Make Email Async

auth/otp.go

@@ -40,10 +40,13 @@ func GenerateOtp(rollNo string) error {
 		return errors.NewHTTPError(err, http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
 	}
 
-	if err = mail.SendOTP(rollNo, otp); err != nil {
-		return errors.NewHTTPError(err, http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
+	emailRequest := mail.EmailRequest{
+		To:     rollNo,
+		OTP:    otp,
 	}
 
+	mail.MailChannel <- emailRequest
+
 	return nil
 }
 

cmd/iitk-coin/main.go

@@ -4,6 +4,7 @@ import (
 	_ "github.com/bhuvansingla/iitk-coin/config"
 	"github.com/bhuvansingla/iitk-coin/database"
 	_ "github.com/bhuvansingla/iitk-coin/logger"
+	"github.com/bhuvansingla/iitk-coin/mail"
 	"github.com/bhuvansingla/iitk-coin/server"
 	log "github.com/sirupsen/logrus"
 )
@@ -15,6 +16,12 @@ func main() {
 		log.Error("Error connecting to database: %s", err)
 		return
 	}
+
+	err =  mail.Test()
+	if err != nil {
+		log.Error("Error sending mail: %s", err)
+		return
+	}
 
 	err = server.Start()
 	if err != nil {

mail/config.go

@@ -0,0 +1,43 @@
+package mail
+
+import (
+	"net/smtp"
+
+	"github.com/spf13/viper"
+)
+
+type smtpServer struct {
+	host string
+	port string
+}
+
+func (s *smtpServer) Address() string {
+	return s.host + ":" + s.port
+}
+
+type EmailRequest struct {
+	To  string
+	OTP string
+}
+
+var MailChannel chan EmailRequest
+var from string
+var password string
+var server smtpServer
+var auth smtp.Auth
+var otpValidity string
+
+func init() {
+	MailChannel = make(chan EmailRequest)
+	from = viper.GetString("MAIL.FROM")
+	password = viper.GetString("MAIL.PASSWORD")
+
+	otpValidity = viper.GetString("OTP.EXPIRY_PERIOD_IN_MIN")
+
+	server = smtpServer{host: viper.GetString("MAIL.HOST"), port: viper.GetString("MAIL.PORT")}
+	go mailService(MailChannel)
+}
+
+func authorize() {
+	auth = smtp.PlainAuth("", from, password, server.host)
+}

mail/service.go

@@ -0,0 +1,34 @@
+package mail
+
+import (
+	"net/smtp"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func mailService(mailChannel chan EmailRequest) {
+	authorize()
+	for request := range mailChannel {
+		to := []string{request.To+"@iitk.ac.in"}
+		msg := []byte("To: " + request.To + "@iitk.ac.in" + "\n" +
+			"From: " + "IITK-Coin<" + from + ">\n" +
+			"Subject: IITK-Coin One Time Password\n" +
+			"Your OTP is " + request.OTP + "\n" +
+			"This OTP is valid for " + otpValidity + " minutes and don't share it with anyone." + 
+			"\n")
+
+		err := smtp.SendMail(server.Address(), auth, from, to, msg)
+
+		// if error, try to login again
+		if err != nil {
+			authorize()
+			err = smtp.SendMail(server.Address(), auth, from, to, msg)
+			if err != nil {
+				log.Error("Error sending mail: " + err.Error())
+				continue
+			}
+		}
+
+		log.Info("Mail sent to ", request.To)
+	}
+}

mail/test.go

@@ -0,0 +1,24 @@
+package mail
+
+import (
+	"net/smtp"
+
+	log "github.com/sirupsen/logrus"
+)
+
+func Test() (err error) {
+	authorize()
+	to := []string{from}
+	msg := []byte("To: " + from + "\n" +
+		"From: " + "IITK-Coin<" + from + ">\n" +
+		"Subject: IITK-Coin Test Mail\n" +
+		"This is a Test Mail" + 
+		"\n")
+
+	err = smtp.SendMail(server.Address(), auth, from, to, msg)
+	if err != nil {
+		return
+	}
+	log.Info("Test mail sent")
+	return
+}