'use strict';

function cssHasPseudo(document) {
  const observedItems = []; // document.createAttribute() doesn't support `:` in the name. innerHTML does

  const attributeElement = document.createElement('x'); // walk all stylesheets to collect observed css rules

  [].forEach.call(document.styleSheets, walkStyleSheet);
  transformObservedItems(); // observe DOM modifications that affect selectors

  const mutationObserver = new MutationObserver(mutationsList => {
    mutationsList.forEach(mutation => {
      [].forEach.call(mutation.addedNodes || [], node => {
        // walk stylesheets to collect observed css rules
        if (node.nodeType === 1 && node.sheet) {
          walkStyleSheet(node.sheet);
        }
      }); // transform observed css rules

      cleanupObservedCssRules();
      transformObservedItems();
    });
  });
  mutationObserver.observe(document, {
    childList: true,
    subtree: true
  }); // observe DOM events that affect pseudo-selectors

  document.addEventListener('focus', transformObservedItems, true);
  document.addEventListener('blur', transformObservedItems, true);
  document.addEventListener('input', transformObservedItems); // transform observed css rules

  function transformObservedItems() {
    requestAnimationFrame(() => {
      observedItems.forEach(item => {
        const nodes = [];
        [].forEach.call(document.querySelectorAll(item.scopeSelector), element => {
          const nthChild = [].indexOf.call(element.parentNode.children, element) + 1;
          const relativeSelectors = item.relativeSelectors.map(relativeSelector => item.scopeSelector + ':nth-child(' + nthChild + ') ' + relativeSelector).join(); // find any relative :has element from the :scope element

          const relativeElement = element.parentNode.querySelector(relativeSelectors);
          const shouldElementMatch = item.isNot ? !relativeElement : relativeElement;

          if (shouldElementMatch) {
            // memorize the node
            nodes.push(element); // set an attribute with an irregular attribute name
            // document.createAttribute() doesn't support special characters

            attributeElement.innerHTML = '<x ' + item.attributeName + '>';
            element.setAttributeNode(attributeElement.children[0].attributes[0].cloneNode()); // trigger a style refresh in IE and Edge

            document.documentElement.style.zoom = 1;
            document.documentElement.style.zoom = null;
          }
        }); // remove the encoded attribute from all nodes that no longer match them

        item.nodes.forEach(node => {
          if (nodes.indexOf(node) === -1) {
            node.removeAttribute(item.attributeName); // trigger a style refresh in IE and Edge

            document.documentElement.style.zoom = 1;
            document.documentElement.style.zoom = null;
          }
        }); // update the

        item.nodes = nodes;
      });
    });
  } // remove any observed cssrules that no longer apply


  function cleanupObservedCssRules() {
    [].push.apply(observedItems, observedItems.splice(0).filter(item => item.rule.parentStyleSheet && item.rule.parentStyleSheet.ownerNode && document.documentElement.contains(item.rule.parentStyleSheet.ownerNode)));
  } // walk a stylesheet to collect observed css rules


  function walkStyleSheet(styleSheet) {
    try {
      // walk a css rule to collect observed css rules
      [].forEach.call(styleSheet.cssRules || [], rule => {
        if (rule.selectorText) {
          // decode the selector text in all browsers to:
          // [1] = :scope, [2] = :not(:has), [3] = :has relative, [4] = :scope relative
          const selectors = decodeURIComponent(rule.selectorText.replace(/\\(.)/g, '$1')).match(/^(.*?)\[:(not-)?has\((.+?)\)\](.*?)$/);

          if (selectors) {
            const attributeName = ':' + (selectors[2] ? 'not-' : '') + 'has(' + // encode a :has() pseudo selector as an attribute name
            encodeURIComponent(selectors[3]).replace(/%3A/g, ':').replace(/%5B/g, '[').replace(/%5D/g, ']').replace(/%2C/g, ',') + ')';
            observedItems.push({
              rule,
              scopeSelector: selectors[1],
              isNot: selectors[2],
              relativeSelectors: selectors[3].split(/\s*,\s*/),
              attributeName,
              nodes: []
            });
          }
        } else {
          walkStyleSheet(rule);
        }
      });
    } catch (error) {
      /* do nothing and continue */
    }
  }
}

module.exports = cssHasPseudo;
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