package utils

// IP 地理位置识别：复用 opsx-waf 的 GeoLite2-City 方案（中文优先，内网标记）。
// 数据文件默认 /data/geoip/GeoLite2-City.mmdb（容器卷内），缺失时静默返回空串，不影响业务。 // Logan.Li

import (
	"backend/internal/service/appconfig"
	"net/netip"
	"strings"
	"sync"

	geoip2 "github.com/oschwald/geoip2-golang/v2"
)

var geoIPReader struct {
	once sync.Once
	db   *geoip2.Reader
}

// LookupIPLocation 返回 "国家 / 省份 / 城市"（中文优先）；内网返回"内网"，无法识别返回空串 // Logan.Li
func LookupIPLocation(value string) string {
	ip, err := netip.ParseAddr(strings.TrimSpace(value))
	if err != nil {
		return ""
	}
	if ip.IsPrivate() || ip.IsLoopback() || ip.IsLinkLocalUnicast() {
		return "内网"
	}
	geoIPReader.once.Do(func() {
		path := appconfig.String("GEOIP_DB_PATH")
		if path == "" {
			path = "/data/geoip/GeoLite2-City.mmdb"
		}
		geoIPReader.db, _ = geoip2.Open(path)
	})
	if geoIPReader.db == nil {
		return ""
	}
	record, err := geoIPReader.db.City(ip)
	if err != nil {
		return ""
	}
	parts := localizedNames(record.Country.Names, record.Country.ISOCode)
	if len(record.Subdivisions) > 0 {
		if sub := localizedNames(record.Subdivisions[0].Names, record.Subdivisions[0].ISOCode); sub != "" && sub != parts {
			parts = joinLocation(parts, sub)
		}
	}
	if city := localizedNames(record.City.Names, ""); city != "" {
		parts = joinLocation(parts, city)
	}
	return parts
}

// localizedNames 中文优先；GeoLite2 少数中国城市只有英文名，走兜底映射 // Logan.Li
func localizedNames(names geoip2.Names, fallback string) string {
	if names.SimplifiedChinese != "" {
		return names.SimplifiedChinese
	}
	if names.English != "" {
		return names.English
	}
	return fallback
}

func joinLocation(left, right string) string {
	if left == "" {
		return right
	}
	return left + " / " + right
}