Add hash for unsubscribe option

.gitignore

@@ -1,3 +1,4 @@
 ### Hugo ###
 /public/
 /resources/_gen/
+scripts/mail-scripts/Mercurius

scripts/mail-scripts/emails.json

@@ -1,6 +1,3 @@
 {
-    "subscribers": [
-        "[email protected]",
-        "[email protected]"
-    ]
-}
+  "subscribers": ["[email protected]"]
+}

scripts/mail-scripts/go.mod

@@ -4,7 +4,7 @@ go 1.15
 
 require (
 	github.com/yuin/goldmark v1.3.5
-	github.com/yuin/goldmark-meta v1.0.0 // indirect
+	github.com/yuin/goldmark-meta v1.0.0
 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect
-	gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df // indirect
+	gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df
 )

scripts/mail-scripts/main.go

@@ -2,7 +2,13 @@ package main
 
 import (
 	"bytes"
+	"crypto/aes"
+	"crypto/cipher"
+	"crypto/rand"
+	"encoding/base64"
 	"encoding/json"
+	"fmt"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
@@ -12,64 +18,143 @@ import (
 	"gopkg.in/gomail.v2"
 )
 
+// Struct to store subscribers list array
 type subscriberList struct {
 	Subscribers []string `json:"subscribers"`
 }
 
+// Domain of cloudfare serverless endpoint
+var domain string
+
 func main() {
+
+	log.SetFlags(log.LstdFlags | log.Lshortfile)
+
+	domain = os.Getenv("DOMAIN_NAME")
+
+	// Init goldmark configuration
 	markdown := goldmark.New(
 		goldmark.WithExtensions(
 			meta.Meta,
 		),
 	)
 
-	jsonFile, err := os.Open("emails.json")
-
+	// Open emails file for reading emails (Will be replaced in future)
+	emailFile, err := os.Open("emails.json")
 	if err != nil {
 		log.Print(err)
 	}
+	defer emailFile.Close()
 
-	defer jsonFile.Close()
+	// Read emails from the file into a buffer
+	byteValue, _ := ioutil.ReadAll(emailFile)
 
-	byteValue, _ := ioutil.ReadAll(jsonFile)
+	// Transferring email data to a var
+	var subsList subscriberList
+	json.Unmarshal(byteValue, &subsList)
 
-	var list subscriberList
+	// Reading content to be sent
+	// TODO: Replace this with logic to read file containing the latest post
+	content, _ := ioutil.ReadFile("../../content/post/example.md")
 
-	json.Unmarshal(byteValue, &list)
+	// Convert the markdown into a compatible HTML format
+	var htmlContent bytes.Buffer
+	if err := markdown.Convert(content, &htmlContent); err != nil {
+		log.Fatalln(err)
+	}
+	// Convert to string for using and tweaking it everywhere
+	contentString := htmlContent.String()
 
-	content, _ := ioutil.ReadFile("../../content/post/example.md")
+	// Iterate over emails list and start sending
+	for _, email := range subsList.Subscribers {
 
-	var buf bytes.Buffer
+		// Get the unsubscribe hash string
+		completeContent := addUnsubscribeLink(contentString, email)
 
-	if err := markdown.Convert(content, &buf); err != nil {
-		panic(err)
+		// TODO here: Add image to the top of content if needed
+
+		// Send the email to the recipient
+		err := send(completeContent, email)
+		if err != nil {
+			log.Println("Error while sending mail to subscriber", email, "\nError : ", err)
+		}
 	}
 
-	log.Print(string(buf.String()))
+}
+
+// Utility to get the unsubscribe hash
+func addUnsubscribeLink(contentString string, email string) string {
 
-	send(string(buf.String()), list.Subscribers)
+	// Get the encrypted hash to be sent
+	unsubString := encryptUnsubscribeString(email)
+
+	// Prepare the HTML template of the unsubscribe option (raw as of now)
+	unSubscribeTemplate := fmt.Sprintf("<a href=\"%s/unsubscribe?uniqhash=%s\">UnSubscribe</a>", domain, unsubString)
+
+	// Append the hash to the email body
+	newContent := fmt.Sprintf("%s\n\n%s", contentString, unSubscribeTemplate)
+
+	return newContent
 }
 
-func send(body string, to []string) {
+// Helper function to above to encrypt user email in order to find
+// unsubscribe link hash
+func encryptUnsubscribeString(email string) string {
+
+	// THE EMAIL_ENC_KEY is the base64 encoded string of a 32 byte character string (I hope its right!)
+	encKey := os.Getenv("EMAIL_ENC_KEY")
+
+	// Decode the key to bytes from base64
+	key, err := base64.StdEncoding.DecodeString(encKey)
+	if err != nil {
+		log.Fatalln("Error in decoding key :", err)
+	}
+
+	// convert the string to encrypt to bytes
+	byteSecret := []byte(email)
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		panic(err.Error())
+	}
+
+	// Creating a new GCM
+	aesGCM, err := cipher.NewGCM(block)
+	if err != nil {
+		panic(err.Error())
+	}
+
+	// Creating a nonce. Nonce should be from GCM
+	nonce := make([]byte, aesGCM.NonceSize())
+	if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
+		panic(err.Error())
+	}
+
+	ciphertext := aesGCM.Seal(nonce, nonce, byteSecret, nil)
+	return base64.StdEncoding.EncodeToString(ciphertext)
+}
+
+// Utility to send emails using gomail
+func send(body string, to string) error {
 	from := os.Getenv("MAIL_ID")
 	pass := os.Getenv("MAIL_PASSWORD")
 
-	d := gomail.NewDialer("smtp.gmail.com", 587, from, pass)
-	s, err := d.Dial()
+	dialer := gomail.NewDialer("smtp.gmail.com", 587, from, pass)
+	s, err := dialer.Dial()
 	if err != nil {
-		panic(err)
+		log.Println(err)
+		return err
 	}
 
 	m := gomail.NewMessage()
-	for _, r := range to {
-		m.SetHeader("From", from)
-		m.SetAddressHeader("To", r, r)
-		m.SetHeader("Subject", "Newsletter Test")
-		m.SetBody("text/html", body)
-
-		if err := gomail.Send(s, m); err != nil {
-			log.Printf("Could not send email to %q: %v", r, err)
-		}
-		m.Reset()
+	m.SetHeader("From", from)
+	m.SetAddressHeader("To", to, to)
+	m.SetHeader("Subject", "Newsletter Test")
+	m.SetBody("text/html", body)
+
+	if err := gomail.Send(s, m); err != nil {
+		log.Printf("Could not send email to %q: %v", body, err)
+		return err
 	}
+	m.Reset()
+	return nil
 }

scripts/workers/.gitignore

@@ -0,0 +1,11 @@
+/target
+/dist
+**/*.rs.bk
+Cargo.lock
+bin/
+pkg/
+wasm-pack.log
+worker/
+node_modules/
+.cargo-ok
+wrangler.toml

scripts/workers/README.md

@@ -0,0 +1,15 @@
+# 👷 `worker-template` Hello World
+
+A template for kick starting a Cloudflare worker project.
+
+[`index.js`](https://github.com/cloudflare/worker-template/blob/master/index.js) is the content of the Workers script.
+
+#### Wrangler
+
+To generate using [wrangler](https://github.com/cloudflare/wrangler)
+
+```
+wrangler generate projectname https://github.com/cloudflare/worker-template
+```
+
+Further documentation for Wrangler can be found [here](https://developers.cloudflare.com/workers/tooling/wrangler).

scripts/workers/index.js

@@ -0,0 +1,32 @@
+addEventListener("fetch", (event) => {
+  event.respondWith(handleRequest(event.request));
+});
+
+async function handleRequest(request) {
+  let pathname = new URL(request.url).pathname;
+  if (pathname === "/subscribe") {
+    //TODO check HTTP Request type
+    try {
+      const body = await request.text();
+      let date = Date.now();
+      //TODO perform email validation
+      //TODO check if email already exists
+      //TODO send a confirmation email before actually adding to DB
+      await NL_EMAIL.put(body, date);
+      return new Response("Subscribed", { status: 201 });
+    } catch (error) {
+      return new Response(error || "error", { status: 400 });
+    }
+  } else if (pathname === "/unsubscribe") {
+    try {
+      const body = await request.text();
+      //TODO maybe use encoded request and decode it here
+      await NL_EMAIL.delete(body);
+      return new Response("Unubscribed", { status: 204 });
+    } catch (error) {
+      return new Response(error || "error", { status: 400 });
+    }
+  }
+  const value = await NL_EMAIL.list();
+  return new Response(JSON.stringify(value.keys));
+}

scripts/workers/package.json

@@ -0,0 +1,12 @@
+{
+  "private": true,
+  "name": "workers",
+  "version": "1.0.0",
+  "description": "A template for kick starting a Cloudflare Workers project",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "daemon1024 <[email protected]>",
+  "license": "MIT"
+}

scripts/workers/wrangler.sample.toml

@@ -0,0 +1,5 @@
+name = "workers"
+type = "javascript"
+account_id = ""
+workers_dev = true
+kv_namespaces = [ { binding = "NL_EMAIL", preview_id = "", id = "" }]