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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
 * See the lgpl.txt file in the root directory or .
 */
package org.hibernate.envers.internal.entities.mapper.id;

import java.io.Serializable;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Map;

import org.hibernate.Session;
import org.hibernate.envers.boot.internal.EnversService;
import org.hibernate.envers.internal.entities.PropertyData;
import org.hibernate.envers.internal.tools.ReflectionTools;
import org.hibernate.property.access.spi.Getter;
import org.hibernate.property.access.spi.Setter;
import org.hibernate.proxy.HibernateProxy;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.type.EntityType;

/**
 * An extension to the {@link SingleIdMapper} implementation that supports the use case of an {@code @IdClass}
 * mapping that contains an entity association where the {@code @IdClass} stores the primary key of the
 * associated entity rather than the entity object itself.
 *
 * Internally this mapper is capable of transforming the primary key values into the associated entity object
 * and vice versa depending upon the operation.
 *
 * @author Chris Cranford
 */
public class VirtualEntitySingleIdMapper extends SingleIdMapper {

	private final PropertyData propertyData;
	private final String entityName;

	private IdMapper entityIdMapper;

	public VirtualEntitySingleIdMapper(ServiceRegistry serviceRegistry, PropertyData propertyData) {
		super( serviceRegistry, propertyData );
		this.propertyData = propertyData;
		this.entityName = resolveEntityName( this.propertyData );
	}

	@Override
	public void mapToMapFromId(Session session, Map data, Object obj) {
		final Serializable value = AccessController.doPrivileged(
				new PrivilegedAction() {
					@Override
					public Serializable run() {
						final Getter getter = ReflectionTools.getGetter(
								obj.getClass(),
								propertyData,
								getServiceRegistry()
						);
						return (Serializable) getter.get( obj );
					}
				}
		);

		// Either loads the entity from the session's 1LC if it already exists or potentially creates a
		// proxy object to represent the entity by identifier so that we can reference it in the map.
		final Object entity = session.load( this.entityName, value );
		data.put( propertyData.getName(), entity );
	}

	@Override
	public void mapToEntityFromEntity(Object objTo, Object objFrom) {
		if ( objTo == null || objFrom == null ) {
			return;
		}

		AccessController.doPrivileged(
				new PrivilegedAction() {
					@Override
					public Object run() {
						final Getter getter = ReflectionTools.getGetter(
								objFrom.getClass(),
								propertyData,
								getServiceRegistry()
						);

						final Setter setter = ReflectionTools.getSetter(
								objTo.getClass(),
								propertyData,
								getServiceRegistry()
						);

						// Get the value from the containing entity
						final Object value = getter.get( objFrom );
						if ( value == null ) {
							return null;
						}

						if ( !value.getClass().equals( propertyData.getVirtualReturnClass() ) ) {
							setter.set( objTo, getAssociatedEntityIdMapper().mapToIdFromEntity( value ), null );
						}
						else {
							// This means we're setting the object
							setter.set( objTo, value, null );
						}

						return null;
					}
				}
		);
	}

	@Override
	public boolean mapToEntityFromMap(Object obj, Map data) {
		if ( data == null || obj == null ) {
			return false;
		}

		final Object value = data.get( propertyData.getName() );
		if ( value == null ) {
			return false;
		}

		return AccessController.doPrivileged(
				new PrivilegedAction() {
					@Override
					public Boolean run() {
						final Setter setter = ReflectionTools.getSetter(
								obj.getClass(),
								propertyData,
								getServiceRegistry()
						);
						final Class paramClass = ReflectionTools.getType(
								obj.getClass(),
								propertyData,
								getServiceRegistry()
						);

						if ( paramClass != null && paramClass.equals( propertyData.getVirtualReturnClass() ) ) {
							setter.set( obj, getAssociatedEntityIdMapper().mapToIdFromEntity( value ), null );
						}
						else {
							setter.set( obj, value, null );
						}

						return true;
					}
				}
		);
	}

	@Override
	public void mapToMapFromEntity(Map data, Object obj) {
		if ( obj == null ) {
			data.put( propertyData.getName(), null );
		}
		else {
			if ( obj instanceof HibernateProxy ) {
				final HibernateProxy proxy = (HibernateProxy) obj;
				data.put( propertyData.getName(), proxy.getHibernateLazyInitializer().getInternalIdentifier() );
			}
			else {
				final Object value = AccessController.doPrivileged(
						new PrivilegedAction() {
							@Override
							public Object run() {
								final Getter getter = ReflectionTools.getGetter(
										obj.getClass(),
										propertyData,
										getServiceRegistry()
								);
								return getter.get( obj );
							}
						}
				);

				if ( propertyData.getVirtualReturnClass().isInstance( value ) ) {
					// The value is the primary key, need to map it via IdMapper
					getPrefixedAssociatedEntityIdMapper( propertyData ).mapToMapFromId( data, value );
				}
				else {
					data.put( propertyData.getName(), value );
				}
			}
		}
	}

	private IdMapper getAssociatedEntityIdMapper() {
		if ( entityIdMapper == null ) {
			entityIdMapper = resolveEntityIdMapper( getServiceRegistry(), entityName );
		}
		return entityIdMapper;
	}

	private IdMapper getPrefixedAssociatedEntityIdMapper(PropertyData propertyData) {
		return getAssociatedEntityIdMapper().prefixMappedProperties( propertyData.getName() + "." );
	}

	private static String resolveEntityName(PropertyData propertyData) {
		if ( EntityType.class.isInstance( propertyData.getType() ) ) {
			final EntityType entityType = (EntityType) propertyData.getType();
			return entityType.getAssociatedEntityName();
		}
		return null;
	}

	private static IdMapper resolveEntityIdMapper(ServiceRegistry serviceRegistry, String entityName) {
		final EnversService enversService = serviceRegistry.getService( EnversService.class );
		return enversService.getEntitiesConfigurations().get( entityName ).getIdMapper();
	}

}
 















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