/**
 * Copyright (c) 2010 Yahoo! Inc. All rights reserved.
 * 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. See accompanying LICENSE file.
 */
package org.apache.oozie.command;

import org.apache.oozie.client.Job;

/**
 * Transition command for start the job. The derived class has to override these following functions:
 * <p/>
 * loadState() : load the job's and/or actions' state
 * updateJob() : update job status and attributes
 * StartChildren() : submit or queue commands to start children
 * notifyParent() : update the status to upstream if any
 */
public abstract class StartTransitionXCommand extends TransitionXCommand<Void> {

    /**
     * The constructor for abstract class {@link StartTransitionXCommand}
     *
     * @param name the command name
     * @param type the command type
     * @param priority the command priority
     */
    public StartTransitionXCommand(String name, String type, int priority) {
        super(name, type, priority);
    }

    /**
     * The constructor for abstract class {@link StartTransitionXCommand}
     *
     * @param name the command name
     * @param type the command type
     * @param priority the command priority
     * @param dryrun true if dryrun is enable
     */
    public StartTransitionXCommand(String name, String type, int priority, boolean dryrun) {
        super(name, type, priority, dryrun);
    }

    /**
     * Start actions associated with the job
     *
     * @throws CommandException thrown if failed to start actions
     */
    public abstract void StartChildren() throws CommandException;

    /* (non-Javadoc)
     * @see org.apache.oozie.command.TransitionXCommand#transitToNext()
     */
    @Override
    public final void transitToNext() {
        if (job == null) {
            job = this.getJob();
        }
        job.setStatus(Job.Status.RUNNING);
        job.setPending();
    }

    /* (non-Javadoc)
     * @see org.apache.oozie.command.TransitionXCommand#execute()
     */
    @Override
    protected Void execute() throws CommandException {
        transitToNext();
        updateJob();
        StartChildren();
        notifyParent();
        return null;
    }
}