/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j.tree;

import org.dom4j.DocumentFactory;
import org.dom4j.Namespace;
import org.dom4j.QName;

import java.util.*;

/**
 * <p>
 * <code>QNameCache</code> caches instances of <code>QName</code> for reuse
 * both across documents and within documents.
 *
 * @author <a href="mailto:james.strachan@metastuff.com">James Strachan </a>
 * @version $Revision: 1.16 $
 * 
 */
public class QNameCache {
    /** Cache of {@link QName}instances with no namespace */
    protected Map<String, QName> noNamespaceCache = Collections.synchronizedMap(new WeakHashMap<String, QName>());

    /**
     * Cache of {@link Map}instances indexed by namespace which contain caches
     * of {@link QName}for each name
     */
    protected Map<Namespace, Map<String, QName>> namespaceCache = Collections.synchronizedMap(new WeakHashMap<Namespace, Map<String, QName>>());

    /**
     * The document factory associated with new QNames instances in this cache
     * or null if no instances should be associated by default
     */
    private DocumentFactory documentFactory;

    public QNameCache() {
    }

    public QNameCache(DocumentFactory documentFactory) {
        this.documentFactory = documentFactory;
    }

    /**
     * Returns a list of all the QName instances currently used
     * 
     * @return DOCUMENT ME!
     */
    public List<QName> getQNames() {
        List<QName> answer = new ArrayList<QName>();
	synchronized(noNamespaceCache) {
            answer.addAll(noNamespaceCache.values());
	}

	synchronized(namespaceCache) {
            for (Map<String, QName> map : namespaceCache.values()) {
                answer.addAll(map.values());
            }
	}

        return answer;
    }

    /**
     * DOCUMENT ME!
     * 
     * @param name
     *            DOCUMENT ME!
     * 
     * @return the QName for the given name and no namepsace
     */
    public QName get(String name) {
        QName answer = null;

        if (name != null) {
            answer = noNamespaceCache.get(name);
        } else {
            name = "";
        }

        if (answer == null) {
            answer = createQName(name);
            answer.setDocumentFactory(documentFactory);
            noNamespaceCache.put(name, answer);
        }

        return answer;
    }

    /**
     * DOCUMENT ME!
     * 
     * @param name
     *            DOCUMENT ME!
     * @param namespace
     *            DOCUMENT ME!
     * 
     * @return the QName for the given local name and namepsace
     */
    public QName get(String name, Namespace namespace) {
        Map<String, QName> cache = getNamespaceCache(namespace);
        QName answer = null;

        if (name != null) {
            answer = cache.get(name);
        } else {
            name = "";
        }

        if (answer == null) {
            answer = createQName(name, namespace);
            answer.setDocumentFactory(documentFactory);
            cache.put(name, answer);
        }

        return answer;
    }

    /**
     * DOCUMENT ME!
     * 
     * @param localName
     *            DOCUMENT ME!
     * @param namespace
     *            DOCUMENT ME!
     * @param qName
     *            DOCUMENT ME!
     * 
     * @return the QName for the given local name, qualified name and namepsace
     */
    public QName get(String localName, Namespace namespace, String qName) {
        Map<String, QName> cache = getNamespaceCache(namespace);
        QName answer = null;

        if (localName != null) {
            answer = cache.get(localName);
        } else {
            localName = "";
        }

        if (answer == null) {
            answer = createQName(localName, namespace, qName);
            answer.setDocumentFactory(documentFactory);
            cache.put(localName, answer);
        }

        return answer;
    }

    public QName get(String qualifiedName, String uri) {
        int index = qualifiedName.indexOf(':');

        if (index < 0) {
            return get(qualifiedName, Namespace.get(uri));
        } else if (index == 0){
            throw new IllegalArgumentException("Qualified name cannot start with ':'.");
        } else {
            String name = qualifiedName.substring(index + 1);
            String prefix = qualifiedName.substring(0, index);

            return get(name, Namespace.get(prefix, uri));
        }
    }

    /**
     * DOCUMENT ME!
     * 
     * @param qname
     *            DOCUMENT ME!
     * 
     * @return the cached QName instance if there is one or adds the given qname
     *         to the cache if not
     */
    public QName intern(QName qname) {
        return get(qname.getName(), qname.getNamespace(), qname
                .getQualifiedName());
    }

    /**
     * DOCUMENT ME!
     * 
     * @param namespace
     *            DOCUMENT ME!
     * 
     * @return the cache for the given namespace. If one does not currently
     *         exist it is created.
     */
    protected Map<String, QName> getNamespaceCache(Namespace namespace) {
        if (namespace == Namespace.NO_NAMESPACE) {
            return noNamespaceCache;
        }

        Map<String, QName> answer = null;

        if (namespace != null) {
            answer = namespaceCache.get(namespace);
        }

        if (answer == null) {
            answer = createMap();
            namespaceCache.put(namespace, answer);
        }

        return answer;
    }

    /**
     * A factory method
     * 
     * @return a newly created {@link Map}instance.
     */
    protected Map<String, QName> createMap() {
        return Collections.synchronizedMap(new HashMap<String, QName>());
    }

    /**
     * Factory method to create a new QName object which can be overloaded to
     * create derived QName instances
     * 
     * @param name
     *            DOCUMENT ME!
     * 
     * @return DOCUMENT ME!
     */
    protected QName createQName(String name) {
        return new QName(name);
    }

    /**
     * Factory method to create a new QName object which can be overloaded to
     * create derived QName instances
     * 
     * @param name
     *            DOCUMENT ME!
     * @param namespace
     *            DOCUMENT ME!
     * 
     * @return DOCUMENT ME!
     */
    protected QName createQName(String name, Namespace namespace) {
        return new QName(name, namespace);
    }

    /**
     * Factory method to create a new QName object which can be overloaded to
     * create derived QName instances
     * 
     * @param name
     *            DOCUMENT ME!
     * @param namespace
     *            DOCUMENT ME!
     * @param qualifiedName
     *            DOCUMENT ME!
     * 
     * @return DOCUMENT ME!
     */
    protected QName createQName(String name, Namespace namespace,
            String qualifiedName) {
        return new QName(name, namespace, qualifiedName);
    }
}



/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived
 * from this Software without prior written permission of MetaStuff, Ltd. For
 * written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may
 * "DOM4J" appear in their names without prior written permission of MetaStuff,
 * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
