/*
 * Copyright 2014-2020 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
 *
 *      https://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.data.jpa.repository.support;

import static org.springframework.data.jpa.util.BeanDefinitionUtils.*;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.AutowireCandidateQualifier;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.core.Ordered;
import org.springframework.data.jpa.util.BeanDefinitionUtils.EntityManagerFactoryBeanDefinition;
import org.springframework.orm.jpa.SharedEntityManagerCreator;

BeanFactoryPostProcessor to register a SharedEntityManagerCreator for every EntityManagerFactory bean definition found in the application context to enable autowiring EntityManager instances into constructor arguments. Adds the EntityManagerFactory bean name as qualifier to the EntityManager BeanDefinition to enable explicit references in case of multiple EntityManagerFactory instances. 
Author:
Oliver Gierke/**
 * {@link BeanFactoryPostProcessor} to register a {@link SharedEntityManagerCreator} for every
 * {@link EntityManagerFactory} bean definition found in the application context to enable autowiring
 * {@link EntityManager} instances into constructor arguments. Adds the {@link EntityManagerFactory} bean name as
 * qualifier to the {@link EntityManager} {@link BeanDefinition} to enable explicit references in case of multiple
 * {@link EntityManagerFactory} instances.
 *
 * @author Oliver Gierke
 */
public class EntityManagerBeanDefinitionRegistrarPostProcessor implements BeanFactoryPostProcessor, Ordered {

	/* 
	 * (non-Javadoc)
	 * @see org.springframework.core.Ordered#getOrder()
	 */
	@Override
	public int getOrder() {
		return Ordered.HIGHEST_PRECEDENCE + 10;
	}

	/* 
	 * (non-Javadoc)
	 * @see org.springframework.beans.factory.config.BeanFactoryPostProcessor#postProcessBeanFactory(org.springframework.beans.factory.config.ConfigurableListableBeanFactory)
	 */
	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {

		if (!ConfigurableListableBeanFactory.class.isInstance(beanFactory)) {
			return;
		}

		ConfigurableListableBeanFactory factory = (ConfigurableListableBeanFactory) beanFactory;

		for (EntityManagerFactoryBeanDefinition definition : getEntityManagerFactoryBeanDefinitions(factory)) {

			BeanFactory definitionFactory = definition.getBeanFactory();

			if (!(definitionFactory instanceof BeanDefinitionRegistry)) {
				continue;
			}

			BeanDefinitionRegistry definitionRegistry = (BeanDefinitionRegistry) definitionFactory;

			BeanDefinitionBuilder builder = BeanDefinitionBuilder
					.rootBeanDefinition("org.springframework.orm.jpa.SharedEntityManagerCreator");
			builder.setFactoryMethod("createSharedEntityManager");
			builder.addConstructorArgReference(definition.getBeanName());

			AbstractBeanDefinition emBeanDefinition = builder.getRawBeanDefinition();

			emBeanDefinition.addQualifier(new AutowireCandidateQualifier(Qualifier.class, definition.getBeanName()));
			emBeanDefinition.setScope(definition.getBeanDefinition().getScope());
			emBeanDefinition.setSource(definition.getBeanDefinition().getSource());
			emBeanDefinition.setLazyInit(true);

			BeanDefinitionReaderUtils.registerWithGeneratedName(emBeanDefinition, definitionRegistry);
		}
	}
}