import express from 'express'
import promBundle from 'express-prom-bundle'
import http from 'http'
import { HEALTHCHECK_URL } from './logger'

export const app = express()
export const server = http.createServer(app)
export const serverListen = () => server.listen(port)

// display express metrics endpoint at `/metrics`
app.use(
  promBundle({
    includeMethod: true,
    includePath: true,
    bypass: (req) => [HEALTHCHECK_URL, '/metrics'].includes(req.url),
    normalizePath: [[/^\/([^\/]*).*$/, '$1']],
  })
)

const port = normalizePort(process.env.PORT || '3000')
app.set('port', port)
server.on('error', onError)
server.on('listening', onListening)

/**
 * Normalize a port into a number, string, or false.
 */
function normalizePort(val: any) {
  const port = parseInt(val, 10)
  if (isNaN(port)) {
    // named pipe
    return val
  }
  if (port >= 0) {
    // port number
    return port
  }
  return false
}

/**
 * Event listener for HTTP server "error" event.
 */

function onError(error: any) {
  if (error.syscall !== 'listen') {
    throw error
  }

  const bind = typeof port === 'string' ? 'Pipe ' + port : 'Port ' + port

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(bind + ' requires elevated privileges')
      process.exit(1)
      break
    case 'EADDRINUSE':
      console.error(bind + ' is already in use')
      process.exit(1)
      break
    default:
      throw error
  }
}

/**
 * Event listener for HTTP server "listening" event.
 */

function onListening() {
  const addr = server.address()
  if (addr == null) {
    console.log('server address is null')
    return
  }
  const bind = typeof addr === 'string' ? 'pipe ' + addr : 'port ' + addr.port
  console.log('Server listening on ' + bind + ' 🚀')
}