package geoip

import (
	"fmt"
	"net"

	"github.com/oschwald/geoip2-golang"
)

// Service holds optional GeoLite2 City and/or ASN MMDB readers.
// Country-only DB не нужен: страна уже есть в City.
type Service struct {
	city *geoip2.Reader
	asn  *geoip2.Reader
}

// Open opens a single MMDB (City or ASN) — для тестов и простых случаев.
func Open(path string) (*Service, error) {
	r, err := geoip2.Open(path)
	if err != nil {
		return nil, fmt.Errorf("geoip open %q: %w", path, err)
	}
	return &Service{city: r}, nil
}

// OpenDatabases opens city and/or asn paths; at least one must be non-empty.
func OpenDatabases(cityPath, asnPath string) (*Service, error) {
	var s Service
	if cityPath != "" {
		r, err := geoip2.Open(cityPath)
		if err != nil {
			return nil, fmt.Errorf("geoip city open %q: %w", cityPath, err)
		}
		s.city = r
	}
	if asnPath != "" {
		r, err := geoip2.Open(asnPath)
		if err != nil {
			if s.city != nil {
				_ = s.city.Close()
			}
			return nil, fmt.Errorf("geoip asn open %q: %w", asnPath, err)
		}
		s.asn = r
	}
	if s.city == nil && s.asn == nil {
		return nil, fmt.Errorf("geoip: no database paths")
	}
	return &s, nil
}

// Close releases database handles.
func (s *Service) Close() error {
	if s == nil {
		return nil
	}
	var first error
	if s.city != nil {
		if err := s.city.Close(); err != nil {
			first = err
		}
		s.city = nil
	}
	if s.asn != nil {
		if err := s.asn.Close(); err != nil && first == nil {
			first = err
		}
		s.asn = nil
	}
	return first
}

// Result combines City + ASN fields when available.
type Result struct {
	CountryCode string
	CountryName string
	CityName    string
	Latitude    float64
	Longitude   float64
	ASN         uint64
	ASOrg       string
}

// Lookup fills geographic and/or ASN data for an IP string (IPv4/IPv6).
func (s *Service) Lookup(ipStr string) (Result, bool) {
	var out Result
	if s == nil {
		return out, false
	}
	ip := net.ParseIP(ipStr)
	if ip == nil {
		return out, false
	}
	ok := false
	if s.city != nil {
		if rec, err := s.city.City(ip); err == nil {
			out.CountryCode = rec.Country.IsoCode
			if rec.Country.Names != nil {
				out.CountryName = rec.Country.Names["en"]
			}
			if rec.City.Names != nil {
				out.CityName = rec.City.Names["en"]
			}
			// Для карты важны координаты. Даже если MaxMind вернул (0,0),
			// лучше прокидывать их дальше, чем скрывать все точки.
			out.Latitude = rec.Location.Latitude
			out.Longitude = rec.Location.Longitude

			if out.CountryCode != "" || out.CountryName != "" || out.CityName != "" {
				ok = true
			}
		}
	}
	if s.asn != nil {
		if rec, err := s.asn.ASN(ip); err == nil {
			out.ASN = uint64(rec.AutonomousSystemNumber)
			out.ASOrg = rec.AutonomousSystemOrganization
			if out.ASN != 0 || out.ASOrg != "" {
				ok = true
			}
		}
	}
	return out, ok
}