worker/internal/notifier/email.go

// Package notifier provides functionality.
package notifier

import (
	"crypto/tls"
	"errors"
	"fmt"
	"net/mail"

	"github.com/microcosm-cc/bluemonday"
	"gopkg.in/gomail.v2"

	"rocketgit.ru/rsmon/worker/app/models"
)

// SendEmail provides functionality.
func SendEmail(to, subject, body string) error {
	p := bluemonday.StripTagsPolicy()
	cred, err := firstSMTPCredential()
	if err != nil {
		return err
	}

	fromAddr := &mail.Address{Name: cred.fromName, Address: cred.fromAddress}
	from := fromAddr.String()

	m := gomail.NewMessage()
	m.SetHeader("From", from)
	m.SetHeader("To", to)
	m.SetHeader("Subject", subject)
	// m.SetBody("text/html", body)
	m.AddAlternative("text/plain", p.Sanitize(body))
	m.AddAlternative("text/html", body)

	d := gomail.NewDialer(
		cred.server,
		cred.port,
		cred.login,
		cred.password,
	)
	if cred.insecureSkipVerify {
		d.TLSConfig = &tls.Config{InsecureSkipVerify: true}
	}

	return d.DialAndSend(m)
}

type smtpCredential struct {
	server             string
	port               int
	login              string
	password           string
	fromName           string
	fromAddress        string
	insecureSkipVerify bool
}

func firstSMTPCredential() (*smtpCredential, error) {
	creds, err := models.EnabledCredentialsByKind(models.CredentialKindSMTP)
	if err != nil {
		return nil, err
	}
	if len(creds) == 0 {
		return nil, errors.New("smtp credential is not configured")
	}
	c := &creds[0]
	password, err := c.GetSecret()
	if err != nil {
		return nil, fmt.Errorf("smtp credential secret: %w", err)
	}
	out := &smtpCredential{password: password, insecureSkipVerify: c.InsecureSkipVerify}
	if c.Server != nil {
		out.server = *c.Server
	}
	if c.Port != nil {
		out.port = *c.Port
	}
	if c.Login != nil {
		out.login = *c.Login
	}
	if c.FromName != nil {
		out.fromName = *c.FromName
	}
	if c.FromAddr != nil {
		out.fromAddress = *c.FromAddr
	}
	return out, nil
}