package config

// EffectiveCheck overlays one upstream's non-zero check fields on the global
// defaults. A non-nil URL slice is an explicit override, including an empty
// slice that intentionally disables URL-based EGRESS checks for that upstream.
func EffectiveCheck(defaults, override Check) Check {
	effective := defaults
	if override.Interval != 0 {
		effective.Interval = override.Interval
	}
	if override.Jitter != 0 {
		effective.Jitter = override.Jitter
	}
	if override.MaxInFlight != 0 {
		effective.MaxInFlight = override.MaxInFlight
	}
	if override.Timeout != 0 {
		effective.Timeout = override.Timeout
	}
	if override.MaxAttempts != 0 {
		effective.MaxAttempts = override.MaxAttempts
	}
	if override.MaxConsecutiveFailures != 0 {
		effective.MaxConsecutiveFailures = override.MaxConsecutiveFailures
	}
	if override.UnhealthyRemoveAfter != 0 {
		effective.UnhealthyRemoveAfter = override.UnhealthyRemoveAfter
	}
	if override.URLs != nil {
		effective.URLs = cloneCheckURLs(override.URLs)
	} else {
		effective.URLs = cloneCheckURLs(defaults.URLs)
	}
	return effective
}

func cloneCheckURLs(source []string) []string {
	if source == nil {
		return nil
	}
	result := make([]string, len(source))
	copy(result, source)
	return result
}