OnlineLibrary

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package lang
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import (
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	"errors"
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	"os"
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	"path/filepath"
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	"unsafe"
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	"OnlineLibrary/internal/config"
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	"github.com/leonelquinteros/gotext"
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	"golang.org/x/sys/windows"
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)
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const (
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	LOCALE_SNATIVELANGUAGENAME = 0x00000004
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)
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var kernel32 = windows.NewLazySystemDLL("kernel32.dll")
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var (
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	procGetUserDefaultUILanguage = kernel32.NewProc("GetUserDefaultUILanguage")
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	procGetLocaleInfoW           = kernel32.NewProc("GetLocaleInfoW")
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	procLocaleNameToLCID         = kernel32.NewProc("LocaleNameToLCID")
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	procLCIDToLocaleName         = kernel32.NewProc("LCIDToLocaleName")
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)
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type Language struct {
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	ID          string
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	Description string
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}
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type LCID uint
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func GetUserDefaultUILanguage() LCID {
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	lcid, _, _ := procGetUserDefaultUILanguage.Call()
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	return LCID(lcid)
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}
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func GetLocaleDescription(lcid LCID) (string, error) {
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	buf := make([]uint16, 1024)
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	r, _, _ := procGetLocaleInfoW.Call(uintptr(lcid), LOCALE_SNATIVELANGUAGENAME, uintptr(unsafe.Pointer(&buf[0])), uintptr(len(buf)))
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	if r == 0 {
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		return "", errors.New("invalid lcid")
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	}
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	return windows.UTF16ToString(buf), nil
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}
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func LocaleNameToLCID(localeName string) (LCID, error) {
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	buf, err := windows.UTF16FromString(localeName)
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	if err != nil {
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		return 0, err
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	}
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	lcid, _, _ := procLocaleNameToLCID.Call(uintptr(unsafe.Pointer(&buf[0])), 0)
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	if lcid == 0 {
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		return 0, errors.New("invalid locale name")
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	}
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	return LCID(lcid), nil
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}
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func LCIDToLocaleName(lcid LCID) (string, error) {
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	buf := make([]uint16, 128)
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	r, _, _ := procLCIDToLocaleName.Call(uintptr(lcid), uintptr(unsafe.Pointer(&buf[0])), uintptr(len(buf)), 0)
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	if r == 0 {
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		return "", errors.New("invalid lcid")
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	}
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	return windows.UTF16ToString(buf), nil
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}
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func availableLanguages(lib string) []Language {
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	langs := make([]Language, 0)
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	path, err := filepath.Abs(lib)
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	if err != nil {
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		return langs
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	}
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	entrys, err := os.ReadDir(path)
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	if err != nil {
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		return langs
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	}
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	locales := []string{"en"}
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	for _, e := range entrys {
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		if e.IsDir() && e.Name() != "en" {
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			locales = append(locales, e.Name())
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		}
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	}
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	for _, locale := range locales {
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		lcid, err := LocaleNameToLCID(locale)
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		if err != nil {
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			continue
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		}
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		description, err := GetLocaleDescription(lcid)
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		if err != nil {
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			continue
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		}
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		l := Language{ID: locale, Description: description}
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		langs = append(langs, l)
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	}
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	return langs
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}
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func Init(lang string) ([]Language, bool) {
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	lib := "locale"
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	langs := availableLanguages(lib)
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	langIsAvailable := false
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	for _, l := range langs {
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		if lang == l.ID {
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			langIsAvailable = true
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			break
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		}
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	}
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	if !langIsAvailable {
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		lang = "en"
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		lcid := GetUserDefaultUILanguage()
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		if locale, err := LCIDToLocaleName(lcid); err == nil {
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			lang = locale
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		}
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	}
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	gotext.Configure(lib, lang, config.ProgramName)
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	return langs, langIsAvailable
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}
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