package geo

import (
	"errors"
	"net"

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

type mmdbResolver struct {
	db *geoip2.Reader
}

func newMMDBResolver(dbPath string) (Resolver, error) {
	if dbPath == "" {
		return nil, errors.New("mmdb path is required")
	}

	db, err := geoip2.Open(dbPath)
	if err != nil {
		return nil, err
	}

	return &mmdbResolver{db: db}, nil
}

func (r *mmdbResolver) Close() error {
	return r.db.Close()
}

func (r *mmdbResolver) Lookup(ipStr string) (Location, error) {
	ip := net.ParseIP(ipStr)
	if ip == nil {
		return Location{}, ErrInvalidIP
	}

	record, err := r.db.City(ip)
	if err != nil {
		return Location{}, err
	}

	country := record.Country.Names["en"]
	region := ""
	if len(record.Subdivisions) > 0 {
		region = record.Subdivisions[0].Names["en"]
	}

	city := record.City.Names["en"]

	return Location{
		IP:        ip.String(),
		Country:   country,
		Region:    region,
		City:      city,
		Address:   buildAddress(city, region, country),
		Latitude:  record.Location.Latitude,
		Longitude: record.Location.Longitude,
	}, nil
}