Detect system locale and estimate best default locale setting

core/config.go

@@ -3,7 +3,11 @@ package core
 import (
 	"flag"
 
+	locale "github.com/Xuanwo/go-locale"
+	"golang.org/x/exp/slices"
+
 	"github.com/safing/portbase/config"
+	"github.com/safing/portbase/log"
 )
 
 // Configuration Keys.
@@ -14,7 +18,7 @@ var (
 	CfgNetworkServiceKey      = "core/networkService"
 	defaultNetworkServiceMode bool
 
-	CfgLocaleKey = "core/localeID"
+	CfgLocaleKey = "core/locale"
 )
 
 func init() {
@@ -44,21 +48,21 @@ func registerConfig() error {
 	}
 
 	if err := config.Register(&config.Option{
-		Name:           "Locale",
+		Name:           "Time and Date Format",
 		Key:            CfgLocaleKey,
-		Description:    "Configures the locale for the user interface. This mainly affects rendering of dates, currency and numbers. Note that the Portmaster does not yet support different languages.",
+		Description:    "Configures the time and date format for the user interface. Selection is an example and correct formatting in the UI is a continual work in progress.",
 		OptType:        config.OptTypeString,
 		ExpertiseLevel: config.ExpertiseLevelUser,
 		ReleaseLevel:   config.ReleaseLevelStable,
-		DefaultValue:   "en-GB",
+		DefaultValue:   getDefaultLocale(),
 		PossibleValues: []config.PossibleValue{
 			{
-				Name:  "en-GB",
-				Value: "en-GB",
+				Name:  "24h DD-MM-YYYY",
+				Value: enGBLocale,
 			},
 			{
-				Name:  "en-US",
-				Value: "en-US",
+				Name:  "12h MM/DD/YYYY",
+				Value: enUSLocale,
 			},
 		},
 		Annotations: config.Annotations{
@@ -72,3 +76,37 @@ func registerConfig() error {
 
 	return nil
 }
+
+func getDefaultLocale() string {
+	// Get locales from system.
+	detectedLocales, err := locale.DetectAll()
+	if err != nil {
+		log.Warningf("core: failed to detect locale: %s", err)
+		return enGBLocale
+	}
+
+	// log.Debugf("core: detected locales: %s", detectedLocales)
+
+	// Check if there is a locale that corresponds to the en-US locale.
+	for _, detectedLocale := range detectedLocales {
+		if slices.Contains[[]string, string](defaultEnUSLocales, detectedLocale.String()) {
+			return enUSLocale
+		}
+	}
+
+	// Otherwise, return the en-GB locale as default.
+	return enGBLocale
+}
+
+var (
+	enGBLocale = "en-GB"
+	enUSLocale = "en-US"
+
+	defaultEnUSLocales = []string{
+		"en-AS", // English (American Samoa)
+		"en-GU", // English (Guam)
+		"en-UM", // English (U.S. Minor Outlying Islands)
+		"en-US", // English (United States)
+		"en-VI", // English (U.S. Virgin Islands)
+	}
+)