add messages persistancy, channels does not persist

packages/postgresql/postgresql.go

@@ -578,6 +578,35 @@ func HubChannelMessageGet(ctx context.Context, message *types.Message) error {
 	`, message.Id).Scan(&message.Sender, &message.Receiver, &message.CreatedAt, &message.Content, &message.AttachedFile)
 }
 
+func HubChannelGetMessagesBefore(ctx context.Context, before time.Time, channelId uuid.UUID, cap uint32) ([]*types.Message, error) {
+	rows, err := dbConn.Query(ctx, `
+		SELECT id, sender_id, receiver_id, created_at, content, attached_file
+		FROM (
+			SELECT id, sender_id, receiver_id, created_at, content, attached_file
+			FROM hub_channel_messages
+			WHERE receiver_id = $1
+			  AND created_at < $2
+			ORDER BY created_at DESC
+			LIMIT $3
+		) sub
+		ORDER BY created_at ASC
+	`, channelId, before, cap)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	messages := make([]*types.Message, 0, cap)
+	for rows.Next() {
+		msg := &types.Message{}
+		if err = rows.Scan(&msg.Id, &msg.Sender, &msg.Receiver, &msg.CreatedAt, &msg.Content, &msg.AttachedFile); err != nil {
+			return nil, err
+		}
+		messages = append(messages, msg)
+	}
+	return messages, rows.Err()
+}
+
 func HubUpdate(ctx context.Context, hub *types.Hub, updateList *types.HubUpdate) error {
 	setClauses := make([]string, 0, 6)
 	args := make([]any, 0, 7)