invites: reply with accept, accept-tentative or decline

Reply to iCalendar invitations with three commands: :accept,
:accept-tentative or :decline. Parse a text/calendar request, create a
reply and append it to the composer.

Suggested-by: Ondřej Synáček <ondrej@synacek.org>
Signed-off-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 190 insertions, 0 deletions

diff --git a/commands/msg/invite.go b/commands/msg/invite.go
new file mode 100644
index 00000000..c15e2653
--- /dev/null
+++ b/commands/msg/invite.go
@@ -0,0 +1,190 @@
+package msg
+
+import (
+	"errors"
+	"fmt"
+	"io"
+
+	"git.sr.ht/~rjarry/aerc/lib"
+	"git.sr.ht/~rjarry/aerc/lib/calendar"
+	"git.sr.ht/~rjarry/aerc/lib/format"
+	"git.sr.ht/~rjarry/aerc/models"
+	"git.sr.ht/~rjarry/aerc/widgets"
+	"github.com/emersion/go-message/mail"
+)
+
+type invite struct{}
+
+func init() {
+	register(invite{})
+}
+
+func (invite) Aliases() []string {
+	return []string{"accept", "accept-tentative", "decline"}
+}
+
+func (invite) Complete(aerc *widgets.Aerc, args []string) []string {
+	return nil
+}
+
+func (invite) Execute(aerc *widgets.Aerc, args []string) error {
+
+	acct := aerc.SelectedAccount()
+	if acct == nil {
+		return errors.New("no account selected")
+	}
+	store := acct.Store()
+	if store == nil {
+		return errors.New("cannot perform action: messages still loading")
+	}
+	msg, err := acct.SelectedMessage()
+	if err != nil {
+		return err
+	}
+
+	part := lib.FindCalendartext(msg.BodyStructure, nil)
+	if part == nil {
+		return fmt.Errorf("no invitation found (missing text/calendar)")
+	}
+
+	subject := trimLocalizedRe(msg.Envelope.Subject)
+	switch args[0] {
+	case "accept":
+		subject = "Accepted: " + subject
+	case "accept-tentative":
+		subject = "Tentatively Accepted: " + subject
+	case "decline":
+		subject = "Declined: " + subject
+	default:
+		return fmt.Errorf("no participation status defined")
+	}
+
+	conf := acct.AccountConfig()
+	from, err := mail.ParseAddress(conf.From)
+	if err != nil {
+		return err
+	}
+	var aliases []*mail.Address
+	if conf.Aliases != "" {
+		aliases, err = mail.ParseAddressList(conf.Aliases)
+		if err != nil {
+			return err
+		}
+	}
+
+	// figure out the sending from address if we have aliases
+	if len(aliases) != 0 {
+		rec := newAddrSet()
+		rec.AddList(msg.Envelope.To)
+		rec.AddList(msg.Envelope.Cc)
+		// test the from first, it has priority over any present alias
+		if rec.Contains(from) {
+			// do nothing
+		} else {
+			for _, a := range aliases {
+				if rec.Contains(a) {
+					from = a
+					break
+				}
+			}
+		}
+	}
+
+	var (
+		to []*mail.Address
+	)
+
+	if len(msg.Envelope.ReplyTo) != 0 {
+		to = msg.Envelope.ReplyTo
+	} else {
+		to = msg.Envelope.From
+	}
+
+	if !aerc.Config().Compose.ReplyToSelf {
+		for i, v := range to {
+			if v.Address == from.Address {
+				to = append(to[:i], to[i+1:]...)
+				break
+			}
+		}
+		if len(to) == 0 {
+			to = msg.Envelope.To
+		}
+	}
+
+	recSet := newAddrSet() // used for de-duping
+	recSet.AddList(to)
+
+	h := &mail.Header{}
+	h.SetAddressList("from", []*mail.Address{from})
+	h.SetSubject(subject)
+	h.SetMsgIDList("in-reply-to", []string{msg.Envelope.MessageId})
+	err = setReferencesHeader(h, msg.RFC822Headers)
+	if err != nil {
+		aerc.PushError(fmt.Sprintf("could not set references: %v", err))
+	}
+	original := models.OriginalMail{
+		From:          format.FormatAddresses(msg.Envelope.From),
+		Date:          msg.Envelope.Date,
+		RFC822Headers: msg.RFC822Headers,
+	}
+
+	handleInvite := func(reader io.Reader) (*calendar.Reply, error) {
+		cr, err := calendar.CreateReply(reader, from, args[0])
+		if err != nil {
+			return nil, err
+		}
+		for _, org := range cr.Organizers {
+			organizer, err := mail.ParseAddress(org)
+			if err != nil {
+				continue
+			}
+			if !recSet.Contains(organizer) {
+				to = append(to, organizer)
+			}
+		}
+		h.SetAddressList("to", to)
+		return cr, nil
+	}
+
+	addTab := func(cr *calendar.Reply) error {
+		composer, err := widgets.NewComposer(aerc, acct, aerc.Config(),
+			acct.AccountConfig(), acct.Worker(), "", h, original)
+		if err != nil {
+			aerc.PushError("Error: " + err.Error())
+			return err
+		}
+
+		composer.SetContents(cr.PlainText)
+		composer.AppendPart(cr.MimeType, cr.Params, cr.CalendarText)
+		composer.FocusTerminal()
+
+		tab := aerc.NewTab(composer, subject)
+		composer.OnHeaderChange("Subject", func(subject string) {
+			if subject == "" {
+				tab.Name = "New email"
+			} else {
+				tab.Name = subject
+			}
+			tab.Content.Invalidate()
+		})
+
+		composer.OnClose(func(c *widgets.Composer) {
+			if c.Sent() {
+				store.Answered([]uint32{msg.Uid}, true, nil)
+			}
+		})
+
+		return nil
+	}
+
+	store.FetchBodyPart(msg.Uid, part, func(reader io.Reader) {
+		if cr, err := handleInvite(reader); err != nil {
+			aerc.PushError(err.Error())
+			return
+		} else {
+			addTab(cr)
+		}
+	})
+	return nil
+}