package main

import (
	"bytes"
	"compress/gzip"
	_ "embed"
	"io"
	"net"
	"sync"

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

//go:embed assets/world.json
var trafficWorld []byte

//go:embed assets/dbip-country-lite-2026-10.mmdb.gz
var trafficGeoCompressed []byte

const trafficGeoDate = "2026-10"

var trafficGeo struct {
	sync.Once
	db *maxminddb.Reader
}

func trafficGeoReady() bool {
	trafficGeo.Do(func() {
		r, err := gzip.NewReader(bytes.NewReader(trafficGeoCompressed))
		if err != nil {
			return
		}
		defer r.Close()
		data, err := io.ReadAll(io.LimitReader(r, 32<<20))
		if err != nil {
			return
		}
		trafficGeo.db, _ = maxminddb.FromBytes(data)
	})
	return trafficGeo.db != nil
}
func lookupTrafficCountry(ipText string) string {
	ip := net.ParseIP(ipText)
	if ip == nil {
		return ""
	}
	if ip.IsPrivate() || ip.IsLoopback() || ip.IsLinkLocalUnicast() {
		return "LAN"
	}
	if !ip.IsGlobalUnicast() {
		return ""
	}
	if !trafficGeoReady() {
		return ""
	}
	var record struct {
		Country struct {
			Code string `maxminddb:"iso_code"`
		} `maxminddb:"country"`
	}
	if trafficGeo.db.Lookup(ip, &record) != nil {
		return ""
	}
	return record.Country.Code
}