message-info: add explicit References field

Add an explicit References field to message info. This is useful for
storing information needed for threading without storing all of the
header values, keeping system RAM usage lower.

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Tested-by: Inwit <inwit@sindominio.net>
Acked-by: Robin Jarry <robin@jarry.cc>

models/models.go

@@ -71,6 +71,7 @@ type MessageInfo struct {
 	Labels        []string
 	InternalDate  time.Time
 	RFC822Headers *mail.Header
+	Refs          []string
 	Size          uint32
 	Uid           uint32
 	Error         error
@@ -110,6 +111,9 @@ func (mi *MessageInfo) References() ([]string, error) {
 	if mi == nil {
 		return []string{}, errors.New("msg is nil")
 	}
+	if mi.Refs != nil {
+		return mi.Refs, nil
+	}
 	if mi.RFC822Headers == nil {
 		return []string{}, errors.New("header is nil")
 	}

worker/imap/cache.go

@@ -118,6 +118,10 @@ func (w *IMAPWorker) getCachedHeaders(msg *types.FetchMessageHeaders) []uint32 {
 			Uid:           ch.Uid,
 			RFC822Headers: hdr,
 		}
+		refs, err := hdr.MsgIDList("references")
+		if err != nil {
+			mi.Refs = refs
+		}
 		logging.Debugf("located cached header %s.%s", uv, u)
 		w.worker.PostMessage(&types.MessageInfo{
 			Message:    types.RespondTo(msg),

worker/imap/fetch.go

@@ -62,6 +62,10 @@ func (imapw *IMAPWorker) handleFetchMessageHeaders(
 				RFC822Headers: header,
 				Uid:           _msg.Uid,
 			}
+			refs, err := header.MsgIDList("references")
+			if err != nil {
+				info.Refs = refs
+			}
 			imapw.worker.PostMessage(&types.MessageInfo{
 				Message: types.RespondTo(msg),
 				Info:    info,

worker/lib/parse.go

@@ -348,11 +348,16 @@ func MessageHeaders(raw RawMessage) (*models.MessageInfo, error) {
 	if err != nil {
 		return nil, err
 	}
+	refs, err := h.MsgIDList("references")
+	if err != nil {
+		return nil, err
+	}
 	return &models.MessageInfo{
 		Envelope:     env,
 		Flags:        flags,
 		Labels:       labels,
 		InternalDate: recDate,
+		Refs:         refs,
 		Size:         0,
 		Uid:          raw.UID(),
 		Error:        parseErr,