@trusthab/composable-resources/src/resources/kpi/devices_active.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');

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

    getMetricId() {
      return 'devices_active';
    }

    getMetricType() {
      return 'gauge';
    }

    getValue() {
      const { location_type } = this.get('obj');
      const { oldValue } = this.get('diff');

      switch (this.get('transaction')) {
        case 'created':
          return location_type === 'unit' ? 1 : 0;
        case 'updated':
          if (oldValue === 'unit' && location_type !== 'unit') { return 0; }
          if (oldValue !== 'unit' && location_type === 'unit') { return 1; }
          break;
        case 'deleted':
          return 0;
        default:
          return 0;
      }

      return null;
    }
  }

  return composer(DevicesActiveResource, App);
};