shields/lib/log.js

'use strict'
const Raven = require('raven')
const throttle = require('lodash.throttle')

const listeners = []

// Zero-pad a number in a string.
// eg. 4 becomes 04 but 17 stays 17.
function pad(string) {
  string = String(string)
  return string.length < 2 ? '0' + string : string
}

// Compact date representation.
// eg. 0611093840 for June 11, 9:38:40 UTC.
function date() {
  const date = new Date()
  return (
    pad(date.getUTCMonth() + 1) +
    pad(date.getUTCDate()) +
    pad(date.getUTCHours()) +
    pad(date.getUTCMinutes()) +
    pad(date.getUTCSeconds())
  )
}

module.exports = function log(...msg) {
  const d = date()
  listeners.forEach(f => f(d, ...msg))
  console.log(d, ...msg)
}

const throttledConsoleError = throttle(console.error, 10000, {
  trailing: false,
})

module.exports.error = function error(...msg) {
  const d = date()
  listeners.forEach(f => f(d, ...msg))
  Raven.captureException(msg, function(sendErr) {
    if (sendErr) {
      throttledConsoleError(
        'Failed to send captured exception to Sentry',
        sendErr.message
      )
    }
  })
  console.error(d, ...msg)
}

module.exports.addListener = function addListener(func) {
  listeners.push(func)
}

module.exports.removeListener = function removeListener(func) {
  const index = listeners.indexOf(func)
  if (index < 0) {
    return
  }
  listeners.splice(index, 1)
}