mailblog/imap.go

package main

import (
	"bytes"
	"fmt"
	"html/template"
	"io"
	"log"
	"mime"
	"sort"
	"strconv"
	"strings"

	/*
		_ "golang.org/x/net/html"
		_ "golang.org/x/net/html/atom"
	*/
	"github.com/emersion/go-imap/v2"
	"github.com/emersion/go-imap/v2/imapclient"
	"github.com/emersion/go-message/charset"
	"github.com/emersion/go-message/mail"
	"golang.org/x/net/html"
)

type MailBox struct {
	Server   string
	Port     uint16
	User     string
	Password string
	SSL      string
	InBox    string
	Client   *imapclient.Client
}

func (mb *MailBox) Configure(conf *MailBoxConfiguration) error {

	mb.Server = conf.Server
	port, err := strconv.ParseUint(conf.Port, 10, 16)
	if err != nil {
		return err
	}
	mb.Port = uint16(port)
	mb.User = conf.User
	mb.Password = conf.Password
	mb.SSL = conf.SSL
	mb.InBox = conf.InBox
	return nil
}
func (mb *MailBox) ListMessages() (string, error) {
	return "", nil
}

func (mb *MailBox) Connect() error {
	options := &imapclient.Options{
		WordDecoder: &mime.WordDecoder{CharsetReader: charset.Reader},
	}
	var err error
	imapServer := fmt.Sprintf("%s:%d", mb.Server, mb.Port)
	switch mb.SSL {
	case "SSL/TLS":
		mb.Client, err = imapclient.DialTLS(imapServer, options)
	case "StartTLS":
		mb.Client, err = imapclient.DialStartTLS(imapServer, options)
	case "NoTLS":
		mb.Client, err = imapclient.DialInsecure(imapServer, options)
	default:
		return fmt.Errorf("bad tls configuration")
	}
	if err != nil {
		log.Println("Error connnecting to", imapServer, ":", err)
		return err
	}

	err = mb.Client.Login(mb.User, mb.Password).Wait()
	if err != nil {
		log.Fatal("failed to login:", err)
	}
	return nil
}
func (mb *MailBox) ListFolders() ([]string, error) {
	folders := make([]string, 0)
	mailBoxes, err := mb.Client.List("", "%", nil).Collect()
	if err != nil {
		return nil, err
	}
	for _, mbox := range mailBoxes {
		folders = append(folders, mbox.Mailbox)
	}
	return folders, nil
}
func (mb *MailBox) GetMessages() ([]Post, error) {

	inbox, err := mb.Client.Select(mb.InBox, nil).Wait()
	if err != nil {
		log.Fatal("Error selecting mailbox:", mb.InBox, err)
	}
	log.Println("Inbox has", inbox.NumMessages, "messages")

	if inbox.NumMessages <= 0 {
		return nil, fmt.Errorf("nomessages")
	}
	posts := make([]Post, 0)
	for i := uint32(1); i <= inbox.NumMessages; i++ {
		var post Post
		seqSet := imap.SeqSetNum(i)
		bodySection := &imap.FetchItemBodySection{}
		fetchOptions := &imap.FetchOptions{
			Envelope:    true,
			BodySection: []*imap.FetchItemBodySection{bodySection},
		}
		messages, err := mb.Client.Fetch(seqSet, fetchOptions).Collect()
		if err != nil {
			log.Fatal("Error fetching mails:", err)
		}
		post.Title = strings.Trim(messages[0].Envelope.Subject, "\t ")
		if !strings.HasPrefix(strings.ToLower(post.Title), "blog ") {
			continue
		}

		post.Id = messages[0].Envelope.MessageID
		post.Title = post.Title[5:] // remove first chars = blog+whitespace
		post.Author = messages[0].Envelope.To[0].Name

		post.Date = messages[0].Envelope.Date.Format("2006/01/02 15:04")
		post.DateTime = messages[0].Envelope.Date

		section := messages[0].FindBodySection(bodySection)

		ioReader := bytes.NewReader(section)
		mailReader, err := mail.CreateReader(ioReader)
		if err != nil {
			return nil, err
		}
		for {
			part, err := mailReader.NextPart()
			if err == io.EOF {
				break
			} else if err != nil {
				return nil, err
			}

			switch part.Header.(type) {
			case *mail.AttachmentHeader:
				/*
					filename, _ := header.Filename()

					log.Println("------------FILE-----------")
					log.Println("Attachment:", filename)
				*/
			case *mail.InlineHeader:

				body, _ := io.ReadAll(part.Body)
				contentTypeFull := strings.TrimPrefix(
					strings.ToLower(part.Header.Get("Content-Type")), "content-type")
				mediaType, _, err := mime.ParseMediaType(strings.TrimLeft(contentTypeFull, ": "))
				if err != nil {
					return nil, err
				}
				switch mediaType {
				case "text/plain":
					if len(post.HTML) == 0 {
						post.Text = string(body)
						post.GenerateExcerpt()
					}
				case "text/html":
					post.HTML = ""
					nodes, err := html.Parse(strings.NewReader(string(body)))
					if err != nil {
						post.HTML = ""
						break
					}
					htmlNode, err := findHTMLNode(nodes)
					if err != nil {
						post.HTML = ""
						break
					}
					var buf bytes.Buffer
					err = nil
					for child := htmlNode.FirstChild; child != nil; child = child.NextSibling {
						err = html.Render(&buf, child)
						if err != nil {
							post.HTML = ""
							break
						}
					}
					if err == nil {
						post.HTML = template.HTML(buf.String())
						post.GenerateExcerpt()
					}
				default:
					log.Println("Content-Type:", part.Header.Get("Content-Type"))

				}

			default:
				log.Printf("Unkown part type %+v", part)
			}
		}
		posts = append(posts, post)
	}
	sort.Slice(posts, func(i, j int) bool {
		return posts[i].DateTime.After(posts[j].DateTime)
	})
	return posts, nil
}

func (mb *MailBox) Close() {
	mb.Client.Close()
}

func findHTMLNode(node *html.Node) (*html.Node, error) {
	if node.Type == html.ElementNode && node.Data == "body" {
		return node, nil
	}
	for e := node.FirstChild; e != nil; e = node.NextSibling {
		n, err := findHTMLNode(e)
		if err == nil {
			return n, nil
		}

	}
	return nil, fmt.Errorf("notfound")
}