index.js

'use strict';

require('dotenv').config({ silent: true });
const env = process.env;

// Server
// Used for ping and Heroku's web process
const server = require('./server');
server.start();

// Firebase + Slack
const firebase = require('firebase-admin');
const moment = require('moment');
const Slack = require('node-slack');
const slack = new Slack(env.SLACK_WEBHOOK_URL);

initializeFirebaseApp();
watchForSupplyRequests();

// Functions
function initializeFirebaseApp() {
  firebase.initializeApp({
    credential: firebase.credential.cert({
      projectId: env.FIREBASE_SERVICE_ACCOUNT_PROJECT_ID,
      clientEmail: env.FIREBASE_SERVICE_ACCOUNT_CLIENT_EMAIL,
      privateKey: env.FIREBASE_SERVICE_ACCOUNT_PRIVATE_KEY.replace(/\\n/g, '\n'),
    }),
    databaseURL: env.FIREBASE_DATABASE_URL,
  });
}

function watchForSupplyRequests(objectKeys) {
  const db = firebase.database();

  db.ref('roomSupplies').on('child_added', (roomSupplyChildSnapshot) => {
    db.ref(`roomSupplies/${roomSupplyChildSnapshot.key}`).on('value', (roomSupplySnapshot) => {
      const roomSupply = roomSupplySnapshot.val();
      if (!roomSupply.requested) return;

      // Check if a message has been sent recently
      const cooldown = parseInt(env.SLACK_MESSAGE_COOLDOWN_IN_MINUTES, 10) * 60 * 1e3;
      if (roomSupply.requested - roomSupply.notified < cooldown) return;

      Promise.all([
        db
          .ref(`rooms/${roomSupply.room}`)
          .once('value')
          .then((roomSnapshot) => roomSnapshot.val()),
        db
          .ref(`supplies/${roomSupply.supply}`)
          .once('value')
          .then((supplySnapshot) => supplySnapshot.val()),
      ])
        .then(([room, supply]) => {
          const timestamp = Math.min(roomSupply.requested, Date.now());
          return db
            .ref(`roomSupplies/${roomSupplySnapshot.key}`)
            .update({ notified: firebase.database.ServerValue.TIMESTAMP })
            .then(() => sendSupplyRequestNotificationToSlack(room, supply, timestamp));
        })
        .catch(console.error);
    });
  });
}

function sendSupplyRequestNotificationToSlack(room, supply, timestamp) {
  const timeago = moment(timestamp).fromNow();
  const attachment = {
    color: 'warning',
    fallback: `${supply.name} requested in ${room.name} ${timeago}`,
    text: `*${supply.name}* requested in *${room.name}* _${timeago}_`,
    mrkdwn_in: ['text'],
  };

  if (supply.imageUrl) {
    attachment.thumb_url = supply.imageUrl;
  }

  return slack.send({
    attachments: [attachment],
    icon_url: env.SLACK_ICON_URL,
    // Send message without text:
    // https://github.com/xoxco/node-slack/issues/24
    text: { toString: () => '' },
  });
}