/*******************************************************************************
 * Copyright (c) 2003, 2007 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.Job;

import tango.core.Thread;
import dwt.dwthelper.utils;

import dwtx.core.internal.jobs.InternalJob;
import dwtx.core.internal.jobs.JobManager;
import dwtx.core.runtime.IAdaptable;
import dwtx.core.runtime.IProgressMonitor;
import dwtx.core.runtime.IStatus;
import dwtx.core.runtime.QualifiedName;
import dwtx.core.runtime.Status;
import dwtx.core.runtime.jobs.IJobManager;
import dwtx.core.runtime.jobs.IJobChangeListener;
import dwtx.core.runtime.jobs.ISchedulingRule;

/**
 * Jobs are units of runnable work that can be scheduled to be run with the job
 * manager.  Once a job has completed, it can be scheduled to run again (jobs are
 * reusable).
 * <p>
 * Jobs have a state that indicates what they are currently doing.  When constructed,
 * jobs start with a state value of <code>NONE</code>.  When a job is scheduled
 * to be run, it moves into the <code>WAITING</code> state.  When a job starts
 * running, it moves into the <code>RUNNING</code> state.  When execution finishes
 * (either normally or through cancelation), the state changes back to
 * <code>NONE</code>.
 * </p><p>
 * A job can also be in the <code>SLEEPING</code> state.  This happens if a user
 * calls Job.sleep() on a waiting job, or if a job is scheduled to run after a specified
 * delay.  Only jobs in the <code>WAITING</code> state can be put to sleep.
 * Sleeping jobs can be woken at any time using Job.wakeUp(), which will put the
 * job back into the <code>WAITING</code> state.
 * </p><p>
 * Jobs can be assigned a priority that is used as a hint about how the job should
 * be scheduled.  There is no guarantee that jobs of one priority will be run before
 * all jobs of lower priority.  The javadoc for the various priority constants provide
 * more detail about what each priority means.  By default, jobs start in the
 * <code>LONG</code> priority class.
 *
 * @see IJobManager
 * @since 3.0
 */
public abstract class Job : InternalJob, IAdaptable {
    // DWT from IAdaptable
    public Object getAdapter(ClassInfo adapter){
        return super.getAdapter(adapter);
    }

    /**
     * Job status return value that is used to indicate asynchronous job completion.
     * @see Job#run(IProgressMonitor)
     * @see Job#done(IStatus)
     */
    private static IStatus ASYNC_FINISH_;
    public static IStatus ASYNC_FINISH(){
        if( ASYNC_FINISH_ is null ){
            synchronized( Job.classinfo ) {
                if( ASYNC_FINISH_ is null ){
                    ASYNC_FINISH_ = new Status(IStatus.OK, JobManager.PI_JOBS, 1, "", null);//$NON-NLS-1$
                }
            }
        }
        return ASYNC_FINISH_;
    }

    /* Job priorities */
    /**
     * Job priority constant (value 10) for interactive jobs.
     * Interactive jobs generally have priority over all other jobs.
     * Interactive jobs should be either fast running or very low on CPU
     * usage to avoid blocking other interactive jobs from running.
     *
     * @see #getPriority()
     * @see #setPriority(int)
     * @see #run(IProgressMonitor)
     */
    public static const int INTERACTIVE = 10;
    /**
     * Job priority constant (value 20) for short background jobs.
     * Short background jobs are jobs that typically complete within a second,
     * but may take longer in some cases.  Short jobs are given priority
     * over all other jobs except interactive jobs.
     *
     * @see #getPriority()
     * @see #setPriority(int)
     * @see #run(IProgressMonitor)
     */
    public static const int SHORT = 20;
    /**
     * Job priority constant (value 30) for long-running background jobs.
     *
     * @see #getPriority()
     * @see #setPriority(int)
     * @see #run(IProgressMonitor)
     */
    public static const int LONG = 30;
    /**
     * Job priority constant (value 40) for build jobs.  Build jobs are
     * generally run after all other background jobs complete.
     *
     * @see #getPriority()
     * @see #setPriority(int)
     * @see #run(IProgressMonitor)
     */
    public static const int BUILD = 40;

    /**
     * Job priority constant (value 50) for decoration jobs.
     * Decoration jobs have lowest priority.  Decoration jobs generally
     * compute extra information that the user may be interested in seeing
     * but is generally not waiting for.
     *
     * @see #getPriority()
     * @see #setPriority(int)
     * @see #run(IProgressMonitor)
     */
    public static const int DECORATE = 50;
    /**
     * Job state code (value 0) indicating that a job is not
     * currently sleeping, waiting, or running (i.e., the job manager doesn't know
     * anything about the job).
     *
     * @see #getState()
     */
    public static const int NONE = 0;
    /**
     * Job state code (value 1) indicating that a job is sleeping.
     *
     * @see #run(IProgressMonitor)
     * @see #getState()
     */
    public static const int SLEEPING = 0x01;
    /**
     * Job state code (value 2) indicating that a job is waiting to be run.
     *
     * @see #getState()
     */
    public static const int WAITING = 0x02;
    /**
     * Job state code (value 4) indicating that a job is currently running
     *
     * @see #getState()
     */
    public static const int RUNNING = 0x04;

    /**
     * Returns the job manager.
     *
     * @return the job manager
     * @since dwtx.core.jobs 3.2
     */
    public static final IJobManager getJobManager() {
        return manager;
    }

    /**
     * Creates a new job with the specified name.  The job name is a human-readable
     * value that is displayed to users.  The name does not need to be unique, but it
     * must not be <code>null</code>.
     *
     * @param name the name of the job.
     */
    public this(String name) {
        super(name);
    }

    /**
     * Registers a job listener with this job
     * Has no effect if an identical listener is already registered.
     *
     * @param listener the listener to be added.
     */
    public final void addJobChangeListener(IJobChangeListener listener) {
        super.addJobChangeListener(listener);
    }

    /**
     * Returns whether this job belongs to the given family.  Job families are
     * represented as objects that are not interpreted or specified in any way
     * by the job manager.  Thus, a job can choose to belong to any number of
     * families.
     * <p>
     * Clients may override this method.  This default implementation always returns
     * <code>false</code>.  Overriding implementations must return <code>false</code>
     * for families they do not recognize.
     * </p>
     *
     * @param family the job family identifier
     * @return <code>true</code> if this job belongs to the given family, and
     * <code>false</code> otherwise.
     */
    public bool belongsTo(Object family) {
        return false;
    }

    /**
     * Stops the job.  If the job is currently waiting,
     * it will be removed from the queue.  If the job is sleeping,
     * it will be discarded without having a chance to resume and its sleeping state
     * will be cleared.  If the job is currently executing, it will be asked to
     * stop but there is no guarantee that it will do so.
     *
     * @return <code>false</code> if the job is currently running (and thus may not
     * respond to cancelation), and <code>true</code> in all other cases.
     */
    public final bool cancel() {
        return super.cancel();
    }

    /**
     * A hook method indicating that this job is running and {@link #cancel()}
     * is being called for the first time.
     * <p>
     * Subclasses may override this method to perform additional work when
     * a cancelation request is made.  This default implementation does nothing.
     * @since 3.3
     */
    protected void canceling() {
        //default implementation does nothing
    }

    /**
     * Jobs that complete their execution asynchronously must indicate when they
     * are finished by calling this method.  This method must not be called by
     * a job that has not indicated that it is executing asynchronously.
     * <p>
     * This method must not be called from within the scope of a job's <code>run</code>
     * method.  Jobs should normally indicate completion by returning an appropriate
     * status from the <code>run</code> method.  Jobs that return a status of
     * <code>ASYNC_FINISH</code> from their run method must later call
     * <code>done</code> to indicate completion.
     *
     * @param result a status object indicating the result of the job's execution.
     * @see #ASYNC_FINISH
     * @see #run(IProgressMonitor)
     */
    public final void done(IStatus result) {
        super.done(result);
    }

    /**
     * Returns the human readable name of this job.  The name is never
     * <code>null</code>.
     *
     * @return the name of this job
     */
    public final String getName() {
        return super.getName();
    }

    /**
     * Returns the priority of this job.  The priority is used as a hint when the job
     * is scheduled to be run.
     *
     * @return the priority of the job.  One of INTERACTIVE, SHORT, LONG, BUILD,
     *  or DECORATE.
     */
    public final int getPriority() {
        return super.getPriority();
    }

    /**
     * Returns the value of the property of this job identified by the given key,
     * or <code>null</code> if this job has no such property.
     *
     * @param key the name of the property
     * @return the value of the property,
     *     or <code>null</code> if this job has no such property
     * @see #setProperty(QualifiedName, Object)
     */
    public final Object getProperty(QualifiedName key) {
        return super.getProperty(key);
    }

    /**
     * Returns the result of this job's last run.
     *
     * @return the result of this job's last run, or <code>null</code> if this
     * job has never finished running.
     */
    public final IStatus getResult() {
        return super.getResult();
    }

    /**
     * Returns the scheduling rule for this job.  Returns <code>null</code> if this job has no
     * scheduling rule.
     *
     * @return the scheduling rule for this job, or <code>null</code>.
     * @see ISchedulingRule
     * @see #setRule(ISchedulingRule)
     */
    public final ISchedulingRule getRule() {
        return super.getRule();
    }

    /**
     * Returns the state of the job. Result will be one of:
     * <ul>
     * <li><code>Job.RUNNING</code> - if the job is currently running.</li>
     * <li><code>Job.WAITING</code> - if the job is waiting to be run.</li>
     * <li><code>Job.SLEEPING</code> - if the job is sleeping.</li>
     * <li><code>Job.NONE</code> - in all other cases.</li>
     * </ul>
     * <p>
     * Note that job state is inherently volatile, and in most cases clients
     * cannot rely on the result of this method being valid by the time the
     * result is obtained.  For example, if <tt>getState</tt> returns
     * <tt>RUNNING</tt>,  the job may have actually completed by the
     * time the <tt>getState</tt> method returns.  All clients can infer from
     * invoking this method is that  the job was recently in the returned state.
     *
     * @return the job state
     */
    public final int getState() {
        return super.getState();
    }

    /**
     * Returns the thread that this job is currently running in.
     *
     * @return the thread this job is running in, or <code>null</code>
     * if this job is not running or the thread is unknown.
     */
    public final Thread getThread() {
        return super.getThread();
    }

    /**
     * Returns whether this job is blocking a higher priority non-system job from
     * starting due to a conflicting scheduling rule.  Returns <code>false</code>
     * if this job is not running, or is not blocking a higher priority non-system job.
     *
     * @return <code>true</code> if this job is blocking a higher priority non-system
     * job, and <code>false</code> otherwise.
     * @see #getRule()
     * @see #isSystem()
     */
    public final bool isBlocking() {
        return super.isBlocking();
    }

    /**
     * Returns whether this job is a system job.  System jobs are typically not
     * revealed to users in any UI presentation of jobs.  Other than their UI presentation,
     * system jobs act exactly like other jobs.  If this value is not explicitly set, jobs
     * are treated as non-system jobs.  The default value is <code>false</code>.
     *
     * @return <code>true</code> if this job is a system job, and
     * <code>false</code> otherwise.
     * @see #setSystem(bool)
     */
    public final bool isSystem() {
        return super.isSystem();
    }

    /**
     * Returns whether this job has been directly initiated by a UI end user.
     * These jobs may be presented differently in the UI.  The default value
     * is <code>false</code>.
     *
     * @return <code>true</code> if this job is a user-initiated job, and
     * <code>false</code> otherwise.
     * @see #setUser(bool)
     */
    public final bool isUser() {
        return super.isUser();
    }

    /**
     * Waits until this job is finished.  This method will block the calling thread until the
     * job has finished executing, or until this thread has been interrupted.  If the job
     * has not been scheduled, this method returns immediately.  A job must not
     * be joined from within the scope of its run method.
     * <p>
     * If this method is called on a job that reschedules itself from within the
     * <tt>run</tt> method, the join will return at the end of the first execution.
     * In other words, join will return the first time this job exits the
     * {@link #RUNNING} state, or as soon as this job enters the {@link #NONE} state.
     * </p>
     * <p>
     * If this method is called while the job manager is suspended, this job
     * will only be joined if it is already running; if this job is waiting or sleeping,
     * this method returns immediately.
     * </p>
     * <p>
     * Note that there is a deadlock risk when using join.  If the calling thread owns
     * a lock or object monitor that the joined thread is waiting for, deadlock
     * will occur.
     * </p>
     *
     * @exception InterruptedException if this thread is interrupted while waiting
     * @see ILock
     * @see IJobManager#suspend()
     */
    public final void join() {
        super.join();
    }

    /**
     * Removes a job listener from this job.
     * Has no effect if an identical listener is not already registered.
     *
     * @param listener the listener to be removed
     */
    public final void removeJobChangeListener(IJobChangeListener listener) {
        super.removeJobChangeListener(listener);
    }

    /**
     * Executes this job.  Returns the result of the execution.
     * <p>
     * The provided monitor can be used to report progress and respond to
     * cancellation.  If the progress monitor has been canceled, the job
     * should finish its execution at the earliest convenience and return a result
     * status of severity {@link IStatus#CANCEL}.  The singleton
     * cancel status {@link Status#CANCEL_STATUS} can be used for
     * this purpose.  The monitor is only valid for the duration of the invocation
     * of this method.
     * <p>
     * This method must not be called directly by clients.  Clients should call
     * <code>schedule</code>, which will in turn cause this method to be called.
     * <p>
     * Jobs can optionally finish their execution asynchronously (in another thread) by
     * returning a result status of {@link #ASYNC_FINISH}.  Jobs that finish
     * asynchronously <b>must</b> specify the execution thread by calling
     * <code>setThread</code>, and must indicate when they are finished by calling
     * the method <code>done</code>.
     *
     * @param monitor the monitor to be used for reporting progress and
     * responding to cancelation. The monitor is never <code>null</code>
     * @return resulting status of the run. The result must not be <code>null</code>
     * @see #ASYNC_FINISH
     * @see #done(IStatus)
     */
    protected abstract IStatus run(IProgressMonitor monitor);

    /**
     * Schedules this job to be run.  The job is added to a queue of waiting
     * jobs, and will be run when it arrives at the beginning of the queue.
     * <p>
     * This is a convenience method, fully equivalent to
     * <code>schedule(0L)</code>.
     * </p>
     * @see #schedule(long)
     */
    public final void schedule() {
        super.schedule(0L);
    }

    /**
     * Schedules this job to be run after a specified delay.  The job is put in the
     * {@link #SLEEPING} state until the specified delay has elapsed, after which
     * the job is added to a queue of {@link #WAITING} jobs. Once the job arrives
     * at the beginning of the queue, it will be run at the first available opportunity.
     * </p><p>
     * Jobs of equal priority and <code>delay</code> with conflicting scheduling
     * rules are guaranteed to run in the order they are scheduled. No guarantees
     * are made about the relative execution order of jobs with unrelated or
     * <code>null</code> scheduling rules, or different priorities.
     * <p>
     * If this job is currently running, it will be rescheduled with the specified
     * delay as soon as it finishes.  If this method is called multiple times
     * while the job is running, the job will still only be rescheduled once,
     * with the most recent delay value that was provided.
     * </p><p>
     * Scheduling a job that is waiting or sleeping has no effect.
     * </p>
     *
     * @param delay a time delay in milliseconds before the job should run
     * @see ISchedulingRule
     */
    public final void schedule(long delay) {
        super.schedule(delay);
    }

    /**
     * Changes the name of this job.  If the job is currently running, waiting,
     * or sleeping, the new job name may not take effect until the next time the
     * job is scheduled.
     * <p>
     * The job name is a human-readable value that is displayed to users.  The name
     * does not need to be unique, but it must not be <code>null</code>.
     *
     * @param name the name of the job.
     */
    public final void setName(String name) {
        super.setName(name);
    }

    /**
     * Sets the priority of the job.  This will not affect the execution of
     * a running job, but it will affect how the job is scheduled while
     * it is waiting to be run.
     *
     * @param priority the new job priority.  One of
     * INTERACTIVE, SHORT, LONG, BUILD, or DECORATE.
     */
    public final void setPriority(int priority) {
        super.setPriority(priority);
    }

    /**
     * Associates this job with a progress group.  Progress feedback
     * on this job's next execution will be displayed together with other
     * jobs in that group. The provided monitor must be a monitor
     * created by the method <tt>IJobManager.createProgressGroup</tt>
     * and must have at least <code>ticks</code> units of available work.
     * <p>
     * The progress group must be set before the job is scheduled.
     * The group will be used only for a single invocation of the job's
     * <tt>run</tt> method, after which any association of this job to the
     * group will be lost.
     *
     * @see IJobManager#createProgressGroup()
     * @param group The progress group to use for this job
     * @param ticks the number of work ticks allocated from the
     *    parent monitor, or {@link IProgressMonitor#UNKNOWN}
     */
    public final void setProgressGroup(IProgressMonitor group, int ticks) {
        super.setProgressGroup(group, ticks);
    }

    /**
     * Sets the value of the property of this job identified
     * by the given key. If the supplied value is <code>null</code>,
     * the property is removed from this resource.
     * <p>
     * Properties are intended to be used as a caching mechanism
     * by ISV plug-ins. They allow key-object associations to be stored with
     * a job instance.  These key-value associations are maintained in
     * memory (at all times), and the information is never discarded automatically.
     * </p><p>
     * The qualifier part of the property name must be the unique identifier
     * of the declaring plug-in (e.g. <code>"com.example.plugin"</code>).
     * </p>
     *
     * @param key the qualified name of the property
     * @param value the value of the property,
     *     or <code>null</code> if the property is to be removed
     * @see #getProperty(QualifiedName)
     */
    public void setProperty(QualifiedName key, Object value) {
        super.setProperty(key, value);
    }

    /**
     * Sets the scheduling rule to be used when scheduling this job.  This method
     * must be called before the job is scheduled.
     *
     * @param rule the new scheduling rule, or <code>null</code> if the job
     * should have no scheduling rule
     * @see #getRule()
     */
    public final void setRule(ISchedulingRule rule) {
        super.setRule(rule);
    }

    /**
     * Sets whether or not this job is a system job.  System jobs are typically not
     * revealed to users in any UI presentation of jobs.  Other than their UI presentation,
     * system jobs act exactly like other jobs.  If this value is not explicitly set, jobs
     * are treated as non-system jobs. This method must be called before the job
     * is scheduled.
     *
     * @param value <code>true</code> if this job should be a system job, and
     * <code>false</code> otherwise.
     * @see #isSystem()
     */
    public final void setSystem(bool value) {
        super.setSystem(value);
    }

    /**
     * Sets whether or not this job has been directly initiated by a UI end user.
     * These jobs may be presented differently in the UI. This method must be
     * called before the job is scheduled.
     *
     * @param value <code>true</code> if this job is a user-initiated job, and
     * <code>false</code> otherwise.
     * @see #isUser()
     */
    public final void setUser(bool value) {
        super.setUser(value);
    }

    /**
     * Sets the thread that this job is currently running in, or <code>null</code>
     * if this job is not running or the thread is unknown.
     * <p>
     * Jobs that use the {@link #ASYNC_FINISH} return code should tell
     * the job what thread it is running in.  This is used to prevent deadlocks.
     *
     * @param thread the thread that this job is running in.
     *
     * @see #ASYNC_FINISH
     * @see #run(IProgressMonitor)
     */
    public final void setThread(Thread thread) {
        super.setThread(thread);
    }

    /**
     * Returns whether this job should be run.
     * If <code>false</code> is returned, this job will be discarded by the job manager
     * without running.
     * <p>
     * This method is called immediately prior to calling the job's
     * run method, so it can be used for last minute pre-condition checking before
     * a job is run. This method must not attempt to schedule or change the
     * state of any other job.
     * </p><p>
     * Clients may override this method.  This default implementation always returns
     * <code>true</code>.
     * </p>
     *
     * @return <code>true</code> if this job should be run
     *   and <code>false</code> otherwise
     */
    public bool shouldRun() {
        return true;
    }

    /**
     * Returns whether this job should be scheduled.
     * If <code>false</code> is returned, this job will be discarded by the job manager
     * without being added to the queue.
     * <p>
     * This method is called immediately prior to adding the job to the waiting job
     * queue.,so it can be used for last minute pre-condition checking before
     * a job is scheduled.
     * </p><p>
     * Clients may override this method.  This default implementation always returns
     * <code>true</code>.
     * </p>
     *
     * @return <code>true</code> if the job manager should schedule this job
     *   and <code>false</code> otherwise
     */
    public bool shouldSchedule() {
        return true;
    }

    /**
     * Requests that this job be suspended.  If the job is currently waiting to be run, it
     * will be removed from the queue move into the {@link #SLEEPING} state.
     * The job will remain asleep until either resumed or canceled.  If this job is not
     * currently waiting to be run, this method has no effect.
     * <p>
     * Sleeping jobs can be resumed using <code>wakeUp</code>.
     *
     * @return <code>false</code> if the job is currently running (and thus cannot
     * be put to sleep), and <code>true</code> in all other cases
     * @see #wakeUp()
     */
    public final bool sleep() {
        return super.sleep();
    }

    /**
     * Puts this job immediately into the {@link #WAITING} state so that it is
     * eligible for immediate execution. If this job is not currently sleeping,
     * the request is ignored.
     * <p>
     * This is a convenience method, fully equivalent to
     * <code>wakeUp(0L)</code>.
     * </p>
     * @see #sleep()
     */
    public final void wakeUp() {
        super.wakeUp(0L);
    }

    /**
     * Puts this job back into the {@link #WAITING} state after
     * the specified delay. This is equivalent to canceling the sleeping job and
     * rescheduling with the given delay.  If this job is not currently sleeping,
     * the request  is ignored.
     *
     * @param delay the number of milliseconds to delay
     * @see #sleep()
     */
    public final void wakeUp(long delay) {
        super.wakeUp(delay);
    }
}