Server configuration service backed by mongodb for use with discord

server-config-service-demo.js

const MongoClient = require('mongodb').MongoClient;
const configService = require('./server-config-service');

function randint(max) {
  return Math.round(Math.random() * max);
}

function randomstring() {
  const letters = 'ABCDEFHIJKLMNOPQRSTUVWXYZ';
  let result = '';
  for (let i = 0; i < 10; i++) {
    let index = randint(letters.length - 1);
    result += letters[index];
  }
  return result;
}

let mongoClient;

async function start() {
  mongoClient = await MongoClient.connect('mongodb://localhost:27017', { useNewUrlParser: true });
  const db = mongoClient.db('my-cool-bot-db');
  await configService.initialize(db.collection('server-configs'));

  console.log(`Channel Id For Server A Before Set: ${await configService.get('A', 'channel-id')}`);
  console.log(`Channel Id For Server B Before Set: ${await configService.get('B', 'channel-id')}`);

  await configService.set('A', 'channel-id', randomstring());
  await configService.set('B', 'channel-id', randomstring());

  console.log(`Channel Id For Server A Before Set: ${await configService.get('A', 'channel-id')}`);
  console.log(`Channel Id For Server B Before Set: ${await configService.get('B', 'channel-id')}`);
}

start().then(() => {
  mongoClient.close().catch(err => {
    console.log('Error closing database: ' + err);
  });
}).catch(err => {
  console.log('Error running demo: ' + err);
  mongoClient.close().catch(err => {
    console.log('Error closing database: ' + err);
  });
});

server-config-service.js

const AsyncLock = require('async-lock');

let configMap = new Map();
let lock = new AsyncLock();
let configCollection;

async function initialize(collection) {
  configCollection = collection;
  const configs = await configCollection.find().toArray();
  for(const configRecord of configs) {
    configMap.set(configRecord.serverId, configRecord.config);
  }
}

async function set(serverId, configKey, value) {
  await lock.acquire('key', async () => {
    const serverConfig = await findOrCreateServerConfig(serverId);
    serverConfig[configKey] = value;
    await configCollection.updateOne({ serverId }, { $set: { config: serverConfig } });
  });
}

async function get(serverId, configKey) {
  const serverConfig = await findOrUndefinedServerConfig(serverId);
  if (serverConfig) {
    return serverConfig[configKey];
  }
  return undefined;
}

async function findOrCreateServerConfig(serverId) {
  let result = findOrUndefinedServerConfig(serverId);
  if (!result) {
    result = {};
    configMap.set(serverId, result);
    await configCollection.insertOne({ serverId, config: result });
  }
  return result;
}

function findOrUndefinedServerConfig(serverId) {
  return configMap.get(serverId);
}

module.exports = {
  initialize,
  get,
  set
};