package resolver

import (
	_ "embed"
	"codeberg.org/miekg/dns"
	"strings"
)

//go:embed named.root
var rootHintsData []byte

func loadRootServers() []string {
	var addrs []string
	seen := make(map[string]bool)

	zp := dns.NewZoneParser(strings.NewReader(string(rootHintsData)), "", "")
	for {
		rr, ok := zp.Next()
		if !ok {
			break
		}
		a, ok := rr.(*dns.A)
		if !ok {
			continue
		}
		ip := a.A.Addr.String()
		if !seen[ip] {
			seen[ip] = true
			addrs = append(addrs, ip)
		}
	}

	if err := zp.Err(); err != nil || len(addrs) == 0 {
		return hardcodedRoots()
	}
	return addrs
}

func hardcodedRoots() []string {
	return []string{
		"198.41.0.4",
		"170.247.170.2",
		"192.33.4.12",
		"199.7.91.13",
		"192.203.230.10",
		"192.5.5.241",
		"192.112.36.4",
		"198.97.190.53",
		"192.36.148.17",
		"192.58.128.30",
		"193.0.14.129",
		"199.7.83.42",
		"202.12.27.33",
	}
}