/**
 * Test helpers for reaching a mounted module artifact's DOM.
 *
 * Since ADR 0040 the generic loader mounts every declared browser artifact inside its own Shadow DOM
 * root, so a module's elements are deliberately *not* in the host document's tree: `querySelector`
 * on the shell's container cannot see them, and neither can a stray Dashboard stylesheet. These
 * helpers walk into those open roots so a shell test can still assert on what a module rendered —
 * which is exactly what a host's own diagnostics would do, and is why the roots are `open`.
 *
 * Deliberately test-only. Production shell code never reaches into an artifact's root; the module
 * owns its contents.
 */

const ISOLATION_HOST_SELECTOR = "[data-ekklesia-module-ui]";

function isolatedRoots(root: ParentNode): readonly ShadowRoot[] {
  return [...root.querySelectorAll(ISOLATION_HOST_SELECTOR)]
    .map((host) => host.shadowRoot)
    .filter((shadowRoot): shadowRoot is ShadowRoot => shadowRoot !== null);
}

/** The first match anywhere in `root`, including inside every mounted artifact's isolated root. */
export function deepQuery(root: ParentNode, selector: string): Element | null {
  const direct = root.querySelector(selector);
  if (direct) {
    return direct;
  }
  for (const shadowRoot of isolatedRoots(root)) {
    const nested = deepQuery(shadowRoot, selector);
    if (nested) {
      return nested;
    }
  }
  return null;
}

/** Every match anywhere in `root`, host tree first, then each artifact's isolated root in order. */
export function deepQueryAll(root: ParentNode, selector: string): readonly Element[] {
  return [
    ...root.querySelectorAll(selector),
    ...isolatedRoots(root).flatMap((shadowRoot) => [...deepQueryAll(shadowRoot, selector)]),
  ];
}

/** The text an artifact rendered, read from the exact element the loader hands its `mount` — so the
 * stylesheet the loader installed alongside it is never mistaken for content. */
export function isolatedText(container: Element | null | undefined): string {
  return isolatedMountTarget(container)?.textContent ?? "";
}

/** The element the loader passed to a mounted artifact's `mount`, for identity assertions. */
export function isolatedMountTarget(container: Element | null | undefined): Element | null {
  const host = container?.querySelector(ISOLATION_HOST_SELECTOR);
  return host?.shadowRoot?.querySelector("[data-ekklesia-module-ui-root]") ?? null;
}