/*
 * Copyright 2006-2013 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.batch.core.configuration.xml;

import org.springframework.batch.core.repository.JobRepository;
import org.springframework.batch.core.step.AbstractStep;
import org.springframework.beans.BeansException;
import org.springframework.beans.MutablePropertyValues;
import org.springframework.beans.PropertyValue;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.RuntimeBeanReference;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.transaction.PlatformTransactionManager;

/**
 * Post-process jobs and steps defined using the batch namespace to inject
 * dependencies.
 *
 * @author Dan Garrette
 * @since 2.0.1
 */
public class CoreNamespacePostProcessor implements BeanPostProcessor, BeanFactoryPostProcessor, ApplicationContextAware {

	private static final String DEFAULT_JOB_REPOSITORY_NAME = "jobRepository";

	private static final String DEFAULT_TRANSACTION_MANAGER_NAME = "transactionManager";

	private static final String JOB_FACTORY_PROPERTY_NAME = "jobParserJobFactoryBeanRef";

	private static final String JOB_REPOSITORY_PROPERTY_NAME = "jobRepository";

	private ApplicationContext applicationContext;

	@Override
	public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
		for (String beanName : beanFactory.getBeanDefinitionNames()) {
			injectJobRepositoryIntoSteps(beanName, beanFactory);
			overrideStepClass(beanName, beanFactory);
		}
	}

	/**
	 * Automatically inject job-repository from a job into its steps. Only
	 * inject if the step is an AbstractStep or StepParserStepFactoryBean.
	 *
	 * @param beanName
	 * @param beanFactory
	 */
	private void injectJobRepositoryIntoSteps(String beanName, ConfigurableListableBeanFactory beanFactory) {
		BeanDefinition bd = beanFactory.getBeanDefinition(beanName);
		if (bd.hasAttribute(JOB_FACTORY_PROPERTY_NAME)) {
			MutablePropertyValues pvs = bd.getPropertyValues();
			if (beanFactory.isTypeMatch(beanName, AbstractStep.class)) {
				String jobName = (String) bd.getAttribute(JOB_FACTORY_PROPERTY_NAME);
				PropertyValue jobRepository = BeanDefinitionUtils.getPropertyValue(jobName,
						JOB_REPOSITORY_PROPERTY_NAME, beanFactory);
				if (jobRepository != null) {
					// Set the job's JobRepository onto the step
					pvs.addPropertyValue(jobRepository);
				}
				else {
					// No JobRepository found, so inject the default
					RuntimeBeanReference jobRepositoryBeanRef = new RuntimeBeanReference(DEFAULT_JOB_REPOSITORY_NAME);
					pvs.addPropertyValue(JOB_REPOSITORY_PROPERTY_NAME, jobRepositoryBeanRef);
				}
			}
		}
	}

	/**
	 * If any of the beans in the parent hierarchy is a <step/> with a
	 * <tasklet/>, then the bean class must be
	 * {@link StepParserStepFactoryBean}.
	 *
	 * @param beanName
	 * @param beanFactory
	 */
	private void overrideStepClass(String beanName, ConfigurableListableBeanFactory beanFactory) {
		BeanDefinition bd = beanFactory.getBeanDefinition(beanName);
		Object isNamespaceStep = BeanDefinitionUtils
				.getAttribute(beanName, "isNamespaceStep", beanFactory);
		if (isNamespaceStep != null && (Boolean) isNamespaceStep == true) {
			((AbstractBeanDefinition) bd).setBeanClass(StepParserStepFactoryBean.class);
		}
	}

	@Override
	public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
		return injectDefaults(bean);
	}

	/**
	 * Inject defaults into factory beans.
	 * <ul>
	 * <li>Inject "jobRepository" into any {@link JobParserJobFactoryBean}
	 * without a jobRepository.
	 * <li>Inject "transactionManager" into any
	 * {@link StepParserStepFactoryBean} without a transactionManager.
	 * </ul>
	 *
	 * @param bean
	 * @return
	 */
	private Object injectDefaults(Object bean) {
		if (bean instanceof JobParserJobFactoryBean) {
			JobParserJobFactoryBean fb = (JobParserJobFactoryBean) bean;
			JobRepository jobRepository = fb.getJobRepository();
			if (jobRepository == null) {
				fb.setJobRepository((JobRepository) applicationContext.getBean(DEFAULT_JOB_REPOSITORY_NAME));
			}
		} else if (bean instanceof StepParserStepFactoryBean) {
			StepParserStepFactoryBean<?, ?> fb = (StepParserStepFactoryBean<?, ?>) bean;
			JobRepository jobRepository = fb.getJobRepository();
			if (jobRepository == null) {
				fb.setJobRepository((JobRepository) applicationContext.getBean(DEFAULT_JOB_REPOSITORY_NAME));
			}
			PlatformTransactionManager transactionManager = fb.getTransactionManager();
			if (transactionManager == null && fb.requiresTransactionManager()) {
				fb.setTransactionManager((PlatformTransactionManager) applicationContext
						.getBean(DEFAULT_TRANSACTION_MANAGER_NAME));
			}
		}
		return bean;
	}

	@Override
	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
		return bean;
	}

	@Override
	public void setApplicationContext(ApplicationContext applicationContext) {
		this.applicationContext = applicationContext;
	}
}