humidity: Add class sensor

Note this type is not yet specified
Some hints: look for ambientHumidty or relative humidity.

Real driver will need to be ingrated next

Relate-to: bbx10/node-htu21d#2
Change-Id: I476b0ac5b0f84117ed708aeb23e469687de21ef5
Signed-off-by: Philippe Coval <[email protected]>

lib/humidity/index.js

@@ -0,0 +1,110 @@
+/* -*- mode: js; js-indent-level:2; -
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright 2020-present Philippe Coval and other contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+'use strict';
+
+var console = require('console');
+var Sensor = require('./simulator');
+
+/**
+ * Class inspired by W3C's generic-sensor
+ * @related: https://www.w3.org/TR/ambient-light/
+ **/
+function Humidity(options) {
+  var self = this;
+  this.type = 'humidity';
+  this.properties = ['level'];
+  for (var property in self.properties) {
+    property = this.properties[property];
+    self[property] = null;
+  }
+  this.onerror = function (err) {
+    throw new Error(err)
+  }
+  this.options = options || {};
+  this.options.frequency = this.options.frequency || 1;
+
+  return this;
+}
+
+Humidity.prototype.update = function update() {
+  var self = this;
+  try {
+    self.hasReading = false;
+    self.sensor.read(function(err, data) {
+      if (err || data === null || typeof data === 'undefined') {
+        return self.onerror(data);
+      }
+      self.timestamp = new Date();
+      for (var property in self.properties) {
+        property = self.properties[property];
+        self[property] = data[property]
+      }
+      self.hasReading = true;
+      if (self.onreading) {
+        self.onreading();
+      }
+    });
+  } catch (err) {
+    self.onerror(err);
+  }
+}
+
+Humidity.prototype.stop = function stop() {
+  if ( this.state === 'idle' ) return;
+  this.interval = clearInterval(this.interval);
+  this.state = 'idle';
+}
+
+Humidity.prototype.start = function start() {
+  var self = this;
+  this.state = 'activating';
+  if (!this.sensor) {
+    try {
+      this.sensor = new Sensor();
+    } catch (err) {
+      if (this.onerror) {
+        return this.onerror(err)
+      }
+    }
+  }
+
+  try {
+    if (!self.interval) {
+      self.interval = setInterval(function() { self.update(); },
+                                  1000. / self.options.frequency);
+      if (self.onactivate) {
+        self.onactivate();
+      }
+      self.state = 'activated';
+    }
+  } catch(err) {
+    self.onerror(err);
+  }
+}
+
+module.exports = Humidity;
+
+
+if (module.parent === null) {
+  var sensor = new Humidity();
+  sensor.onreading = function() {
+    console.log('log: level=' + this.level);
+    this.stop();
+  }
+  sensor.start();
+}