package org.eclipse.core.runtime;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */

/**
 * A progress monitor that uses the a given amount of work ticks
 * form a parent monitor. It can be used as follows:
 * <pre>
 *     try {
 *         pm.beginTask("Main Task", 100);
 *         doSomeWork(pm, 30);
 *         SubProgressMonitor subMonitor= new SubProgressMonitor(pm, 40);
 *         try {
 *             subMonitor.beginTask("", 300);
 *             doSomeWork(subMonitor, 300);
 *         } finally {
 *             subMonitor.done();
 *         }
 *         doSomeWork(pm, 30);
 *     } finally {
 *         pm.done();
 *     }
 * </pre>
 * <p>
 * This class may be instantiated or subclassed by clients.
  * </p>
 */
public class SubProgressMonitor extends ProgressMonitorWrapper {

	/**
	 * Style constant indicating that calls to <code>subTask</code>
	 * should not have any effect.
	 *
	 * @see #SubProgressMonitor(IProgressMonitor,int,int)
	 */
	public static final int SUPPRESS_SUBTASK_LABEL= 1 << 1;
	/**
	 * Style constant indicating that the main task label 
	 * should be prepended to the subtask label.
	 *
	 * @see #SubProgressMonitor(IProgressMonitor,int,int)
	 */
	public static final int PREPEND_MAIN_LABEL_TO_SUBTASK= 1 << 2;

	private int parentTicks = 0;
	private double sentToParent = 0.0;
	private double scale = 0.0;
	private int nestedBeginTasks = 0;
	private boolean usedUp = false;
	private int style;
	private String mainTaskLabel;

/**
 * Creates a new sub-progress monitor for the given monitor. The sub 
 * progress monitor uses the given number of work ticks from its 
 * parent monitor.
 *
 * @param monitor the parent progress monitor
 * @param ticks the number of work ticks allocated from the
 *    parent monitor
 */
public SubProgressMonitor(IProgressMonitor monitor, int ticks) {
	this(monitor, ticks, 0);
}
/**
 * Creates a new sub-progress monitor for the given monitor. The sub 
 * progress monitor uses the given number of work ticks from its 
 * parent monitor.
 *
 * @param monitor the parent progress monitor
 * @param ticks the number of work ticks allocated from the
 *    parent monitor
 * @param styles one of
 *    <ul>
 *    <li> <code>SUPPRESS_SUBTASK_LABEL</code> </li>
 *    <li> <code>PREPEND_MAIN_LABEL_TO_SUBTASK</code> </li>
 *    </ul>
 * @see #SUPPRESS_SUBTASK_LABEL
 * @see #PREPEND_MAIN_LABEL_TO_SUBTASK
 */
public SubProgressMonitor(IProgressMonitor monitor, int ticks, int style) {
	super(monitor);
	this.parentTicks = ticks;
	this.style = style;
}
/* (Intentionally not javadoc'd)
 * Implements the method <code>IProgressMonitor.beginTask</code>.
 *
 * Starts a new main task. Since this progress monitor is a sub
 * progress monitor, the given name will NOT be used to update
 * the progress bar's main task label. That means the given 
 * string will be ignored. If style <code>PREPEND_MAIN_LABEL_TO_SUBTASK
 * <code> is specified, then the given string will be prepended to
 * every string passed to <code>subTask(String)</code>.
 */
public void beginTask(String name, int totalWork) {
	nestedBeginTasks++;
	// Ignore nested begin task calls.
	if (nestedBeginTasks > 1) {
		return;
	}
	// be safe:  if the argument would cause math errors (zero or 
	// negative), just use 0 as the scale.  This disables progress for
	// this submonitor. 
	scale = totalWork <= 0 ? 0 : (double) parentTicks / (double) totalWork;
	if ((style & PREPEND_MAIN_LABEL_TO_SUBTASK) != 0) {
		mainTaskLabel = name;
	}
}
/* (Intentionally not javadoc'd)
 * Implements the method <code>IProgressMonitor.done</code>.
 */
public void done() {
	// Ignore if more done calls than beginTask calls or if we are still
	// in some nested beginTasks
	if (nestedBeginTasks == 0 || --nestedBeginTasks > 0)
		return;
	// Send any remaining ticks and clear out the subtask text
	double remaining = (double) parentTicks - sentToParent;
	if (remaining > 0) 
		super.internalWorked(remaining);
	subTask("");
	sentToParent = 0;
}
/* (Intentionally not javadoc'd)
 * Implements the internal method <code>IProgressMonitor.internalWorked</code>.
 */
public void internalWorked(double work) {
	if (usedUp || nestedBeginTasks != 1) {
		return;
	}

	double realWork = scale * work;
	// System.out.println("Sub monitor: " + realWork);
	super.internalWorked(realWork);
	sentToParent += realWork;
	if (sentToParent >= parentTicks) {
		usedUp = true;
	}
}
/* (Intentionally not javadoc'd)
 * Implements the method <code>IProgressMonitor.subTask</code>.
 */
public void subTask(String name) {
	if ((style & SUPPRESS_SUBTASK_LABEL) != 0) {
		return;
	}

	String label = name;
	if ((style & PREPEND_MAIN_LABEL_TO_SUBTASK) != 0 && mainTaskLabel != null && mainTaskLabel.length() > 0) {
		label = mainTaskLabel + " " + label;
	}
	super.subTask(label);
}
/* (Intentionally not javadoc'd)
 * Implements the method <code>IProgressMonitor.worked</code>.
 */
public void worked(int work) {
	internalWorked(work);
}
}