//
// $Id: AnimationSequencer.java,v 1.12 2002/11/06 07:40:05 shaper Exp $

package com.threerings.media.animation;

import java.awt.Graphics2D;
import java.awt.Rectangle;

import java.util.ArrayList;

import com.samskivert.util.StringUtil;

import com.threerings.media.Log;

/**
 * An animation that provides facilities for adding a sequence of
 * animations that are fired after a fixed time interval has elapsed or
 * after previous animations in the sequence have completed. Facilities
 * are also provided for running code upon the completion of animations in
 * the sequence.
 */
public abstract class AnimationSequencer extends Animation
{
    /**
     * Constructs an animation sequencer with the expectation that
     * animations will be added via subsequent calls to {@link
     * #addAnimation}.
     */
    public AnimationSequencer ()
    {
        super(new Rectangle());
    }

    /**
     * Adds the supplied animation to the sequence with the given
     * parameters. Note that care should be taken if this is called after
     * the animation sequence has begun firing animations. Do not add new
     * animations after the final animation in the sequence has been
     * started or you run the risk of attempting to add an animation to
     * the sequence after it thinks that it has finished (in which case
     * this method will fail).
     *
     * @param anim the animation to be sequenced, or null if the
     * completion action should be run immediately when this "animation"
     * is ready to fired.
     * @param delta the number of milliseconds following the
     * <em>start</em> of the previous animation in the queue that this
     * animation should be started; 0 if it should be started
     * simultaneously with its predecessor int the queue; -1 if it should
     * be started when its predecessor has completed.
     * @param completionAction a runnable to be executed when this
     * animation completes.
     */
    public void addAnimation (
        Animation anim, long delta, Runnable completionAction)
    {
        // sanity check
        if (_finished) {
            throw new IllegalStateException(
                "Animation added to finished sequencer");
        }

        // if this guy is triggering on a previous animation, grab that
        // good fellow here
        AnimRecord trigger = null;
        if (delta == -1) {
            if (_queued.size() > 0) {
                // if there are queued animations we want the most
                // recently queued animation
                trigger = (AnimRecord)_queued.get(_queued.size()-1);
            } else if (_running.size() > 0) {
                // otherwise, if there are running animations, we want the
                // last one in that list
                trigger = (AnimRecord)_running.get(_running.size()-1);
            }
            // otherwise we have no trigger, we'll just start ASAP
        }

        AnimRecord arec = new AnimRecord(
            anim, delta, trigger, completionAction);
//         Log.info("Queued " + arec + ".");
        _queued.add(arec);
    }

    /**
     * Clears out the animations being managed by this sequencer.
     */
    public void clear ()
    {
        _queued.clear();
        _lastStamp = 0;
    }

    // documentation inherited
    public void tick (long tickStamp)
    {
        if (_lastStamp == 0) {
            _lastStamp = tickStamp;
        }

        // add all animations whose time has come
        while (_queued.size() > 0) {
            AnimRecord arec = (AnimRecord)_queued.get(0);
            if (!arec.readyToFire(tickStamp, _lastStamp)) {
                // if it's not time to add this animation, all subsequent
                // animations must surely wait as well
                break;
            }

            // remove it from queued and put it on the running list
            _queued.remove(0);
            _running.add(arec);

            // note that we've advanced to the next animation
            _lastStamp = tickStamp;

            // fire in the hole!
            arec.fire(tickStamp);
        }

        // we're done when both lists are empty
//         boolean finished = _finished;
        _finished = ((_queued.size() + _running.size()) == 0);
//         if (!finished && _finished) {
//             Log.info("Finishing sequence at " + (tickStamp%10000) + ".");
//         }
    }

    // documentation inherited
    public void paint (Graphics2D gfx)
    {
        // don't care
    }

    // documentation inherited
    public void fastForward (long timeDelta)
    {
        _lastStamp += timeDelta;
    }

    /**
     * Called when the time comes to start an animation.  Derived classes
     * must implement this method and pass the animation on to their
     * animation manager and do whatever else they need to do with
     * operating animations.
     *
     * @param anim the animation to be displayed.
     * @param tickStamp the timestamp at which this animation was fired.
     */
    protected abstract void startAnimation (Animation anim, long tickStamp);

    protected class AnimRecord
        implements AnimationObserver
    {
        public AnimRecord (Animation anim, long delta, AnimRecord trigger,
                           Runnable completionAction)
        {
            _anim = anim;
            _delta = delta;
            _trigger = trigger;
            _completionAction = completionAction;
        }

        public boolean readyToFire (long now, long lastStamp)
        {
            if (_delta == -1) {
                // if we have no trigger, that means we should start
                // immediately, otherwise we wait until our trigger is no
                // longer running (they are guaranteed not to be still
                // queued at this point because readyToFire is only called
                // on an animation after all animations previous in the
                // queue have been started)
                return (_trigger == null) ?
                    true : !_running.contains(_trigger);

            } else {
                return (lastStamp + _delta <= now);
            }
        }

        public void fire (long when)
        {
//             Log.info("Firing " + this + " at " + (when%10000) + ".");

            // if we have an animation, start it up and await its
            // completion
            if (_anim != null) {
                startAnimation(_anim, when);
                _anim.addAnimationObserver(this);

            } else {
                // since there's no animation, we need to fire our
                // completion routine immediately
                fireCompletion(when);
            }
        }

        public void fireCompletion (long when)
        {
//             Log.info("Completing " + this + " at " + (when%10000) + ".");

            // call the completion action, if there is one
            if (_completionAction != null) {
                try {
                    _completionAction.run();
                } catch (Throwable t) {
                    Log.logStackTrace(t);
                }
            }

            // make a note that this animation is complete
            _running.remove(this);

            // kids, don't try this at home; we call tick() immediately so
            // that any animations triggered on the completion of previous
            // animations can trigger on the completion of this animation
            // rather than having to wait until the next tick to do so
            tick(when);
        }

        public void handleEvent (AnimationEvent event)
        {
            if (event instanceof AnimationCompletedEvent) {
                fireCompletion(event.getWhen());
            }
        }

        public String toString ()
        {
            return "[anim=" + StringUtil.shortClassName(_anim) +
                ((_anim == null) ? "" : ("/" + _anim.hashCode())) +
                ", action=" + _completionAction +
                ", delta=" + _delta + ", trig=" + (_trigger != null) + "]";
        }

        protected Animation _anim;
        protected Runnable _completionAction;
        protected long _delta;
        protected AnimRecord _trigger;
    }

    /** Animations that have not been fired. */
    protected ArrayList _queued = new ArrayList();

    /** Animations that are currently running. */
    protected ArrayList _running = new ArrayList();

    /** The timestamp at which we fired the last animation. */
    protected long _lastStamp;
}