package app

import (
	"encoding/json"
	"os"
	"path/filepath"
)

func saveDNSUpstreamPoolFile(items []DNSUpstreamPoolItem) error {
	state := DNSUpstreamPoolState{Items: normalizeDNSUpstreamPoolItems(items)}
	if err := os.MkdirAll(filepath.Dir(dnsUpstreamPool), 0o755); err != nil {
		return err
	}
	tmp := dnsUpstreamPool + ".tmp"
	b, err := json.MarshalIndent(state, "", "  ")
	if err != nil {
		return err
	}
	if err := os.WriteFile(tmp, b, 0o644); err != nil {
		return err
	}
	return os.Rename(tmp, dnsUpstreamPool)
}

func loadDNSUpstreamPoolState() []DNSUpstreamPoolItem {
	data, err := os.ReadFile(dnsUpstreamPool)
	if err == nil {
		var st DNSUpstreamPoolState
		if json.Unmarshal(data, &st) == nil {
			items := normalizeDNSUpstreamPoolItems(st.Items)
			if len(items) > 0 {
				return items
			}
		}
	}
	legacy := loadDNSUpstreamsConfFile()
	items := dnsUpstreamPoolFromLegacy(legacy)
	if len(items) > 0 {
		_ = saveDNSUpstreamPoolFile(items)
	}
	return items
}

func saveDNSUpstreamPoolState(items []DNSUpstreamPoolItem) error {
	items = normalizeDNSUpstreamPoolItems(items)
	if len(items) == 0 {
		items = dnsUpstreamPoolFromLegacy(loadDNSUpstreamsConfFile())
	}
	if err := saveDNSUpstreamPoolFile(items); err != nil {
		return err
	}
	return saveDNSUpstreamsConfFile(dnsUpstreamPoolToLegacy(items))
}