/*
 * Catroid: An on-device visual programming system for Android devices
 * Copyright (C) 2010-2016 The Catrobat Team
 * (<http://developer.catrobat.org/credits>)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * An additional term exception under section 7 of the GNU Affero
 * General Public License, version 3, is available at
 * http://developer.catrobat.org/license_additional_term
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

// Code adapted from: http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/ThreadPoolExecutor.html

package org.catrobat.catroid.utils;

import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;

public class PausableScheduledThreadPoolExecutor extends ScheduledThreadPoolExecutor {
	private boolean isPaused;
	private ReentrantLock pauseLock = new ReentrantLock();
	private Condition unpaused = pauseLock.newCondition();

	public PausableScheduledThreadPoolExecutor(int corePoolSize) {
		super(corePoolSize);
	}

	@Override
	protected void beforeExecute(Thread t, Runnable r) {
		super.beforeExecute(t, r);
		pauseLock.lock();
		try {
			while (isPaused) {
				unpaused.await();
			}
		} catch (InterruptedException ie) {
			t.interrupt();
		} finally {
			pauseLock.unlock();
		}
	}

	public void pause() {
		pauseLock.lock();
		try {
			isPaused = true;
		} finally {
			pauseLock.unlock();
		}
	}

	public void resume() {
		pauseLock.lock();
		try {
			isPaused = false;
			unpaused.signalAll();
		} finally {
			pauseLock.unlock();
		}
	}
}