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 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 *
 * Copyright 2008, 2010 Oracle and/or its affiliates. All rights reserved.
 *
 * Use is subject to license terms.
 *
 * 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. You can also
 * obtain a copy of the License at http://odftoolkit.org/docs/license.txt
 *
 * 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.odftoolkit.odfdom.pkg;

import java.util.HashMap;
import java.util.Map;

/**
 * Class wrapping the XML Namespace URI and XML Namespace prefix as a single entity.
 */
public class OdfNamespace implements Comparable<OdfNamespace>, NamespaceName {

	private static Map<String, OdfNamespace> mNamespacesByURI = new HashMap<String, OdfNamespace>();
	private String mUri;
	private String mPrefix;

	private OdfNamespace() {
	}

	private OdfNamespace(String prefix, String uri) {
		mUri = uri;
		mPrefix = prefix;
	}

	/** Returns the OdfNamespace for the given name.
	 *  Creates a new one, if the name was not asked before.
	 * @param name represents a W3C Namespace Name. The interface <code>NamespaceName</code> is often implemented by an enum.
	 * @return the OdfNamespace for the given name.
	 */
	public static OdfNamespace newNamespace(NamespaceName name) {
		OdfNamespace ns = null;
		if (name != null) {
			ns = newNamespace(name.getPrefix(), name.getUri());
		}
		return ns;
	}

	/** Returns the OdfNamespace for the given name.
	 *  Creates a new one, if the name was not asked before.
	 * @param uri identifying the namespace.
	 * @return the namespace.
	 */
	public static OdfNamespace newNamespace(String prefix, String uri) {
		OdfNamespace odfNamespace = null;
		if (uri != null && uri.length() > 0
				&& prefix != null && prefix.length() > 0) {
			odfNamespace = mNamespacesByURI.get(uri);
			if (odfNamespace == null) {
				odfNamespace = new OdfNamespace(prefix, uri);
				mNamespacesByURI.put(uri, odfNamespace);
			} else {
				// prefix will be adapted for all OdfNamespaces (last wins)
				odfNamespace.mPrefix = prefix;
			}
		} 
		return odfNamespace;
	}

	/** Returns the namespace for the given uri.
	 * @param uri identifying the namespace.
	 * @return the namespace identified by the given uri.
	 */
	public static OdfNamespace getNamespace(String uri) {
		OdfNamespace ns = null;
		if (uri != null) {
			ns = mNamespacesByURI.get(uri);
		}
		return ns;
	}

	public String getPrefix() {
		return mPrefix;
	}

	public String getUri() {
		return mUri;
	}

	@Override
	@SuppressWarnings("EqualsWhichDoesntCheckParameterClass")
	public boolean equals(Object obj) {
		if (mUri != null) {
			return mUri.equals(obj.toString());
		} else {
			return mUri == obj;
		}
	}

	@Override
	public int hashCode() {
		if (mUri != null) {
			return mUri.hashCode();
		} else {
			return 0;
		}
	}

	@Override
	public String toString() {
		return mUri;
	}

	/** Splits the XML Qname into the local name and the prefix.
	 *
	 * @param qname is the qualified name to be splitted.
	 * @return an array of two strings containing first the prefix and the second the local part.
	 * @throws IllegalArgumentException if no qualified name was given.
	 */
	public static String[] splitQName(String qname) throws IllegalArgumentException {
		String localpart = qname;
		String prefix = null;
		int colon = qname.indexOf(':');
		if (colon > 0) {
			localpart = qname.substring(colon + 1);
			prefix = qname.substring(0, colon);
		} else {
			throw new IllegalArgumentException("A qualified name was required, but '" + qname + "' was given!");
		}
		return new String[]{prefix, localpart};
	}

	/** 
	 * @param qname is the qualified name to be splitted.
	 * @return the local name of the XML Qname.
	 * @throws IllegalArgumentException if no qualified name was given.
	 */
	public static String getPrefixPart(String qname) {
		return splitQName(qname)[0];
	}

	/**
	 * @param qname is the qualified name to be splitted.
	 * @return the prefix of the XML Qname.
	 * @throws IllegalArgumentException if no qualified name was given.
	 */
	public static String getLocalPart(String qname) {
		return splitQName(qname)[1];
	}

	public int compareTo(OdfNamespace namespace) {
		return toString().compareTo(namespace.toString());
	}
}