@trusthab/composable-resources/src/resources/kpi/devices_unknown.js

migrating https://github.com/knetikmedia/hab-api/tree/integration/app/resources/composable

const composer = require('../../mixin_loader');

module.exports = (App) => {
  const { underscore } = require('inflected');
  const PROPERTY_VALUE = 'unknown';

  class DevicesUnknownResource {
    static mixins() {
      return ['Kpi'];
    }

    getMetricId() {
      return 'devices_unknown';
    }

    getMetricType() {
      return 'gauge';
    }

    getValue() {
      if (this.get('obj').device_type === 'gateway') { return 0; }

      const { value, oldValue } = this.get('diff');
      if (oldValue !== PROPERTY_VALUE && value === PROPERTY_VALUE) { return 1; }

      return 0;
    }
  }

  return composer(DevicesUnknownResource, App);
};