plugins/core/src/main/java/org/apache/cxf/fediz/core/util/DOMUtils.java

/**
 * 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 org.apache.cxf.fediz.core.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.WeakHashMap;

import javax.xml.XMLConstants;
import javax.xml.namespace.QName;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
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.transform.stream.StreamSource;

import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.Text;

import org.xml.sax.EntityResolver;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

/**
 * Few simple utils to read DOM. This is originally from the Jakarta Commons Modeler.
 * 
 * @author Costin Manolache
 */
public final class DOMUtils {
    private static final String XMLNAMESPACE = "xmlns";

    private static final Map<ClassLoader, DocumentBuilder> DOCUMENT_BUILDERS = Collections
        .synchronizedMap(new WeakHashMap<ClassLoader, DocumentBuilder>());

    private DOMUtils() {
    }

    private static DocumentBuilder getBuilder() throws ParserConfigurationException {
        ClassLoader loader = Thread.currentThread().getContextClassLoader();
        if (loader == null) {
            loader = DOMUtils.class.getClassLoader();
        }
        if (loader == null) {
            DocumentBuilderFactory dbf = createDocumentBuilderFactory();
            return dbf.newDocumentBuilder();
        }
        DocumentBuilder builder = DOCUMENT_BUILDERS.get(loader);
        if (builder == null) {
            DocumentBuilderFactory dbf = createDocumentBuilderFactory();
            builder = dbf.newDocumentBuilder();
            DOCUMENT_BUILDERS.put(loader, builder);
        }
        return builder;
    }

    /**
     * This function is much like getAttribute, but returns null, not "", for a nonexistent attribute.
     * 
     * @param e
     * @param attributeName
     */
    public static String getAttributeValueEmptyNull(Element e, String attributeName) {
        Attr node = e.getAttributeNode(attributeName);
        if (node == null) {
            return null;
        }
        return node.getValue();
    }

    /**
     * Get the trimmed text content of a node or null if there is no text
     */
    public static String getContent(Node n) {
        String s = getRawContent(n);
        if (s != null) {
            s = s.trim();
        }
        return s;
    }

    /**
     * Get the raw text content of a node or null if there is no text
     */
    public static String getRawContent(Node n) {
        if (n == null) {
            return null;
        }
        StringBuilder b = null;
        String s = null;
        Node n1 = n.getFirstChild();
        while (n1 != null) {
            if (n1.getNodeType() == Node.TEXT_NODE) {
                if (b != null) {
                    b.append(((Text)n1).getNodeValue());
                } else if (s == null) {
                    s = ((Text)n1).getNodeValue();
                } else {
                    b = new StringBuilder(s).append(((Text)n1).getNodeValue());
                    s = null;
                }
            }
            n1 = n1.getNextSibling();
        }
        if (b != null) {
            return b.toString();
        }
        return s;
    }

    /**
     * Get the first element child.
     * 
     * @param parent lookup direct childs
     * @param name name of the element. If null return the first element.
     */
    public static Node getChild(Node parent, String name) {
        if (parent == null) {
            return null;
        }

        Node first = parent.getFirstChild();
        if (first == null) {
            return null;
        }

        for (Node node = first; node != null; node = node.getNextSibling()) {
            // System.out.println("getNode: " + name + " " +
            // node.getNodeName());
            if (node.getNodeType() != Node.ELEMENT_NODE) {
                continue;
            }
            if (name != null && name.equals(node.getNodeName())) {
                return node;
            }
            if (name == null) {
                return node;
            }
        }
        return null;
    }

    public static String getAttribute(Node element, String attName) {
        NamedNodeMap attrs = element.getAttributes();
        if (attrs == null) {
            return null;
        }
        Node attN = attrs.getNamedItem(attName);
        if (attN == null) {
            return null;
        }
        return attN.getNodeValue();
    }

    public static String getAttribute(Element element, QName attName) {
        Attr attr;
        if (StringUtils.isEmpty(attName.getNamespaceURI())) {
            attr = element.getAttributeNode(attName.getLocalPart());
        } else {
            attr = element.getAttributeNodeNS(attName.getNamespaceURI(), attName.getLocalPart());
        }
        return attr == null ? null : attr.getValue();
    }

    public static void setAttribute(Node node, String attName, String val) {
        NamedNodeMap attributes = node.getAttributes();
        Node attNode = node.getOwnerDocument().createAttributeNS(null, attName);
        attNode.setNodeValue(val);
        attributes.setNamedItem(attNode);
    }

    public static void removeAttribute(Node node, String attName) {
        NamedNodeMap attributes = node.getAttributes();
        attributes.removeNamedItem(attName);
    }

    /**
     * Set or replace the text value
     */
    public static void setText(Node node, String val) {
        Node chld = DOMUtils.getChild(node, Node.TEXT_NODE);
        if (chld == null) {
            Node textN = node.getOwnerDocument().createTextNode(val);
            node.appendChild(textN);
            return;
        }
        // change the value
        chld.setNodeValue(val);
    }

    /**
     * Find the first direct child with a given attribute.
     * 
     * @param parent
     * @param elemName name of the element, or null for any
     * @param attName attribute we're looking for
     * @param attVal attribute value or null if we just want any
     */
    public static Node findChildWithAtt(Node parent, String elemName, String attName, String attVal) {

        Node child = DOMUtils.getChild(parent, Node.ELEMENT_NODE);
        if (attVal == null) {
            while (child != null && (elemName == null || elemName.equals(child.getNodeName()))
                   && DOMUtils.getAttribute(child, attName) != null) {
                child = getNext(child, elemName, Node.ELEMENT_NODE);
            }
        } else {
            while (child != null && (elemName == null || elemName.equals(child.getNodeName()))
                   && !attVal.equals(DOMUtils.getAttribute(child, attName))) {
                child = getNext(child, elemName, Node.ELEMENT_NODE);
            }
        }
        return child;
    }

    /**
     * Get the first child's content ( ie it's included TEXT node ).
     */
    public static String getChildContent(Node parent, String name) {
        Node first = parent.getFirstChild();
        if (first == null) {
            return null;
        }
        for (Node node = first; node != null; node = node.getNextSibling()) {
            // System.out.println("getNode: " + name + " " +
            // node.getNodeName());
            if (name.equals(node.getNodeName())) {
                return getRawContent(node);
            }
        }
        return null;
    }

    public static QName getElementQName(Element el) {
        return new QName(el.getNamespaceURI(), el.getLocalName());
    }

    /**
     * Get the first direct child with a given type
     */
    public static Element getFirstElement(Node parent) {
        Node n = parent.getFirstChild();
        while (n != null && Node.ELEMENT_NODE != n.getNodeType()) {
            n = n.getNextSibling();
        }
        if (n == null) {
            return null;
        }
        return (Element)n;
    }

    public static Element getNextElement(Element el) {
        Node nd = el.getNextSibling();
        while (nd != null) {
            if (nd.getNodeType() == Node.ELEMENT_NODE) {
                return (Element)nd;
            }
            nd = nd.getNextSibling();
        }
        return null;
    }

    /**
     * Return the first element child with the specified qualified name.
     * 
     * @param parent
     * @param q
     */
    public static Element getFirstChildWithName(Element parent, QName q) {
        String ns = q.getNamespaceURI();
        String lp = q.getLocalPart();
        return getFirstChildWithName(parent, ns, lp);
    }

    /**
     * Return the first element child with the specified qualified name.
     * 
     * @param parent
     * @param ns
     * @param lp
     */
    public static Element getFirstChildWithName(Element parent, String ns, String lp) {
        for (Node n = parent.getFirstChild(); n != null; n = n.getNextSibling()) {
            if (n instanceof Element) {
                Element e = (Element)n;
                String ens = (e.getNamespaceURI() == null) ? "" : e.getNamespaceURI();
                if (ns.equals(ens) && lp.equals(e.getLocalName())) {
                    return e;
                }
            }
        }
        return null;
    }

    /**
     * Return child elements with specified name.
     * 
     * @param parent
     * @param ns
     * @param localName
     */
    public static List<Element> getChildrenWithName(Element parent, String ns, String localName) {
        List<Element> r = new ArrayList<>();
        for (Node n = parent.getFirstChild(); n != null; n = n.getNextSibling()) {
            if (n instanceof Element) {
                Element e = (Element)n;
                String eNs = (e.getNamespaceURI() == null) ? "" : e.getNamespaceURI();
                if (ns.equals(eNs) && localName.equals(e.getLocalName())) {
                    r.add(e);
                }
            }
        }
        return r;
    }

    /**
     * Returns all child elements with specified namespace.
     * 
     * @param parent the element to search under
     * @param ns the namespace to find elements in
     * @return all child elements with specified namespace
     */
    public static List<Element> getChildrenWithNamespace(Element parent, String ns) {
        List<Element> r = new ArrayList<>();
        for (Node n = parent.getFirstChild(); n != null; n = n.getNextSibling()) {
            if (n instanceof Element) {
                Element e = (Element)n;
                String eNs = (e.getNamespaceURI() == null) ? "" : e.getNamespaceURI();
                if (ns.equals(eNs)) {
                    r.add(e);
                }
            }
        }
        return r;
    }

    /**
     * Get the first child of the specified type.
     * 
     * @param parent
     * @param type
     */
    public static Node getChild(Node parent, int type) {
        Node n = parent.getFirstChild();
        while (n != null && type != n.getNodeType()) {
            n = n.getNextSibling();
        }
        if (n == null) {
            return null;
        }
        return n;
    }

    /**
     * Get the next sibling with the same name and type
     */
    public static Node getNext(Node current) {
        String name = current.getNodeName();
        int type = current.getNodeType();
        return getNext(current, name, type);
    }

    /**
     * Return the next sibling with a given name and type
     */
    public static Node getNext(Node current, String name, int type) {
        Node first = current.getNextSibling();
        if (first == null) {
            return null;
        }

        for (Node node = first; node != null; node = node.getNextSibling()) {

            if (type >= 0 && node.getNodeType() != type) {
                continue;
            }

            if (name == null) {
                return node;
            }
            if (name.equals(node.getNodeName())) {
                return node;
            }
        }
        return null;
    }

    public static class NullResolver implements EntityResolver {
        public InputSource resolveEntity(String publicId, String systemId) throws SAXException, IOException {
            return new InputSource(new StringReader(""));
        }
    }
    
    private static DocumentBuilderFactory createDocumentBuilderFactory() throws ParserConfigurationException {
        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);

        dbf.setValidating(false);
        dbf.setIgnoringComments(false);
        dbf.setIgnoringElementContentWhitespace(true);
        dbf.setNamespaceAware(true);
        // dbf.setCoalescing(true);
        // dbf.setExpandEntityReferences(true);
        
        return dbf;
    }

    /**
     * Read XML as DOM.
     */
    public static Document readXml(InputStream is) throws SAXException, IOException,
        ParserConfigurationException {
        DocumentBuilder db = getBuilder();
        return db.parse(is);
    }

    public static Document readXml(Reader is) throws SAXException, IOException, ParserConfigurationException {
        InputSource ips = new InputSource(is);
        DocumentBuilder db = getBuilder();
        return db.parse(ips);
    }

    public static Document readXml(StreamSource is) throws SAXException, IOException,
        ParserConfigurationException {
        InputSource is2 = new InputSource();
        is2.setSystemId(is.getSystemId());
        is2.setByteStream(is.getInputStream());
        is2.setCharacterStream(is.getReader());

        DocumentBuilder db = getBuilder();
        return db.parse(is2);
    }

    public static void writeXml(Node n, OutputStream os) throws TransformerException {
        TransformerFactory tf = TransformerFactory.newInstance();
        tf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
        // identity
        Transformer t = tf.newTransformer();
        t.setOutputProperty(OutputKeys.INDENT, "yes");
        t.transform(new DOMSource(n), new StreamResult(os));
    }

    public static DocumentBuilder createDocumentBuilder() {
        try {
            return getBuilder();
        } catch (ParserConfigurationException e) {
            throw new RuntimeException("Couldn't find a DOM parser.", e);
        }
    }

    public static Document createDocument() {
        try {
            return getBuilder().newDocument();
        } catch (ParserConfigurationException e) {
            throw new RuntimeException("Couldn't find a DOM parser.", e);
        }
    }

    public static String getPrefixRecursive(Element el, String ns) {
        String prefix = getPrefix(el, ns);
        if (prefix == null && el.getParentNode() instanceof Element) {
            prefix = getPrefixRecursive((Element)el.getParentNode(), ns);
        }
        return prefix;
    }

    public static String getPrefix(Element el, String ns) {
        NamedNodeMap atts = el.getAttributes();
        for (int i = 0; i < atts.getLength(); i++) {
            Node node = atts.item(i);
            String name = node.getNodeName();
            if (ns.equals(node.getNodeValue())
                && (name != null && (XMLNAMESPACE.equals(name) || name.startsWith(XMLNAMESPACE + ":")))) {
                return node.getLocalName();
            }
        }
        return null;
    }

    /**
     * Get all prefixes defined, up to the root, for a namespace URI.
     * 
     * @param element
     * @param namespaceUri
     * @param prefixes
     */
    public static void getPrefixesRecursive(Element element, String namespaceUri, List<String> prefixes) {
        getPrefixes(element, namespaceUri, prefixes);
        Node parent = element.getParentNode();
        if (parent instanceof Element) {
            getPrefixesRecursive((Element)parent, namespaceUri, prefixes);
        }
    }

    /**
     * Get all prefixes defined on this element for the specified namespace.
     * 
     * @param element
     * @param namespaceUri
     * @param prefixes
     */
    public static void getPrefixes(Element element, String namespaceUri, List<String> prefixes) {
        NamedNodeMap atts = element.getAttributes();
        for (int i = 0; i < atts.getLength(); i++) {
            Node node = atts.item(i);
            String name = node.getNodeName();
            if (namespaceUri.equals(node.getNodeValue())
                && (name != null && (XMLNAMESPACE.equals(name) || name.startsWith(XMLNAMESPACE + ":")))) {
                prefixes.add(node.getPrefix());
            }
        }
    }

    public static String createNamespace(Element el, String ns) {
        String p = "ns1";
        int i = 1;
        while (getPrefix(el, ns) != null) {
            p = "ns" + i;
            i++;
        }
        addNamespacePrefix(el, ns, p);
        return p;
    }

    /**
     * Starting from a node, find the namespace declaration for a prefix. for a matching namespace
     * declaration.
     * 
     * @param node search up from here to search for namespace definitions
     * @param searchPrefix the prefix we are searching for
     * @return the namespace if found.
     */
    public static String getNamespace(Node node, String searchPrefix) {

        Element el;
        while (!(node instanceof Element)) {
            node = node.getParentNode();
        }
        el = (Element)node;

        NamedNodeMap atts = el.getAttributes();
        for (int i = 0; i < atts.getLength(); i++) {
            Node currentAttribute = atts.item(i);
            String currentLocalName = currentAttribute.getLocalName();
            String currentPrefix = currentAttribute.getPrefix();
            if (searchPrefix.equals(currentLocalName) && XMLNAMESPACE.equals(currentPrefix)) {
                return currentAttribute.getNodeValue();
            } else if (StringUtils.isEmpty(searchPrefix) && XMLNAMESPACE.equals(currentLocalName)
                       && StringUtils.isEmpty(currentPrefix)) {
                return currentAttribute.getNodeValue();
            }
        }

        Node parent = el.getParentNode();
        if (parent instanceof Element) {
            return getNamespace((Element)parent, searchPrefix);
        }

        return null;
    }

    public static List<Element> findAllElementsByTagNameNS(Element elem, String nameSpaceURI, String localName) {
        List<Element> ret = new LinkedList<>();
        findAllElementsByTagNameNS(elem, nameSpaceURI, localName, ret);
        return ret;
    }

    private static void findAllElementsByTagNameNS(Element el, String nameSpaceURI, String localName,
                                                   List<Element> elementList) {

        if (localName.equals(el.getLocalName()) && nameSpaceURI.contains(el.getNamespaceURI())) {
            elementList.add(el);
        }
        Element elem = getFirstElement(el);
        while (elem != null) {
            findAllElementsByTagNameNS(elem, nameSpaceURI, localName, elementList);
            elem = getNextElement(elem);
        }
    }

    public static List<Element> findAllElementsByTagName(Element elem, String tagName) {
        List<Element> ret = new LinkedList<>();
        findAllElementsByTagName(elem, tagName, ret);
        return ret;
    }

    private static void findAllElementsByTagName(Element el, String tagName, List<Element> elementList) {

        if (tagName.equals(el.getTagName())) {
            elementList.add(el);
        }
        Element elem = getFirstElement(el);
        while (elem != null) {
            findAllElementsByTagName(elem, tagName, elementList);
            elem = getNextElement(elem);
        }
    }

    public static boolean hasElementInNS(Element el, String namespace) {

        if (namespace.equals(el.getNamespaceURI())) {
            return true;
        }
        Element elem = getFirstElement(el);
        while (elem != null) {
            if (hasElementInNS(elem, namespace)) {
                return true;
            }
            elem = getNextElement(elem);
        }
        return false;
    }

    /**
     * Set a namespace/prefix on an element if it is not set already. First off, it searches for the element
     * for the prefix associated with the specified namespace. If the prefix isn't null, then this is
     * returned. Otherwise, it creates a new attribute using the namespace/prefix passed as parameters.
     * 
     * @param element
     * @param namespace
     * @param prefix
     * @return the prefix associated with the set namespace
     */
    public static String setNamespace(Element element, String namespace, String prefix) {
        String pre = getPrefixRecursive(element, namespace);
        if (pre != null) {
            return pre;
        }
        element.setAttributeNS(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, "xmlns:" + prefix, namespace);
        return prefix;
    }

    /**
     * Add a namespace prefix definition to an element.
     * 
     * @param element
     * @param namespaceUri
     * @param prefix
     */
    public static void addNamespacePrefix(Element element, String namespaceUri, String prefix) {
        element.setAttributeNS(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, "xmlns:" + prefix, namespaceUri);
    }
}