This is the v1 version, had the v2 before.

backend/updates.go

@@ -0,0 +1,98 @@
+package backend
+
+import (
+	"github.com/emersion/go-imap"
+)
+
+// Update contains user and mailbox information about an unilateral backend
+// update.
+type Update interface {
+	// The user targeted by this update. If empty, all connected users will
+	// be notified.
+	Username() string
+	// The mailbox targeted by this update. If empty, the update targets all
+	// mailboxes.
+	Mailbox() string
+	// Done returns a channel that is closed when the update has been broadcast to
+	// all clients.
+	Done() chan struct{}
+}
+
+// NewUpdate creates a new update.
+func NewUpdate(username, mailbox string) Update {
+	return &update{
+		username: username,
+		mailbox:  mailbox,
+	}
+}
+
+type update struct {
+	username string
+	mailbox  string
+	done     chan struct{}
+}
+
+func (u *update) Username() string {
+	return u.username
+}
+
+func (u *update) Mailbox() string {
+	return u.mailbox
+}
+
+func (u *update) Done() chan struct{} {
+	if u.done == nil {
+		u.done = make(chan struct{})
+	}
+	return u.done
+}
+
+// StatusUpdate is a status update. See RFC 3501 section 7.1 for a list of
+// status responses.
+type StatusUpdate struct {
+	Update
+	*imap.StatusResp
+}
+
+// MailboxUpdate is a mailbox update.
+type MailboxUpdate struct {
+	Update
+	*imap.MailboxStatus
+}
+
+// MailboxInfoUpdate is a maiblox info update.
+type MailboxInfoUpdate struct {
+	Update
+	*imap.MailboxInfo
+}
+
+// MessageUpdate is a message update.
+type MessageUpdate struct {
+	Update
+	*imap.Message
+}
+
+// ExpungeUpdate is an expunge update.
+type ExpungeUpdate struct {
+	Update
+	SeqNum uint32
+}
+
+// BackendUpdater is a Backend that implements Updater is able to send
+// unilateral backend updates. Backends not implementing this interface don't
+// correctly send unilateral updates, for instance if a user logs in from two
+// connections and deletes a message from one of them, the over is not aware
+// that such a mesage has been deleted. More importantly, backends implementing
+// Updater can notify the user for external updates such as new message
+// notifications.
+type BackendUpdater interface {
+	// Updates returns a set of channels where updates are sent to.
+	Updates() <-chan Update
+}
+
+// MailboxPoller is a Mailbox that is able to poll updates for new messages or
+// message status updates during a period of inactivity.
+type MailboxPoller interface {
+	// Poll requests mailbox updates.
+	Poll() error
+}