import { defaultLocale, locales } from '$lib/translations';
import type { Handle } from '@sveltejs/kit';

const routeRegex = new RegExp(/^\/[^.]*([?#].*)?$/);

/** @type {import('@sveltejs/kit').Handle} */
export const handle: Handle = async ({ event, resolve }) => {
  const { url, request } = event;
  const { pathname } = url;

  // If this request is a route request
  if (routeRegex.test(pathname)) {
    const supportedLocales = locales.get().map((l) => l.toLowerCase());
    let locale = supportedLocales.find((l) => l === `${pathname.match(/[^/]+?(?=\/|$)/)}`.toLowerCase());
    if (locale === defaultLocale && !request.headers.get('prevent-redirect')) {
      const localeRegex = new RegExp(`^/${locale}`);
      const location = `${pathname}`.replace(localeRegex, '') || '/';
      return new Response(undefined, { headers: { location }, status: 301 });
    } else if (!locale) {
      locale = defaultLocale;
    }

    return resolve(
      { ...event, locals: { lang: locale } },
      {
        transformPageChunk: ({ html }) => html.replace('%lang%', `${locale}`),
      }
    );
  }

  return resolve(event);
};