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/*
 * Copyright 2012 Atteo.
 *
 * Licensed 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.atteo.xmlcombiner;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

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

import com.google.common.collect.LinkedListMultimap;
import com.google.common.collect.ListMultimap;

/**
 * DOM {@link Element} with any other non-element nodes which precede it.
 */
class Context {
	public static final String KEYS_ATTRIBUTE_NAME = "combine.keys";
	public static final String ID_ATTRIBUTE_NAME = "combine.id";
	private final List neighbours = new ArrayList<>();
	private Element element;

	public Context() {
	}

	public static Context fromElement(Element element) {
		Context context = new Context();
		context.setElement(element);
		return context;
	}

	public void addNeighbour(Node node) {
		neighbours.add(node);
	}

	public List getNeighbours() {
		return neighbours;
	}

	public void setElement(Element element) {
		this.element = element;
	}

	public Element getElement() {
		return element;
	}

	public void addAsChildTo(Node node) {
		for (Node neighbour : neighbours) {
			node.appendChild(neighbour);
		}
		node.appendChild(element);
	}

	public void addAsChildTo(Node node, Document document) {
		for (Node neighbour : neighbours) {
			node.appendChild(document.importNode(neighbour, true));
		}
		if (element != null) {
			node.appendChild(document.importNode(element, true));
		}
	}

	public List groupChildContexts() {
		if (element == null) {
			return Collections.emptyList();
		}
		NodeList nodes = element.getChildNodes();
		List contexts = new ArrayList<>(nodes.getLength());

		Context context = new Context();
		for (int i = 0; i < nodes.getLength(); i++) {
			Node node = nodes.item(i);
			if (node instanceof Element) {
				context.setElement((Element) node);
				contexts.add(context);
				context = new Context();
			} else {
				context.addNeighbour(node);
			}
		}
		// add last with empty element
		contexts.add(context);
		return contexts;
	}

	public ListMultimap mapChildContexts(List keyAttributeNames) {
		List contexts = groupChildContexts();

		ListMultimap map = LinkedListMultimap.create();
		for (Context context : contexts) {
			Element contextElement = context.getElement();

			if (contextElement != null) {
				Map keys = new HashMap<>();
				for (String keyAttributeName : keyAttributeNames) {
					Attr keyNode = contextElement.getAttributeNode(keyAttributeName);
					if (keyNode != null) {
						keys.put(keyAttributeName, keyNode.getValue());
					}
				}
				{
					Attr keyNode = contextElement.getAttributeNode(Context.ID_ATTRIBUTE_NAME);
					if (keyNode != null) {
						keys.put(Context.ID_ATTRIBUTE_NAME, keyNode.getValue());
					}
				}
				Key key = new Key(contextElement.getTagName(), keys);
				map.put(key, context);
			} else {
				map.put(Key.BEFORE_END, context);
			}
		}
		return map;
	}

	@Override
	public String toString() {
		return "[" + neighbours + ", " + element + "]";
	}
}