config.js

/* eslint-disable no-sync */
/* global __dirname */
/** @module config */
const memoizee = require("memoizee");
const _ = require("lodash");
const fs = require("fs");
const path = require("path");
const { intOr } = require("keyu");

/** Global state where we store the config */
let data = null;

/** Loads a configuration file and fails over the previous loaded data. Crashes if there is no previous data
 * @method
 */
const loadConfig = (filename = "config.json", { logger = console, fileLoader = fs.readFileSync } = {}) => {
  try {
    const content = JSON.parse(
      fileLoader(filename && filename.startsWith("..") ? `${path.join(__dirname, filename)}` : filename, "utf8")
    );
    if (typeof content === "object") {
      data = content;
    }
  } catch (err) {
    logger.error(`Config -> Cannot load or parse the file ${filename}, reason `, err);
  }
  if (typeof data !== "object" || data === null) {
    throw Error(`Config -> ${filename} content must be an object.`);
  }
  return data;
};

/** Cached version of loadConfig
 * @method
 */

/** Loads the config and returns the passed key or the entire object if the key is empty. Crashes on not found key
 * @argument {String} filename file were config is located
 * @argument {Object} [opt] options to pass like logger
 * @method
 */
const getConf = (filename, iopt, iloader) => {
  //Assume that you get the maxAge as a key value pair in opts: it can or cannot exist
  const opt = { maxAge: 60000, ...iopt };
  opt.maxAge = intOr(60000, opt.maxAge);

  const loader = iloader || memoizee(loadConfig, opt);

  return (key, def) => {
    const config = loader(filename, opt);
    if (!key) {
      return config;
    }
    const value = _.get(config, key, def);

    if (typeof value === "undefined") {
      throw Error(`Config -> Key ${key} not found.`);
    }
    return value;
  };
};

module.exports = getConf;