generate_average_co2.js

/**
 * @fileoverview This script generates average CO2 emissions intensity data for countries using the Ember API.
 * It processes the data and saves it in various formats for use in the CO2.js library.
 * @author Chris Adams
 * @version 1.0.0
 */

const fs = require("fs");

/**
 * The URL for the Ember API that provides country overview data on a yearly basis.
 * @constant {string}
 */
const sourceURL =
  "https://ember-data-api-scg3n.ondigitalocean.app/ember/country_overview_yearly.json?_sort=rowid&_shape=array";

/**
 * Object to store the grid intensity results for each country.
 * @type {Object.<string, number>}
 */
const gridIntensityResults = {};

/**
 * Object to store general results including additional country information.
 * @type {Object.<string, Object>}
 */
const generalResults = {};

/**
 * The type of intensity data being processed (average or marginal).
 * @constant {string}
 */
const type = "average";

/**
 * Fetches data from the Ember API, processes it to extract the latest average CO2 emissions
 * intensity data for each country, and saves the results in various formats.
 * @async
 * @function
 * @returns {Promise<void>}
 */

// Use async/await
// Use fetch to get the data from the API
// Use the reduce method to group the data by country_code
// Use the reduce method again to find the latest year for each country
// Use a for loop to get the emissions intensity data
// Save the data to the gridIntensityResults object
// Save the full data set to a JSON file
// Save the country code and emissions data only to a JS file
// Save a minified version of the JS file to the src/data folder

(async () => {
  try {
    const response = await fetch(sourceURL);
    if (!response.ok) {
      throw new Error(`Network response was not ok: ${response.statusText}`);
    }
    const data = await response.json();

    /**
     * Groups the API data by country code.
     * @type {Object.<string, Array>}
     */
    const groupedData = await data.reduce((acc, item) => {
      const key =
        item.country_code === "" ? item.country_or_region : item.country_code;
      if (!acc[key]) {
        acc[key] = [];
      }
      acc[key].push(item);
      return acc;
    }, {});

    /**
     * Extracts the latest year's data for each country.
     * @type {Object.<string, Object>}
     */
    const latestData = await Object.keys(groupedData).reduce((acc, key) => {
      // Find the last year in the array with emissions intensity data
      const latestYear = groupedData[key].reduce((acc, item, index) => {
        if (
          item.emissions_intensity_gco2_per_kwh === null ||
          item.emissions_intensity_gco2_per_kwh === ""
        ) {
          return acc;
        }
        return index;
      }, 0);

      acc[key] = groupedData[key][latestYear];
      return acc;
    }, {});

    // Loop through the data and extract the emissions intensity data
    // Save it to the gridIntensityResults object with the country code as the key
    Object.values(latestData).forEach((row) => {
      if (
        row.emissions_intensity_gco2_per_kwh === null ||
        row.emissions_intensity_gco2_per_kwh === ""
      ) {
        return;
      }

      const country =
        row.country_code === "" ? row.country_or_region : row.country_code;

      gridIntensityResults[country.toUpperCase()] =
        row.emissions_intensity_gco2_per_kwh;

      generalResults[country] = {
        country_code: row.country_code,
        country_or_region: row.country_or_region,
        year: row.year,
        emissions_intensity_gco2_per_kwh: row.emissions_intensity_gco2_per_kwh,
      };
    });

    // Ensure directories exist
    fs.mkdirSync("data/output", { recursive: true });
    fs.mkdirSync("src/data", { recursive: true });

    const jsDocComments = `/**
 * @fileoverview Minified average CO2 emissions intensity data for countries.
 * @generated Generated by generate_average_co2.js
 * @version 1.0.0
*/
/**
 * @constant {Object.<string, number>} data - Average CO2 emissions intensity data for various countries.
 * @constant {string} type - Type of data being represented.
 */`;

    /**
     * Saves the country code and emissions data for use in the CO2.js library.
     * @type {void}
     */
    fs.writeFileSync(
      "data/output/average-intensities.js",
      `const data = ${JSON.stringify(gridIntensityResults, null, "  ")}; 
      const type = "${type}";
      export { data, type }; 
      export default { data, type };
      `
    );

    /**
     * Saves a minified version of the data for easy import into the library.
     * @type {void}
     */
    fs.writeFileSync(
      "src/data/average-intensities.min.js",
      `${jsDocComments}
      const data = ${JSON.stringify(
        gridIntensityResults
      )}; const type = "${type}"; export { data, type }; export default { data, type };`
    );

    /**
     * Saves the full data set as a JSON file for reference.
     * @type {void}
     */
    fs.writeFileSync(
      "data/output/average-intensities.json",
      JSON.stringify(generalResults, null, "  ")
    );
  } catch (error) {
    console.error("Error fetching or processing data:", error);
  }
})();