Settings.js

const fs = require("fs");
const _ = require('lodash');

/**
 * @class Settings
 * @classdesc loads and saves settings for the entire app.
 */
class Settings {
    /**
     * Global settings loaded in memory.
     * @private
     * @var {object} setting
     */
    setting = {};
    permVoiceTemplate = _.template(`g-<%= guildId %>.permVoice.c-<%= channelId %>`);

    /**
     * Loads settings from file into memory.
     */
    constructor() {
        let file = {};
        try {
        if (!fs.existsSync(process.env.SETTINGSFILE)) {
            const pathPieces = process.env.SETTINGSFILE.split('/');
            pathPieces.pop();
            fs.mkdirSync(pathPieces.join('/'), { recursive: true });
            fs.writeFileSync(process.env.SETTINGSFILE, '{}', 'utf8');
        }
        file = fs.readFileSync(process.env.SETTINGSFILE, 'utf8');
        } catch(e) {
            console.error(`Error loading settings file from ${process.env.SETTINGSFILE}`, e.message);
        }

        try {
        this.setting = JSON.parse(file);
        } catch (e) {
            console.error('Error parsing JSON from settings file!!', e.message);
        }
        // Will save after 10 seconds of the last update call, but will save every 60 seconds no matter what.
        this._save = _.debounce(_.bind(this._save, this), 10000, { 'maxWait': 60000 });
    }

    /**
     * async save/update settings file after an update to the data has been made.
     * This function is debounced
     * @private
     */
    _save() {
        fs.writeFile(process.env.SETTINGSFILE, JSON.stringify(this.setting), 'utf8', (err) => {
            if (err) {
                console.error('Settings have been updated but failed to save!', err.message);
            } else {
                console.log('Settings have been updated');
            }
        });
    }

    /**
     * Toggles the permission for voice of a channel
     * @param {string} guildId The guild id to get the settings for
     * @param {string} channelId The channel id to add or delete from th settings file
     */
    togglePermVoiceChannel(guildId, channelId) {
        _.set(this.setting,
            this.permVoiceTemplate({ guildId, channelId }),
            !_.get(this.setting, this.permVoiceTemplate({ guildId, channelId }), false));
            this._save();
    }

    /**
     * Checks if a channel has permission or not.
     * @param {string} guildId The guild id to get the settings for
     * @param {string} channelId The channel id to check
     * @return {boolean}
     */
    doesChannelHavePermVoice(guildId, channelId) {
        return _.get(this.setting, this.permVoiceTemplate({ guildId, channelId }), false);
    }
}

module.exports = new Settings();