export async function waitForDomSettle() {
  return new Promise<void>((resolve) => {
    const createTimeout = () => {
      return setTimeout(() => {
        resolve();
      }, 2000);
    };
    let timeout = createTimeout();
    const observer = new MutationObserver(() => {
      clearTimeout(timeout);
      timeout = createTimeout();
    });
    observer.observe(window.document.body, { childList: true, subtree: true });
  });
}

window.waitForDomSettle = waitForDomSettle;

export function calculateViewportHeight() {
  return Math.ceil(window.innerHeight * 0.75);
}

/**
 * Tests if the element actually responds to .scrollTo(...)
 * and that scrollTop changes as expected.
 */
export function canElementScroll(elem: HTMLElement): boolean {
  // Quick check if scrollTo is a function
  if (typeof elem.scrollTo !== "function") {
    console.warn("canElementScroll: .scrollTo is not a function.");
    return false;
  }

  try {
    const originalTop = elem.scrollTop;

    // try to scroll
    elem.scrollTo({
      top: originalTop + 100,
      left: 0,
      behavior: "instant",
    });

    // If scrollTop never changed, consider it unscrollable
    if (elem.scrollTop === originalTop) {
      throw new Error("scrollTop did not change");
    }

    // Scroll back to original place
    elem.scrollTo({
      top: originalTop,
      left: 0,
      behavior: "instant",
    });

    return true;
  } catch (error) {
    console.warn("canElementScroll error:", (error as Error).message || error);
    return false;
  }
}

export function getNodeFromXpath(xpath: string) {
  return document.evaluate(
    xpath,
    document.documentElement,
    null,
    XPathResult.FIRST_ORDERED_NODE_TYPE,
    null,
  ).singleNodeValue;
}