#ifdef INTERFACE
CLASS(Keyframe) EXTENDS(Animation)
	METHOD(Keyframe, addEasing, entity(entity, float, float, float(float, float, float, float)))
	METHOD(Keyframe, addAnim, void(entity, entity))
	METHOD(Keyframe, calcValue, float(entity, float, float, float, float))
	ATTRIB(Keyframe, currentChild, entity, NULL)
	ATTRIB(Keyframe, firstChild, entity, NULL)
	ATTRIB(Keyframe, lastChild, entity, NULL)
ENDCLASS(Animation)
entity makeHostedKeyframe(entity, void(entity, float), float, float, float);
entity makeKeyframe(entity, void(entity, float), float, float, float);
float getNewChildStart(entity);
float getNewChildDuration(entity, float);
float getNewChildValue(entity);
#endif

#ifdef IMPLEMENTATION
entity makeHostedKeyframe(entity obj, void(entity, float) setter, float duration, float start, float end)
{
	entity me;
	me = makeKeyframe(obj, setter, duration, start, end);
	anim.addAnim(anim, me);
	return me;
}

entity makeKeyframe(entity obj, void(entity, float) setter, float duration, float start, float end)
{
	entity me;
	me = spawnKeyframe();
	me.configureAnimation(me, obj, setter, time, duration, start, end);
	return me;
}

entity addEasingKeyframe(entity me, float durationTime, float end, float(float, float, float, float) func)
{
	entity other;
	other = makeEasing(me.object, me.setter, func, getNewChildStart(me), getNewChildDuration(me, durationTime), getNewChildValue(me), end);
	me.addAnim(me, other);
	return other;
}

float getNewChildStart(entity me)
{
	if (me.lastChild)
		return (me.lastChild.startTime + me.lastChild.duration);
	else
		return 0;
}

float getNewChildDuration(entity me, float durationTime)
{
	float dura, maxDura;
	maxDura = me.duration;
	if (me.lastChild) maxDura = maxDura - (me.lastChild.startTime + me.lastChild.duration);
	dura = durationTime;
	if (0 >= dura || dura > maxDura) dura = maxDura;
	return dura;
}

float getNewChildValue(entity me)
{
	if (me.lastChild)
		return (me.lastChild.startValue + me.lastChild.delta);
	else
		return me.startValue;
}

void addAnimKeyframe(entity me, entity other)
{
	if(other.parent)
		error("Can't add already added anim!");

	if(other.isFinished(other))
		error("Can't add finished anim!");

	other.parent = me;

	entity f, l;
	f = me.firstChild;
	l = me.lastChild;

	if(l)
		l.nextSibling = other;
	else
	{
		me.currentChild = other;
		me.firstChild = other;
	}

	other.prevSibling = l;
	other.nextSibling = NULL;
	me.lastChild = other;
}

float calcValueKeyframe(entity me, float time, float duration, float startValue, float delta)
{
	if (me.currentChild)
		if (me.currentChild.isFinished(me.currentChild))
			me.currentChild = me.currentChild.nextSibling;

	if (me.currentChild)
	{
		me.currentChild.tick(me.currentChild, time);
		return me.currentChild.value;
	}

	return startValue + delta;
}
#endif