backup-utils

package main

import (

	"fmt"

	"log"

	"os"

	"path/filepath"

	"github.com/alexflint/go-arg"

	"github.com/emersion/go-imap"

	"github.com/emersion/go-imap/client"

)

const Version = "0.0.1"

func main() {

	var args struct {

		Address  string `arg:"positional,required"`

		Username string `arg:"positional,required"`

		Password string `arg:"positional,required"`

		Output   string `arg:"-o" help:"Output directory" default:"mail"`

	}

	if err := arg.Parse(&args); err != nil {

		switch err {

		case arg.ErrHelp:

			fmt.Print(help)

			os.Exit(0)

		case arg.ErrVersion:

			fmt.Print(version)

			os.Exit(0)

		}

		fmt.Println(err.Error())

		os.Exit(-1)

	}

	c, err := client.DialTLS(args.Address, nil)

	if err != nil {

		log.Fatalln(err.Error())

	}

	defer c.Logout()

	if err := c.Login(args.Username, args.Password); err != nil {

		log.Fatalln(err.Error())

	}

	mailboxes, err := Mailboxes(c)

	if err != nil {

		log.Fatalln(err.Error())

	}

	for _, m := range mailboxes {

		if m.Name == "Trash" {

			log.Println("Skipping Trash")

			continue

		}

		log.Println(m.Name)

		if err := FetchMailbox(c, m, args.Output); err != nil {

			log.Fatalln(err.Error())

		}

	}

}

/* Get list of Mailboxes. */

func Mailboxes(c *client.Client) ([]*imap.MailboxInfo, error) {

	ch := make(chan *imap.MailboxInfo, 6)

	done := make(chan error, 1)

	go func() { done <- c.List("", "*", ch) }()

	var mailboxes []*imap.MailboxInfo

	for m := range ch {

		mailboxes = append(mailboxes, m)

	}

	if err := <-done; err != nil {

		return nil, err

	}

	return mailboxes, nil

}

func FetchMailbox(c *client.Client, mailbox *imap.MailboxInfo, dir string) error {

	mbox, err := c.Select(mailbox.Name, true)

	if err != nil {

		return err

	}

	if err := os.MkdirAll(filepath.Join(dir, mailbox.Name), 0o777); err != nil {

		return err

	}

	if mbox.Messages == 0 {

		return nil

	}

	seqset := new(imap.SeqSet)

	seqset.AddRange(1, mbox.Messages)

	section := &imap.BodySectionName{Peek: false}

	items := []imap.FetchItem{imap.FetchAll, section.FetchItem()}

	messages := make(chan *imap.Message, 10)

	done := make(chan error, 1)

	go func() {

		done <- c.Fetch(seqset, items, messages)

	}()

	for msg := range messages {

		body := msg.GetBody(section)

		if body == nil {

			return fmt.Errorf("message body is nil")

		}

		data := make([]byte, body.Len())

		if _, err := body.Read(data); err != nil {

			return err

		}

		file, err := os.Create(

			filepath.Join(dir, mailbox.Name, fmt.Sprintf(

				"%s_%d.eml", msg.InternalDate.UTC().Format("20060102T150405Z"), msg.SeqNum,

			)),

		)

		if err != nil {

			return err

		}

		if _, err := file.Write(data); err != nil {

			file.Close()

			return err

		}

		log.Println(mailbox.Name, "->", msg.Envelope.Subject)

		file.Close()

	}

	if err := <-done; err != nil {

		return err

	}

	return nil

}

const help = ``

const version = "backup-imap, version " + Version + "\n"