app_localization_helper.dart

import 'dart:async';
import 'dart:io';

import 'package:flutter/material.dart';
import 'package:get/get.dart';
import 'package:shared_preferences/shared_preferences.dart';

/// This class allows to change app locale
class AppLocaleHelper {
  static const en = 'en';
  static const de = 'de';
  static const enLocale = Locale(en);
  static const deLocale = Locale(de);

  static const _languageCode = 'languageCode';
  static String? lastSelectedCode;

  static Future<void> updateLocale(Locale locale, BuildContext context) async {
    var prefs = await SharedPreferences.getInstance();
    lastSelectedCode = locale.languageCode;
    await prefs.setString(_languageCode, locale.languageCode);
    unawaited(Get.updateLocale(locale));
  }

  /// Returns last selected language code, if there is not selected language
  /// code it returns default language code (see [fetchDefaultLanguageCode]).
  static Future<String?> fetchLanguageCode() async {
    if (lastSelectedCode != null) {
      return lastSelectedCode;
    }
    var prefs = await SharedPreferences.getInstance();
    lastSelectedCode = prefs.getString(_languageCode) ?? await fetchDefaultLanguageCode();
    return lastSelectedCode;
  }

  /// Returns language code based on device locale.
  static Future<String> fetchDefaultLanguageCode() async {
    final locale = Platform.localeName;
    if(locale.toLowerCase().contains(de)){
      return de;
    }else{
      return en;
    }
  }
}