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/**
 *  Copyright 2005-2016 Red Hat, Inc.
 *
 *  Red Hat 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 io.fabric8.utils;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

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 java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.StringWriter;

/**
 * A collection of helper methods for working with the DOM API
 */
public class DomHelper {

    private static TransformerFactory transformerFactory;
    private static Transformer transformer;

    public static Element addChildElement(Node parent, String elementName) {
        Document ownerDocument = parent.getOwnerDocument();
        Objects.notNull(ownerDocument, "nodes ownerDocument " + parent);
        Element element = ownerDocument.createElement(elementName);
        parent.appendChild(element);
        return element;
    }

    public static Element addChildElement(Node parent, String elementName, String textContent) {
        Element element = addChildElement(parent, elementName);
        element.setTextContent(textContent);
        return element;
    }

    public static void save(Document document, File file) throws FileNotFoundException, TransformerException {
        Transformer transformer = getTransformer();
        transformer.transform(new DOMSource(document), new StreamResult(new FileOutputStream(file)));
    }


    public static String toXml(Document document) throws TransformerException {
        Transformer transformer = getTransformer();
        StringWriter buffer = new StringWriter();
        transformer.transform(new DOMSource(document), new StreamResult(buffer));
        return buffer.toString();
    }

    public static Transformer getTransformer() throws TransformerConfigurationException {
        if (transformer == null) {
            transformer = getTransformerFactory().newTransformer();
        }
        return transformer;
    }

    public static void setTransformer(Transformer transformer) {
        DomHelper.transformer = transformer;
    }

    public static TransformerFactory getTransformerFactory() {
        if (transformerFactory == null){
            transformerFactory = TransformerFactory.newInstance();
        }
        return transformerFactory;
    }

    public static void setTransformerFactory(TransformerFactory transformerFactory) {
        DomHelper.transformerFactory = transformerFactory;
    }

    /**
     * If the node is attached to a parent then detach it
     */
    public static void detach(Node node) {
        if (node != null) {
            Node parentNode = node.getParentNode();
            if (parentNode != null) {
                parentNode.removeChild(node);
            }
        }
    }

    /**
     * Replaces the old node with the new node
     */
    public static void replaceWith(Node oldNode, Node newNode) {
        Node parentNode = oldNode.getParentNode();
        if (parentNode != null) {
            parentNode.replaceChild(newNode, oldNode);
        }
    }

    /**
     * Removes any previous siblings text nodes
     */
    public static void removePreviousSiblingText(Element element) {
        while (true) {
            Node sibling = element.getPreviousSibling();
            if (sibling instanceof Text) {
                detach(sibling);
            } else {
                break;
            }
        }
    }

    /**
     * Removes any next siblings text nodes
     */
    public static void removeNextSiblingText(Element element) {
        while (true) {
            Node sibling = element.getNextSibling();
            if (sibling instanceof Text) {
                detach(sibling);
            } else {
                break;
            }
        }
    }

    /**
     * Returns the first child element for the given name
     */
    public static Element firstChild(Element element, String name) {
        NodeList nodes = element.getChildNodes();
        if (nodes != null) {
            for (int i = 0, size = nodes.getLength(); i < size; i++) {
                Node item = nodes.item(i);
                if (item instanceof Element) {
                    Element childElement = (Element) item;

                    if (name.equals(childElement.getTagName())) {
                        return childElement;
                    }
                }
            }
        }
        return null;
    }

    /**
     * Returns true if this node has at least one child element
     */
    public static Element firstChildElement(Node node) {
        if (node != null) {
            NodeList nodes = node.getChildNodes();
            for (int i = 0, size = nodes.getLength(); i < size; i++) {
                Node item = nodes.item(i);
                if (item instanceof Element) {
                    return(Element) item;
                }
            }
        }
        return null;
    }

}