Fix locale detection on Windows and Linux

CHANGELOG

@@ -1,3 +1,6 @@
+1.4.1:
+- Fix locale detection on Windows and Linux
+
 1.4.0:
 - Auto-scale font size to fit text
 - Support returning to the main menu

flags.go

@@ -11,6 +11,7 @@ import (
 	"os"
 	"os/exec"
 	"strconv"
+	"strings"
 	"time"
 
 	"code.rocket9labs.com/tslocum/bgammon"
@@ -87,14 +88,21 @@ func parseFlags() *game.Game {
 
 	var forceLanguage *language.Tag
 	if locale == "" {
-		locale = game.DefaultLocale()
+		var err error
+		locale, err = game.GetLocale()
+		if err != nil {
+			locale = ""
+		}
 	}
 	if locale != "" {
-		tag, err := language.Parse(locale)
-		if err != nil {
-			log.Fatalf("unknown locale: %s", locale)
+		dotIndex := strings.IndexByte(locale, '.')
+		if dotIndex != -1 {
+			locale = locale[:dotIndex]
+		}
+		tag, err := language.Parse(locale)
+		if err == nil {
+			forceLanguage = &tag
 		}
-		forceLanguage = &tag
 	}
 	game.LoadLocale(forceLanguage)
 

flags_web.go

@@ -9,8 +9,8 @@ import (
 
 func parseFlags() *game.Game {
 	var forceLanguage *language.Tag
-	locale := game.DefaultLocale()
-	if locale != "" {
+	locale, err := game.GetLocale()
+	if err == nil && locale != "" {
 		tag, err := language.Parse(locale)
 		if err == nil {
 			forceLanguage = &tag

game/client.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"log"
 	"net"
-	"runtime/debug"
 	"strings"
 	"time"
 
@@ -89,7 +88,6 @@ func (c *Client) LoggedIn() bool {
 
 func (c *Client) connectWebSocket() {
 	if !c.connecting {
-		debug.PrintStack()
 		return
 	}
 
@@ -101,7 +99,6 @@ func (c *Client) connectWebSocket() {
 		}
 		for {
 			if !c.connecting {
-				debug.PrintStack()
 				return
 			}
 			if !focused() {

game/game_android.go

@@ -15,7 +15,6 @@ import (
 	"time"
 
 	"code.rocket9labs.com/tslocum/gotext"
-	"golang.org/x/text/language"
 )
 
 const (
@@ -61,21 +60,6 @@ func init() {
 		return
 	}
 	time.Local = tz
-
-	// Detect locale.
-	out, err = exec.Command("/system/bin/getprop", "persist.sys.locale").Output()
-	if err != nil {
-		return
-	}
-	tag, err := language.Parse(strings.TrimSpace(string(out)))
-	if err != nil {
-		return
-	}
-	LoadLocale(&tag)
-}
-
-func DefaultLocale() string {
-	return ""
 }
 
 func focused() bool {

game/game_standard.go

@@ -21,10 +21,6 @@ const (
 	targetFPS          = 144
 )
 
-func DefaultLocale() string {
-	return ""
-}
-
 func focused() bool {
 	return true
 }

game/game_web.go

@@ -36,10 +36,6 @@ func init() {
 	}
 }
 
-func DefaultLocale() string {
-	return js.Global().Get("navigator").Get("language").String()
-}
-
 func focused() bool {
 	document := js.Global().Get("document")
 	hasFocus := document.Call("hasFocus", nil)

game/locale_android.go

@@ -0,0 +1,31 @@
+//go:build android
+
+package game
+
+import (
+	"os/exec"
+	"strings"
+
+	"golang.org/x/text/language"
+)
+
+func init() {
+	// Load locale early on Android.
+	locale, err := GetLocale()
+	if err != nil {
+		return
+	}
+	tag, err := language.Parse(strings.TrimSpace(locale))
+	if err != nil {
+		return
+	}
+	LoadLocale(&tag)
+}
+
+func GetLocale() (string, error) {
+	out, err := exec.Command("/system/bin/getprop", "persist.sys.locale").Output()
+	if err != nil {
+		return "", err
+	}
+	return string(out), nil
+}

game/locale_linux.go

@@ -0,0 +1,11 @@
+//go:build linux && !android
+
+package game
+
+import (
+	"os"
+)
+
+func GetLocale() (string, error) {
+	return os.Getenv("LANG"), nil
+}

game/locale_wasm.go

@@ -0,0 +1,9 @@
+//go:build js && wasm
+
+package game
+
+import "syscall/js"
+
+func GetLocale() (string, error) {
+	return js.Global().Get("navigator").Get("language").String(), nil
+}

game/locale_windows.go

@@ -0,0 +1,103 @@
+//go:build windows
+
+package game
+
+import (
+	"fmt"
+	"strings"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+// Source code in this file was copied from https://github.com/jeandeaual/go-locale
+// The following license applies to the source code in this file:
+//
+// MIT License
+//
+// Copyright (c) 2020 Alexis Jeandeau
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// LocaleNameMaxLength is the maximum length of a locale name on Windows.
+// See https://docs.microsoft.com/en-us/windows/win32/intl/locale-name-constants.
+const LocaleNameMaxLength uint32 = 85
+
+func splitLocale(locale string) (string, string) {
+	// Remove the encoding, if present.
+	formattedLocale, _, _ := strings.Cut(locale, ".")
+
+	// Normalize by replacing the hyphens with underscores
+	formattedLocale = strings.ReplaceAll(formattedLocale, "-", "_")
+
+	// Split at the underscore.
+	language, territory, _ := strings.Cut(formattedLocale, "_")
+	return language, territory
+}
+
+func getWindowsLocaleFromProc(syscall string) (string, error) {
+	dll, err := windows.LoadDLL("kernel32")
+	if err != nil {
+		return "", fmt.Errorf("could not find the kernel32 DLL: %v", err)
+	}
+
+	proc, err := dll.FindProc(syscall)
+	if err != nil {
+		return "", fmt.Errorf("could not find the %s proc in kernel32: %v", syscall, err)
+	}
+
+	buffer := make([]uint16, LocaleNameMaxLength)
+
+	// See https://docs.microsoft.com/en-us/windows/win32/api/winnls/nf-winnls-getuserdefaultlocalename
+	// and https://docs.microsoft.com/en-us/windows/win32/api/winnls/nf-winnls-getsystemdefaultlocalename
+	// GetUserDefaultLocaleName and GetSystemDefaultLocaleName both take a buffer and a buffer size,
+	// and return the length of the locale name (0 if not found).
+	ret, _, err := proc.Call(uintptr(unsafe.Pointer(&buffer[0])), uintptr(LocaleNameMaxLength))
+	if ret == 0 {
+		return "", fmt.Errorf("locale not found when calling %s: %v", syscall, err)
+	}
+
+	return windows.UTF16ToString(buffer), nil
+}
+
+func getWindowsLocale() (string, error) {
+	var (
+		locale string
+		err    error
+	)
+
+	for _, proc := range [...]string{"GetUserDefaultLocaleName", "GetSystemDefaultLocaleName"} {
+		locale, err = getWindowsLocaleFromProc(proc)
+		if err == nil {
+			return locale, err
+		}
+	}
+
+	return locale, err
+}
+
+// GetLocale retrieves the IETF BCP 47 language tag set on the system.
+func GetLocale() (string, error) {
+	locale, err := getWindowsLocale()
+	if err != nil {
+		return "", fmt.Errorf("cannot determine locale: %v", err)
+	}
+
+	return locale, err
+}