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This nifi-utils module should be a general purpose place to store widely and generally useful functions that any component might want to leverage. NO DEPENDENCIES should be added. This module is likely to be leveraged by every extension and should not bring along any other dependencies. The only dependency intended is the nifi-api and even this is expected to be already provided in any case where it would be used. The typical place this util would be found is within a nar and all nars already have nifi-api as a parent dependency. The nifi-api can be thought of as a NiFi Application Container level dependency.

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/*
 * 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.nifi.util;

import java.util.ArrayList;
import java.util.List;

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

public class DomUtils {

    public static String getChildText(final Element element, final String tagName) {
        final Element childElement = getChild(element, tagName);
        if (childElement == null) {
            return null;
        }

        final String text = childElement.getTextContent();
        return (text == null) ? null : text.trim();
    }

    public static Element getChild(final Element element, final String tagName) {
        final List children = getChildElementsByTagName(element, tagName);
        if (children.isEmpty()) {
            return null;
        }

        if (children.size() > 1) {
            return null;
        }

        return children.get(0);
    }

    public static List getChildElementsByTagName(final Element element, final String tagName) {
        final List matches = new ArrayList<>();
        final NodeList nodeList = element.getChildNodes();
        for (int i = 0; i < nodeList.getLength(); i++) {
            final Node node = nodeList.item(i);
            if (!(node instanceof Element)) {
                continue;
            }

            final Element child = (Element) nodeList.item(i);
            if (child.getNodeName().equals(tagName)) {
                matches.add(child);
            }
        }

        return matches;
    }

    public static NodeList getChildNodesByTagName(final Element element, final String tagName) {
        final List elements = getChildElementsByTagName(element, tagName);

        return new NodeList() {
            @Override
            public Node item(final int index) {
                if (index >= elements.size()) {
                    return null;
                }

                return elements.get(index);
            }

            @Override
            public int getLength() {
                return elements.size();
            }
        };
    }

}