package resolver

func ComputeNextLiveBatchTarget(current, minV, maxV int, dnsStats DNSMetrics, deferred int) (int, string) {
	if current < minV {
		current = minV
	}
	if current > maxV {
		current = maxV
	}
	next := current
	reason := "stable"
	attempts := dnsStats.Attempts
	timeoutRate := 0.0
	if attempts > 0 {
		timeoutRate = float64(dnsStats.Timeout) / float64(attempts)
	}

	switch {
	case attempts == 0:
		reason = "no_dns_attempts"
	case dnsStats.Skipped > 0 || timeoutRate >= 0.15:
		next = int(float64(current) * 0.75)
		reason = "timeout_high_or_cooldown"
	case timeoutRate >= 0.08:
		next = int(float64(current) * 0.90)
		reason = "timeout_medium"
	case timeoutRate <= 0.03 && deferred > 0:
		next = int(float64(current) * 1.15)
		reason = "timeout_low_expand"
	case timeoutRate <= 0.03:
		next = int(float64(current) * 1.10)
		reason = "timeout_low"
	}

	if next < minV {
		next = minV
	}
	if next > maxV {
		next = maxV
	}
	if next == current && reason == "timeout_low" {
		reason = "stable"
	}
	return next, reason
}

func ComputeNextLiveBatchNXHeavyPct(
	current, minV, maxV int,
	dnsStats DNSMetrics,
	resolvedNowDNS int,
	selectedP3 int,
	nxTotal int,
	liveNXHeavySkip int,
) (int, string) {
	if current < minV {
		current = minV
	}
	if current > maxV {
		current = maxV
	}
	next := current
	reason := "stable"

	attempts := dnsStats.Attempts
	timeoutRate := 0.0
	okRate := 0.0
	nxRate := 0.0
	if attempts > 0 {
		timeoutRate = float64(dnsStats.Timeout) / float64(attempts)
		okRate = float64(dnsStats.OK) / float64(attempts)
		nxRate = float64(dnsStats.NXDomain) / float64(attempts)
	}
	nxSelectedRatio := 0.0
	if nxTotal > 0 {
		nxSelectedRatio = float64(selectedP3) / float64(nxTotal)
	}

	switch {
	case attempts == 0:
		reason = "no_dns_attempts"
	case timeoutRate >= 0.20 || dnsStats.Skipped > 0:
		next = current - 3
		reason = "timeout_very_high_or_cooldown"
	case timeoutRate >= 0.12:
		next = current - 2
		reason = "timeout_high"
	case dnsStats.OK == 0 && dnsStats.NXDomain > 0:
		next = current - 2
		reason = "no_success_nx_only"
	case nxRate >= 0.90 && resolvedNowDNS == 0:
		next = current - 2
		reason = "nx_dominant_no_resolve"
	case nxSelectedRatio >= 0.95 && resolvedNowDNS == 0:
		next = current - 1
		reason = "nxheavy_selected_dominant"
	case timeoutRate <= 0.02 && okRate >= 0.10 && liveNXHeavySkip > 0:
		next = current + 2
		reason = "healthy_fast_reintroduce_nxheavy"
	case timeoutRate <= 0.04 && resolvedNowDNS > 0 && liveNXHeavySkip > 0:
		next = current + 1
		reason = "healthy_reintroduce_nxheavy"
	}
	if next < minV {
		next = minV
	}
	if next > maxV {
		next = maxV
	}
	if next == current && reason != "no_dns_attempts" {
		reason = "stable"
	}
	return next, reason
}