export const defaultLocale = 'de';
export const supportedLocales = ['de', 'en'] as const;

export type Locale = (typeof supportedLocales)[number];

export const localeLabels: Record<Locale, string> = {
  de: 'Deutsch',
  en: 'English',
};

export const localeHtmlLang: Record<Locale, string> = {
  de: 'de',
  en: 'en',
};

export const localeOg: Record<Locale, string> = {
  de: 'de_DE',
  en: 'en_US',
};

export function isLocale(value: string | undefined): value is Locale {
  return supportedLocales.includes(value as Locale);
}

export function getLocaleFromPath(pathname: string): Locale {
  const firstSegment = pathname.split('/').filter(Boolean)[0];

  return isLocale(firstSegment) ? firstSegment : defaultLocale;
}

export function stripLocalePrefix(pathname: string): string {
  const segments = pathname.split('/').filter(Boolean);

  if (isLocale(segments[0])) {
    segments.shift();
  }

  const stripped = `/${segments.join('/')}`;

  return stripped === '/' ? '/' : stripped.replace(/\/+$/, '');
}

export function localizedPath(pathname: string, locale: Locale): string {
  const basePath = stripLocalePrefix(pathname);
  const keepTrailingSlash = pathname !== '/' && pathname.endsWith('/');
  const withTrailingSlash = (path: string) =>
    keepTrailingSlash && !path.endsWith('/') ? `${path}/` : path;

  if (locale === defaultLocale) {
    return withTrailingSlash(basePath === '' ? '/' : basePath);
  }

  if (basePath === '/' || basePath === '') {
    return `/${locale}/`;
  }

  return withTrailingSlash(`/${locale}${basePath}`);
}

export function localizeHref(href: string, locale: Locale): string {
  if (
    href.startsWith('http://') ||
    href.startsWith('https://') ||
    href.startsWith('mailto:') ||
    href.startsWith('tel:') ||
    href.startsWith('#')
  ) {
    return href;
  }

  const [path, hash] = href.split('#');
  const localized = localizedPath(path || '/', locale);

  return hash ? `${localized}#${hash}` : localized;
}