/*
 *    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.xml.impl.jxpath;

import org.apache.commons.jxpath.ri.QName;
import org.apache.commons.jxpath.ri.model.NodePointer;
import org.opengis.feature.simple.SimpleFeature;


/**
 * Pointer to a single property of a feature.
 * <p>
 * THe property of the feature is specified via index. Setting the index to
 * -1 will cause the pointer to point at the feature id.
 * </p>
 * @author Justin Deoliveira, The Open Planning Project
 *
 *
 *
 * @source $URL$
 */
public class FeaturePropertyPointer extends NodePointer {
    /**
     * the feature
     */
    SimpleFeature feature;

    /**
     * The parent pointer
     */
    FeaturePointer parent;

    /**
     * the indedx of hte property being pointed at
     */
    int index;

    /**
     * Creates the pointer.
     *
     * @param parent The parent pointer, pointer at the feature.
     * @param index The index of hte property to point to, or -1 to point
     *         to the feature id.
     */
    public FeaturePropertyPointer(FeaturePointer parent, int index) {
        super(parent);
        this.index = index;
        this.feature = (SimpleFeature) parent.getImmediateNode();
    }

    /**
     * Return <code>true</code>.
     */
    public boolean isLeaf() {
        return true;
    }

    /**
     * Return <code>false</code>.
     */
    public boolean isCollection() {
        return false;
    }

    /**
     * Return <code>1</code>
     */
    public int getLength() {
        return 1;
    }

    /**
     * Returns the qname with prefix as <code>null</code>, and local part the name of the
     * feature attribute.
     */
    public QName getName() {
        return (index != -1)
        ? new QName(null, feature.getFeatureType().getDescriptor(index).getLocalName())
        : new QName(null, "fid");
    }

    public Object getBaseValue() {
        return feature;
    }

    public Object getImmediateNode() {
        return (index != -1) ? feature.getAttribute(index) : feature.getID();
    }

    public void setValue(Object value) {
        if (index == -1) {
            return; //fids arent settable
        }

        try {
            feature.setAttribute(index, value);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Always return <code>0</code>, can never have child pointers.
     */
    public int compareChildNodePointers(NodePointer pointer1, NodePointer pointer2) {
        return 0;
    }
}