gomailer/pkg/mail.go

package gomailer

import (
	"crypto/tls"
	"github.com/wneessen/go-mail"
	ht "html/template"
	"log"
)

type MailSettings struct {
	Subject  string
	From     string
	To       string
	Cc       string
	Inline   bool
	Template string
}

type MailServer struct {
	Port       int
	Host       string
	Username   string
	Password   string
	Tls        string
	Authtype   string
	Skipverify bool
}

func SendMail(mailsettings MailSettings, serversettings MailServer) {
	html := LoadTemplate(mailsettings.Template, true)

	m := mail.NewMsg()
	if err := m.From(mailsettings.From); err != nil {
		log.Fatalf("failed to set From address: %s", err)
	}
	if err := m.To(mailsettings.From); err != nil {
		log.Fatalf("failed to set To address: %s", err)
	}

	m.Subject(mailsettings.Subject)

	htpl, err := ht.New("htmltpl").Parse(html)
	if err != nil {
		log.Fatalf("failed to parse text template: %s", err)
	}

	// embedd images
	for _, val := range FindSrcInHtml(html) {
		log.Println("Embedding: " + val)
		m.EmbedFile(val)
	}

	// set template
	m.SetBodyHTMLTemplate(htpl, nil)

	// generate client
	c, err := getClient(serversettings)
	if err != nil {
		log.Fatalf("failed to create mail client: %s", err)
	}

	// send mail
	if err := c.DialAndSend(m); err != nil {
		log.Fatalf("failed to send mail: %s", err)
	}
}

func getClient(config MailServer) (*mail.Client, error) {
	var authType mail.SMTPAuthType
	switch config.Authtype {
	case "plain":
		authType = mail.SMTPAuthPlain
	case "login":
		authType = mail.SMTPAuthLogin
	case "cram-md5":
		authType = mail.SMTPAuthCramMD5
	}

	// tlsPolicy := mail.TLSOpportunistic
	tlsPolicy := mail.DefaultTLSPolicy
	switch config.Tls {
	case "notls":
		tlsPolicy = mail.NoTLS
	case "mandatory":
		tlsPolicy = mail.TLSMandatory
	}

	opts := []mail.Option{
		mail.WithPort(config.Port),
		mail.WithTLSPolicy(tlsPolicy),
		mail.WithTLSConfig(&tls.Config{
			InsecureSkipVerify: config.Skipverify,
		}),
	}

	if config.Authtype != "nologin" {
		opts = append(opts, mail.WithSMTPAuth(authType))
	}

	if config.Username != "" {
		opts = append(opts, mail.WithUsername(config.Username))
	}

	if config.Password != "" {
		opts = append(opts, mail.WithPassword(config.Password))
	}

	return mail.NewClient(
		config.Host,
		opts...,
	)
}