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/**
 * Copyright (c) 2000-present Liferay, Inc. All rights reserved.
 *
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 */

package com.liferay.util.xml;

import com.liferay.util.xml.descriptor.XMLDescriptor;

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

import org.dom4j.Document;
import org.dom4j.Element;

/**
 * @author Brian Wing Shun Chan
 * @author Alan Zimmerman
 * @author Jorge Ferrer
 */
public class XMLMerger {

	public XMLMerger(XMLDescriptor descriptor) {
		_descriptor = descriptor;
	}

	public XMLElementComparator getElementComparator() {
		return new XMLElementComparator(_descriptor);
	}

	public Document merge(Document masterDocument, Document slaveDocument) {
		Document mergedDocument = (Document)masterDocument.clone();

		Element mergedRootElement = mergedDocument.getRootElement();

		Element slaveRootElement = slaveDocument.getRootElement();

		for (Element slaveElement :
				(List)slaveRootElement.elements()) {

			Element clonedSlaveElement = (Element)slaveElement.clone();

			clonedSlaveElement.detach();

			mergedRootElement.add(clonedSlaveElement);
		}

		organizeXML(mergedDocument);

		return mergedDocument;
	}

	public void organizeXML(Document document) {
		Element rootElement = document.getRootElement();

		_orderChildren(rootElement, _descriptor.getRootChildrenOrder());
		_mergeDuplicateElements(rootElement, getElementComparator());
	}

	private void _addChildren(
		Element firstElement, Collection childElements) {

		List elements = firstElement.elements();

		for (Element childElement : childElements) {
			elements.add((Element)childElement.clone());
		}

		_orderChildren(
			firstElement, _descriptor.getChildrenOrder(firstElement));
	}

	private boolean _containsObjectEqualTo(
		Element element, List elements,
		ElementComparator elementComparator) {

		for (Element curElement : elements) {
			if (elementComparator.compare(element, curElement) == 0) {
				return true;
			}
		}

		return false;
	}

	private Element _findObjectEqualTo(
		Element element, List elements,
		ElementComparator elementComparator) {

		for (Element curElement : elements) {
			if (elementComparator.compare(element, curElement) == 0) {
				return curElement;
			}
		}

		return element;
	}

	private void _mergeDuplicateElements(
		Element element, ElementComparator elementComparator) {

		List childElements = element.elements();

		if (childElements.isEmpty()) {
			return;
		}

		List originalElements = new ArrayList<>();
		List duplicateElements = new ArrayList<>();

		for (Element childElement : childElements) {
			if (_containsObjectEqualTo(
					childElement, originalElements, elementComparator)) {

				if (_descriptor.canJoinChildren(childElement)) {
					Element firstElement = _findObjectEqualTo(
						childElement, originalElements, elementComparator);

					_addChildren(firstElement, childElement.elements());
				}

				duplicateElements.add(childElement);
			}
			else {
				originalElements.add(childElement);
			}

			_orderChildren(
				childElement, _descriptor.getChildrenOrder(childElement));
		}

		for (Element duplicateElement : duplicateElements) {
			duplicateElement.detach();
		}

		for (Element childElement : originalElements) {
			_mergeDuplicateElements(childElement, elementComparator);
		}
	}

	private void _orderChildren(
		Element parentElement, String[] orderedChildrenNames) {

		if (orderedChildrenNames == null) {
			return;
		}

		List elements = new ArrayList<>();

		for (String orderedChildrenName : orderedChildrenNames) {
			elements.addAll(parentElement.elements(orderedChildrenName));
		}

		for (Element element : elements) {
			element.detach();

			parentElement.add(element);
		}
	}

	private final XMLDescriptor _descriptor;

}