/*
 *    GeoTools - The Open Source Java GIS Toolkit
 *    http://geotools.org
 * 
 *    (C) 2002-2008, 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.filter.expression;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.atomic.AtomicReference;

import org.geotools.factory.FactoryRegistry;
import org.geotools.factory.Hints;

/**
 * Convenience class for looking up a property accessor for a particular object type.
 * 
 * @author Justin Deoliveira, The Open Planning Project
 * 
 *
 *
 * @source $URL$
 */
public class PropertyAccessors {
    static final PropertyAccessorFactory[] FACTORY_CACHE;
    
    static {
        List<PropertyAccessorFactory> cache = new ArrayList<PropertyAccessorFactory>();

        // add the simple feature property accessor factory first for performance
        // reasons         
        cache.add( new NullPropertyAccessorFactory()); //NC - added       
        cache.add( new SimpleFeaturePropertyAccessorFactory());
        cache.add( new DirectPropertyAccessorFactory());       
        Iterator factories = FactoryRegistry
                 .lookupProviders(PropertyAccessorFactory.class);
         while (factories.hasNext()) {
            Object factory = factories.next();
            if ( factory instanceof SimpleFeaturePropertyAccessorFactory || factory instanceof DirectPropertyAccessorFactory
                 || factory instanceof NullPropertyAccessorFactory )
                continue;
            
            cache.add((PropertyAccessorFactory) factory);
         }
         FACTORY_CACHE = (PropertyAccessorFactory[]) cache.toArray(new PropertyAccessorFactory[cache.size()]);
    }
    
    /**
     * Make sure this class won't be instantianted
     */
    private PropertyAccessors() {}

    //NC - old method, not used anymore
    /**
     * Looks up a {@link PropertyAccessor} for a particular object.
     * <p>
     * This method will return the first accessor that is capabile of handling the object and xpath
     * expression provided, no order is guaranteed.
     * </p>
     * 
     * @param object
     *            The target object.
     * @param xpath
     *            An xpath expression denoting a property of the target object.
     * @param hints
     *            Hints to pass on to factories.
     * 
     * @return A property accessor, or <code>null</code> if one could not be found.
     * 
     * @deprecated Use findPropertyAccessors, returned property accessor might not work
     * @see findPropertyAccessors
     */
     public static PropertyAccessor findPropertyAccessor(Object object, String xpath, Class target,
            Hints hints) {
        if (object == null)
            return null;

        for(PropertyAccessorFactory factory : FACTORY_CACHE) {
            PropertyAccessor accessor = factory.createPropertyAccessor(object.getClass(), xpath,
                    target, hints);
            if (accessor != null && accessor.canHandle(object, xpath, target)) {
                return accessor;
            }
        }
        return null;
    } 
    
    
    /**
     * Looks up a list of {@link PropertyAccessor} for a particular object.
     * <p>
     * This method will return all accessors that is capable of handling the object and xpath
     * expression provided, no order is guaranteed.
     * </p>
     * 
     * @param object
     *            The target object.
     * @param xpath
     *            An xpath expression denoting a property of the target object.
     * @param hints
     *            Hints to pass on to factories.
     * 
     * @return List of Property accessors, or <code>null</code> if object is null
     */
    public static List<PropertyAccessor> findPropertyAccessors(Object object, String xpath,
            Class target, Hints hints) {
        if (object == null)
            return null;

        List<PropertyAccessor> list = new ArrayList<PropertyAccessor>();

        for (PropertyAccessorFactory factory : FACTORY_CACHE) {
            PropertyAccessor accessor = factory.createPropertyAccessor(object.getClass(), xpath,
                    target, hints);
            if (accessor != null && accessor.canHandle(object, xpath, target)) {
                list.add(accessor);
            }
        }
        return list;
    }
    
    
 }