package validation

import (
	"context"
	"net"
	"net/url"
	"strings"
	"time"
)

// DomainResolves checks that the given domain or URL has a DNS record (A or AAAA).
// Input can be "git.example.com" or "https://git.example.com".
func DomainResolves(input string, timeout time.Duration) bool {
	host := extractHost(input)
	if host == "" {
		return false
	}
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()
	var r net.Resolver
	addrs, err := r.LookupHost(ctx, host)
	return err == nil && len(addrs) > 0
}

func extractHost(input string) string {
	s := strings.TrimSpace(strings.ToLower(input))
	if s == "" {
		return ""
	}
	if !strings.Contains(s, "//") {
		s = "//" + s
	}
	u, err := url.Parse(s)
	if err != nil {
		return ""
	}
	host := u.Hostname()
	if host == "" || host == "." {
		return ""
	}
	return host
}