index.js

const express = require('express')
const pg = require('pg')
require('dotenv').config();
const app = express();
const rateLimiter = require('./rateLimiter');

/*
  1. use rate limiter
  2. setup user header for redis
  3. setup process.env for database
  4. connect to database with pg.pool
  5. setup other endpoints to get data from postgres
*/ 

app.use(rateLimiter);
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('user', 'Nana');
  next();
});

const pool = new pg.Pool({
  user: process.env.PGUSER,
  host: process.env.PGHOST,
  database: process.env.PGDATABASE,
  password: process.env.PGPASSWORD,
  port: process.env.PGPORT
});

const queryHandler = (req, res, next) => {
  pool.query(req.sqlQuery).then((r) => {
    return res.json(r.rows || [])
  }).catch(next)
}


app.get('/', (req, res) => {
  res.send('Welcome to EQ Works 😎')
})

app.get('/events', (req, res, next) => {
  req.sqlQuery = `
    SELECT *
    FROM public.hourly_events
    ORDER BY date, hour
    LIMIT 168;
  `
  return next()
}, queryHandler)

app.get('/events/hourly', (req, res, next) => {
  req.sqlQuery = `
    SELECT date, hour, events
    FROM public.hourly_events
    ORDER BY date, hour
    LIMIT 168;
  `
  return next()
}, queryHandler);


app.get('/events/daily', (req, res, next) => {
  req.sqlQuery = `
    SELECT date, SUM(events) AS events
    FROM public.hourly_events
    GROUP BY date
    ORDER BY date
    LIMIT 7;
  `
  return next()
}, queryHandler)

app.get('/stats', (req, res, next) => {
  req.sqlQuery = `
    SELECT *
    FROM public.hourly_stats
    ORDER BY date, hour
    LIMIT 168;
  `
  return next()
}, queryHandler)

app.get('/stats/hourly', (req, res, next) => {
  req.sqlQuery = `
    SELECT date, hour, impressions, clicks, revenue
    FROM public.hourly_stats
    ORDER BY date, hour
    LIMIT 168;
  `
  return next()
}, queryHandler)

app.get('/stats/daily', (req, res, next) => {
  req.sqlQuery = `
    SELECT date,
        SUM(impressions) AS impressions,
        SUM(clicks) AS clicks,
        SUM(revenue) AS revenue
    FROM public.hourly_stats
    GROUP BY date
    ORDER BY date
    LIMIT 7;
  `
  return next()
}, queryHandler)

app.get('/poi', (req, res, next) => {
  req.sqlQuery = `
    SELECT *
    FROM public.poi;
  `
  return next()
}, queryHandler)

app.listen(process.env.PORT || 5555, (err) => {
  if (err) {
    console.error(err)
    process.exit(1)
  } else {
    console.log(`Running on ${process.env.PORT || 5555}`)
  }
})

// last resorts
process.on('uncaughtException', (err) => {
  console.log(`Caught exception: ${err}`)
  process.exit(1)
})
process.on('unhandledRejection', (reason, p) => {
  console.log('Unhandled Rejection at: Promise', p, 'reason:', reason)
  process.exit(1)
})