/*
 * Copyright 2004,2005 The Apache Software Foundation.
 * Copyright 2006 International Business Machines Corp.
 *
 * 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.apache.axis2.jaxws.message.util.impl;

import java.util.ArrayList;
import java.util.Iterator;

import javax.xml.namespace.NamespaceContext;

import org.w3c.dom.Attr;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;


/**
 * Namespace information available at the current scope.
 * Utility class for XMLStreamReaderFromDOM
 * @see org.apache.axis2.jaxws.message.util.impl.XMLStreamReaderFromDOM
 */
public class NamespaceContextFromDOM implements NamespaceContext {

	private Element element;
	/**
	 * @param element representing the current scope
	 */
	NamespaceContextFromDOM(Element element) {
		this.element = element;
	}

	/* (non-Javadoc)
	 * @see javax.xml.namespace.NamespaceContext#getPrefix(java.lang.String)
	 */
	public String getPrefix(String namespaceURI) {
		return element.lookupPrefix(namespaceURI);
	}

	/* (non-Javadoc)
	 * @see javax.xml.namespace.NamespaceContext#getPrefixes(java.lang.String)
	 */
	public Iterator getPrefixes(String namespaceURI) {
		if (element instanceof javax.xml.soap.SOAPElement) {
			Iterator it = ((javax.xml.soap.SOAPElement)element).getVisibleNamespacePrefixes();
			ArrayList list = new ArrayList();
			while (it.hasNext()) {
				String prefix = (String) it.next();
				if (getNamespaceURI(prefix).equals(namespaceURI)) {
					if (prefix != null && prefix.length() == 0) {
						prefix = null;
					}
					list.add(prefix);
				}
			}
			return list.iterator();
		} else {
			ArrayList list = new ArrayList();
			Node node = element;
			while (node != null) {
				if (node instanceof Element) {
					// Walk the attributes looking for namespace declarations
					NamedNodeMap attrs =((Element) node).getAttributes();
					for (int i=0; i<attrs.getLength(); i++) {
						Attr attr = (Attr) attrs.item(i);
						if (attr.getNodeValue().equals(namespaceURI)) {
							String name = attr.getNodeName();
							
							if (name.startsWith("xmlns")) {
								String prefix = "";
								if (name.startsWith("xmlns:")) {
									prefix = name.substring(6);
								}
								// Found a namespace declaration with the prefix.
								// Make sure this is not overridden by a declaration 
								// in a closer scope.
								if (!list.contains(prefix) &&
										getNamespaceURI(prefix).equals(namespaceURI)) {
									list.add(prefix);
								}
							}
						}
					}
				}
				// Pop up to the parent node
				node = node.getParentNode();
			}
			return list.iterator();
		}
	}

	public String getNamespaceURI(String prefix) {
		return element.lookupNamespaceURI(prefix);
	}

}