/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 *
 *    (C) 2002-2010, Open Source Geospatial Foundation (OSGeo)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 */
package org.geotools.gml2;

import java.util.ArrayList;
import java.util.ConcurrentModificationException;
import java.util.Iterator;

import org.eclipse.emf.common.notify.Adapter;
import org.eclipse.emf.common.notify.Notification;
import org.eclipse.emf.common.notify.Notifier;
import org.eclipse.xsd.XSDElementDeclaration;
import org.eclipse.xsd.XSDFactory;
import org.eclipse.xsd.XSDPackage;
import org.geotools.util.Utilities;

/**
 * Adapter for preventing memory leaks created by substitution group affiliations.
 * <p>
 * When an application schema contains an element in the gml:_Feature substitution group a link 
 * from gml:_Feature back to the app schema element is created. Since the gml schema (and thus the
 * gml:_Feature) element is a singleton this creates a memory leak. This adapter watches the 
 * {@link XSDElementDeclaration#getSubstitutionGroup()} of the gml:_Feature element and prevents it
 * from growing in size by making it a unique list of {@link XSDElementDeclaration} based on 
 * qualified name.
 * </p>
 * 
 * @author Justin Deoliveira, OpenGeo
 *
 * @source $URL: http://svn.osgeo.org/geotools/trunk/modules/extension/xsd/xsd-gml2/src/main/java/org/geotools/gml2/SubstitutionGroupLeakPreventer.java $
 */
public class SubstitutionGroupLeakPreventer implements Adapter {

    XSDElementDeclaration target;
    
    public Notifier getTarget() {
        return target;
    }
    
    public void setTarget(Notifier newTarget) {
        target = (XSDElementDeclaration) newTarget;
    }

    public boolean isAdapterForType(Object type) {
        return type instanceof XSDElementDeclaration;
    }

    public void notifyChanged(Notification notification) {
        int featureId = notification.getFeatureID(target.getClass());
        if (featureId != XSDPackage.XSD_ELEMENT_DECLARATION__SUBSTITUTION_GROUP) {
            return;
        }
           
        if (notification.getEventType() != Notification.ADD) {
            return;
        }
        if (!(notification.getNewValue() instanceof XSDElementDeclaration)) {
                return;
        }
            
        XSDElementDeclaration el = (XSDElementDeclaration) notification.getNewValue();
        XSDElementDeclaration e = target;
            
        while(e != null) {
            synchronized(e) {
                ArrayList<Integer> toremove = new ArrayList();
                for (int i = 0; i < e.getSubstitutionGroup().size(); i++) {
                    XSDElementDeclaration se = (XSDElementDeclaration) e.getSubstitutionGroup().get(i);
                    if (se == null || (Utilities.equals(el.getTargetNamespace(), se.getTargetNamespace())
                            && Utilities.equals(el.getName(), se.getName()))) {
                        toremove.add(i);
                    }
                }
                
                //iterate back in reverse order and skip the last element as to keep the latest
                // version of the element
                ArrayList<XSDElementDeclaration> removed = new ArrayList();
                for (int i = toremove.size()-2; i > -1; i--) {
                    XSDElementDeclaration se = (XSDElementDeclaration)
                        e.getSubstitutionGroup().remove(toremove.get(i).intValue());
                    removed.add(e);
                }
                
                //set the removed elements sub affiliation to a clone of the actual element
                for (XSDElementDeclaration se : removed) {
                    if (se != null && e.equals(se.getSubstitutionGroupAffiliation())) {
                        XSDElementDeclaration clone = 
                            (XSDElementDeclaration) e.cloneConcreteComponent(false, false);
                        clone.setTargetNamespace(GML.NAMESPACE);
                        
                        se.setSubstitutionGroupAffiliation(clone);
                    }
                }
            }
            e = e.getSubstitutionGroupAffiliation();
        }
        
    }


}