/* 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.activiti.engine.impl.cmd;

import java.io.Serializable;

import org.activiti.engine.ActivitiIllegalArgumentException;
import org.activiti.engine.delegate.event.impl.ActivitiEventBuilder;
import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.interceptor.CommandContext;
import org.activiti.engine.impl.persistence.entity.JobEntity;
import org.flowable.common.engine.api.delegate.event.FlowableEngineEventType;
import org.flowable.common.engine.impl.interceptor.EngineConfigurationConstants;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * @author Tijs Rademakers
 */
public class ExecuteAsyncJobCmd implements Command<Object>, Serializable {

    private static final long serialVersionUID = 1L;

    private static final Logger LOGGER = LoggerFactory.getLogger(ExecuteAsyncJobCmd.class);

    protected JobEntity job;

    public ExecuteAsyncJobCmd(JobEntity job) {
        this.job = job;
    }

    @Override
    public Object execute(CommandContext commandContext) {

        if (job == null) {
            throw new ActivitiIllegalArgumentException("job is null");
        }

        // We need to refetch the job, as it could have been deleted by another concurrent job
        // For example: an embedded subprocess with a couple of async tasks and a timer on the boundary of the subprocess
        // when the timer fires, all executions and thus also the jobs inside of the embedded subprocess are destroyed.
        // However, the async task jobs could already have been fetched and put in the queue.... while in reality they have been deleted.
        // A refetch is thus needed here to be sure that it exists for this transaction.

        JobEntity refetchedJob = commandContext.getJobEntityManager().findJobById(job.getId());
        if (refetchedJob == null) {
            LOGGER.debug("Job does not exist anymore and will not be executed. It has most likely been deleted "
                    + "as part of another concurrent part of the process instance.");
            return null;
        }

        if (LOGGER.isDebugEnabled()) {
            LOGGER.debug("Executing async job {}", refetchedJob.getId());
        }

        refetchedJob.execute(commandContext);

        if (commandContext.getEventDispatcher().isEnabled()) {
            commandContext.getEventDispatcher().dispatchEvent(ActivitiEventBuilder.createEntityEvent(
                    FlowableEngineEventType.JOB_EXECUTION_SUCCESS, refetchedJob), EngineConfigurationConstants.KEY_PROCESS_ENGINE_CONFIG);
        }

        return null;
    }
}
