import { DEFAULT_LOCALE, LOCALE_CODES, removeTrailingSlash, useTranslatedPaths } from '@i18n';
import { defineMiddleware } from 'astro:middleware';
import { handleRedirect } from './redirects';

export const onRequest = defineMiddleware((context, next) => {
  const [_, langParam, ...restUrl] = context.url.pathname.split('/');

  const noLangPathname = LOCALE_CODES.includes(langParam)
    ? `/${restUrl.join('/')}`
    : context.url.pathname;

  // if it's an astro-reserved path,
  // or an api path, skip it
  if (noLangPathname.startsWith('/_') || noLangPathname.startsWith('/api')) {
    return next();
  }

  // check for redirections first
  const redirectedUrl = handleRedirect(noLangPathname) ?? handleRedirect(context.url.pathname);
  if (redirectedUrl) {
    return context.redirect(removeTrailingSlash(redirectedUrl));
  }

  // if there's no lang parameter, detect language and redirect
  if (!langParam || !LOCALE_CODES.includes(langParam)) {
    const headerLang = context.request.headers.get('Accept-Language');
    const pathnameWithParams = context.url.href.replace(context.url.origin, '');
    const path = removeTrailingSlash(pathnameWithParams);

    // if the lang is french, serve the content in french
    if (headerLang?.includes('fr')) {
      const translatePaths = useTranslatedPaths('fr');
      return context.redirect(translatePaths(path));
    }

    // otherwise serve english
    const translatePaths = useTranslatedPaths(DEFAULT_LOCALE);
    return context.redirect(translatePaths(path));
  }

  return next();
});