Added WaterLevel capability

sensors/index.js

@@ -19,3 +19,4 @@ module.exports.Temperature = require('./temperature');
 module.exports.SmokeDetection = require('./smoke-detection');
 module.exports.Voltage = require('./voltage');
 module.exports.WaterDetection = require('./water-detection');
+module.exports.WaterLevel = require('./water-level');

sensors/water-level.js

@@ -0,0 +1,46 @@
+'use strict';
+
+const Thing = require('../thing');
+const Sensor = require('./sensor');
+const { percentage } = require('../values');
+
+module.exports = Thing.mixin(Parent => class extends Parent.with(Sensor) {
+	static get capability() {
+		return 'water-level';
+	}
+
+	static availableAPI(builder) {
+		builder.event('waterLevelChanged')
+			.type('percentage')
+			.description('Current water level has changed')
+			.done();
+
+		builder.action('waterLevel')
+			.description('Get the current water level')
+			.getterForState('waterLevel')
+			.returns('percentage', 'Current water level')
+			.done();
+
+		builder.action('wl')
+			.description('Get the current water level')
+			.getterForState('waterLevel')
+			.returns('percentage', 'Current water level')
+			.done();
+	}
+
+	get sensorTypes() {
+		return [ ...super.sensorTypes, 'waterLevel' ];
+	}
+
+	waterLevel() {
+		return this.value('waterLevel');
+	}
+
+	wl() {
+		return this.value('waterLevel');
+	}
+
+	updateWaterLevel(value) {
+		this.updateValue('waterLevel', percentage(value));
+	}
+});