feat: activity log backend foundation

internal/domain/audit/auditSettings.go

@@ -0,0 +1,57 @@
+package audit
+
+import "time"
+
+const (
+	DefaultRetentionDays = 90
+	ForeverRetentionDays = 0
+	CleanupHour          = 3
+	KeepRecentHours      = 24
+)
+
+func RetentionOptions() []int {
+	return []int{30, 90, 365, ForeverRetentionDays}
+}
+
+func ValidateRetentionDays(days int) error {
+	for _, option := range RetentionOptions() {
+		if option == days {
+			return nil
+		}
+	}
+	return ErrInvalidRetention
+}
+
+type Settings struct {
+	RetentionDays      int        `json:"activity_retention_days"`
+	LastCleanupAt      *time.Time `json:"activity_last_cleanup_at"`
+	LastCleanupRemoved int        `json:"activity_last_cleanup_removed"`
+}
+
+func DefaultSettings() Settings {
+	return Settings{RetentionDays: DefaultRetentionDays}
+}
+
+func (s Settings) CleanupDue(now time.Time) bool {
+	todayRun := time.Date(now.Year(), now.Month(), now.Day(), CleanupHour, 0, 0, 0, now.Location())
+	if now.Before(todayRun) {
+		return false
+	}
+	return s.LastCleanupAt == nil || s.LastCleanupAt.Before(todayRun)
+}
+
+func ClampCutoff(now time.Time, cutoff time.Time) time.Time {
+	newest := now.Add(-KeepRecentHours * time.Hour)
+	if cutoff.After(newest) {
+		return newest
+	}
+	return cutoff
+}
+
+func RetentionCutoff(now time.Time, retentionDays int) time.Time {
+	return ClampCutoff(now, now.Add(-time.Duration(retentionDays)*24*time.Hour))
+}
+
+type CleanupResult struct {
+	Removed int
+}