/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jbpm.pvm.internal.jobexecutor;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Date;
import java.util.List;

import org.jbpm.api.cmd.Command;
import org.jbpm.api.cmd.Environment;
import org.jbpm.internal.log.Log;
import org.jbpm.pvm.internal.job.JobImpl;
import org.jbpm.pvm.internal.session.DbSession;


/**
 * @author Tom Baeyens
 */
public class AcquireJobsCmd implements Command<Collection<Long>> {

  private static final long serialVersionUID = 1L;

  private static final Log log = Log.getLog(AcquireJobsCmd.class.getName());
  private static final DateFormat timeFormat = new SimpleDateFormat("HH:mm:ss,SSS");
  
  JobExecutor jobExecutor;

  public AcquireJobsCmd(JobExecutor jobExecutor) {
    this.jobExecutor = jobExecutor;
  }

  public Collection<Long> execute(Environment environment) throws Exception {
    Collection<Long> acquiredJobDbids = new ArrayList<Long>();

    try {
      Collection<JobImpl<?>> acquiredJobs = new ArrayList<JobImpl<?>>();
      
      DbSession dbSession = environment.get(DbSession.class);
      if (log.isTraceEnabled()) log.trace("start querying first acquirable job...");

      JobImpl<?> job = dbSession.findFirstAcquirableJob();

      if (job!=null) {
        if (job.isExclusive()) {
          if (log.isTraceEnabled()) log.trace("exclusive acquirable job found ("+job+"). querying for other exclusive jobs to lock them all in one tx...");
          List<JobImpl<?>> otherExclusiveJobs = dbSession.findExclusiveJobs(job.getProcessInstance());
          acquiredJobs.addAll(otherExclusiveJobs);
        } else {
          acquiredJobs.add(job);
        }

        for (JobImpl<?> acquiredJob: acquiredJobs) {
          long lockExpirationTime = System.currentTimeMillis()+jobExecutor.getLockMillis();
          if (log.isTraceEnabled()) log.trace("trying to obtain a lock for '"+acquiredJob+"' with exp "+timeFormat.format(new Date(lockExpirationTime)));
          acquiredJob.acquire(jobExecutor.getName(), new Date(lockExpirationTime));
          acquiredJobDbids.add(acquiredJob.getDbid());
        }

      } else {
        if (log.isTraceEnabled()) log.trace("no acquirable jobs in job table");
      }
      
      if (log.isTraceEnabled()) log.trace("locking jobs "+acquiredJobDbids);
      
    } catch (Exception e) {
      // if jboss is still booting exceptions that are due to improper 
      // dependency configuration can be swallowed
      // https://jira.jboss.org/jira/browse/JBPM-2501
      if (e.getMessage().indexOf("JbpmDS not bound")==-1) {
        throw e;
      }
    }
    
    return acquiredJobDbids;
  }
}