/*
 * Copyright (c) 2003 Sun Microsystems, Inc. All Rights Reserved.
 * Copyright (c) 2010 JogAmp Community. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 * 
 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES,
 * INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A
 * PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN
 * MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL NOT BE LIABLE FOR
 * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
 * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES. IN NO EVENT WILL SUN OR
 * ITS LICENSORS BE LIABLE FOR ANY LOST REVENUE, PROFIT OR DATA, OR FOR
 * DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, INCIDENTAL OR PUNITIVE
 * DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY OF LIABILITY,
 * ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE, EVEN IF
 * SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 * 
 * You acknowledge that this software is not designed or intended for use
 * in the design, construction, operation or maintenance of any nuclear
 * facility.
 * 
 * Sun gratefully acknowledges that this software was originally authored
 * and developed by Kenneth Bradley Russell and Christopher John Kline.
 */
package com.jogamp.opengl.util;

import java.util.*;
import javax.media.opengl.*;

/** 
 * An Animator subclass which attempts to achieve a target
 * frames-per-second rate to avoid using all CPU time. The target FPS
 * is only an estimate and is not guaranteed. 
 * <p>
 * The Animator execution thread does not run as a daemon thread,
 * so it is able to keep an application from terminating.<br>
 * Call {@link #stop() } to terminate the animation and it's execution thread.
 * </p>
 */
public class FPSAnimator extends AnimatorBase {
    private Timer timer = null;
    private TimerTask task = null;
    private int fps;
    private boolean scheduleAtFixedRate;
    private volatile boolean shouldRun;

    protected String getBaseName(String prefix) {
        return "FPS" + prefix + "Animator" ;
    }

    /** Creates an FPSAnimator with a given target frames-per-second
    value. Equivalent to <code>FPSAnimator(null, fps)</code>. */
    public FPSAnimator(int fps) {
        this(null, fps);
    }

    /** Creates an FPSAnimator with a given target frames-per-second
    value and a flag indicating whether to use fixed-rate
    scheduling. Equivalent to <code>FPSAnimator(null, fps,
    scheduleAtFixedRate)</code>. */
    public FPSAnimator(int fps, boolean scheduleAtFixedRate) {
        this(null, fps, scheduleAtFixedRate);
    }

    /** Creates an FPSAnimator with a given target frames-per-second
    value and an initial drawable to animate. Equivalent to
    <code>FPSAnimator(null, fps, false)</code>. */
    public FPSAnimator(GLAutoDrawable drawable, int fps) {
        this(drawable, fps, false);
    }

    /** Creates an FPSAnimator with a given target frames-per-second
    value, an initial drawable to animate, and a flag indicating
    whether to use fixed-rate scheduling. */
    public FPSAnimator(GLAutoDrawable drawable, int fps, boolean scheduleAtFixedRate) {
        this.fps = fps;
        if (drawable != null) {
            add(drawable);
        }
        this.scheduleAtFixedRate = scheduleAtFixedRate;
    }

    public final boolean isStarted() {
        stateSync.lock();
        try {
            return (timer != null);
        } finally {
            stateSync.unlock();
        }
    }

    public final boolean isAnimating() {
        stateSync.lock();
        try {
            return (timer != null) && (task != null);
        } finally {
            stateSync.unlock();
        }
    }

    public final boolean isPaused() {
        stateSync.lock();
        try {
            return (timer != null) && (task == null);
        } finally {
            stateSync.unlock();
        }
    }

    private void startTask() {
        if(null != task) {
            return;
        }
        final long period = (long) (1000.0f / (float) fps);
        task = new TimerTask() {
            public void run() {
                if(FPSAnimator.this.shouldRun) {
                    FPSAnimator.this.animThread = Thread.currentThread();
                    // display impl. uses synchronized block on the animator instance
                    display();
                }
            }
        };

        fpsCounter.resetFPSCounter();
        shouldRun = true;

        if (scheduleAtFixedRate) {
            timer.scheduleAtFixedRate(task, 0, period);
        } else {
            timer.schedule(task, 0, period);
        }
    }

    public synchronized boolean  start() {
        if (timer != null) {
            return false;
        }
        stateSync.lock();
        try {
            timer = new Timer();
            startTask();
        } finally {
            stateSync.unlock();
        }
        return true;
    }

    /** Stops this FPSAnimator. Due to the implementation of the
    FPSAnimator it is not guaranteed that the FPSAnimator will be
    completely stopped by the time this method returns. */
    public synchronized boolean stop() {
        if (timer == null) {
            return false;
        }
        stateSync.lock();
        try {
            shouldRun = false;
            if(null != task) {
                task.cancel();
                task = null;
            }
            if(null != timer) {
                timer.cancel();
                timer = null;
            }
            animThread = null;
            try {
                final long periodx2 = 2L * (long) (1000.0f / (float) fps);
                Thread.sleep(periodx2 > 20L ? periodx2 : 20L); // max(2 x timer period, ~ 1/60), since we can't ctrl stopped threads
            } catch (InterruptedException e) { }
        } finally {
            stateSync.unlock();
        }
        return true;
    }

    public synchronized boolean pause() {
        if (timer == null) {
            return false;
        }
        stateSync.lock();
        try {
            shouldRun = false;
            if(null != task) {
                task.cancel();
                task = null;
            }
            animThread = null;
            try {
                final long periodx2 = 2L * (long) (1000.0f / (float) fps);
                Thread.sleep(periodx2 > 20L ? periodx2 : 20L); // max(2 x timer period, ~ 1/60), since we can't ctrl stopped threads
            } catch (InterruptedException e) { }
        } finally {
            stateSync.unlock();
        }
        return true;
    }

    public synchronized boolean resume() {
        if (timer == null) {
            return false;
        }
        stateSync.lock();
        try {
            startTask();
        } finally {
            stateSync.unlock();
        }
        return true;
    }
}