/*******************************************************************************
 * Copyright 2014 Federal Chancellery Austria
 * MOA-ID has been developed in a cooperation between BRZ, the Federal
 * Chancellery Austria - ICT staff unit, and Graz University of Technology.
 *
 * Licensed under the EUPL, Version 1.1 or - as soon they will be approved by
 * the European Commission - subsequent versions of the EUPL (the "Licence");
 * You may not use this work except in compliance with the Licence.
 * You may obtain a copy of the Licence at:
 * http://www.osor.eu/eupl/
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the Licence is distributed on an "AS IS" basis,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing permissions and
 * limitations under the Licence.
 *
 * This product combines work with different licenses. See the "NOTICE" text
 * file for details on the various modules and licenses.
 * The "NOTICE" text file is part of the distribution. Any derivative works
 * that you distribute must include a readable copy of the "NOTICE" text file.
 *******************************************************************************/
package at.gv.egovernment.moa.id.commons.db;

import java.util.Properties;

import org.apache.commons.lang3.StringUtils;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

import at.gv.egovernment.moa.id.commons.db.ex.MOADatabaseException;
import at.gv.egovernment.moa.logging.Logger;

public final class MOASessionDBUtils {

   private static SessionFactory sessionFactory;
   private static ServiceRegistry serviceRegistry;
   
   @SuppressWarnings("rawtypes")
   private static final ThreadLocal THREAD_LOCAL = new ThreadLocal();
   private static boolean automaticSessionHandling = false;

   private static final String[] AUTOMATIC_SESSION_HANDLING_VALUES = new String[] { "jta", "thread" };
   private static final String SESSION_HANDLING_KEY = "hibernate.current_session_context_class";
   
   protected MOASessionDBUtils() { }
   	   
   public static void initHibernate(Configuration config, Properties hibernateProperties) {
	     
     String scm = StringUtils.trimToNull(hibernateProperties.getProperty(SESSION_HANDLING_KEY));
     if (scm != null) {
        automaticSessionHandling = scm.indexOf(AUTOMATIC_SESSION_HANDLING_VALUES[0]) != -1 || scm.indexOf(AUTOMATIC_SESSION_HANDLING_VALUES[1]) != -1;
     }
     Logger.debug("Evaluating hibernate property \"" + SESSION_HANDLING_KEY + "\".");
     if (automaticSessionHandling) {
    	 Logger.info("Hibernate is automatically handling session context management.");
     } else {
    	 Logger.info("Hibernate is NOT automatically handling session context management. Using build-in ThreadLocal session handling.");
     }
     try {
       //Create the SessionFactory
       Logger.debug("Creating initial MOASession session factory...");
              
       config.configure("hibernate_moasession.cfg.xml");
       //serviceRegistry = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
       
       serviceRegistry = new StandardServiceRegistryBuilder().
    		   applySettings(config.getProperties()).build();
       
       sessionFactory = config.buildSessionFactory(serviceRegistry);
       Logger.debug("Initial MOASession session factory successfully created.");
       
     } catch (Throwable ex) {
    	Logger.error("Initial MOASession session factory creation failed: " + ex.getMessage());
        throw new ExceptionInInitializerError(ex);
     }
   }
   
   /**
    * Checks if a session factory is currently available. If necessary a new
    * session factory is created.
    * 
    * @return current (or new) session factory
    * @throws HibernateException
    *            thrown if a hibernate error occurs
    */
   public static Session getCurrentSession() {
      if (automaticSessionHandling) {
         return sessionFactory.getCurrentSession();
      }
      Session session = (Session) THREAD_LOCAL.get();
      // Open a new Session, if this Thread has none yet
      if (session == null || !session.isConnected()) {
         session = getNewSession();
      }
      return session;
   }

   @SuppressWarnings("unchecked")
  public static Session getNewSession() {
      if (automaticSessionHandling) {
    	  Logger.warn("Session is being automatically handled by hibernate. Therefore this session maybe not being newly created. Use HibernateUtil.getCurrentSession() instead.");
         return sessionFactory.getCurrentSession();
      }
      Session session = (Session) THREAD_LOCAL.get();
      if (session != null) {
    	  Logger.warn("Previous MOASession session has not been closed; closing session now.");
         closeSession();
      }
      Logger.debug("Opening new MOASession hibernate session...");
      try {
         session = sessionFactory.openSession();
         THREAD_LOCAL.set(session);
      } catch (HibernateException hex) {
    	  Logger.error(hex.getMessage());
      }
      return session;
   }

   /**
    * Closes the current session.
    * 
    * @throws HibernateException
    *            thrown if session is already closed or a hibernate error
    *            occurs.
    */
   @SuppressWarnings("unchecked")
  public static void closeSession() {
      if (automaticSessionHandling) {
    	  Logger.warn("Session is being automatically handled by hibernate. Therefore the current session cannot be closed on demand.");
         return;
      }
      Logger.debug("Closing current MOASession hibernate session...");
      Session session = (Session) THREAD_LOCAL.get();
      THREAD_LOCAL.set(null);
      if (session != null) {
         try {
            session.close();
            
         } catch (HibernateException hex) {
            Logger.error(hex.getMessage());
         }
      }
   }
   
   public static boolean saveOrUpdate(Object dbo) throws MOADatabaseException {
	  	 Transaction tx =  null;
	  	 try {
		  	 Session session = MOASessionDBUtils.getCurrentSession();
		  	 
		  	synchronized (session) {
		  		tx = session.beginTransaction();
		  		session.saveOrUpdate(dbo);
		  		tx.commit();
		  	}
		     return true;
		     
	  	 } catch(HibernateException e) {
	  		Logger.warn("Error during MOASession database saveOrUpdate. Rollback.", e);
	  		 tx.rollback();
	  		 throw new MOADatabaseException(e);
	  	 }
	   }
	   
	   public static boolean delete(Object dbo) {
	  	 Transaction tx =  null;
	  	 try {
		  	 Session session = MOASessionDBUtils.getCurrentSession();
		  	 
		  	 synchronized (session) {
		  		tx = session.beginTransaction();
			    session.delete(dbo);
			    tx.commit();
			}
		     
		     return true;
		     
	  	 } catch(HibernateException e) {
	  		Logger.warn("Error during MOASession database delete. Rollback.", e);
	  		 tx.rollback();
	  		 return false;
	  	 }
	   }
   
}