import { a as assert } from './assert.js';

function compare(a, b) {
  if (a === b)
    throw new Error("Cannot compare node with itself");
  const ancestors = {
    a: getAncestors(a),
    b: getAncestors(b)
  };
  let common_ancestor;
  while (ancestors.a.at(-1) === ancestors.b.at(-1)) {
    a = ancestors.a.pop();
    b = ancestors.b.pop();
    common_ancestor = a;
  }
  assert(common_ancestor);
  const z_indexes = {
    a: getZIndex(findStackingContext(ancestors.a)),
    b: getZIndex(findStackingContext(ancestors.b))
  };
  if (z_indexes.a === z_indexes.b) {
    const children = common_ancestor.childNodes;
    const furthest_ancestors = {
      a: ancestors.a.at(-1),
      b: ancestors.b.at(-1)
    };
    let i = children.length;
    while (i--) {
      const child = children[i];
      if (child === furthest_ancestors.a)
        return 1;
      if (child === furthest_ancestors.b)
        return -1;
    }
  }
  return Math.sign(z_indexes.a - z_indexes.b);
}
const props = /\b(?:position|zIndex|opacity|transform|webkitTransform|mixBlendMode|filter|webkitFilter|isolation)\b/;
function isFlexItem(node) {
  const display = getComputedStyle(getParent(node)).display;
  return display === "flex" || display === "inline-flex";
}
function createsStackingContext(node) {
  const style = getComputedStyle(node);
  if (style.position === "fixed")
    return true;
  if (style.zIndex !== "auto" && (style.position !== "static" || isFlexItem(node))) {
    return true;
  }
  if (+style.opacity < 1)
    return true;
  if ("transform" in style && style.transform !== "none")
    return true;
  if ("webkitTransform" in style && style.webkitTransform !== "none")
    return true;
  if ("mixBlendMode" in style && style.mixBlendMode !== "normal")
    return true;
  if ("filter" in style && style.filter !== "none")
    return true;
  if ("webkitFilter" in style && style.webkitFilter !== "none")
    return true;
  if ("isolation" in style && style.isolation === "isolate")
    return true;
  if (props.test(style.willChange))
    return true;
  if (style.webkitOverflowScrolling === "touch")
    return true;
  return false;
}
function findStackingContext(nodes) {
  let i = nodes.length;
  while (i--) {
    const node = nodes[i];
    assert(node);
    if (createsStackingContext(node))
      return node;
  }
  return null;
}
function getZIndex(node) {
  return node && Number(getComputedStyle(node).zIndex) || 0;
}
function getAncestors(node) {
  const ancestors = [];
  while (node) {
    ancestors.push(node);
    node = getParent(node);
  }
  return ancestors;
}
function getParent(node) {
  return node.parentNode instanceof DocumentFragment && node.parentNode?.host || node.parentNode;
}

export { compare as c };
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