#6: implement IMAP IDLE (RFC 2177) and CONDSTORE (RFC 7162)

services/protocols/internal/application/usecase/mailbox_tracker_manager.go

@@ -0,0 +1,72 @@
+package usecase
+
+import (
+	"sync"
+
+	"github.com/emersion/go-imap/v2"
+	"github.com/emersion/go-imap/v2/imapserver"
+)
+
+// MailboxTrackerManager maintains imapserver.MailboxTracker instances per folder ID.
+// This allows active IMAP sessions to receive real-time notifications when emails arrive,
+// flags change, or messages are expunged (IDLE / RFC 2177).
+type MailboxTrackerManager struct {
+	mu       sync.RWMutex
+	trackers map[string]*imapserver.MailboxTracker
+}
+
+func NewMailboxTrackerManager() *MailboxTrackerManager {
+	return &MailboxTrackerManager{
+		trackers: make(map[string]*imapserver.MailboxTracker),
+	}
+}
+
+// GetTracker retrieves or initializes the MailboxTracker for folderID.
+func (m *MailboxTrackerManager) GetTracker(folderID string, initialNumMessages uint32) *imapserver.MailboxTracker {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+
+	tracker, ok := m.trackers[folderID]
+	if !ok {
+		tracker = imapserver.NewMailboxTracker(initialNumMessages)
+		m.trackers[folderID] = tracker
+	}
+	return tracker
+}
+
+// NotifyNumMessages informs all sessions watching folderID of a new EXISTS count.
+func (m *MailboxTrackerManager) NotifyNumMessages(folderID string, n uint32) {
+	m.mu.RLock()
+	tracker, ok := m.trackers[folderID]
+	m.mu.RUnlock()
+
+	if ok {
+		tracker.QueueNumMessages(n)
+	}
+}
+
+// NotifyMessageFlags informs sessions watching folderID of updated flags on a message.
+func (m *MailboxTrackerManager) NotifyMessageFlags(folderID string, seqNum uint32, uid uint32, flags []string, source *imapserver.SessionTracker) {
+	m.mu.RLock()
+	tracker, ok := m.trackers[folderID]
+	m.mu.RUnlock()
+
+	if ok {
+		imapFlags := make([]imap.Flag, len(flags))
+		for i, f := range flags {
+			imapFlags[i] = imap.Flag(f)
+		}
+		tracker.QueueMessageFlags(seqNum, imap.UID(uid), imapFlags, source)
+	}
+}
+
+// NotifyExpunge informs sessions watching folderID that seqNum was expunged.
+func (m *MailboxTrackerManager) NotifyExpunge(folderID string, seqNum uint32) {
+	m.mu.RLock()
+	tracker, ok := m.trackers[folderID]
+	m.mu.RUnlock()
+
+	if ok {
+		tracker.QueueExpunge(seqNum)
+	}
+}