/*******************************************************************************
 * 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.storage;

import java.util.Date;
import java.util.List;

import org.apache.commons.lang.SerializationUtils;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;

import at.gv.egovernment.moa.id.commons.db.MOASessionDBUtils;
import at.gv.egovernment.moa.id.commons.db.dao.session.ExceptionStore;
import at.gv.egovernment.moa.id.commons.db.ex.MOADatabaseException;
import at.gv.egovernment.moa.id.util.Random;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.MiscUtil;

public class DBExceptionStoreImpl implements IExceptionStore {

	private static DBExceptionStoreImpl store;
	
	public static DBExceptionStoreImpl getStore() {
		if(store == null) {
			store = new DBExceptionStoreImpl();
		}
		return store;
	}
	
	public String storeException(Throwable e) {		
		String id = Random.nextRandom();

		Logger.debug("Store Exception with ID " + id);
		
		ExceptionStore dbexception = new ExceptionStore();
		dbexception.setExid(id);
		
		byte[] data = SerializationUtils.serialize(e);
		dbexception.setException(data);
		
		dbexception.setTimestamp(new Date());
		
		try {			
			MOASessionDBUtils.saveOrUpdate(dbexception);
			
		} catch (MOADatabaseException e1) {
			Logger.warn("Exception can not be stored in Database.", e);
			return null;
		}
		
		return id;
	}

	public Throwable fetchException(String id) {
		
		try {
			Logger.debug("Fetch Exception with ID " + id);
			
			ExceptionStore ex = searchInDatabase(id);
			
			Object data = SerializationUtils.deserialize(ex.getException());
			if (data instanceof Throwable)
				return (Throwable) data;
			
			else {
				Logger.warn("Exeption is not of classtype Throwable");
				return null;
			}
			
			
		} catch (MOADatabaseException e) {
			Logger.info("No Exception found with ID=" + id);
			return null;
			
		} catch (Exception e) {
			Logger.warn("Exception can not deserialized from Database.",e);
			return null;
		}
		
	}

	public void removeException(String id) {
		try {
			ExceptionStore ex = searchInDatabase(id);
			MOASessionDBUtils.delete(ex);
			
			Logger.debug("Delete Execption with ID " + id);
			
		} catch (MOADatabaseException e) {
			Logger.info("No Exception found with ID=" + id);
		}
		

	}
	
	public void clean(long now, long exceptionTimeOut) {
		Date expioredate = new Date(now - exceptionTimeOut);		
		
		List<ExceptionStore> results;
		Session session = MOASessionDBUtils.getCurrentSession();
		
		synchronized (session) {			
			session.beginTransaction();
			Query query = session.getNamedQuery("getExceptionWithTimeOut");
			query.setTimestamp("timeout", expioredate);		
			results = query.list();
			session.getTransaction().commit();
				
			if (results.size() != 0) {
				for(ExceptionStore result : results) {
					try { 
						MOASessionDBUtils.delete(result);
						Logger.info("Remove Exception with ID=" + result.getExid() 
								+ " after timeout.");
					
					} catch (HibernateException e){
						Logger.warn("Exception with ID=" + result.getExid() 
								+ " not removed after timeout! (Error during Database communication)", e);
					}
	
				}	
			}
		}
	}
	
	@SuppressWarnings("rawtypes")
	private ExceptionStore searchInDatabase(String id) throws MOADatabaseException {
		  MiscUtil.assertNotNull(id, "exceptionID");	  
		  Logger.trace("Getting Exception with ID " + id + " from database.");
		  Session session = MOASessionDBUtils.getCurrentSession();
		  List result;
		  
		  synchronized (session) {
			  session.beginTransaction();
			  Query query = session.getNamedQuery("getExceptionWithID");
			  query.setParameter("id", id);
			  result = query.list();
		  
			  //send transaction
			  session.getTransaction().commit();
		  }
		  
		  Logger.trace("Found entries: " + result.size());
		  
		  //Assertion requires an unique artifact
		  if (result.size() != 1) {
			 Logger.trace("No entries found.");
		   	throw new MOADatabaseException("No Exception found with ID " + id);
		  }
		  
		  return (ExceptionStore) result.get(0);
	}

}