/*
    * Copyright 2009-2010 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.launch;
  
  import java.util.Date;
  import java.util.HashSet;
  import java.util.Set;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.aspectj.lang.annotation.AfterReturning;
  import org.aspectj.lang.annotation.Aspect;
  import org.aspectj.lang.annotation.Before;
  import org.springframework.batch.core.BatchStatus;
  import org.springframework.batch.core.ExitStatus;
  import org.springframework.batch.core.Job;
  import org.springframework.batch.core.JobExecution;
  import org.springframework.batch.core.explore.JobExplorer;
  import org.springframework.batch.core.launch.JobLauncher;
  import org.springframework.batch.core.repository.JobExecutionAlreadyRunningException;
  import org.springframework.batch.core.repository.JobRepository;
  import org.springframework.beans.factory.InitializingBean;
  import org.springframework.jmx.export.annotation.ManagedAttribute;
  import org.springframework.jmx.export.annotation.ManagedOperation;
  import org.springframework.jmx.export.annotation.ManagedResource;
  import org.springframework.util.Assert;
  
  /**
   * Wrapper for a {@link JobLauncher} that synchronizes jobs globally so that
   * only one execution of a given Job can be active at once.
   * 
   * @author Dave Syer
   * 
   */
  @Aspect
  @ManagedResource
  public class JobLauncherSynchronizer implements InitializingBean {
  
  	private static final Log logger = LogFactory.getLog(JobLauncherSynchronizer.class);
  
  	private JobExplorer jobExplorer;
  
  	private JobRepository jobRepository;
  
  	private Set<String> jobNames = new HashSet<String>();
  
  	/**
  	 * The {@link JobExplorer} to use to inspect existing executions.
  	 * 
  	 * @param jobExplorer a {@link JobExplorer}
  	 */
  	public void setJobExplorer(JobExplorer jobExplorer) {
  		this.jobExplorer = jobExplorer;
  	}
  
  	/**
  	 * The {@link JobRepository} needed for updates to execution data.
  	 * 
  	 * @param jobRepository a {@link JobRepository}
  	 */
  	public void setJobRepository(JobRepository jobRepository) {
  		this.jobRepository = jobRepository;
  	}
  
  	/**
  	 * Set of job names that will be synchronized. Others are ignored.
  	 * 
  	 * @param jobNames the job names
  	 */
  	public void setJobNames(Set<String> jobNames) {
  		this.jobNames = jobNames;
  	}
  	
  	/**
  	 * A job name that will be synchronized.
  	 * 
  	 * @param jobName the job name
  	 */
  	@ManagedOperation
  	public void addJobName(String jobName) {
  		this.jobNames.add(jobName);
  	}
  	
  	/**
  	 * Remove a job name from the list to synchronize.
  	 * 
 	 * @param jobName the job name
 	 */
 	@ManagedOperation
 	public void removeJobName(String jobName) {
 		this.jobNames.remove(jobName);
 	}
 	
 	/**
 	 * @return the jobNames
 	 */
 	@ManagedAttribute
 	public Set<String> getJobNames() {
 		return jobNames;
 	}
 
 	public void afterPropertiesSet() throws Exception {
 		Assert.notNull(jobExplorer, "A JobExplorer must be provided");
 		Assert.notNull(jobRepository, "A JobRepository must be provided");
 	}
 
 	@Before("execution(* org.springframework.batch..JobLauncher+.*(..)) && args(job,..)")
 	public void checkJobBeforeLaunch(Job job) throws JobExecutionAlreadyRunningException {
 		String jobName = job.getName();
 		logger.debug("Checking for synchronization on Job: " + jobName);
 		if (!jobNames.contains(jobName)) {
 			logger.debug("Not synchronizing Job: " + jobName);
 			return;
 		}
 		Set<JobExecution> running = jobExplorer.findRunningJobExecutions(jobName);
 		if (!running.isEmpty()) {
 			throw new JobExecutionAlreadyRunningException("An instance of this job is already active: "+jobName);
 		}
 		logger.debug("Job checked and no duplicates detected: " + jobName);
 	}
 
 	@AfterReturning(value = "execution(* org.springframework.batch..JobRepository+.createJobExecution(..)) && args(jobName,..)", returning = "jobExecution")
 	public void checkJobDuringLaunch(String jobName, JobExecution jobExecution)
 			throws JobExecutionAlreadyRunningException {
 		logger.debug("Re-checking for synchronization on JobExecution: " + jobExecution);
 		if (!jobNames.contains(jobName)) {
 			logger.debug("Not re-checking for synchronization of Job: " + jobName);
 			return;
 		}
 		Set<JobExecution> running = jobExplorer.findRunningJobExecutions(jobName);
 		if (running.size() > 1) {
 			jobExecution.setEndTime(new Date());
 			jobExecution.upgradeStatus(BatchStatus.ABANDONED);
 			jobExecution.setExitStatus(jobExecution.getExitStatus().and(ExitStatus.NOOP).addExitDescription(
 					"Not executed because another execution was detected for the same Job."));
 			jobRepository.update(jobExecution);
 			throw new JobExecutionAlreadyRunningException("An instance of this job is already active: "+jobName);
 		}
 	}
 }