@kth/kth-node-web-common/lib/error.js

Common components for node-web projects

'use strict'

const fs = require('fs')
const path = require('path')
const handlebars = require('handlebars')
const log = require('@kth/log')

const errorHandlebar = fs.readFileSync(path.join(__dirname, '/errorTemplate.handlebars'), 'utf8')

/**
 * Method taking care of the rendering of error pages.
 *
 * @param {*} res the given response
 * @param {*} req the given request
 * @param {*} statusCode the given status code
 * @param {*} i18n the given language information
 * @param {*} isProd variable indicating if the application is run in the production environment
 * @param {*} lang the given language
 * @param {*} err the givven error object
 */
function _renderErrorPage(res, req, statusCode, i18n, isProd, lang, err) {
  let headTitle
  let headDescription
  let title
  let text
  let text1
  let text2
  let linkText1
  let link1
  let linkText2
  let link2
  let linkText3
  let link3

  switch (statusCode) {
    case 400:
      log.info(`400 Bad request ${err.message}`, { err })
      headTitle = i18n.message('error_400_head_title', lang)
      headDescription = i18n.message('error_400_description', lang)
      title = i18n.message('error_400_title', lang)
      text = i18n.message('error_400_text', lang)
      break
    case 401:
      log.info(`401 Unauthorized ${err.message}`, { err })
      headTitle = i18n.message('error_401_head_title', lang)
      headDescription = i18n.message('error_401_description', lang)
      title = i18n.message('error_401_title', lang)
      text = i18n.message('error_401_text', lang)
      break
    case 403:
      log.info(`403 Forbidden ${err.message}`, { err })
      headTitle = i18n.message('error_403_head_title', lang)
      headDescription = i18n.message('error_403_description', lang)
      title = i18n.message('error_403_title', lang)
      text = i18n.message('error_403_text', lang)
      break
    case 404:
      log.info(`404 Not found ${err.message}`)
      headTitle = i18n.message('error_404_head_title', lang)
      headDescription = i18n.message('error_404_description', lang)
      title = i18n.message('error_404_title', lang)
      text1 = i18n.message('error_404_text_1', lang)
      text2 = i18n.message('error_404_text_2', lang)
      linkText1 = i18n.message('error_404_link_text_1', lang)
      link1 = i18n.message('error_404_link_1', lang)
      linkText2 = i18n.message('error_404_link_text_2', lang)
      link2 = i18n.message('error_404_link_2', lang)
      linkText3 = i18n.message('error_404_link_text_3', lang)
      link3 = i18n.message('error_404_link_3', lang)
      break
    default:
      // Log err as first parameter here, which will cause an Exception event in application-insights
      log.error({ err }, `Unhandled error ${err.message}`)
      headTitle = i18n.message('error_500_head_title', lang)
      headDescription = i18n.message('error_500_description', lang)
      title = i18n.message('error_500_title', lang)
      text = i18n.message('error_500_text', lang)
  }

  res.format({
    'text/html': () => {
      if (!errorHelpersExists()) {
        res.sendStatus(statusCode)
        return
      }

      const errorTemplate = handlebars.compile(errorHandlebar)
      const errorPage = errorTemplate({
        statusCode,
        headTitle,
        headDescription,
        title,
        text,
        text1,
        text2,
        linkText1,
        link1,
        linkText2,
        link2,
        linkText3,
        link3,
        message: err.message,
        error: isProd ? {} : err,
        statusCodeLabel: i18n.message('error_status_code', lang),
      })
      res.status(statusCode).send(errorPage)
    },

    'application/json': () => {
      res.status(statusCode).json({
        message: err.message,
        error: isProd ? undefined : err.stack,
      })
    },

    default: () => {
      res
        .status(statusCode)
        .type('text')
        .send(isProd ? err.message : err.stack)
    },
  })
}

const requiredHelpers = ['prefixStyle', 'render', 'extend']

const errorHelpersExists = () =>
  requiredHelpers.every(helperName => Object.keys(handlebars.helpers).includes(helperName))

module.exports = {
  renderErrorPage: _renderErrorPage,
}