/*******************************************************************************
 * Copyright (c) 2007, 2008 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:
 *    Hisashi MIYASHITA - initial API and implementation
 *******************************************************************************/

package org.eclipse.actf.ui.util.timer;

import java.lang.reflect.Method;

import org.eclipse.swt.widgets.Display;

/**
 * Utility class for thread execution related to {@link Display}.
 */
public class Yield {
	private static Display display;

	/**
	 * Initialize method of this utility.
	 */
	public static void initialize() {
		display = Display.getCurrent();
	}

	private static class InvocationRunnable implements Runnable {
		public Object ret;
		public Method method;
		public Object target;
		public Object[] args;

		public void run() {
			try {
				ret = method.invoke(target, args);
			} catch (Exception e) {
				e.printStackTrace();
				ret = null;
			}
		}
	}

	private static InvocationRunnable invocationRunnable = new InvocationRunnable();

	/**
	 * Invoke method (m.invoke(o, args)) by using syncExec method of current
	 * Display.
	 * 
	 * @param m
	 *            target {@link Method}
	 * @param o
	 *            target {@link Object}
	 * @param args
	 *            target arguments
	 * @return resulting Object of the target method
	 * @see Display
	 * @throws {@link Exception}
	 */
	public static Object syncInvoke(Method m, Object o, Object[] args)
			throws Exception {
		invocationRunnable.method = m;
		invocationRunnable.target = o;
		invocationRunnable.args = args;
		display.syncExec(invocationRunnable);
		return invocationRunnable.ret;
	}

	/**
	 * Call readAndDispatch method of the current Display while the specified
	 * duration
	 * 
	 * @param duration
	 *            target duration in msec
	 */
	public static void forWhile(int duration) {
		long end = System.currentTimeMillis() + duration;
		while (end > System.currentTimeMillis()) {
			display.readAndDispatch();
		}
	}

	/**
	 * Call readAndDispatch method of the current Display.
	 * 
	 * @see Display
	 */
	public static void once() {
		display.readAndDispatch();
	}
}