appcore/email/transport_smtp.go

// Copyright 2024 Patial Tech (Ankit Patial).
//
// This file is part of code.patial.tech/go/appcore, which is MIT licensed.
// See http://opensource.org/licenses/MIT

package email

import (
	"fmt"
	"log/slog"
	"strings"

	"code.patial.tech/go/appcore/email/gomail"
	"code.patial.tech/go/appcore/uid"
)

// SMTP mailer
type SMTP struct {
	Host     string
	Port     int
	Username string
	Password string
	// Domain name for smtp
	Domain string
}

func (t SMTP) Send(msg *Message) error {
	slog.Info("sending mail", slog.String("smtp", t.Host))
	// validate msg
	if err := msg.Validate(); err != nil {
		return err
	}

	toCount := len(msg.To)
	m := gomail.NewMessage()
	if msg.ID != "" {
		m.SetHeader("Message-ID", fmt.Sprintf("<%s>", msg.ID))
	} else {
		uid, err := uid.NewUUID()
		if err != nil {
			return err
		}

		id := strings.Replace(uid, "-", "", -1)
		msgID := fmt.Sprintf("<autogen-%s@%s>", id, t.Domain)
		m.SetHeader("Message-ID", msgID)
	}

	m.SetHeader("From", msg.From)

	// TO
	to := make([]string, toCount)
	for i, address := range msg.To {
		to[i] = address.String()
	}
	m.SetHeader("To", to...)

	// subject
	m.SetHeader("Subject", msg.Subject)

	// CC
	ccCount := len(msg.Cc)
	if ccCount > 0 {
		cc := make([]string, ccCount)
		for i, address := range msg.Cc {
			cc[i] = address.String()
		}
		m.SetHeader("Cc", cc...)
	}

	// BCC
	bccCount := len(msg.Bcc)
	if bccCount > 0 {
		bcc := make([]string, bccCount)
		for i, address := range msg.Bcc {
			bcc[i] = address.String()
		}
		m.SetHeader("Bcc", bcc...)
	}

	m.SetBody("text/html", msg.HtmlBody)

	slog.Info("dialing...", slog.String("host", t.Host), slog.Int("port", t.Port))
	d := gomail.NewDialer(t.Host, t.Port, t.Username, t.Password)
	if err := d.DialAndSend(m); err != nil {
		return err
	}

	slog.Info("sent email %s" + msg.Subject)
	return nil
}