sweeper: release custom URLs on expiry and after 30-day reservation (#29)

main.go

@@ -23,6 +23,7 @@ var webFS embed.FS
 
 const (
 	softDeleteGraceDays = 7
+	customSlugReservationDays = 30
 )
 
 type Config struct {
@@ -272,11 +273,34 @@ func (s *Store) SweepExpired() {
 	s.db.Exec(`DELETE FROM pastes WHERE deleted_at IS NOT NULL AND deleted_at < ?`, grace)
 }
 
+// ReleaseCustomSlugs frees custom URLs so they can be reused:
+//   - pastes whose expires_at has passed (expired or soft-deleted/expired),
+//   - pastes created more than 30 days ago (custom URLs are a reservation, not permanent).
+//
+// It returns the number of pastes whose custom_slug was released.
+func (s *Store) ReleaseCustomSlugs() (int64, error) {
+	now := time.Now().Unix()
+	res, err := s.db.Exec(`UPDATE pastes SET custom_slug = NULL
+		WHERE custom_slug IS NOT NULL
+		  AND (expires_at IS NOT NULL AND expires_at > 0 AND expires_at < ?
+		   OR created_at < ?)`,
+		now, now-customSlugReservationDays*86400)
+	if err != nil {
+		return 0, err
+	}
+	n, _ := res.RowsAffected()
+	if n > 0 {
+		log.Printf("released %d custom slug(s)", n)
+	}
+	return n, nil
+}
+
 func (s *Store) StartSweeper(every time.Duration) {
 	go func() {
 		t := time.NewTicker(every)
 		for range t.C {
 			s.SweepExpired()
+			s.ReleaseCustomSlugs()
 		}
 	}()
 }