import { mergeUrlParams, setUrlFragment } from '~/lib/utils/url_utility';

/**
 * Ensure the given URL fragment is preserved by appending it to sign-in/sign-up form actions and
 * OAuth/SAML login links.
 *
 * @param fragment {string} - url fragment to be preserved
 */
export default function preserveUrlFragment(fragment = '') {
  if (fragment) {
    const normalFragment = fragment.replace(/^#/, '');

    // Append the fragment to all sign-in/sign-up form actions so it is preserved when the user is
    // eventually redirected back to the originally requested URL.
    const forms = document.querySelectorAll('#signin-container .tab-content form');
    Array.prototype.forEach.call(forms, form => {
      const actionWithFragment = setUrlFragment(form.getAttribute('action'), `#${normalFragment}`);
      form.setAttribute('action', actionWithFragment);
    });

    // Append a redirect_fragment query param to all oauth provider links. The redirect_fragment
    // query param will be available in the omniauth callback upon successful authentication
    const oauthForms = document.querySelectorAll('#signin-container .omniauth-container form');
    Array.prototype.forEach.call(oauthForms, oauthForm => {
      const newHref = mergeUrlParams(
        { redirect_fragment: normalFragment },
        oauthForm.getAttribute('action'),
      );
      oauthForm.setAttribute('action', newHref);
    });
  }
}
