/**
 * Copyright 2014 Microsoft Open Technologies Inc.
 *
 * Licensed 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.microsoftopentechnologies.intellij.helpers;

import org.apache.xerces.dom.DeferredElementImpl;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;

public class XmlHelper {

    public static Object getXMLValue(String xml, String xQuery, QName resultType) throws XPathExpressionException, IOException, SAXException, ParserConfigurationException {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        DocumentBuilder db = dbf.newDocumentBuilder();

        Document doc = db.parse(new InputSource(new StringReader(xml)));

        XPathFactory xPathfactory = XPathFactory.newInstance();

        XPath xPath = xPathfactory.newXPath();
        XPathExpression xPathExpression = xPath.compile(xQuery);
        return xPathExpression.evaluate(doc, resultType);
    }

    public static String getAttributeValue(Node node, String attributeName) {
        Node n = node.getAttributes().getNamedItem(attributeName);
        return (n == null) ? null : n.getNodeValue();
    }

    public static String getChildNodeValue(Node node, String elementName) {
        return ((DeferredElementImpl) node).getElementsByTagName(elementName).item(0).getTextContent();
    }


    public static String saveXmlToStreamWriter(Document doc) throws TransformerException {
        TransformerFactory tf = TransformerFactory.newInstance();
        Transformer transformer = tf.newTransformer();
        StringWriter writer = new StringWriter();
        transformer.transform(new DOMSource(doc), new StreamResult(writer));

        return writer.getBuffer().toString();
    }
}