package speiger.src.coreengine.math.value;

public abstract class Value implements IValue
{
	final float start;
	final float duration;
	byte flags = 0;
	int done = 0;
	
	float progress = 0F;
	float value;
	
	public Value(float duration)
	{
		this(0F, duration);
	}
	
	public Value(float start, float duration)
	{
		this.duration = duration;
		this.start = start;
	}
	
	@Override
	public float update(float particleTime)
	{
		if((flags & 2) != 0)
		{
			return value;
		}
		progress += particleTime;
		if(progress < start)
		{
			if((flags & 1) == 0)
			{
				value = calculateProgress(0F);
				onInitialValueSet();
			}
			return value;
		}
		value = calculateProgress((progress - start) / duration);
		if(progress >= start + duration)
		{
			onFinished();
		}
		return value;
	}
	
	@Override
	public float get()
	{
		return value;
	}
	
	@Override
	public boolean isDone()
	{
		return done > 0;
	}
	
	protected abstract float calculateProgress(float time);
	
	protected void onFinished()
	{
		progress = start;
		done++;
	}
	
	protected void onInitialValueSet()
	{
		flags |= 1;
	}
	
	protected void finishProgress()
	{
		flags |= 2;
		done++;
	}
}