import {
  DEFAULT_LANGUAGE,
  isLanguage,
  type Language,
} from '@/domain/language/entities';
import type { LanguageRepository } from '@/domain/language/repository';

export function detectBrowserLanguage(): Language {
  if (typeof navigator === 'undefined') return DEFAULT_LANGUAGE;

  const browserLang = navigator.language.toLowerCase();
  if (browserLang.startsWith('sv')) return 'sv';
  if (browserLang.startsWith('ar')) return 'ar';
  if (browserLang.startsWith('tr')) return 'tr';
  if (browserLang.startsWith('hi')) return 'hi';
  if (browserLang.startsWith('ur')) return 'ur';
  if (browserLang.startsWith('en')) return 'en';
  return DEFAULT_LANGUAGE;
}

export function resolveInitialLanguage(repository: LanguageRepository): Language {
  const saved = repository.load();
  if (saved && isLanguage(saved)) return saved;
  return detectBrowserLanguage();
}

export function persistLanguage(repository: LanguageRepository, language: Language): void {
  repository.save(language);
}