Implement notifications service with shared messaging and email drivers (#36)

backend/shared/messaging/reliable/durable_settings_behavior.go

@@ -0,0 +1,25 @@
+package reliable
+
+import "time"
+
+func (s DurableSettings) StreamMaxAge() time.Duration {
+	if s.Stream.MaxAgeHours <= 0 {
+		return 48 * time.Hour
+	}
+	return time.Duration(s.Stream.MaxAgeHours) * time.Hour
+}
+
+func (s DurableSettings) IsProductionValidation() bool {
+	return s.Provisioning.Environment == DurableEnvironmentProduction
+}
+
+func (s DurableSettings) AllowsAutoProvision() bool {
+	switch s.Provisioning.Mode {
+	case DurableProvisioningApp:
+		return true
+	case DurableProvisioningHybrid:
+		return s.Provisioning.Environment != DurableEnvironmentProduction
+	default:
+		return false
+	}
+}