/*******************************************************************************
 * 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.io.Serializable;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceException;
import javax.persistence.Query;

import org.apache.commons.lang.SerializationUtils;
import org.hibernate.HibernateException;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

import at.gv.egiz.eaaf.core.api.storage.ITransactionStorage;
import at.gv.egovernment.moa.id.auth.exception.AuthenticationException;
import at.gv.egovernment.moa.id.auth.exception.BuildException;
import at.gv.egovernment.moa.id.commons.db.dao.session.AssertionStore;
import at.gv.egovernment.moa.id.commons.db.ex.MOADatabaseException;
import at.gv.egovernment.moa.id.data.EncryptedData;
import at.gv.egovernment.moa.id.util.SessionEncrytionUtil;
import at.gv.egovernment.moa.logging.Logger;
import at.gv.egovernment.moa.util.MiscUtil;

@Repository
@Transactional("sessionTransactionManager")
public class DBTransactionStorage implements ITransactionStorage {
	
	@PersistenceContext(unitName="session")
	private EntityManager entityManager;
	
	public boolean containsKey(String key) {
		try {	
			searchInDatabase(key);
			return true;
			
		} catch (MOADatabaseException e) {
			return false;
		}
		
	}
	
	/* (non-Javadoc)
	 * @see at.gv.egovernment.moa.id.storage.ITransactionStorage#changeKey(java.lang.String, java.lang.String, java.lang.Object)
	 */
	@Override
	public void changeKey(String oldKey, String newKey, Object value) throws MOADatabaseException {
		//search if key already exists
		AssertionStore element = searchInDatabase(oldKey);		
		if (element == null) {
			Logger.info("No transaction-data with oldKey:" + oldKey 
					+ " found. Process gets stopped.");
			throw new MOADatabaseException("No transaction-data with oldKey:" + oldKey 
					+ " found. Process gets stopped.");
			
		}
		
		put(element, newKey, value);
		
	}
	
	public void put(String key, Object value, int timeout_ms) throws MOADatabaseException {
		//search if key already exists
		AssertionStore element = searchInDatabase(key);
		
		//create a new entry if key does not exists already
		if (element == null) {
			element = new AssertionStore();
						
		}
		
		put(element, key, value);
	}
		 
	public <T> T get(String key,
			final Class<T> clazz) throws MOADatabaseException {

		try {
			return get(key, clazz, -1);
			
		} catch (AuthenticationException e) {
			//this execption only occurs if an additional timeOut is used
			Logger.error("This exeption should not occur!!!!", e);
			return null;
			
		}	
	}
		
	public Object get(String key) throws MOADatabaseException {
		  AssertionStore element = searchInDatabase(key);
		  
		  if (element == null)
			  return null;
		  		  
		  Object data = SerializationUtils.deserialize(element.getAssertion());
		  
		//decrypt data if required
		  Object resultData = null;
		  if (data instanceof EncryptedData) {
			  Logger.trace("Find encrypted data. --> Starting decryption process ...");
			  try {
				byte[] decData = decryptData((EncryptedData)data);
				resultData = SerializationUtils.deserialize(decData);
				
			  } catch (BuildException e) {
				  Logger.warn("Transaction information decryption FAILED.", e);
				  throw new MOADatabaseException("Transaction information decryption FAILED.", e);
				  
			  }
			  		  
		  } else {
			  Logger.trace("Find unencrypted data. --> Use it as is");
			  resultData = data;
			  
		  }
		  
		  return resultData;
		
		
	}
	
	public <T> T get(String key, final Class<T> clazz, long dataTimeOut) throws MOADatabaseException, AuthenticationException {
	 
	  AssertionStore element = searchInDatabase(key);
	  
	  if (element == null)
		  return null;
	  	  
	  if (dataTimeOut > -1) {
		  //check timeout
			long now = new Date().getTime();
			
			if (now - element.getDatatime().getTime() > dataTimeOut) {
				Logger.info("Transaction-Data with key: " + key + " is out of time.");
				throw new AuthenticationException("1207", new Object[] { key });
				
			}
	  }
	  
	  
	  //Deserialize Assertion	  
	  Object data = SerializationUtils.deserialize(element.getAssertion());
	  
	  //decrypt data if required
	  Object resultData = null;
	  if (data instanceof EncryptedData) {
		  Logger.trace("Find encrypted data. --> Starting decryption process ...");
		  try {
			byte[] decData = decryptData((EncryptedData)data);
			resultData = SerializationUtils.deserialize(decData);
			
		  } catch (BuildException e) {
			  Logger.warn("Transaction information decryption FAILED.", e);
			  throw new MOADatabaseException("Transaction information decryption FAILED.", e);
			  
		  }
		  		  
	  } else {
		  Logger.trace("Find unencrypted data. --> Use it as is");
		  resultData = data;
		  
	  }
		  
	  
	  //check if assertion has the correct class type 
	  try {
		  @SuppressWarnings("unchecked")
		T test = (T) Class.forName(element.getType()).cast(resultData);
		return test;
		
	  } catch (Exception e) {
		Logger.warn("Sessioninformation Cast-Exception by using Artifact=" + key);
		throw new MOADatabaseException("Sessioninformation Cast-Exception");
		
	  }
	}
	
	public List<String> clean(Date now, long dataTimeOut) {
		Date expioredate = new Date(now.getTime() - dataTimeOut);		
		
		List<AssertionStore> results;
		List<String> returnValues = new ArrayList<String>();;
		
		Query query =  entityManager.createNamedQuery("getAssertionWithTimeOut");
		query.setParameter("timeout", expioredate);
		
		results = query.getResultList();

		if (results != null) {
			for (AssertionStore el : results)
				returnValues.add(el.getArtifact());
							
		}
		return returnValues;
	}
	 
	public void remove(String key) {
		
		 try {
			AssertionStore element = searchInDatabase(key);
			if (element == null) {
				Logger.debug("Sessioninformation not removed! (Sessioninformation with ID=" + key 
						+ "not found)");
				return;
			}
			
			cleanDelete(element);
			Logger.debug("Remove stored information with ID: " + key);
			
			
		} catch (MOADatabaseException e) {
			Logger.info("Sessioninformation not removed! (Message:"+ e.getMessage() + ")");

		} catch (HibernateException e) {
			Logger.warn("Sessioninformation not removed! (Erreor during Database communication)", e);
		}
	}

	@Override
	public Object getRaw(String key) throws MOADatabaseException {
		return searchInDatabase(key);
		
	}
	
	@Override
	public void putRaw(String key, Object element) throws MOADatabaseException {
		if (element instanceof AssertionStore)
			entityManager.merge(element);
		
		else {
			Logger.error("Can not persist Object of type: " + element.getClass().getName());
			throw new RuntimeException("Can not persist Object of type: " + element.getClass().getName());
			
		}
	}
	
	private void cleanDelete(AssertionStore element) {
	
			
			try{
				element.setAssertion("blank".getBytes());
				entityManager.merge(element);
				entityManager.remove(element);
			}catch(PersistenceException e){
				Logger.error("ShortTime session with artifact=" + element.getArtifact() 
							+ " not removed! (Error during Database communication)");
			}
		
	}
	
	@SuppressWarnings("rawtypes")
	private AssertionStore searchInDatabase(String artifact) throws MOADatabaseException {
		  MiscUtil.assertNotNull(artifact, "artifact");	  
		  Logger.trace("Getting sessioninformation with ID " + artifact + " from database.");
		  List<AssertionStore> results;
		  
		  Query query =  entityManager.createNamedQuery("getAssertionWithArtifact");
		  query.setParameter("artifact", artifact);
		  
		  results = query.getResultList();
		  
		  Logger.trace("Found entries: " + results.size());
		  
		  //Assertion requires an unique artifact
		  if (results.size() != 1) {
			 Logger.debug("No transaction information with ID:" + artifact + " found.");
			 return null;
			 
		  }
		  
		  return results.get(0);
	}
	
	private void put(AssertionStore element, String key, Object value) throws MOADatabaseException {	
		element.setArtifact(key);
		element.setType(value.getClass().getName());
		element.setDatatime(new Date());

		if (!Serializable.class.isInstance(value)) {
			Logger.warn("Transaction-Storage can only store objects which implements the 'Seralizable' interface");
			throw new MOADatabaseException("Transaction-Storage can only store objects which implements the 'Seralizable' interface", null);
			
		}	
	
		try {
			//serialize the Assertion for Database storage
			byte[] data = SerializationUtils.serialize((Serializable) value);
			element.setAssertion(encryptData(data));

			//store AssertionStore element to Database
			entityManager.persist(element);
			Logger.debug(value.getClass().getName() + " with ID: " + key + " is stored in Database");			
			
		} catch (BuildException e) {
			Logger.warn("Sessioninformation could not be stored.");
			throw new MOADatabaseException("Can not store data into transaction-storage", e);
			
		}
		
	}
	
	private static byte[] encryptData(byte[] data) throws BuildException {		
		EncryptedData encdata = SessionEncrytionUtil.getInstance().encrypt(data);
		return SerializationUtils.serialize(encdata);

	}
	
	private static byte[] decryptData(EncryptedData encdata) throws BuildException {
		return SessionEncrytionUtil.getInstance().decrypt(encdata);
						
	}

}