) {
                LayoutEventListener lel=(LayoutEventListener)i.next();
                if(isChannel) {
                    lel.channelMoved(ev);
                } else {
                    lel.folderMoved(ev);
                }
            }
            return true;
        } else {
            return false;
        }
    }

    public boolean deleteNode(String nodeId) throws PortalException {
        if(canDeleteNode(nodeId)) {
            IUserLayoutNodeDescription nodeDescription=this.getNode(nodeId);
            String parentNodeId=this.getParentId(nodeId);

            Document ulm=this.getUserLayoutDOM();
            Element childElement=(Element)ulm.getElementById(nodeId);
            Node parent=childElement.getParentNode();
            if(parent!=null) {
                parent.removeChild(childElement);
            } else {
                throw new PortalException("Node \""+nodeId+"\" has a NULL parent !");
            }
            markLayoutDirty();
            // clearMarkings(); // this one is questionable
            this.updateCacheKey();

            // inform the listeners
            boolean isChannel=false;
            if(nodeDescription instanceof IUserLayoutChannelDescription) {
                isChannel=true;
            }
            LayoutMoveEvent ev=new LayoutMoveEvent(this,nodeDescription,parentNodeId);
            for(Iterator i=listeners.iterator();i.hasNext();) {
                LayoutEventListener lel=(LayoutEventListener)i.next();
                if(isChannel) {
                    lel.channelDeleted(ev);
                } else {
                    lel.folderDeleted(ev);
                }
            }

            return true;
        } else {
            return false;
        }
    }

    public String getRootFolderId() {
     try {
      if ( rootNodeId == null ) {
       Element rootNode = (Element) XPathAPI.selectSingleNode(this.getUserLayoutDOM(),"//layout/folder");
       rootNodeId = rootNode.getAttribute("ID");
      }
     } catch ( Exception e ) {
         log.error( e);
       }
       return rootNodeId;
    }

    public synchronized boolean updateNode(IUserLayoutNodeDescription node) throws PortalException {
        boolean isChannel=false;
        if(canUpdateNode(node)) {
            // normally here, one would determine what has changed
            // but we'll just make sure that the node type has not
            // changed and then regenerate the node Element from scratch,
            // and attach any children it might have had to it.

            String nodeId=node.getId();
            String nextSiblingId=getNextSiblingId(nodeId);
            Element nextSibling=null;
            if(nextSiblingId!=null) {
                Document ulm=this.getUserLayoutDOM();
                nextSibling=ulm.getElementById(nextSiblingId);
            }

            IUserLayoutNodeDescription oldNode=getNode(nodeId);

            if(oldNode instanceof IUserLayoutChannelDescription) {
                IUserLayoutChannelDescription oldChannel=(IUserLayoutChannelDescription) oldNode;
                if(node instanceof IUserLayoutChannelDescription) {
                    isChannel=true;
                    Document ulm=this.getUserLayoutDOM();
                    // generate new XML Element
                    Element newChannelElement=node.getXML(ulm);
    
                    // If channel is editable, check if user has permission to edit this channel
                    if (newChannelElement.getAttribute("editable") == "true") {
                      EntityIdentifier ei = owner.getEntityIdentifier();
                      IAuthorizationPrincipal ap = AuthorizationService.instance().newPrincipal(ei.getKey(),ei.getType());
                      // Remove edit attribute if user doesn't have access 
                      if (!ap.canEdit(Integer.parseInt(newChannelElement.getAttribute("chanID")))) {
                        newChannelElement.setAttribute("editable", "false");
                      }
                    }

                    Element oldChannelElement=(Element)ulm.getElementById(nodeId);
                    Node parent=oldChannelElement.getParentNode();
                    parent.removeChild(oldChannelElement);
                    parent.insertBefore(newChannelElement,nextSibling);
                    // register new child instead
                    if (ulm instanceof IPortalDocument) {
                        ((IPortalDocument)ulm).putIdentifier(
                            node.getId(),newChannelElement);
                    } else {
                        StringBuffer msg = new StringBuffer(128);
                        msg.append("SimpleUserLayoutManager::updateNode() : ");
                        msg.append("User Layout does not implement ");
                        msg.append("IPortalDocument, ");
                        msg.append("so element caching cannot be performed.");
                        log.error( msg.toString());
                    }

                    // inform the listeners
                    LayoutEvent ev=new LayoutEvent(this,node);
                    for(Iterator i=listeners.iterator();i.hasNext();) {
                        LayoutEventListener lel=(LayoutEventListener)i.next();
                        lel.channelUpdated(ev);
                    }
                } else {
                    throw new PortalException("Change channel to folder is not allowed by updateNode() method!");
                }
            } else {
                 // must be a folder
                IUserLayoutFolderDescription oldFolder=(IUserLayoutFolderDescription) oldNode;
                if(node instanceof IUserLayoutFolderDescription) {
                    Document ulm=this.getUserLayoutDOM();
                    // generate new XML Element
                    Element newFolderElement=node.getXML(ulm);
                    Element oldFolderElement=(Element)ulm.getElementById(nodeId);
                    Node parent=oldFolderElement.getParentNode();

                    // move children
                    Vector children=new Vector();
                    for(Node n=oldFolderElement.getFirstChild(); n!=null;n=n.getNextSibling()) {
                        children.add(n);
                    }

                    for(int i=0;i<children.size();i++) {
                        newFolderElement.appendChild((Node)children.get(i));
                    }

                    // replace the actual node
                    parent.removeChild(oldFolderElement);
                    parent.insertBefore(newFolderElement,nextSibling);
                    // register new child instead
                    if (ulm instanceof IPortalDocument) {
                        ((IPortalDocument)ulm).putIdentifier(
                            node.getId(), newFolderElement);
                    } else {
                        StringBuffer msg = new StringBuffer(128);
                        msg.append("SimpleUserLayoutManager::updateNode() : ");
                        msg.append("User Layout does not implement ");
                        msg.append("IPortalDocument, ");
                        msg.append("so element caching cannot be performed.");
                        log.error( msg.toString());
                    }

                    // inform the listeners
                    LayoutEvent ev=new LayoutEvent(this,node);
                    for(Iterator i=listeners.iterator();i.hasNext();) {
                        LayoutEventListener lel=(LayoutEventListener)i.next();
                        lel.folderUpdated(ev);
                    }
                }
            }
            markLayoutDirty();
            this.updateCacheKey();

            return true;
        } else {
            return false;
        }
    }


    public boolean canAddNode(IUserLayoutNodeDescription node, String parentId, String nextSiblingId) throws PortalException {
        return this.canAddNode(node,this.getNode(parentId),nextSiblingId);
    }

    protected boolean canAddNode(IUserLayoutNodeDescription node,IUserLayoutNodeDescription parent, String nextSiblingId) throws PortalException {
        // make sure sibling exists and is a child of nodeId
        if(nextSiblingId!=null) {
            IUserLayoutNodeDescription sibling=getNode(nextSiblingId);
            if(sibling==null) {
                throw new PortalException("Unable to find a sibling node with id=\""+nextSiblingId+"\"");
            }
            if(!parent.getId().equals(getParentId(nextSiblingId))) {
                throw new PortalException("Given sibling (\""+nextSiblingId+"\") is not a child of a given parentId (\""+parent.getId()+"\")");
            }
        }

        return (parent!=null && parent instanceof IUserLayoutFolderDescription && !parent.isImmutable());
    }

    public boolean canMoveNode(String nodeId, String parentId,String nextSiblingId) throws PortalException {
        return this.canMoveNode(this.getNode(nodeId),this.getNode(parentId),nextSiblingId);
    }

    protected boolean canMoveNode(IUserLayoutNodeDescription node,IUserLayoutNodeDescription parent, String nextSiblingId) throws PortalException {
        // is the current parent immutable ?
        IUserLayoutNodeDescription currentParent=getNode(getParentId(node.getId()));
        if(currentParent==null) {
            throw new PortalException("Unable to determine a parent node for node with id=\""+node.getId()+"\"");
        }
        return (!currentParent.isImmutable() && canAddNode(node,parent,nextSiblingId));
    }

    public boolean canDeleteNode(String nodeId) throws PortalException {
        return canDeleteNode(this.getNode(nodeId));
    }

    protected boolean canDeleteNode(IUserLayoutNodeDescription node) throws PortalException {
        return !(node==null || node.isUnremovable());
    }

    public boolean canUpdateNode(String nodeId) throws PortalException {
        return canUpdateNode(this.getNode(nodeId));
    }

    public boolean canUpdateNode(IUserLayoutNodeDescription node) {
        return !(node==null || node.isImmutable());
    }

    public void markAddTargets(IUserLayoutNodeDescription node) throws PortalException {
        if(node!=null) {
            this.markingMode=ADD_COMMAND;
        } else {
            clearMarkings();
        }
    }

    public void markMoveTargets(String nodeId) throws PortalException {
        if(nodeId!=null) {
            this.markingMode=MOVE_COMMAND;
            this.markingNode=nodeId;
        } else {
            clearMarkings();
        }
    }

    public String getParentId(String nodeId) throws PortalException {
        Document ulm=this.getUserLayoutDOM();
        Element nelement=(Element)ulm.getElementById(nodeId);
        if(nelement!=null) {
            Node parent=nelement.getParentNode();
            if(parent!=null) {
                if(parent.getNodeType()!=Node.ELEMENT_NODE) {
                    throw new PortalException("Node with id=\""+nodeId+"\" is attached to something other then an element node.");
                } else {
                    Element e=(Element) parent;
                    return e.getAttribute("ID");
                }
            } else {
                return null;
            }
        } else {
            throw new PortalException("Node with id=\""+nodeId+"\" doesn't exist.");
        }
    }

    public String getNextSiblingId(String nodeId) throws PortalException {
        Document ulm=this.getUserLayoutDOM();
        Element nelement=(Element)ulm.getElementById(nodeId);
        if(nelement!=null) {
            Node nsibling=nelement.getNextSibling();
            // scroll to the next element node
            while(nsibling!=null && nsibling.getNodeType()!=Node.ELEMENT_NODE){
                nsibling=nsibling.getNextSibling();
            }
            if(nsibling!=null) {
                Element e=(Element) nsibling;
                return e.getAttribute("ID");
            } else {
                return null;
            }
        } else {
            throw new PortalException("Node with id=\""+nodeId+"\" doesn't exist.");
        }
    }

    public String getPreviousSiblingId(String nodeId) throws PortalException {
        Document ulm=this.getUserLayoutDOM();
        Element nelement=(Element)ulm.getElementById(nodeId);
        if(nelement!=null) {
            Node nsibling=nelement.getPreviousSibling();
            // scroll to the next element node
            while(nsibling!=null && nsibling.getNodeType()!=Node.ELEMENT_NODE){
                nsibling=nsibling.getNextSibling();
            }
            if(nsibling!=null) {
                Element e=(Element) nsibling;
                return e.getAttribute("ID");
            } else {
                return null;
            }
        } else {
            throw new PortalException("Node with id=\""+nodeId+"\" doesn't exist.");
        }
    }

    public Enumeration getChildIds(String nodeId) throws PortalException {
        Vector v=new Vector();
        IUserLayoutNodeDescription node=getNode(nodeId);
        if(node instanceof IUserLayoutFolderDescription) {
            Document ulm=this.getUserLayoutDOM();
            Element felement=(Element)ulm.getElementById(nodeId);
            for(Node n=felement.getFirstChild(); n!=null;n=n.getNextSibling()) {
                if(n.getNodeType()==Node.ELEMENT_NODE) {
                    Element e=(Element)n;
                    if(e.getAttribute("ID")!=null) {
                        v.add(e.getAttribute("ID"));
                    }
                }
            }
        }
        return v.elements();
    }

    public String getCacheKey() {
        if(markingMode==null) {
            return this.cacheKey;
        } else {
            if(markingNode!=null) {
                return this.cacheKey+this.markingMode+this.markingNode;
            } else {
                return this.cacheKey+this.markingMode;
            }
        }
    }

    /**
     * This is outright cheating ! We're supposed to analyze the user layout tree
     * and return a key that corresponds uniqly to the composition and the sturcture of the tree.
     * Here we just return a different key wheneever anything changes. So if one was to move a
     * node back and forth, the key would always never (almost) come back to the original value,
     * even though the changes to the user layout are cyclic.
     *
     */
    private void updateCacheKey() {
        this.cacheKey=Long.toString(rnd.nextLong());
    }

    public int getLayoutId() {
        return profile.getLayoutId();
    }

    /**
     * Returns a subscription id given a functional name.
     *
     * @param fname  the functional name to lookup.
     * @return a <code>String</code> subscription id.
     */
    public String getSubscribeId(String fname) throws PortalException {
        try {
            Element fnameNode = (Element) XPathAPI.selectSingleNode(this.getUserLayoutDOM(),"//channel[@fname=\'"+fname+"\']");
            if(fnameNode!=null) {
                return fnameNode.getAttribute("ID");
            } else {
                return null;
            }
        } catch (Exception e) {
            log.error( "SimpleUserLayoutManager::getSubcribeId() : encountered the following exception, while trying to identify subscribe channel id for the fname=\""+fname+"\" : "+e);
            e.printStackTrace();
            return null;
        }
    }

    public boolean addLayoutEventListener(LayoutEventListener l) {
        return listeners.add(l);
    }
    public boolean removeLayoutEventListener(LayoutEventListener l) {
        return listeners.remove(l);
    }

    /**
     * A factory method to create an empty <code>IUserLayoutNodeDescription</code> instance
     *
     * @param nodeType a node type value
     * @return an <code>IUserLayoutNodeDescription</code> instance
     * @exception PortalException if the error occurs.
     */
    public IUserLayoutNodeDescription createNodeDescription( int nodeType ) throws PortalException {
            switch ( nodeType ) {
              case IUserLayoutNodeDescription.FOLDER:
                return new UserLayoutFolderDescription();
              case IUserLayoutNodeDescription.CHANNEL:
                return new UserLayoutChannelDescription();
              default:
                return null;
            }
    }

    protected boolean isLayoutDirty() { return dirtyState; }
    private void markLayoutDirty() { dirtyState=true; }
    private void clearDirtyFlag() { dirtyState=false; }
}