export type RouteId = 'editor' | 'cards' | 'reset';

type Render = (route: RouteId, root: HTMLElement) => void | (() => void);

export function matchRoute(pathname: string): RouteId {
  const path = pathname.replace(/\/+$/, '') || '/';
  if (path === '/karten') return 'cards';
  if (path === '/passwort-neu') return 'reset';
  return 'editor';
}

// Beendet den laufenden Router (Seiten-Cleanup, Listener); null, solange keiner läuft.
let stopCurrent: (() => void) | null = null;
let renderCurrent: (() => void) | null = null;

export function navigate(path: string): void {
  const url = new URL(path, location.href);
  const target = url.pathname + url.search + url.hash;
  if (target !== location.pathname + location.search + location.hash) {
    history.pushState(null, '', target);
  }
  renderCurrent?.();
}

export function startRouter(render: Render): void {
  stopCurrent?.();

  const root = document.getElementById('app-root');
  if (!root) throw new Error('#app-root fehlt');

  let cleanup: void | (() => void);

  const renderPage = () => {
    cleanup?.();
    cleanup = undefined;
    cleanup = render(matchRoute(location.pathname), root);
  };

  const onClick = (event: MouseEvent) => {
    if (event.defaultPrevented || event.button !== 0) return;
    if (event.metaKey || event.ctrlKey || event.shiftKey || event.altKey) return;
    const anchor = (event.target as Element | null)?.closest<HTMLAnchorElement>('a[data-link]');
    if (!anchor || (anchor.target && anchor.target !== '_self')) return;
    const url = new URL(anchor.href, location.href);
    if (url.origin !== location.origin) return;
    event.preventDefault();
    navigate(url.pathname + url.search + url.hash);
  };

  document.addEventListener('click', onClick);
  window.addEventListener('popstate', renderPage);

  renderCurrent = renderPage;
  stopCurrent = () => {
    document.removeEventListener('click', onClick);
    window.removeEventListener('popstate', renderPage);
    cleanup?.();
    cleanup = undefined;
    renderCurrent = null;
    stopCurrent = null;
  };

  renderPage();
}