package whois

import (
	"errors"
	"fmt"
	"net"
	"strconv"
	"strings"

	"golang.org/x/net/idna"
)

type lookupTargetKind int

const (
	lookupTargetDomain lookupTargetKind = iota
	lookupTargetIP
	lookupTargetASN
)

func normalizeQueryDomainInput(domain string) (string, error) {
	domain = strings.Trim(strings.TrimSpace(domain), ".")
	if domain == "" {
		return "", errors.New("whois: domain is empty")
	}
	if strings.ContainsAny(domain, "/\\") {
		return "", fmt.Errorf("whois: invalid domain=%q", domain)
	}

	if IsASN(domain) {
		if strings.HasPrefix(strings.ToUpper(domain), "AS") {
			return strings.ToUpper(domain), nil
		}
		return "AS" + strings.ToUpper(domain), nil
	}

	if ip := net.ParseIP(domain); ip != nil {
		return ip.String(), nil
	}

	ascii, err := idna.Lookup.ToASCII(domain)
	if err != nil {
		return "", fmt.Errorf("whois: invalid domain=%q: %w", domain, err)
	}
	ascii = strings.ToLower(strings.Trim(ascii, "."))
	if ascii == "" {
		return "", errors.New("whois: domain is empty")
	}
	return ascii, nil
}

func normalizeLookupDomainInput(domain string) (string, error) {
	normalized, kind, err := normalizeLookupTargetInput(domain)
	if err != nil {
		return "", err
	}
	if kind != lookupTargetDomain {
		return "", fmt.Errorf("whois/lookup: invalid domain=%q", domain)
	}
	return normalized, nil
}

func normalizeLookupTargetInput(input string) (string, lookupTargetKind, error) {
	normalized, err := normalizeQueryDomainInput(input)
	if err != nil {
		return "", lookupTargetDomain, err
	}
	if IsASN(normalized) {
		return normalized, lookupTargetASN, nil
	}
	if net.ParseIP(normalized) != nil {
		return normalized, lookupTargetIP, nil
	}
	return normalized, lookupTargetDomain, nil
}

func normalizeASNNumeric(asn string) (string, error) {
	asn = strings.TrimSpace(strings.ToUpper(asn))
	if !IsASN(asn) {
		return "", fmt.Errorf("whois/rdap: invalid asn=%q", asn)
	}
	asn = strings.TrimPrefix(asn, "AS")
	asn = strings.TrimSpace(asn)
	if asn == "" {
		return "", fmt.Errorf("whois/rdap: invalid asn=%q", asn)
	}
	if _, err := strconv.ParseUint(asn, 10, 32); err != nil {
		return "", fmt.Errorf("whois/rdap: invalid asn=%q: %w", asn, err)
	}
	return asn, nil
}