/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/**

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements. See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership. The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License. You may obtain a copy of the License at

 *

 * http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing,

 * software distributed under the License is distributed on an

 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

 * KIND, either express or implied. See the License for the

 * specific language governing permissions and limitations

 * under the License.

 */

package com.sun.org.apache.xml.internal.security.utils;

import javax.xml.XMLConstants;

import javax.xml.transform.TransformerException;

import javax.xml.xpath.XPath;

import javax.xml.xpath.XPathConstants;

import javax.xml.xpath.XPathExpression;

import javax.xml.xpath.XPathExpressionException;

import javax.xml.xpath.XPathFactory;

import javax.xml.xpath.XPathFactoryConfigurationException;

import org.w3c.dom.Node;

import org.w3c.dom.NodeList;

/**

 * An implementation for XPath evaluation that uses the JDK API.

 */

public class JDKXPathAPI implements XPathAPI {

    private XPathFactory xpf;

    private String xpathStr;

    private XPathExpression xpathExpression;

    /**

     *  Use an XPath string to select a nodelist.

     *  XPath namespace prefixes are resolved from the namespaceNode.

     *

     *  @param contextNode The node to start searching from.

     *  @param xpathnode

     *  @param str

     *  @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.

     *  @return A NodeIterator, should never be null.

     *

     * @throws TransformerException

     */

    public NodeList selectNodeList(

        Node contextNode, Node xpathnode, String str, Node namespaceNode

    ) throws TransformerException {

        if (!str.equals(xpathStr) || xpathExpression == null) {

            if (xpf == null) {

                xpf = XPathFactory.newInstance();

                try {

                    xpf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);

                } catch (XPathFactoryConfigurationException ex) {

                    throw new TransformerException(ex);

                }

            }

            XPath xpath = xpf.newXPath();

            xpath.setNamespaceContext(new DOMNamespaceContext(namespaceNode));

            xpathStr = str;

            try {

                xpathExpression = xpath.compile(xpathStr);

            } catch (XPathExpressionException ex) {

                throw new TransformerException(ex);

            }

        }

        try {

            return (NodeList)xpathExpression.evaluate(contextNode, XPathConstants.NODESET);

        } catch (XPathExpressionException ex) {

            throw new TransformerException(ex);

        }

    }

    /**

     * Evaluate an XPath string and return true if the output is to be included or not.

     *  @param contextNode The node to start searching from.

     *  @param xpathnode The XPath node

     *  @param str The XPath expression

     *  @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.

     */

    public boolean evaluate(Node contextNode, Node xpathnode, String str, Node namespaceNode)

        throws TransformerException {

        if (!str.equals(xpathStr) || xpathExpression == null) {

            if (xpf == null) {

                xpf = XPathFactory.newInstance();

                try {

                    xpf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);

                } catch (XPathFactoryConfigurationException ex) {

                    throw new TransformerException(ex);

                }

            }

            XPath xpath = xpf.newXPath();

            xpath.setNamespaceContext(new DOMNamespaceContext(namespaceNode));

            xpathStr = str;

            try {

                xpathExpression = xpath.compile(xpathStr);

            } catch (XPathExpressionException ex) {

                throw new TransformerException(ex);

            }

        }

        try {

            return (Boolean)xpathExpression.evaluate(contextNode, XPathConstants.BOOLEAN);

        } catch (XPathExpressionException ex) {

            throw new TransformerException(ex);

        }

    }

    /**

     * Clear any context information from this object

     */

    public void clear() {

        xpathStr = null;

        xpathExpression = null;

        xpf = null;

    }

}