X-GM-EXT-1 Gmail Label Extension for Proton Bridge

go.mod

@@ -137,6 +137,7 @@ require (
 )
 
 replace (
+	github.com/ProtonMail/gluon => ../gluon
 	github.com/ProtonMail/go-autostart => github.com/ProtonMail/go-autostart v0.0.0-20250402094843-326608c16033
 	github.com/emersion/go-message => github.com/ProtonMail/go-message v0.13.1-0.20240919135104-3bc88e6a9423
 	github.com/emersion/go-smtp => github.com/ProtonMail/go-smtp v0.0.0-20231109081432-2b3d50599865

internal/services/imapservice/connector.go

@@ -522,6 +522,104 @@ func (s *Connector) MarkMessagesForwarded(ctx context.Context, _ connector.IMAPS
 	return s.client.MarkMessagesUnForwarded(ctx, usertypes.MapTo[imap.MessageID, string](messageIDs)...)
 }
 
+func (s *Connector) MarkMessagesWithGmailLabels(ctx context.Context, _ connector.IMAPStateWrite, messageIDs []imap.MessageID, labels []string, add bool) error {
+	msgIDs := usertypes.MapTo[imap.MessageID, string](messageIDs)
+
+	for _, labelName := range labels {
+		labelID, err := s.resolveGmailLabelID(ctx, labelName, add)
+		if err != nil {
+			return err
+		}
+
+		if labelID == "" {
+			// Label not found and we're removing — skip.
+			continue
+		}
+
+		if add {
+			if err := s.client.LabelMessages(ctx, msgIDs, labelID); err != nil {
+				return fmt.Errorf("failed to label messages with %q: %w", labelName, err)
+			}
+		} else {
+			if err := s.client.UnlabelMessages(ctx, msgIDs, labelID); err != nil {
+				return fmt.Errorf("failed to unlabel messages with %q: %w", labelName, err)
+			}
+		}
+	}
+
+	return nil
+}
+
+// resolveGmailLabelID looks up a Proton label by name. If the label does not exist and add is true,
+// it creates a new label. Returns empty string if the label does not exist and add is false.
+func (s *Connector) resolveGmailLabelID(ctx context.Context, labelName string, create bool) (string, error) {
+	rLabels := s.labels.Read()
+	label, ok := rLabels.GetLabelByName(labelName)
+	rLabels.Close()
+
+	if ok {
+		return label.ID, nil
+	}
+
+	if !create {
+		return "", nil
+	}
+
+	// Auto-create the label.
+	newLabel, err := s.client.CreateLabel(ctx, proton.CreateLabelReq{
+		Name:  labelName,
+		Color: "#f66",
+		Type:  proton.LabelTypeLabel,
+	})
+	if err != nil {
+		return "", fmt.Errorf("failed to create label %q: %w", labelName, err)
+	}
+
+	wLabels := s.labels.Write()
+	wLabels.SetLabel(newLabel.ID, newLabel, "resolveGmailLabelID")
+	wLabels.Close()
+
+	logrus.WithFields(logrus.Fields{
+		"labelName": labelName,
+		"labelID":   newLabel.ID,
+	}).Info("Auto-created Proton label for X-GM-LABELS")
+
+	return newLabel.ID, nil
+}
+
+func (s *Connector) GetGmailLabels(ctx context.Context, messageID imap.MessageID) ([]string, error) {
+	msg, err := s.client.GetMessage(ctx, string(messageID))
+	if err != nil {
+		return nil, fmt.Errorf("failed to get message %v: %w", messageID, err)
+	}
+
+	rLabels := s.labels.Read()
+	defer rLabels.Close()
+
+	var labels []string
+
+	for _, labelID := range msg.LabelIDs {
+		label, ok := rLabels.GetLabel(labelID)
+		if ok && label.Type == proton.LabelTypeLabel {
+			labels = append(labels, label.Name)
+		}
+	}
+
+	return labels, nil
+}
+
+func (s *Connector) GetGmailLabelMailboxID(_ context.Context, label string) (imap.MailboxID, bool) {
+	rLabels := s.labels.Read()
+	defer rLabels.Close()
+
+	l, ok := rLabels.GetLabelByName(label)
+	if !ok {
+		return "", false
+	}
+
+	return imap.MailboxID(l.ID), true
+}
+
 func (s *Connector) GetUpdates() <-chan imap.Update {
 	return s.updateCh.GetChannel()
 }

internal/services/imapservice/shared_labels.go

@@ -40,6 +40,7 @@ type labelsRead interface {
 	Close()
 	GetLabel(id string) (proton.Label, bool)
 	GetLabels() []proton.Label
+	GetLabelByName(name string) (proton.Label, bool)
 }
 
 type labelsWrite interface {
@@ -89,6 +90,16 @@ func (r *rwLabels) getLabelsUnsafe() []proton.Label {
 	return maps.Values(r.labels)
 }
 
+func (r *rwLabels) getLabelByNameUnsafe(name string) (proton.Label, bool) {
+	for _, label := range r.labels {
+		if label.Type == proton.LabelTypeLabel && label.Name == name {
+			return label, true
+		}
+	}
+
+	return proton.Label{}, false
+}
+
 func (r *rwLabels) SetLabels(labels []proton.Label) {
 	r.lock.Lock()
 	defer r.lock.Unlock()
@@ -134,6 +145,10 @@ func (r rwLabelsRead) GetLabels() []proton.Label {
 	return r.rw.getLabelsUnsafe()
 }
 
+func (r rwLabelsRead) GetLabelByName(name string) (proton.Label, bool) {
+	return r.rw.getLabelByNameUnsafe(name)
+}
+
 type rwLabelsWrite struct {
 	rw *rwLabels
 }
@@ -150,6 +165,10 @@ func (r rwLabelsWrite) GetLabels() []proton.Label {
 	return r.rw.getLabelsUnsafe()
 }
 
+func (r rwLabelsWrite) GetLabelByName(name string) (proton.Label, bool) {
+	return r.rw.getLabelByNameUnsafe(name)
+}
+
 func (r rwLabelsWrite) SetLabel(id string, label proton.Label, actionSource string) {
 	logAction("SetLabel", actionSource, label.ID)
 	r.rw.labels[id] = label