feat(GODT-2576): Support for Forward flags

Necessary changes required to support forward flags. These are
non-standard IMAP flags that can be assigned to mailboxes. Thunderbird
uses `$Forwarded` and Apple Mail issues both `$Forwarded` and `Forwarded`.
Unfortunately, Outlook (office 365) does not support any non-standard
IMAP flags.

This patch extends the connector with the `MarkMessageForwarded` as the
forwarded setting is applied after a message is sent.

Every time we apply a forward flag, we ensure that all known forwarding
flags are set so that it works with all known variations.

Author: LBeernaertProton

benchmarks/gluon_bench/gluon_benchmarks/sync.go

@@ -156,6 +156,14 @@ func init() {
 
 type nullIMAPStateWriter struct{}
 
+func (n nullIMAPStateWriter) AddFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	panic("implement me")
+}
+
+func (n nullIMAPStateWriter) AddPermFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	panic("implement me")
+}
+
 func (n nullIMAPStateWriter) GetSettings(ctx context.Context) (string, bool, error) {
 	return "", false, nil
 }

connector/connector.go

@@ -54,6 +54,9 @@ type Connector interface {
 	// MarkMessagesFlagged sets the flagged value of the given messages.
 	MarkMessagesFlagged(ctx context.Context, cache IMAPStateWrite, messageIDs []imap.MessageID, flagged bool) error
 
+	// MarkMessagesForwarded sets the forwarded value of the give messages.
+	MarkMessagesForwarded(ctx context.Context, cache IMAPStateWrite, messageIDs []imap.MessageID, forwarded bool) error
+
 	// GetUpdates returns a stream of updates that the gluon server should apply.
 	GetUpdates() <-chan imap.Update
 

connector/dummy.go

@@ -263,6 +263,19 @@ func (conn *Dummy) MarkMessagesFlagged(_ context.Context, _ IMAPStateWrite, mess
 	return nil
 }
 
+func (conn *Dummy) MarkMessagesForwarded(ctx context.Context, cache IMAPStateWrite, messageIDs []imap.MessageID, forwarded bool) error {
+	for _, messageID := range messageIDs {
+		conn.state.setForwarded(messageID, forwarded)
+
+		conn.pushUpdate(imap.NewMessageFlagsUpdated(
+			messageID,
+			conn.state.getMessageFlags(messageID),
+		))
+	}
+
+	return nil
+}
+
 func (conn *Dummy) Sync(ctx context.Context) error {
 	for _, mailbox := range conn.state.getMailboxes() {
 		update := imap.NewMailboxCreated(mailbox)

connector/dummy_state.go

@@ -27,12 +27,13 @@ type dummyMailbox struct {
 }
 
 type dummyMessage struct {
-	literal []byte
-	parsed  *imap.ParsedMessage
-	seen    bool
-	flagged bool
-	date    time.Time
-	flags   imap.FlagSet
+	literal   []byte
+	parsed    *imap.ParsedMessage
+	seen      bool
+	flagged   bool
+	forwarded bool
+	date      time.Time
+	flags     imap.FlagSet
 
 	mboxIDs map[imap.MailboxID]struct{}
 }
@@ -256,6 +257,13 @@ func (state *dummyState) setFlagged(messageID imap.MessageID, flagged bool) {
 	state.messages[messageID].flagged = flagged
 }
 
+func (state *dummyState) setForwarded(messageID imap.MessageID, forwarded bool) {
+	state.lock.Lock()
+	defer state.lock.Unlock()
+
+	state.messages[messageID].forwarded = forwarded
+}
+
 func (state *dummyState) isSeen(messageID imap.MessageID) bool {
 	state.lock.Lock()
 	defer state.lock.Unlock()
@@ -294,6 +302,11 @@ func (state *dummyState) getMessageFlags(messageID imap.MessageID) imap.FlagSet
 		flags.AddToSelf(imap.FlagFlagged)
 	}
 
+	if msg.forwarded {
+		flags.AddToSelf(imap.XFlagForwarded)
+		flags.AddToSelf(imap.XFlagDollarForwarded)
+	}
+
 	return flags
 }
 

connector/state.go

@@ -58,4 +58,8 @@ type IMAPStateWrite interface {
 	// transformation necessary to ensure that new parent or child mailboxes are created as expected by a regular
 	// IMAP rename operation.
 	PatchMailboxHierarchyWithoutTransforms(ctx context.Context, id imap.MailboxID, newName []string) error
+
+	AddFlagsToAllMailboxes(ctx context.Context, flags ...string) error
+
+	AddPermFlagsToAllMailboxes(ctx context.Context, flags ...string) error
 }

db/ops_mailbox.go

@@ -105,6 +105,10 @@ type MailboxWriteOps interface {
 	UpdateRemoteMailboxID(ctx context.Context, mobxID imap.InternalMailboxID, remoteID imap.MailboxID) error
 
 	SetMailboxUIDValidity(ctx context.Context, mboxID imap.InternalMailboxID, uidValidity imap.UID) error
+
+	AddFlagsToAllMailboxes(ctx context.Context, flags ...string) error
+
+	AddPermFlagsToAllMailboxes(ctx context.Context, flags ...string) error
 }
 
 type SnapshotMessageResult struct {

imap/flags.go

@@ -9,23 +9,37 @@ import (
 )
 
 const (
-	FlagSeen     = `\Seen`
-	FlagAnswered = `\Answered`
-	FlagFlagged  = `\Flagged`
-	FlagDeleted  = `\Deleted`
-	FlagDraft    = `\Draft`
-	FlagRecent   = `\Recent` // Read-only!.
+	FlagSeen             = `\Seen`
+	FlagAnswered         = `\Answered`
+	FlagFlagged          = `\Flagged`
+	FlagDeleted          = `\Deleted`
+	FlagDraft            = `\Draft`
+	FlagRecent           = `\Recent`    // Read-only!.
+	XFlagDollarForwarded = "$Forwarded" // Non-Standard flag
+	XFlagForwarded       = "Forwarded"  // Non-Standard flag
 )
 
 const (
-	FlagSeenLowerCase     = `\seen`
-	FlagAnsweredLowerCase = `\answered`
-	FlagFlaggedLowerCase  = `\flagged`
-	FlagDeletedLowerCase  = `\deleted`
-	FlagDraftLowerCase    = `\draft`
-	FlagRecentLowerCase   = `\recent` // Read-only!.
+	FlagSeenLowerCase             = `\seen`
+	FlagAnsweredLowerCase         = `\answered`
+	FlagFlaggedLowerCase          = `\flagged`
+	FlagDeletedLowerCase          = `\deleted`
+	FlagDraftLowerCase            = `\draft`
+	FlagRecentLowerCase           = `\recent` // Read-only!.
+	XFlagDollarForwardedLowerCase = "$forwarded"
+	XFlagForwardedLowerCase       = "forwarded"
 )
 
+var ForwardFlagList = []string{
+	XFlagDollarForwarded,
+	XFlagForwarded,
+}
+
+var ForwardFlagListLowerCase = []string{
+	XFlagDollarForwardedLowerCase,
+	XFlagForwardedLowerCase,
+}
+
 // FlagSet represents a set of IMAP flags. Flags are case-insensitive and no duplicates are allowed.
 type FlagSet map[string]string
 
@@ -89,6 +103,14 @@ func (fs FlagSet) ContainsAny(flags ...string) bool {
 	}) >= 0
 }
 
+// ContainsAnyUnchecked returns true if and only if any of the flags are in the set. The flag list is not converted to
+// lower case.
+func (fs FlagSet) ContainsAnyUnchecked(flags ...string) bool {
+	return xslices.IndexFunc(flags, func(f string) bool {
+		return fs.ContainsUnchecked(f)
+	}) >= 0
+}
+
 // ContainsAll returns true if and only if all of the flags are in the set.
 func (fs FlagSet) ContainsAll(flags ...string) bool {
 	return xslices.IndexFunc(flags, func(f string) bool {

internal/backend/connector_state_write.go

@@ -90,6 +90,14 @@ func (d *DBIMAPStateWrite) PatchMailboxHierarchyWithoutTransforms(ctx context.Co
 	return d.tx.RenameMailboxWithRemoteID(ctx, id, combined)
 }
 
+func (d *DBIMAPStateWrite) AddFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	return d.tx.AddFlagsToAllMailboxes(ctx, flags...)
+}
+
+func (d *DBIMAPStateWrite) AddPermFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	return d.tx.AddPermFlagsToAllMailboxes(ctx, flags...)
+}
+
 func (d *DBIMAPStateWrite) wrapStateUpdates(ctx context.Context, f func(ctx context.Context, tx db.Transaction) ([]state.Update, error)) error {
 	updates, err := f(ctx, d.tx)
 	if err == nil {

internal/backend/state_connector_impl.go

@@ -191,6 +191,23 @@ func (sc *stateConnectorImpl) GetMailboxVisibility(ctx context.Context,
 	return sc.connector.GetMailboxVisibility(ctx, id)
 }
 
+func (sc *stateConnectorImpl) SetMessagesForwarded(
+	ctx context.Context,
+	tx db.Transaction,
+	messageIDs []imap.MessageID,
+	forwarded bool,
+) ([]state.Update, error) {
+	ctx = sc.newContextWithMetadata(ctx)
+
+	cache := sc.newDBIMAPWrite(tx)
+
+	if err := sc.connector.MarkMessagesForwarded(ctx, &cache, messageIDs, forwarded); err != nil {
+		return nil, err
+	}
+
+	return cache.stateUpdates, nil
+}
+
 func (sc *stateConnectorImpl) getMetadataValue(key string) any {
 	v, ok := sc.metadata[key]
 	if !ok {

internal/db_impl/sqlite3/utils/tracer.go

@@ -460,3 +460,15 @@ func (w WriteTracer) StoreConnectorSettings(ctx context.Context, settings string
 
 	return w.TX.StoreConnectorSettings(ctx, settings)
 }
+
+func (w WriteTracer) AddFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	w.Entry.Tracef("AddFlagsToAllMailboxes")
+
+	return w.TX.AddFlagsToAllMailboxes(ctx, flags...)
+}
+
+func (w WriteTracer) AddPermFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	w.Entry.Tracef("AddPermFlagsToAllMailboxes")
+
+	return w.TX.AddPermFlagsToAllMailboxes(ctx, flags...)
+}

internal/db_impl/sqlite3/write_ops.go

@@ -669,3 +669,43 @@ func (w writeOps) StoreConnectorSettings(ctx context.Context, settings string) e
 
 	return err
 }
+
+func (w writeOps) AddFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	flagsJoined := strings.Join(xslices.Map(flags, func(s string) string {
+		return "('" + s + "')"
+	}), ",")
+
+	queryInsert := fmt.Sprintf(
+		"INSERT OR IGNORE INTO %v (`%v`, `%v`) SELECT `%v`,`value` FROM %v CROSS JOIN (WITH T(value) AS (VALUES %v) SELECT * FROM T)",
+		v1.MailboxFlagsTableName,
+		v1.MailboxFlagsFieldMailboxID,
+		v1.MailboxFlagsFieldValue,
+		v1.MailboxesFieldID,
+		v1.MailboxesTableName,
+		flagsJoined,
+	)
+
+	_, err := utils.ExecQuery(ctx, w.qw, queryInsert)
+
+	return err
+}
+
+func (w writeOps) AddPermFlagsToAllMailboxes(ctx context.Context, flags ...string) error {
+	flagsJoined := strings.Join(xslices.Map(flags, func(s string) string {
+		return "('" + s + "')"
+	}), ",")
+
+	queryInsert := fmt.Sprintf(
+		"INSERT OR IGNORE INTO %v (`%v`, `%v`) SELECT `%v`,`value` FROM %v CROSS JOIN (WITH T(value) AS (VALUES %v) SELECT * FROM T)",
+		v1.MailboxPermFlagsTableName,
+		v1.MailboxPermFlagsFieldMailboxID,
+		v1.MailboxPermFlagsFieldValue,
+		v1.MailboxesFieldID,
+		v1.MailboxesTableName,
+		flagsJoined,
+	)
+
+	_, err := utils.ExecQuery(ctx, w.qw, queryInsert)
+
+	return err
+}

internal/state/connector.go

@@ -80,4 +80,7 @@ type Connector interface {
 
 	// GetMailboxVisibility retrieves the visibility status of a mailbox for a client.
 	GetMailboxVisibility(ctx context.Context, id imap.MailboxID) imap.MailboxVisibility
+
+	// SetMessagesForwarded marks the message with the given ID as forwarded.
+	SetMessagesForwarded(ctx context.Context, tx db.Transaction, messageIDs []imap.MessageID, forwarded bool) ([]Update, error)
 }