/*
 * LURE - Linux User REpository
 * Copyright (C) 2023 Elara Musayelyan
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package config

import (
	"context"
	"os"
	"strings"
	"sync"

	"go.elara.ws/lure/pkg/loggerctx"
	"golang.org/x/text/language"
)

var (
	langMtx sync.Mutex
	lang    language.Tag
	langSet bool
)

// Language returns the system language.
// The first time it's called, it'll detect the langauge based on
// the $LANG environment variable.
// Subsequent calls will just return the same value.
func Language(ctx context.Context) language.Tag {
	langMtx.Lock()
	defer langMtx.Unlock()
	log := loggerctx.From(ctx)
	if !langSet {
		syslang := SystemLang()
		tag, err := language.Parse(syslang)
		if err != nil {
			log.Fatal("Error parsing system language").Err(err).Send()
		}
		base, _ := tag.Base()
		lang = language.Make(base.String())
		langSet = true
	}
	return lang
}

// SystemLang returns the system language based on
// the $LANG environment variable.
func SystemLang() string {
	lang := os.Getenv("LANG")
	lang, _, _ = strings.Cut(lang, ".")
	if lang == "" || lang == "C" {
		lang = "en"
	}
	return lang
}