/*
    * Copyright 2009-2013 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.admin.integration;
  
  import java.util.ArrayList;
  import java.util.Collection;
  
  import org.springframework.batch.admin.service.JobService;
  import org.springframework.batch.admin.domain.JobInfo;
  import org.springframework.batch.core.Job;
  import org.springframework.batch.core.configuration.DuplicateJobException;
  import org.springframework.batch.core.configuration.JobRegistry;
  import org.springframework.batch.core.configuration.support.ApplicationContextFactory;
  import org.springframework.batch.core.configuration.support.GenericApplicationContextFactory;
  import org.springframework.batch.core.configuration.support.JobLoader;
  import org.springframework.batch.core.launch.NoSuchJobException;
  import org.springframework.beans.BeansException;
  import org.springframework.context.ApplicationContext;
  import org.springframework.context.ApplicationContextAware;
  import org.springframework.core.io.Resource;
  import org.springframework.integration.annotation.MessageEndpoint;
  import org.springframework.integration.annotation.ServiceActivator;
  
  /**
   * Load XML from a Spring {@link Resource} and create an
   * {@link ApplicationContext}, registering any {@link Job} instances defined in
   * a {@link JobRegistry}. If this component is itself configured with Spring,
   * then its own ApplicationContext will be the parent for the new one, and the
   * child will inherit AOP configuration, as well as property placeholder and
   * custom editor configuration from the parent.
   * 
   * @author Dave Syer
   * @author Michael Minella
   * 
   */
  @MessageEndpoint
  public class JobConfigurationResourceLoader implements ApplicationContextAware {
  
  	private JobLoader jobLoader;
  
  	private JobService jobService;
  
  	private ApplicationContext parent;
  
  	public void setJobLoader(JobLoader jobLoader) {
  		this.jobLoader = jobLoader;
  	}
  
  	public void setJobService(JobService jobService) {
  		this.jobService = jobService;
  	}
  
  	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
  		this.parent = applicationContext;
  	}
  
  	@ServiceActivator
  	public Collection<JobInfo> loadJobs(Resource resource) throws DuplicateJobException {
  
  		Collection<JobInfo> result = new ArrayList<JobInfo>();
  
  		ApplicationContextFactory factory = createApplicationContextFactory(parent, resource);
  		Collection<Job> jobs = jobLoader.reload(factory);
  
  		for (Job job : jobs) {
  			String name = job.getName();
  			int count = 0;
  			try {
  				count = jobService.countJobExecutionsForJob(name);
  			}
  			catch (NoSuchJobException e) {
  				// shouldn't happen
  			}
  			boolean launchable = jobService.isLaunchable(name);
  			boolean incrementable = jobService.isIncrementable(name);
  			result.add(new JobInfo(name, count, null, launchable, incrementable));
  		}
  
  		return result;
  
  	}
  
  	/**
  	 * Create an application context from the resource provided. Extension point
  	 * for subclasses if they need to customize the context in any way. The
  	 * default uses a {@link GenericApplicationContextFactory}.
 	 * 
 	 * @param parent the parent application context (or null if there is none)
 	 * @param resource the location of the XML configuration
 	 * 
 	 * @return an application context containing jobs
 	 */
 	protected ApplicationContextFactory createApplicationContextFactory(ApplicationContext parent, Resource resource) {
 		GenericApplicationContextFactory applicationContextFactory = new GenericApplicationContextFactory(resource);
 		if (parent != null) {
 			applicationContextFactory.setApplicationContext(parent);
 		}
 		return applicationContextFactory;
 	}
 
 }