greenhouse/email_service.go

package main

import (
	"log"
	"strings"
	"time"

	errors "git.sequentialread.com/forest/pkg-errors"

	mail "github.com/xhit/go-simple-mail"
)

type EmailService struct {
	Host       string
	Port       int
	Username   string
	Password   string
	Encryption string
}

func (emailService *EmailService) Initialize() error {
	if emailService.Encryption == "" {
		emailService.Encryption = "STARTTLS"
	}
	if emailService.Encryption != "STARTTLS" && emailService.Encryption != "SMTPS" {
		return errors.New("EmailService.Encryption must be set to STARTTLS or SMTPS")
	}
	return nil
}

func (emailService *EmailService) ValidateEmailAddress(email string) string {
	if len(email) == 0 {
		return "email is required"
	} else if len(email) < 6 || strings.Count(email, "@") != 1 || strings.Count(email, ".") < 1 || strings.LastIndex(email, ".") < strings.LastIndex(email, "@") {
		return "email must be a valid email address, like user@example.com"
	}
	return ""
}

func (emailService *EmailService) SendEmail(subject, recipient, body string) error {

	recipientError := emailService.ValidateEmailAddress(recipient)
	if recipientError != "" {
		return errors.New(recipientError)
	}
	smtpClient := mail.NewSMTPClient()
	smtpClient.Host = emailService.Host
	smtpClient.Port = emailService.Port
	smtpClient.Username = emailService.Username
	smtpClient.Password = emailService.Password
	if emailService.Encryption == "STARTTLS" {
		smtpClient.Encryption = mail.EncryptionTLS
	} else {
		smtpClient.Encryption = mail.EncryptionSSL
	}
	smtpClient.KeepAlive = false
	smtpClient.ConnectTimeout = 10 * time.Second
	smtpClient.SendTimeout = 10 * time.Second
	smtpConn, err := smtpClient.Connect()
	if err != nil {
		log.Printf("SendEmail(): could not connect to email server: %+v", err)
		return errors.New("could not connect to email server")
	}
	email := mail.NewMSG()
	email.SetFrom(emailService.Username)
	email.AddTo(recipient)
	email.SetSubject(subject)
	email.SetBody(mail.TextPlain, body)
	err = email.Send(smtpConn)
	if err != nil {
		log.Printf("SendEmail(): connected to email server, but could not send mail: %+v", err)
		return errors.New("connected to email server, but could not send mail")
	}
	return nil
}