/*******************************************************************************
 * Copyright (c) 2003, 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.core.runtime.jobs.ProgressProvider;

import dwt.dwthelper.utils;

import dwtx.core.runtime.IProgressMonitor;
import dwtx.core.runtime.NullProgressMonitor;
import dwtx.core.runtime.SubProgressMonitor;

import dwtx.core.runtime.jobs.Job;

/**
 * The progress provider supplies the job manager with progress monitors for
 * running jobs.  There can only be one progress provider at any given time.
 * <p>
 * This class is intended for use by the currently executing Eclipse application.
 * Plug-ins outside the currently running application should not reference or
 * subclass this class.
 * </p>
 *
 * @see IJobManager#setProgressProvider(ProgressProvider)
 * @since 3.0
 */
public abstract class ProgressProvider {
    /**
     * Provides a new progress monitor instance to be used by the given job.
     * This method is called prior to running any job that does not belong to a
     * progress group. The returned monitor will be supplied to the job's
     * <code>run</code> method.
     *
     * @see #createProgressGroup()
     * @see Job#setProgressGroup(IProgressMonitor, int)
     * @param job the job to create a progress monitor for
     * @return a progress monitor, or <code>null</code> if no progress monitoring
     * is needed.
     */
    public abstract IProgressMonitor createMonitor(Job job);

    /**
     * Returns a progress monitor that can be used to provide
     * aggregated progress feedback on a set of running jobs.
     * This method implements <code>IJobManager.createProgressGroup</code>,
     * and must obey all rules specified in that contract.
     * <p>
     * This default implementation returns a new
     * <code>NullProgressMonitor</code>  Subclasses may override.
     *
     * @see IJobManager#createProgressGroup()
     * @return a progress monitor
     */
    public IProgressMonitor createProgressGroup() {
        return new NullProgressMonitor();
    }

    /**
     * Returns a progress monitor that can be used by a running job
     * to report progress in the context of a progress group. This method
     * implements <code>Job.setProgressGroup</code>.  One of the
     * two <code>createMonitor</code> methods will be invoked
     * prior to each execution of a job, depending on whether a progress
     * group was specified for the job.
     * <p>
     * The provided monitor must be a monitor returned by the method
     * <code>createProgressGroup</code>.  This method is responsible
     * for asserting this and throwing an appropriate runtime exception
     * if an invalid monitor is provided.
     * <p>
     * This default implementation returns a new
     * <code>SubProgressMonitor</code>.  Subclasses may override.
     *
     * @see IJobManager#createProgressGroup()
     * @see Job#setProgressGroup(IProgressMonitor, int)
     * @param job the job to create a progress monitor for
     * @param group the progress monitor group that this job belongs to
     * @param ticks the number of ticks of work for the progress monitor
     * @return a progress monitor, or <code>null</code> if no progress monitoring
     * is needed.
     */
    public IProgressMonitor createMonitor(Job job, IProgressMonitor group, int ticks) {
        return new SubProgressMonitor(group, ticks);
    }

    /**
     * Returns a progress monitor to use when none has been provided
     * by the client running the job.
     * <p>
     * This default implementation returns a new
     * <code>NullProgressMonitor</code>  Subclasses may override.
     *
     * @return a progress monitor
     */
    public IProgressMonitor getDefaultMonitor() {
        return new NullProgressMonitor();
    }
}