openaq-fetch-adapters-norway.js

/**
 * This code is responsible for implementing all methods related to fetching
 * and returning data for the Norwegian data sources.
 */
'use strict';

import { REQUEST_TIMEOUT } from '../lib/constants';
import { default as baseRequest } from 'request';
const request = baseRequest.defaults({timeout: REQUEST_TIMEOUT});
import { default as moment } from 'moment-timezone';
import log from '../lib/logger';

exports.name = 'norway';

/**
 * Fetches the data for a given source and returns an appropriate object
 * @param {object} source A valid source object
 * @param {function} cb A callback of the form cb(err, data)
 */
exports.fetchData = function (source, cb) {
  request(source.url, function (err, res, body) {
    if (err || res.statusCode !== 200) {
      log.error(err || res.statusCode);
      return cb({message: 'Failure to load data url.'});
    }

    // Wrap everything in a try/catch in case something goes wrong
    try {
      // Format the data
      const data = formatData(body);

      // Make sure the data is valid
      if (data === undefined) {
        return cb({message: 'Failure to parse data.'});
      }
      cb(null, data);
    } catch (e) {
      return cb({message: 'Unknown adapter error.'});
    }
  });
};

/**
 * Given fetched data, turn it into a format our system can use.
 * @param {array} results Fetched source data and other metadata
 * @return {object} Parsed and standarized data our system can use
 */
const formatData = function (data) {
  // Wrap the JSON.parse() in a try/catch in case it fails
  try {
    data = JSON.parse(data);
  } catch (e) {
    // Return undefined to be caught elsewhere
    return undefined;
  }

  /**
   * Given a json object, convert to aq openaq format
   * @param {json object} item coming from source data
   * @return {object} a repacked object
   */
  const aqRepack = (item) => {
    const dateMoment = moment.tz(item.fromTime, 'YYYY-MM-DD HH:mm', 'Europe/Oslo');
    const template = {
      name: item.station,
      measurements: [
        {
          parameter: item.component,
          date: {
            utc: dateMoment.toDate(),
            local: dateMoment.format()
          },
          coordinates: {
            latitude: item.latitude,
            longitude: item.longitude
          },
          value: item.value,
          unit: item.unit
        }
      ]
    };
    return template;
  };

  // Maps array to aq-format
  const result = [...data.map(aqRepack).reduce((m, o) => {
    const name = o.name.toLowerCase();
    let obj = m.get(name);
    return obj ? m.set(name, {
      name: name,
      measurements: [...new Set(obj.measurements.concat(o.measurements))]
    })
      : m.set(name, o);
  },
  new Map()
  ).values()
  ];
  return result;
};