convert plain text newsletter email content to html using markdown-to-html and save it if html is not available

packages/inbound-email-handler/package.json

@@ -24,6 +24,7 @@
     "@types/json-bigint": "^1.0.1",
     "@types/node": "^14.11.2",
     "@types/rfc2047": "^2.0.1",
+    "@types/showdown": "^2.0.1",
     "chai": "^4.3.6",
     "eslint-plugin-prettier": "^4.0.0",
     "mocha": "^10.0.0"
@@ -39,6 +40,7 @@
     "jsonwebtoken": "^8.5.1",
     "parse-headers": "^2.0.4",
     "parse-multipart-data": "^1.2.1",
-    "rfc2047": "^4.0.1"
+    "rfc2047": "^4.0.1",
+    "showdown": "^2.1.0"
   }
 }

packages/inbound-email-handler/src/index.ts

@@ -12,6 +12,7 @@ import * as jwt from 'jsonwebtoken'
 import parseHeaders from 'parse-headers'
 import * as multipart from 'parse-multipart-data'
 import rfc2047 from 'rfc2047'
+import { Converter } from 'showdown'
 import { promisify } from 'util'
 import { Attachment, handleAttachments, isAttachment } from './attachment'
 import {
@@ -36,6 +37,11 @@ const signToken = promisify(jwt.sign)
 const NEWSLETTER_EMAIL_RECEIVED_TOPIC = 'newsletterEmailReceived'
 const NON_NEWSLETTER_EMAIL_TOPIC = 'nonNewsletterEmailReceived'
 const pubsub = new PubSub()
+const converter = new Converter()
+
+export const plainTextToHtml = (text: string): string => {
+  return converter.makeHtml(text)
+}
 
 export const publishMessage = async (
   topic: string,
@@ -163,19 +169,24 @@ export const inboundEmailHandler = Sentry.GCPFunction.wrapHttpFunction(
           await handleAttachments(to, subject, attachments, receivedEmailId)
           return res.send('ok')
         }
+
+        // convert text to html if html is not available
+        const content = html || plainTextToHtml(text)
+
         // all other emails are considered newsletters
         const newsletterMessage = await handleNewsletter({
           from,
           to,
           subject,
-          html,
+          html: content,
           headers,
         })
+
         // queue newsletter emails
         await pubsub.topic(NEWSLETTER_EMAIL_RECEIVED_TOPIC).publishMessage({
           json: {
             email: to,
-            content: html || text, // html is preferred
+            content,
             url: generateUniqueUrl(),
             title: subject,
             author: parseAuthor(from),

packages/inbound-email-handler/test/newsletter.test.ts

@@ -2,7 +2,7 @@ import { expect } from 'chai'
 import 'mocha'
 import parseHeaders from 'parse-headers'
 import rfc2047 from 'rfc2047'
-import { parsedTo } from '../src'
+import { parsedTo, plainTextToHtml } from '../src'
 import {
   getConfirmationCode,
   isGoogleConfirmationEmail,
@@ -138,3 +138,29 @@ describe('decode and parse headers', () => {
     })
   })
 })
+
+describe('plainTextToHtml', () => {
+  it('converts text to html', () => {
+    const text =
+      'DEVOPS WEEKLY\r\n' +
+      'ISSUE #665 - 24th September 2023\r\n' +
+      '\r\n' +
+      'A few posts on CI tooling this week, along with a good introduction to developer portals/platforms and other topics.\r\n' +
+      '\r\n' +
+      'StackHawk sponsors Devops Weekly\r\n' +
+      '============================\r\n' +
+      '\r\n' +
+      'Experience automated security testing without the hassle of connecting your own app or configuring an environment! Follow the Tutorial to try out StackHawk and explore a world where security becomes an accelerator, not a blocker\r\n' +
+      '\r\n' +
+      'https://sthwk.com/tutorial\r\n' +
+      '\r\n'
+    expect(plainTextToHtml(text)).to.eql(
+      `<p>DEVOPS WEEKLY
+ISSUE #665 - 24th September 2023</p>
+<p>A few posts on CI tooling this week, along with a good introduction to developer portals/platforms and other topics.</p>
+<h1 id="stackhawksponsorsdevopsweekly">StackHawk sponsors Devops Weekly</h1>
+<p>Experience automated security testing without the hassle of connecting your own app or configuring an environment! Follow the Tutorial to try out StackHawk and explore a world where security becomes an accelerator, not a blocker</p>
+<p>https://sthwk.com/tutorial</p>`
+    )
+  })
+})

yarn.lock

@@ -7985,6 +7985,11 @@
     "@types/mime" "^1"
     "@types/node" "*"
 
+"@types/showdown@^2.0.1":
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/@types/showdown/-/showdown-2.0.1.tgz#24134738ba3107237d6a783e054a54773e739f81"
+  integrity sha512-xdnAw2nFqomkaL0QdtEk0t7yz26UkaVPl4v1pYJvtE1T0fmfQEH3JaxErEhGByEAl3zUZrkNBlneuJp0WJGqEA==
+
 "@types/sinon-chai@^3.2.8":
   version "3.2.8"
   resolved "https://registry.yarnpkg.com/@types/sinon-chai/-/sinon-chai-3.2.8.tgz#5871d09ab50d671d8e6dd72e9073f8e738ac61dc"
@@ -11214,7 +11219,7 @@ commander@^8.3.0:
   resolved "https://registry.yarnpkg.com/commander/-/commander-8.3.0.tgz#4837ea1b2da67b9c616a67afbb0fafee567bca66"
   integrity sha512-OkTL9umf+He2DZkUq8f8J9of7yL6RJKI24dVITBmNfZBmri9zYZQrKkuXiKhyfPSu8tUhnVBB1iKXevvnlR4Ww==
 
-commander@^9.1.0:
+commander@^9.0.0, commander@^9.1.0:
   version "9.5.0"
   resolved "https://registry.yarnpkg.com/commander/-/commander-9.5.0.tgz#bc08d1eb5cedf7ccb797a96199d41c7bc3e60d30"
   integrity sha512-KRs7WVDKg86PWiuAqhDrAQnTXZKraVcCc6vFdL14qrZ/DcWwuRo7VoiYXalXO7S5GKpqYiVEwCbgFDfxNHKJBQ==
@@ -24526,6 +24531,13 @@ shimmer@^1.2.1:
   resolved "https://registry.yarnpkg.com/shimmer/-/shimmer-1.2.1.tgz#610859f7de327b587efebf501fb43117f9aff337"
   integrity sha512-sQTKC1Re/rM6XyFM6fIAGHRPVGvyXfgzIDvzoq608vM+jeyVD0Tu1E6Np0Kc2zAIFWIj963V2800iF/9LPieQw==
 
+showdown@^2.1.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/showdown/-/showdown-2.1.0.tgz#1251f5ed8f773f0c0c7bfc8e6fd23581f9e545c5"
+  integrity sha512-/6NVYu4U819R2pUIk79n67SYgJHWCce0a5xTP979WbNp0FL9MN1I1QK662IDU1b6JzKTvmhgI7T7JYIxBi3kMQ==
+  dependencies:
+    commander "^9.0.0"
+
 side-channel@^1.0.4:
   version "1.0.4"
   resolved "https://registry.yarnpkg.com/side-channel/-/side-channel-1.0.4.tgz#efce5c8fdc104ee751b25c58d4290011fa5ea2cf"