import getWindow from "./getWindow.js";
import getNodeName from "./getNodeName.js";
import getComputedStyle from "./getComputedStyle.js";
import { isHTMLElement, isShadowRoot } from "./instanceOf.js";
import isTableElement from "./isTableElement.js";
import getParentNode from "./getParentNode.js";
import getUAString from "../utils/userAgent.js";
function getTrueOffsetParent(element) {
  if (!isHTMLElement(element) || // https://github.com/popperjs/popper-core/issues/837
  getComputedStyle(element).position === "fixed") {
    return null;
  }
  return element.offsetParent;
}
function getContainingBlock(element) {
  var isFirefox = /firefox/i.test(getUAString());
  var isIE = /Trident/i.test(getUAString());
  if (isIE && isHTMLElement(element)) {
    var elementCss = getComputedStyle(element);
    if (elementCss.position === "fixed") {
      return null;
    }
  }
  var currentNode = getParentNode(element);
  if (isShadowRoot(currentNode)) {
    currentNode = currentNode.host;
  }
  while (isHTMLElement(currentNode) && ["html", "body"].indexOf(getNodeName(currentNode)) < 0) {
    var css = getComputedStyle(currentNode);
    if (css.transform !== "none" || css.perspective !== "none" || css.contain === "paint" || ["transform", "perspective"].indexOf(css.willChange) !== -1 || isFirefox && css.willChange === "filter" || isFirefox && css.filter && css.filter !== "none") {
      return currentNode;
    } else {
      currentNode = currentNode.parentNode;
    }
  }
  return null;
}
function getOffsetParent(element) {
  var window = getWindow(element);
  var offsetParent = getTrueOffsetParent(element);
  while (offsetParent && isTableElement(offsetParent) && getComputedStyle(offsetParent).position === "static") {
    offsetParent = getTrueOffsetParent(offsetParent);
  }
  if (offsetParent && (getNodeName(offsetParent) === "html" || getNodeName(offsetParent) === "body" && getComputedStyle(offsetParent).position === "static")) {
    return window;
  }
  return offsetParent || getContainingBlock(element) || window;
}
export {
  getOffsetParent as default
};
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