package resolver

import (
	"os"
	"strings"
)

func SmartDNSFallbackForTimeoutEnabled() bool {
	switch strings.ToLower(strings.TrimSpace(os.Getenv("RESOLVE_SMARTDNS_TIMEOUT_FALLBACK"))) {
	case "1", "true", "yes", "on":
		return true
	case "0", "false", "no", "off":
		return false
	default:
		return false
	}
}

func ShouldFallbackToSmartDNS(stats DNSMetrics) bool {
	if stats.OK > 0 {
		return false
	}
	if stats.NXDomain > 0 {
		return false
	}
	if stats.Timeout > 0 || stats.Temporary > 0 {
		return true
	}
	return stats.Other > 0
}

func ClassifyHostErrorKind(stats DNSMetrics) (DNSErrorKind, bool) {
	if stats.Timeout > 0 {
		return DNSErrorTimeout, true
	}
	if stats.Temporary > 0 {
		return DNSErrorTemporary, true
	}
	if stats.Other > 0 {
		return DNSErrorOther, true
	}
	if stats.NXDomain > 0 {
		return DNSErrorNXDomain, true
	}
	return "", false
}

func ShouldUseStaleOnError(stats DNSMetrics) bool {
	if stats.OK > 0 {
		return false
	}
	return stats.Timeout > 0 || stats.Temporary > 0 || stats.Other > 0
}