/*
 * Copyright (C) 2009 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
/**
 * 
 */
/*
 * Copyright (C) 2003-2009 eXo Platform SAS.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License
 * as published by the Free Software Foundation; either version 3
 * 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, see<http://www.gnu.org/licenses/>.
 */
package org.exoplatform.services.organization.hibernate;

import org.exoplatform.commons.utils.ListAccess;
import org.exoplatform.commons.utils.SecurityHelper;
import org.exoplatform.services.database.HibernateService;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;

import java.lang.reflect.Array;
import java.security.PrivilegedAction;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;

/**
 * Created by The eXo Platform SAS.
 * 
 * @author <a href="mailto:anatoliy.bazko@exoplatform.com.ua">Anatoliy Bazko</a>
 * @version $Id: HibernateUserListAccess.java 111 2008-11-11 11:11:11Z $
 */
public class HibernateListAccess<E> implements ListAccess<E>
{

   /**
    * The Hibernate Service.
    */
   protected HibernateService service;

   /**
    * Find query string.
    */
   protected String findQuery;

   /**
    * Count query string.
    */
   protected String countQuery;

   /**
    * Binded fields.
    */
   protected Map<String, Object> binding;

   /**
    * HibernateUserListAccess constructor.
    * 
    * @param service
    *          The Hibernate Service.
    * @param findQuery
    *          Find query string
    * @param countQuery
    *          Count query string
    */
   public HibernateListAccess(HibernateService service, String findQuery, String countQuery)
   {
      this.service = service;
      this.findQuery = findQuery;
      this.countQuery = countQuery;
      this.binding = new HashMap<String, Object>();
   }

   /**
    * HibernateUserListAccess constructor.
    * 
    * @param service
    *          The Hibernate Service.
    * @param findQuery
    *          Find query string
    * @param countQuery
    *          Count query string
    * @param binding
    *          Binded fields
    */
   public HibernateListAccess(HibernateService service, String findQuery, String countQuery, Map<String, Object> binding)
   {
      this.service = service;
      this.findQuery = findQuery;
      this.countQuery = countQuery;
      this.binding = binding;
   }

   /**
    * {@inheritDoc}
    */
   public int getSize() throws Exception
   {
      final Session session = service.openSession();

      Query query = SecurityHelper.doPrivilegedAction(new PrivilegedAction<Query>()
      {
         public Query run()
         {
            return session.createQuery(countQuery);
         }
      });

      bindFields(query);

      List<?> l = query.list();
      if (!l.isEmpty())
      {
         return ((Number)l.get(0)).intValue();
      }

      throw new HibernateException("The query execution " + countQuery + " failed");
   }

   /**
    * {@inheritDoc}
    */
   @SuppressWarnings("unchecked")
   public E[] load(int index, int length) throws Exception, IllegalArgumentException
   {
      final Session session = service.openSession();

      if (index < 0)
      {
         throw new IllegalArgumentException("Illegal index: index must be a positive number");
      }

      if (length < 0)
      {
         throw new IllegalArgumentException("Illegal length: length must be a positive number");
      }

      Query query = SecurityHelper.doPrivilegedAction(new PrivilegedAction<Query>()
      {
         public Query run()
         {
            return session.createQuery(findQuery);
         }
      });
      bindFields(query);

      // here we're creating an array of elements of class E
      // this looks complicated because we use generic class
      E[] entities = (E[])Array.newInstance(query.getReturnTypes()[0].getReturnedClass(), length);
      Iterator<E> results = query.iterate();

      for (int p = 0, counter = 0; counter < length; p++)
      {
         if (!results.hasNext())
         {
            throw new IllegalArgumentException(
               "Illegal index or length: sum of the index and the length cannot be greater than the list size");
         }

         E result = results.next();

         if (p >= index)
         {
            entities[counter++] = result;
         }
      }

      return entities;
   }

   /**
    * BindFields.
    * 
    * @param query
    *          Query
    */
   private void bindFields(Query query)
   {
      for (Entry<String, Object> entry : binding.entrySet())
      {
         query.setParameter(entry.getKey(), entry.getValue());
      }
   }
}
