feat(geoip): implement GeoIP functionality with initialization, IP geolocation retrieval, and unit tests

pkg/geoip/geoip.go

@@ -0,0 +1,55 @@
+package geoip
+
+import (
+	"embed"
+	"net/netip"
+
+	"github.com/enescakir/emoji"
+	"github.com/oschwald/geoip2-golang/v2"
+)
+
+//go:embed resource/*.mmdb
+var dbFS embed.FS
+
+var geoipReader *geoip2.Reader
+
+func Init() error {
+	data, err := dbFS.ReadFile("resource/GeoLite2-Country.mmdb")
+	if err != nil {
+		return err
+	}
+
+	geoipReader, err = geoip2.OpenBytes(data)
+	return err
+}
+
+type IpGeoInfo struct {
+	Country *geoip2.Country
+	Emoji   string
+}
+
+func GetIpGeoInfo(ip string) *IpGeoInfo {
+	if geoipReader == nil || ip == "" {
+		return nil
+	}
+
+	ipAddr, err := netip.ParseAddr(ip)
+	if err != nil {
+		return nil
+	}
+
+	country, err := geoipReader.Country(ipAddr)
+	if err != nil || country.Country.ISOCode == "" {
+		return nil
+	}
+
+	emoji, err := emoji.CountryFlag(country.Country.ISOCode)
+	if err != nil {
+		return nil
+	}
+
+	return &IpGeoInfo{
+		Country: country,
+		Emoji:   emoji.String(),
+	}
+}

pkg/geoip/geoip_test.go

@@ -0,0 +1,48 @@
+package geoip
+
+import (
+	"testing"
+)
+
+func initOrSkip(t *testing.T) {
+	t.Helper()
+	if err := Init(); err != nil {
+		t.Skipf("skipping: geoip database unavailable: %v", err)
+	}
+}
+
+func TestGetIpGeoInfo_Cloudflare(t *testing.T) {
+	initOrSkip(t)
+
+	ip := "223.167.150.96"
+	city := GetIpGeoInfo(ip)
+	if city == nil {
+		t.Fatalf("GetIpGeoInfo(%q) returned nil, expected a result", ip)
+	}
+
+	t.Logf("Country:   %s (%s)", city.Country.Country.Names.English, city.Country.Country.ISOCode)
+	t.Logf("Emoji: %s", city.Emoji)
+}
+
+func TestGetIpGeoInfo_EmptyIP(t *testing.T) {
+	initOrSkip(t)
+
+	if city := GetIpGeoInfo(""); city != nil {
+		t.Errorf("GetIpGeoInfo(\"\") = %+v, want nil", city)
+	}
+}
+
+func TestGetIpGeoInfo_InvalidIP(t *testing.T) {
+	initOrSkip(t)
+
+	if city := GetIpGeoInfo("not-an-ip"); city != nil {
+		t.Errorf("GetIpGeoInfo(\"not-an-ip\") = %+v, want nil", city)
+	}
+}
+
+func TestGetIpGeoInfo_UninitializedReader(t *testing.T) {
+	geoipReader = nil
+	if city := GetIpGeoInfo("103.21.244.12"); city != nil {
+		t.Errorf("expected nil when reader is uninitialized, got %+v", city)
+	}
+}

pkg/geoip/go.mod

@@ -0,0 +1,10 @@
+module pkg/geoip
+
+go 1.25.5
+
+require (
+	github.com/enescakir/emoji v1.0.0 // indirect
+	github.com/oschwald/geoip2-golang/v2 v2.1.0 // indirect
+	github.com/oschwald/maxminddb-golang/v2 v2.1.1 // indirect
+	golang.org/x/sys v0.38.0 // indirect
+)

pkg/geoip/go.sum

@@ -0,0 +1,8 @@
+github.com/enescakir/emoji v1.0.0 h1:W+HsNql8swfCQFtioDGDHCHri8nudlK1n5p2rHCJoog=
+github.com/enescakir/emoji v1.0.0/go.mod h1:Bt1EKuLnKDTYpLALApstIkAjdDrS/8IAgTkKp+WKFD0=
+github.com/oschwald/geoip2-golang/v2 v2.1.0 h1:DjnLhNJu9WHwTrmoiQFvgmyJoczhdnm7LB23UBI2Amo=
+github.com/oschwald/geoip2-golang/v2 v2.1.0/go.mod h1:qdVmcPgrTJ4q2eP9tHq/yldMTdp2VMr33uVdFbHBiBc=
+github.com/oschwald/maxminddb-golang/v2 v2.1.1 h1:lA8FH0oOrM4u7mLvowq8IT6a3Q/qEnqRzLQn9eH5ojc=
+github.com/oschwald/maxminddb-golang/v2 v2.1.1/go.mod h1:PLdx6PR+siSIoXqqy7C7r3SB3KZnhxWr1Dp6g0Hacl8=
+golang.org/x/sys v0.38.0 h1:3yZWxaJjBmCWXqhN1qh02AkOnCQ1poK6oF+a7xWL6Gc=
+golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=