backup/email.go

package main

import (
	"encoding/base64"
	"fmt"
	"net/smtp"
	"sort"
	"strings"
	"sync"
	"time"

	log "github.com/sirupsen/logrus"
)

type Email struct {
	startTime time.Time
	items     []string
	mx        sync.Mutex
}

type EmailConfig struct {
	SmtpHost  string   `json:"smtp"`
	FromEmail string   `json:"email_from"`
	ToEmail   []string `json:"email_to"`
}

func NewEmail(now time.Time) *Email {
	log.WithFields(log.Fields{"now": now}).Debugf("starting")
	defer log.WithFields(log.Fields{"now": now}).Debugf("done")

	return &Email{startTime: now, items: make([]string, 0)}
}

func (e *Email) AddItem(item string) {
	log.WithFields(log.Fields{"item": item}).Debugf("starting")
	defer log.WithFields(log.Fields{"item": item}).Debugf("done")

	e.items = append(e.items, item)
}

func (e *Email) Send() error {
	log.WithFields(log.Fields{}).Debugf("starting")
	defer log.WithFields(log.Fields{}).Debugf("done")

	if len(e.items) == 0 {
		return nil
	}

	sort.Slice(e.items, func(i, j int) bool {
		return e.items[i] < e.items[j]
	})

	body := e.items[0]
	for _, item := range e.items[1:] {
		body = body + "\r\n" + item
	}

	subject := fmt.Sprintf("Autobackup report (%s)", e.startTime)

	if err := SendMail(cfg.Email.SmtpHost, cfg.Email.FromEmail, subject, body, cfg.Email.ToEmail); err != nil {
		log.WithFields(log.Fields{"addr": cfg.Email.SmtpHost, "from": cfg.Email.FromEmail, "subject": subject, "call": "SendMail", "error": err}).Errorf("")
		return err
	}

	return nil

}

func SendMail(addr, from, subject, body string, to []string) error {
	log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject}).Debugf("starting")
	defer log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject}).Debugf("done")

	r := strings.NewReplacer("\r\n", "", "\r", "", "\n", "", "%0a", "", "%0d", "")

	c, err := smtp.Dial(addr)
	if err != nil {
		log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject, "call": "smtp.Dial", "error": err}).Errorf("")
		return err
	}

	defer c.Close()

	if err = c.Mail(r.Replace(from)); err != nil {
		log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject, "call": "client.Mail", "error": err}).Errorf("")
		return err
	}

	for i := range to {
		to[i] = r.Replace(to[i])
		if err = c.Rcpt(to[i]); err != nil {
			log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject, "call": "client.Rcpt", "attr": to[i], "error": err}).Errorf("")
			return err
		}
	}

	w, err := c.Data()
	if err != nil {
		log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject, "call": "client.Date", "error": err}).Errorf("")
		return err
	}

	msg := "Date: " + time.Now().Format("Mon, 02 Jan 2006 15:04:05 -0700") + "\r\n" +
		"To: " + strings.Join(to, ",") + "\r\n" +
		"From: " + from + "\r\n" +
		"Subject: " + subject + "\r\n" +
		"Content-Type: text/plain; charset=\"UTF-8\"\r\n" +
		"Content-Transfer-Encoding: base64\r\n" +
		"\r\n" + base64.StdEncoding.EncodeToString([]byte(body))

	_, err = w.Write([]byte(msg))
	if err != nil {
		log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject, "call": "writer.Write", "error": err}).Errorf("")
		return err
	}

	err = w.Close()
	if err != nil {
		log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject, "call": "writer.Close", "error": err}).Errorf("")
		return err
	}

	if err = c.Quit(); err != nil {
		log.WithFields(log.Fields{"addr": addr, "from": from, "subject": subject, "call": "client.Quit", "error": err}).Errorf("")
		return err
	}
	return nil
}