RoomEnactor.java

package context.apps.demos.roomlight;

import context.arch.discoverer.ComponentDescription;
import context.arch.discoverer.component.NonConstantAttributeElement;
import context.arch.discoverer.query.AbstractQueryItem;
import context.arch.discoverer.query.ElseQueryItem;
import context.arch.discoverer.query.ORQueryItem;
import context.arch.discoverer.query.RuleQueryItem;
import context.arch.discoverer.query.comparison.AttributeComparison;
import context.arch.enactor.Enactor;
import context.arch.enactor.EnactorReference;
import context.arch.service.helper.ServiceInput;
import context.arch.storage.AttributeNameValue;
import context.arch.storage.Attributes;
import context.arch.widget.Widget;
import context.arch.widget.Widget.WidgetData;

public class RoomEnactor extends Enactor {
	
	public static final short BRIGHTNESS_THRESHOLD = 100;

	@SuppressWarnings("serial")
	public RoomEnactor(AbstractQueryItem<?,?> inWidgetQuery, AbstractQueryItem<?,?> outWidgetQuery) {
		super(inWidgetQuery, outWidgetQuery, "light", "");
		
		/*
		 * Set up for enactor references, one for each outcome
		 */
		
		// light off
		AbstractQueryItem<?, ?> offQI = 
			new ORQueryItem(
					RuleQueryItem.instance(
							new NonConstantAttributeElement(AttributeNameValue.instance("presence", 0))), // equal to 0; no one in the room, OR
					RuleQueryItem.instance(
							new NonConstantAttributeElement(AttributeNameValue.instance("brightness", BRIGHTNESS_THRESHOLD)), 
							new AttributeComparison(AttributeComparison.Comparison.GREATER)) // brightness more than BRIGHTNESS_THRESHOLD
					);
		EnactorReference er = new RoomEnactorReference( 
				offQI, 
				LightWidget.LIGHT_OFF);
		er.addServiceInput(new ServiceInput("LightService", "lightOff"));
		addReference(er);
		
		// light on, and brightness dependent
		er = new RoomEnactorReference( 
				new ElseQueryItem(offQI), 
				LightWidget.LIGHT_ON);
		er.addServiceInput(new ServiceInput("LightService", "lightOn", 
				new Attributes() {{
					addAttribute("light", Integer.class);
				}}));
		addReference(er);
		
		start();
	}
	
	private int light;
	
	public int getLight() {
		return light;
	}
	
	private class RoomEnactorReference extends EnactorReference {

		public RoomEnactorReference(AbstractQueryItem<?,?> conditionQuery, String outcomeValue) {
			super(RoomEnactor.this, conditionQuery, outcomeValue);
		}
		
		private double LIGHT_SCALE = Math.pow(BRIGHTNESS_THRESHOLD, 0.33);
		
		@Override
		protected Attributes conditionSatisfied(ComponentDescription inWidgetState, Attributes outAtts) {
			long timestamp = outAtts.getAttributeValue(Widget.TIMESTAMP);
			WidgetData data = new WidgetData("LightWidget", timestamp);
			
			if (outcomeValue == LightWidget.LIGHT_ON) {
				/*
				 * "Proprietary or complicated" way to calculate light voltage level from sensed brightness
				 * Actually, using Steven's power law (http://en.wikipedia.org/wiki/Steven%27s_power_law) for light perception
				 * psi = k*I^0.33
				 * Scaled to 10
				 */
				short brightness = inWidgetState.getAttributeValue(RoomWidget.BRIGHTNESS);
				light = (int)(10*Math.pow(BRIGHTNESS_THRESHOLD - brightness, 0.33) / LIGHT_SCALE); // brightness will never be lower than BRIGHTNESS_THRESHOLD
			}
			else {
				light = 0;
			}			
				        
	        /*
	         * Note that outcomeValue would not equal the light level, so user may not be able to ask about specific level
	         * TODO consider whether and how to support functional relationships
	         */
			
			data.setAttributeValue(LightWidget.LIGHT, light);
			
			outAtts.putAll(data.toAttributes());
	        return outAtts;
		}
		
	}

}