refactor retrieving ICS file

lib/crawler.js

@@ -1,47 +0,0 @@
-const request = require('request')
-const { checkURLFormat, checkNumberURLParameter } = require('./utils')
-
-const useMobileURL = (originalURL) => {
-  const urlWithProtocol = originalURL.includes('http') ?
-    originalURL :
-    `https://${originalURL}`
-  const url = new URL(urlWithProtocol)
-
-  return `${url.protocol}//mobile.facebook.com${url.port}${url.pathname}${url.hash}`
-}
-
-const createURL = (originalURL) => {
-  if (checkURLFormat(originalURL)) {
-    return originalURL
-  }
-
-  if (checkNumberURLParameter(originalURL)) {
-    return `https://facebook.com/events/${originalURL}`
-  }
-
-  return ''
-}
-
-const crawl = async (originalURL) => {
-  const url = useMobileURL(createURL(originalURL))
-  return new Promise((resolve, reject) => {
-    console.info(`Started request for URL: ${url}`)
-    request({
-      url,
-      headers: {
-        'Accept-Language': 'en-US, en',
-        'User-Agent': 'request',
-      },
-    }, (err, res, body) => {
-      if (err) {
-        reject(err)
-        return
-      }
-
-      console.info(`Finished request for URL: ${url}`)
-      resolve(body)
-    })
-  })
-}
-
-module.exports = crawl

lib/index.js

@@ -4,10 +4,12 @@ const path = require('path')
 const favicon = require('serve-favicon')
 const rateLimit = require('express-rate-limit')
 
-const crawl = require('./crawler')
-const parseHTML = require('./parser')
-const generateICS = require('./ics')
-const { genericErrorHandler, checkURLParameter, forceSecure } = require('./middlewares')
+const retrieveICS = require('./services/ics-retriever')
+const {
+  genericErrorHandler,
+  checkURLParameter,
+  forceSecure,
+} = require('./middlewares')
 
 const port = process.env.PORT
 const certEndpoint = process.env.CERT_ENDPOINT || ''
@@ -50,22 +52,17 @@ app.get('*', (req, res) => {
 app.use('/download', checkURLParameter)
 app.use('/download', rateLimit())
 app.post('/download', async (req, res, next) => {
-  const { url } = req.body
-
   try {
-    const html = await crawl(url)
-    const data = parseHTML(html)
-    const ics = await generateICS(data)
+    const { url } = req.body
 
-    if (ics) {
-      return res
-        .contentType('text/calendar')
-        .status(200)
-        .send(new Buffer(ics, 'utf8'))
-    }
+    const ics = await retrieveICS(url)
+
+    res
+      .contentType('text/calendar')
+      .status(200)
+      .send(new Buffer(ics, 'utf8'))
   } catch (err) {
     next(err)
-    return
   }
 })
 

lib/services/crawler.js

@@ -0,0 +1,24 @@
+const request = require('request')
+
+const crawl = async (url) => {
+  return new Promise((resolve, reject) => {
+    console.info(`Started request for URL: ${url}`)
+    request({
+      url,
+      headers: {
+        'Accept-Language': 'en-US, en',
+        'User-Agent': 'request',
+      },
+    }, (err, res, body) => {
+      if (err) {
+        reject(err)
+        return
+      }
+
+      console.info(`Finished request for URL: ${url}`)
+      resolve(body)
+    })
+  })
+}
+
+module.exports = crawl

lib/services/ics-retriever.js

@@ -0,0 +1,18 @@
+const crawl = require('./crawler')
+const parseHTML = require('./parser')
+const generateICS = require('./ics-generator')
+const { getNormalizedUrl } = require('../utils')
+
+const retrieveICS = async (URLparameter) => {
+  try {
+    const url = getNormalizedUrl(URLparameter)
+    const html = await crawl(url)
+    const eventData = parseHTML(html)
+    const icsFile = await generateICS(eventData)
+    return icsFile
+  } catch (err) {
+    throw err
+  }
+}
+
+module.exports = retrieveICS

lib/services/parser.js

@@ -1,6 +1,6 @@
 const dayjs = require('dayjs')
 const cheerio = require('cheerio')
-const { createParserError } = require('./utils')
+const { createParserError } = require('../utils')
 
 // NOTE: Specific formatting for `ics` library
 const parseDates = (startDate, endDate) => {

lib/utils.js

@@ -18,9 +18,44 @@ const createParserError = () => {
   return err
 }
 
+// NOTE: Using mobile facebook URL because it usually
+// contains stringified JSON with event information
+const createMobileURL = (originalURL) => {
+  const urlWithProtocol = originalURL.includes('http') ?
+    originalURL :
+    `https://${originalURL}`
+  const url = new URL(urlWithProtocol)
+
+  return `${url.protocol}//mobile.facebook.com${url.port}${url.pathname}${url.hash}`
+}
+
+// NOTE: Detect whether URL parameter contains
+// number or http address
+const createURL = (param) => {
+  if (checkURLFormat(param)) {
+    return param
+  }
+
+  if (checkNumberURLParameter(param)) {
+    return `https://facebook.com/events/${param}`
+  }
+
+  return ''
+}
+
+const getNormalizedUrl = (URLparameter) => {
+  const fbURL = createURL(URLparameter)
+  const mobileUrl = createMobileURL(fbURL)
+
+  return mobileUrl
+}
+
 module.exports = {
   checkValidURL,
   checkURLFormat,
   checkNumberURLParameter,
   createParserError,
+  createMobileURL,
+  createURL,
+  getNormalizedUrl,
 }