/*
 * Copyright (C) 2005-2007 Alfresco Software Limited.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program 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 General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 * As a special exception to the terms and conditions of version 2.0 of 
 * the GPL, you may redistribute this Program in connection with Free/Libre 
 * and Open Source Software ("FLOSS") applications as described in Alfresco's 
 * FLOSS exception.  You should have recieved a copy of the text describing 
 * the FLOSS exception, and it is also available here: 
 * http://www.alfresco.com/legal/licensing"
 */
package org.alfresco.jcr.query;

import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;

import javax.jcr.Node;
import javax.jcr.RepositoryException;
import javax.jcr.query.InvalidQueryException;
import javax.jcr.query.Query;
import javax.jcr.query.QueryManager;

import org.alfresco.jcr.dictionary.JCRNamespace;
import org.alfresco.jcr.session.SessionImpl;
import org.alfresco.service.namespace.QName;


/**
 * Alfresco implementation of JCR Query Manager
 * 
 * @author David Caruana
 */
public class QueryManagerImpl implements QueryManager
{
    public static QName JCRPATH_COLUMN = QName.createQName(JCRNamespace.JCR_URI, "path");
    public static QName JCRSCORE_COLUMN = QName.createQName(JCRNamespace.JCR_URI, "score");
    
    /** supported query languages */    
    private static Map<String, Class<? extends QueryImpl>> supportedLanguages = new HashMap<String, Class<? extends QueryImpl>>();
    static
    {
        supportedLanguages.put(Query.XPATH, XPathQueryImpl.class);
    }

    private SessionImpl session;
    
    /**
     * Construct
     * 
     * @param session  session
     */
    public QueryManagerImpl(SessionImpl session)
    {
        this.session = session;
    }
    
    /* (non-Javadoc)
     * @see javax.jcr.query.QueryManager#createQuery(java.lang.String, java.lang.String)
     */
    public Query createQuery(String statement, String language) throws InvalidQueryException, RepositoryException
    {
        // is the language known?
        if (!isSupportedLanguage(language))
        {
            throw new InvalidQueryException("Query language " + language + " is not supported");
        }

        // construct the query
        Class<? extends QueryImpl> queryClass = supportedLanguages.get(language);
        try
        {
            Constructor<? extends QueryImpl> constructor = queryClass.getConstructor(new Class[] { SessionImpl.class, String.class } );
            QueryImpl queryImpl = constructor.newInstance(new Object[] { session, statement } );
            queryImpl.isValidStatement();
            return queryImpl.getProxy();
        }
        catch (InstantiationException e)
        {
            throw new RepositoryException("Failed to create query " + statement + " (language: " + language + ")");
        }
        catch (IllegalAccessException e)
        {
            throw new RepositoryException("Failed to create query " + statement + " (language: " + language + ")");
        }
        catch (Exception e)
        {
            throw new RepositoryException("Failed to create query " + statement + " (language: " + language + ")");
        }
    }

    /* (non-Javadoc)
     * @see javax.jcr.query.QueryManager#getQuery(javax.jcr.Node)
     */
    public Query getQuery(Node node) throws InvalidQueryException, RepositoryException
    {
        throw new InvalidQueryException("Persistent queries are not supported by the Repository.");
    }

    /* (non-Javadoc)
     * @see javax.jcr.query.QueryManager#getSupportedQueryLanguages()
     */
    public String[] getSupportedQueryLanguages() throws RepositoryException
    {
        return supportedLanguages.keySet().toArray(new String[supportedLanguages.size()]);
    }

    /**
     * Is supported language?
     * 
     * @param language  language to check
     * @return  true => supported
     */
    private boolean isSupportedLanguage(String language)
    {
        return supportedLanguages.containsKey(language);
    }
    
}