/*
    * Copyright 2002-2015 the original author or authors.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.springframework.orm.jpa.vendor;
  
  import java.lang.reflect.Method;
  import java.sql.Connection;
  import java.sql.SQLException;
  import javax.persistence.EntityManager;
  import javax.persistence.PersistenceException;
  
  import org.hibernate.FlushMode;
  import org.hibernate.HibernateException;
  import org.hibernate.NonUniqueObjectException;
  import org.hibernate.NonUniqueResultException;
  import org.hibernate.ObjectDeletedException;
  import org.hibernate.OptimisticLockException;
  import org.hibernate.PersistentObjectException;
  import org.hibernate.PessimisticLockException;
  import org.hibernate.PropertyValueException;
  import org.hibernate.QueryException;
  import org.hibernate.QueryTimeoutException;
  import org.hibernate.Session;
  import org.hibernate.StaleObjectStateException;
  import org.hibernate.StaleStateException;
  import org.hibernate.TransientObjectException;
  import org.hibernate.UnresolvableObjectException;
  import org.hibernate.WrongClassException;
  import org.hibernate.exception.ConstraintViolationException;
  import org.hibernate.exception.DataException;
  import org.hibernate.exception.JDBCConnectionException;
  import org.hibernate.exception.LockAcquisitionException;
  import org.hibernate.exception.SQLGrammarException;
  
  import org.springframework.dao.CannotAcquireLockException;
  import org.springframework.dao.DataAccessException;
  import org.springframework.dao.DataAccessResourceFailureException;
  import org.springframework.dao.DataIntegrityViolationException;
  import org.springframework.dao.DuplicateKeyException;
  import org.springframework.dao.IncorrectResultSizeDataAccessException;
  import org.springframework.dao.InvalidDataAccessApiUsageException;
  import org.springframework.dao.InvalidDataAccessResourceUsageException;
  import org.springframework.dao.PessimisticLockingFailureException;
  import org.springframework.jdbc.datasource.ConnectionHandle;
  import org.springframework.jdbc.datasource.DataSourceUtils;
  import org.springframework.jdbc.support.JdbcUtils;
  import org.springframework.orm.ObjectOptimisticLockingFailureException;
  import org.springframework.orm.ObjectRetrievalFailureException;
  import org.springframework.orm.jpa.DefaultJpaDialect;
  import org.springframework.orm.jpa.EntityManagerFactoryUtils;
  import org.springframework.orm.jpa.JpaSystemException;
  import org.springframework.transaction.InvalidIsolationLevelException;
  import org.springframework.transaction.TransactionDefinition;
  import org.springframework.transaction.TransactionException;
  import org.springframework.util.ClassUtils;
  import org.springframework.util.ReflectionUtils;
  
  /**
   * {@link org.springframework.orm.jpa.JpaDialect} implementation for
   * Hibernate EntityManager. Developed against Hibernate 3.6 and 4.2/4.3.
   *
   * @author Juergen Hoeller
   * @author Costin Leau
   * @since 2.0
   */
  @SuppressWarnings({"serial", "deprecation"})
  public class HibernateJpaDialect extends DefaultJpaDialect {
  
  	private static Class<?> optimisticLockExceptionClass;
  
  	private static Class<?> pessimisticLockExceptionClass;
  
  	static {
  		// Checking for Hibernate 4.x's Optimistic/PessimisticEntityLockException
  		ClassLoader cl = HibernateJpaDialect.class.getClassLoader();
  		try {
  			optimisticLockExceptionClass = cl.loadClass("org.hibernate.dialect.lock.OptimisticEntityLockException");
  		}
  		catch (ClassNotFoundException ex) {
  			// OptimisticLockException is deprecated on Hibernate 4.x; we're just using it on 3.x anyway
  			optimisticLockExceptionClass = OptimisticLockException.class;
  		}
  		try {
  			pessimisticLockExceptionClass = cl.loadClass("org.hibernate.dialect.lock.PessimisticEntityLockException");
  		}
  		catch (ClassNotFoundException ex) {
 			pessimisticLockExceptionClass = null;
 		}
 	}
 
 
 	private boolean prepareConnection = (HibernateConnectionHandle.sessionConnectionMethod == null);
 
 
 	/**
 	 * Set whether to prepare the underlying JDBC Connection of a transactional
 	 * Hibernate Session, that is, whether to apply a transaction-specific
 	 * isolation level and/or the transaction's read-only flag to the underlying
 	 * JDBC Connection.
 	 * <p>Default is "true" on Hibernate EntityManager 4.x (with its 'on-close'
 	 * connection release mode, and "false" on Hibernate EntityManager 3.6 (due to
 	 * the 'after-transaction' release mode there). <b>Note that Hibernate 4.2+ is
 	 * strongly recommended in order to make isolation levels work efficiently.</b>
 	 * <p>If you turn this flag off, JPA transaction management will not support
 	 * per-transaction isolation levels anymore. It will not call
 	 * {@code Connection.setReadOnly(true)} for read-only transactions anymore either.
 	 * If this flag is turned off, no cleanup of a JDBC Connection is required after
 	 * a transaction, since no Connection settings will get modified.
 	 * <p><b>NOTE:</b> The default behavior in terms of read-only handling changed
 	 * in Spring 4.1, propagating the read-only status to the JDBC Connection now,
 	 * analogous to other Spring transaction managers. This may have the effect
 	 * that you're running into read-only enforcement now where previously write
 	 * access has accidentally been tolerated: Please revise your transaction
 	 * declarations accordingly, removing invalid read-only markers if necessary.
 	 * @since 4.1
 	 * @see java.sql.Connection#setTransactionIsolation
 	 * @see java.sql.Connection#setReadOnly
 	 */
 	public void setPrepareConnection(boolean prepareConnection) {
 		this.prepareConnection = prepareConnection;
 	}
 
 
 	@Override
 	public Object beginTransaction(EntityManager entityManager, TransactionDefinition definition)
 			throws PersistenceException, SQLException, TransactionException {
 
 		Session session = getSession(entityManager);
 
 		if (definition.getTimeout() != TransactionDefinition.TIMEOUT_DEFAULT) {
 			session.getTransaction().setTimeout(definition.getTimeout());
 		}
 
 		boolean isolationLevelNeeded = (definition.getIsolationLevel() != TransactionDefinition.ISOLATION_DEFAULT);
 		Integer previousIsolationLevel = null;
 		boolean resetConnection = false;
 
 		if (isolationLevelNeeded || definition.isReadOnly()) {
 			if (this.prepareConnection) {
 				Connection con = HibernateConnectionHandle.doGetConnection(session);
 				previousIsolationLevel = DataSourceUtils.prepareConnectionForTransaction(con, definition);
 				resetConnection = true;
 			}
 			else if (isolationLevelNeeded) {
 				throw new InvalidIsolationLevelException(getClass().getSimpleName() +
 						" does not support custom isolation levels since the 'prepareConnection' flag is off. " +
 						"This is the case on Hibernate 3.6 by default; either switch that flag at your own risk " +
 						"or upgrade to Hibernate 4.x, with 4.2+ recommended.");
 			}
 		}
 
 		// Standard JPA transaction begin call for full JPA context setup...
 		entityManager.getTransaction().begin();
 
 		// Adapt flush mode and store previous isolation level, if any.
 		FlushMode previousFlushMode = prepareFlushMode(session, definition.isReadOnly());
 		return new SessionTransactionData(session, previousFlushMode, resetConnection, previousIsolationLevel);
 	}
 
 	@Override
 	public Object prepareTransaction(EntityManager entityManager, boolean readOnly, String name)
 			throws PersistenceException {
 
 		Session session = getSession(entityManager);
 		FlushMode previousFlushMode = prepareFlushMode(session, readOnly);
 		return new SessionTransactionData(session, previousFlushMode, false, null);
 	}
 
 	protected FlushMode prepareFlushMode(Session session, boolean readOnly) throws PersistenceException {
 		FlushMode flushMode = session.getFlushMode();
 		if (readOnly) {
 			// We should suppress flushing for a read-only transaction.
 			if (!flushMode.equals(FlushMode.MANUAL)) {
 				session.setFlushMode(FlushMode.MANUAL);
 				return flushMode;
 			}
 		}
 		else {
 			// We need AUTO or COMMIT for a non-read-only transaction.
 			if (flushMode.lessThan(FlushMode.COMMIT)) {
 				session.setFlushMode(FlushMode.AUTO);
 				return flushMode;
 			}
 		}
 		// No FlushMode change needed...
 		return null;
 	}
 
 	@Override
 	public void cleanupTransaction(Object transactionData) {
 		((SessionTransactionData) transactionData).resetSessionState();
 	}
 
 	@Override
 	public ConnectionHandle getJdbcConnection(EntityManager entityManager, boolean readOnly)
 			throws PersistenceException, SQLException {
 
 		Session session = getSession(entityManager);
 		return new HibernateConnectionHandle(session);
 	}
 
 	@Override
 	public DataAccessException translateExceptionIfPossible(RuntimeException ex) {
 		if (ex instanceof HibernateException) {
 			return convertHibernateAccessException((HibernateException) ex);
 		}
 		if (ex instanceof PersistenceException && ex.getCause() instanceof HibernateException) {
 			return convertHibernateAccessException((HibernateException) ex.getCause());
 		}
 		return EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(ex);
 	}
 
 	/**
 	 * Convert the given HibernateException to an appropriate exception
 	 * from the {@code org.springframework.dao} hierarchy.
 	 * @param ex HibernateException that occurred
 	 * @return the corresponding DataAccessException instance
 	 */
 	protected DataAccessException convertHibernateAccessException(HibernateException ex) {
 		if (ex instanceof JDBCConnectionException) {
 			return new DataAccessResourceFailureException(ex.getMessage(), ex);
 		}
 		if (ex instanceof SQLGrammarException) {
 			SQLGrammarException jdbcEx = (SQLGrammarException) ex;
 			return new InvalidDataAccessResourceUsageException(ex.getMessage() + "; SQL [" + jdbcEx.getSQL() + "]", ex);
 		}
 		if (ex instanceof QueryTimeoutException) {
 			QueryTimeoutException jdbcEx = (QueryTimeoutException) ex;
 			return new org.springframework.dao.QueryTimeoutException(ex.getMessage() + "; SQL [" + jdbcEx.getSQL() + "]", ex);
 		}
 		if (ex instanceof LockAcquisitionException) {
 			LockAcquisitionException jdbcEx = (LockAcquisitionException) ex;
 			return new CannotAcquireLockException(ex.getMessage() + "; SQL [" + jdbcEx.getSQL() + "]", ex);
 		}
 		if (ex instanceof PessimisticLockException) {
 			PessimisticLockException jdbcEx = (PessimisticLockException) ex;
 			return new PessimisticLockingFailureException(ex.getMessage() + "; SQL [" + jdbcEx.getSQL() + "]", ex);
 		}
 		if (ex instanceof ConstraintViolationException) {
 			ConstraintViolationException jdbcEx = (ConstraintViolationException) ex;
 			return new DataIntegrityViolationException(ex.getMessage()  + "; SQL [" + jdbcEx.getSQL() +
 					"]; constraint [" + jdbcEx.getConstraintName() + "]", ex);
 		}
 		if (ex instanceof DataException) {
 			DataException jdbcEx = (DataException) ex;
 			return new DataIntegrityViolationException(ex.getMessage() + "; SQL [" + jdbcEx.getSQL() + "]", ex);
 		}
 		// end of JDBCException subclass handling
 
 		if (ex instanceof QueryException) {
 			return new InvalidDataAccessResourceUsageException(ex.getMessage(), ex);
 		}
 		if (ex instanceof NonUniqueResultException) {
 			return new IncorrectResultSizeDataAccessException(ex.getMessage(), 1, ex);
 		}
 		if (ex instanceof NonUniqueObjectException) {
 			return new DuplicateKeyException(ex.getMessage(), ex);
 		}
 		if (ex instanceof PropertyValueException) {
 			return new DataIntegrityViolationException(ex.getMessage(), ex);
 		}
 		if (ex instanceof PersistentObjectException) {
 			return new InvalidDataAccessApiUsageException(ex.getMessage(), ex);
 		}
 		if (ex instanceof TransientObjectException) {
 			return new InvalidDataAccessApiUsageException(ex.getMessage(), ex);
 		}
 		if (ex instanceof ObjectDeletedException) {
 			return new InvalidDataAccessApiUsageException(ex.getMessage(), ex);
 		}
 		if (ex instanceof UnresolvableObjectException) {
 			UnresolvableObjectException hibEx = (UnresolvableObjectException) ex;
 			return new ObjectRetrievalFailureException(hibEx.getEntityName(), hibEx.getIdentifier(), ex.getMessage(), ex);
 		}
 		if (ex instanceof WrongClassException) {
 			WrongClassException hibEx = (WrongClassException) ex;
 			return new ObjectRetrievalFailureException(hibEx.getEntityName(), hibEx.getIdentifier(), ex.getMessage(), ex);
 		}
 		if (ex instanceof StaleObjectStateException) {
 			StaleObjectStateException hibEx = (StaleObjectStateException) ex;
 			return new ObjectOptimisticLockingFailureException(hibEx.getEntityName(), hibEx.getIdentifier(), ex);
 		}
 		if (ex instanceof StaleStateException) {
 			return new ObjectOptimisticLockingFailureException(ex.getMessage(), ex);
 		}
 		if (optimisticLockExceptionClass.isInstance(ex)) {
 			return new ObjectOptimisticLockingFailureException(ex.getMessage(), ex);
 		}
 		if (pessimisticLockExceptionClass != null && pessimisticLockExceptionClass.isInstance(ex)) {
 			if (ex.getCause() instanceof LockAcquisitionException) {
 				return new CannotAcquireLockException(ex.getMessage(), ex.getCause());
 			}
 			return new PessimisticLockingFailureException(ex.getMessage(), ex);
 		}
 
 		// fallback
 		return new JpaSystemException(ex);
 	}
 
 	protected Session getSession(EntityManager entityManager) {
 		return entityManager.unwrap(Session.class);
 	}
 
 
 	private static class SessionTransactionData {
 
 		private final Session session;
 
 		private final FlushMode previousFlushMode;
 
 		private final boolean resetConnection;
 
 		private final Integer previousIsolationLevel;
 
 		public SessionTransactionData(
 				Session session, FlushMode previousFlushMode, boolean resetConnection, Integer previousIsolationLevel) {
 			this.session = session;
 			this.previousFlushMode = previousFlushMode;
 			this.resetConnection = resetConnection;
 			this.previousIsolationLevel = previousIsolationLevel;
 		}
 
 		public void resetSessionState() {
 			if (this.previousFlushMode != null) {
 				this.session.setFlushMode(this.previousFlushMode);
 			}
 			if (this.resetConnection && this.session.isConnected()) {
 				Connection con = HibernateConnectionHandle.doGetConnection(this.session);
 				DataSourceUtils.resetConnectionAfterTransaction(con, this.previousIsolationLevel);
 			}
 		}
 	}
 
 
 	private static class HibernateConnectionHandle implements ConnectionHandle {
 
 		// This will find a corresponding method on Hibernate 3.x but not on 4.x
 		private static final Method sessionConnectionMethod =
 				ClassUtils.getMethodIfAvailable(Session.class, "connection");
 
 		private static volatile Method connectionMethodToUse = sessionConnectionMethod;
 
 		private final Session session;
 
 		public HibernateConnectionHandle(Session session) {
 			this.session = session;
 		}
 
 		@Override
 		public Connection getConnection() {
 			return doGetConnection(this.session);
 		}
 
 		@Override
 		public void releaseConnection(Connection con) {
 			if (sessionConnectionMethod != null) {
 				// Need to explicitly call close() with Hibernate 3.x in order to allow
 				// for eager release of the underlying physical Connection if necessary.
 				// However, do not do this on Hibernate 4.2+ since it would return the
 				// physical Connection to the pool right away, making it unusable for
 				// further operations within the current transaction!
 				JdbcUtils.closeConnection(con);
 			}
 		}
 
 		public static Connection doGetConnection(Session session) {
 			try {
 				if (connectionMethodToUse == null) {
 					// Reflective lookup to find SessionImpl's connection() method on Hibernate 4.x
 					connectionMethodToUse = session.getClass().getMethod("connection");
 				}
 				return (Connection) ReflectionUtils.invokeMethod(connectionMethodToUse, session);
 			}
 			catch (NoSuchMethodException ex) {
 				throw new IllegalStateException("Cannot find connection() method on Hibernate Session", ex);
 			}
 		}
 	}
 
 }