package affectors;

import main.Node;
import main.Globals;

/** Adds white noise to the concentration of a node. The noise is chosen from a flat distribution
that goes from + to - the noiseLevelParam

<p> <b>Formula</b>
<br>dnodex/dt = noise_level * [random white noise generation between -1 and 1]

<p> <b>Parameters</b>
<table width="500" border="1">
<tr><td width="150">Noise level [NoiseLevel]</td><td> The amount of white noise. Should be less than 1</td></tr>
</table>

<p> <b>Usage</b>
<code><font size = "3"><br>&nodex
<blockquote>   &WhiteNoiseAff	noise_nodex</blockquote>
&endnodex</font></code>
*/
public class WhiteNoiseAff extends Affector	{	
	/** The affector picks a new random number from a flat distribution between
		-noiseLevel and +noiseLevel for each timestep of the model */
	final static int	NUM_STORED = 100;
	int					noiseLevelParam;
	float				lastNoiseLevel;
	float			[]	noise = new float[NUM_STORED];
	int					curTime;
	
	static final String		desc = "Adds noise from a flat distribution.";
	static final String	[]	paramDescriptions = {"Amount of noise"};

	public WhiteNoiseAff()	{	}
	
	protected void setLabelsAndTypes()	{
		setDescriptions(this.desc, null, paramDescriptions);

		this.Type[GUI_CAPABLE] = 1;
		this.Type[CERTIFICATION] = Affector.RETURNS_DERIV;
		this.Type[MATHTYPE] = Affector.TT;
		this.Type[TERMTYPE] = Affector.CONVERSION;	// Doesn't really fit any of them
	}

	public void setParameterNumbers(int [] param_nums)
	{
		noiseLevelParam = param_nums[0];
	}
	
	public float getValue(Node which_node)	{
		if(params[noiseLevelParam] == 0) return 0.0f;	// Don't waste time when turned off
	
		int		t = (int)(Globals.time) % NUM_STORED;
		int		t2 = t + 1;
		if(t2 >= NUM_STORED) t2 -= NUM_STORED;
		
		float val = (noise[t2] - noise[t]) * (Globals.time - (float)Math.floor(Globals.time)) + noise[t];
		
// A bunch of code to keep putting new random numbers into the array as models run and reset
		if(curTime > (int)Globals.time) curTime = (int)Globals.time;

		if(lastNoiseLevel != params[noiseLevelParam]) {	// noise level changed so need to add noise
			for(curTime = 0; curTime < NUM_STORED; curTime++)
				noise[curTime] = ((float)Math.random() * 2f - 1.0f) * params[noiseLevelParam];
			curTime = (int)Globals.time;
		}
		
		// Update the stored numbers
		if((int)Globals.time > curTime) {
			t = curTime % NUM_STORED;
			while(curTime < (int)Globals.time) {
				noise[t] = ((float)Math.random() * 2 - 1.0f) * params[noiseLevelParam];
				curTime++;
				t++;
				if(t == NUM_STORED) t = 0;
			}
		}
		
		return val;
	}
}