/*
    * 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;
 	}
 }