/*
 * 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.maven.shared.release.transform.jdom2;

import java.util.Iterator;

import org.jdom2.Element;
import org.jdom2.Namespace;
import org.jdom2.Text;

/**
 * Common JDOM2 functions.
 *
 * @author Robert Scholte
 * @since 3.0
 */
public final class JDomUtils {

    private JDomUtils() {
        // noop
    }

    /**
     * Updates the text value of the given element. The primary purpose of this method is to preserve any whitespace and
     * comments around the original text value.
     *
     * @param element the element to update, must not be <code>null</code>
     * @param value   the text string to set, must not be <code>null</code>
     */
    public static void rewriteValue(Element element, String value) {
        Text text = null;
        if (element.getContent() != null) {
            for (Iterator<?> it = element.getContent().iterator(); it.hasNext(); ) {
                Object content = it.next();
                if ((content instanceof Text) && ((Text) content).getTextTrim().length() > 0) {
                    text = (Text) content;
                    while (it.hasNext()) {
                        content = it.next();
                        if (content instanceof Text) {
                            text.append((Text) content);
                            it.remove();
                        } else {
                            break;
                        }
                    }
                    break;
                }
            }
        }
        if (text == null) {
            element.addContent(value);
        } else {
            String chars = text.getText();
            String trimmed = text.getTextTrim();
            int idx = chars.indexOf(trimmed);
            String leadingWhitespace = chars.substring(0, idx);
            String trailingWhitespace = chars.substring(idx + trimmed.length());
            text.setText(leadingWhitespace + value + trailingWhitespace);
        }
    }

    /**
     * <p>rewriteElement.</p>
     *
     * @param name a {@link java.lang.String} object
     * @param value a {@link java.lang.String} object
     * @param root a {@link org.jdom2.Element} object
     * @param namespace a {@link org.jdom2.Namespace} object
     * @return a {@link org.jdom2.Element} object
     */
    public static Element rewriteElement(String name, String value, Element root, Namespace namespace) {
        Element tagElement = root.getChild(name, namespace);
        if (tagElement != null) {
            if (value != null) {
                rewriteValue(tagElement, value);
            } else {
                int index = root.indexOf(tagElement);
                root.removeContent(index);
                for (int i = index - 1; i >= 0; i--) {
                    if (root.getContent(i) instanceof Text) {
                        root.removeContent(i);
                    } else {
                        break;
                    }
                }
            }
        } else {
            if (value != null) {
                Element element = new Element(name, namespace);
                element.setText(value);
                root.addContent("  ").addContent(element).addContent("\n  ");
                tagElement = element;
            }
        }
        return tagElement;
    }
}
