function isVisible(el) {
  if (!el || !el.getBoundingClientRect) return false;
  const rect = el.getBoundingClientRect();
  const style = window.getComputedStyle(el);
  return rect.width > 0 && rect.height > 0 && style.display !== 'none' && style.visibility !== 'hidden';
}

function walkRoots(root, rows, seen) {
  if (!root || seen.has(root)) return;
  seen.add(root);

  const walker = document.createTreeWalker(root, NodeFilter.SHOW_ELEMENT);
  let node = walker.currentNode;
  while (node) {
    if (node.nodeType === Node.ELEMENT_NODE && node.tagName) rows.push(node);
    if (node.shadowRoot) walkRoots(node.shadowRoot, rows, seen);
    node = walker.nextNode();
  }
}

function allElements() {
  const rows = [];
  walkRoots(document, rows, new Set());
  return rows;
}

function insideInventoryRow(el) {
  return Boolean(el && el.closest && el.closest('div[data-sku]'));
}

function clickTargetFor(checkbox) {
  if (!checkbox) return null;
  if (checkbox.shadowRoot) {
    const shadowTarget = checkbox.shadowRoot.querySelector('[role="checkbox"], .checkbox');
    if (shadowTarget) return shadowTarget;
  }
  return checkbox;
}

const rowCount = document.querySelectorAll('div[data-sku]').length;
if (rowCount <= 0) {
  return { ok: false, reason: 'no inventory rows after status filter', rowCount };
}

const checkboxes = allElements()
  .filter((el) => (el.tagName || '').toLowerCase() === 'kat-checkbox' && isVisible(el))
  .sort((a, b) => {
    const rectA = a.getBoundingClientRect();
    const rectB = b.getBoundingClientRect();
    return rectA.top - rectB.top || rectA.left - rectB.left;
  });

const headerCheckbox = checkboxes.find((el) => !insideInventoryRow(el)) || checkboxes[0];
if (!headerCheckbox) {
  return { ok: false, reason: 'select-all checkbox not found', rowCount, checkboxCount: checkboxes.length };
}

const target = clickTargetFor(headerCheckbox);
target.scrollIntoView({ block: 'center', inline: 'nearest' });
target.click();

return {
  ok: true,
  rowCount,
  checkboxCount: checkboxes.length,
  clicked: {
    tag: headerCheckbox.tagName,
    insideInventoryRow: insideInventoryRow(headerCheckbox),
    outerHTML: (headerCheckbox.outerHTML || '').slice(0, 1000),
  },
};