Fix archive reindex and add target dedup

backend/05-imap-target.go

@@ -18,6 +18,7 @@ type TargetMailbox interface {
 	Append(folder string, m RawMessage) error // mit m.Flags und m.InternalDate
 	Headers(folder string, limit, offset int) ([]MessageHeader, error)
 	FetchOne(folder string, uid uint32) (RawMessage, error)
+	DeleteUIDs(folder string, uids []uint32) error
 	Close() error
 }
 
@@ -129,6 +130,32 @@ func (t *imapTarget) FetchOne(folder string, uid uint32) (RawMessage, error) {
 	return t.mailbox.fetchOne(folder, uid)
 }
 
+func (t *imapTarget) DeleteUIDs(folder string, uids []uint32) error {
+	if len(uids) == 0 {
+		return nil
+	}
+	if _, err := t.mailbox.c.Select(folder, nil).Wait(); err != nil {
+		return err
+	}
+	uidSet := imap.UIDSetNum(uint32sToUIDs(uids)...)
+	flags := &imap.StoreFlags{Op: imap.StoreFlagsAdd, Silent: true, Flags: []imap.Flag{imap.FlagDeleted}}
+	if err := t.mailbox.c.Store(uidSet, flags, nil).Close(); err != nil {
+		return err
+	}
+	_, err := t.mailbox.c.UIDExpunge(uidSet).Collect()
+	return err
+}
+
 func (t *imapTarget) Close() error {
 	return t.mailbox.Close()
 }
+
+func uint32sToUIDs(values []uint32) []imap.UID {
+	out := make([]imap.UID, 0, len(values))
+	for _, value := range values {
+		if value != 0 {
+			out = append(out, imap.UID(value))
+		}
+	}
+	return out
+}