import (
	"context"
	"fmt"
	"net"
	"net/url"

	"github.com/go-ldap/ldap/v3"
)

// ...

var (
	dnsCtx context.Context = context.Background()
)

func srvToUri(records []*net.SRV) (uris []*url.URL, err error) {

	var u *url.URL

	if records == nil {
		return
	}

	uris = make([]*url.URL, len(records))

	for idx, r := range records {
		uris[idx] = &url.URL{
			Scheme: "ldap",
			Host:   fmt.Sprintf("%v:%v", r.Target, r.Port),
		}
	}

	return
}

func ldapUriFromSrv(domain string, resolver net.Resolver) (uris []*url.URL, err error) {

	var srvRecords []*net.SRV

	if resolver == nil {
		resolver = net.DefaultResolver
	}

	if _, srvRecords, err = resolver.LookupSRV(dnsCtx, "ldap", "tcp", domain); err != nil {
		return
	}

	// There is no need to sort/shuffle records according to prio/weight;
	// the (net.Resolver).LookupSRV() method does this for us.

	if srvUris, dnsErr = srvToUri(srvRecords); err != nil {
		return
	}
}