"use strict";
  const DOMException = require("domexception/webidl2js-wrapper");
  const idlUtils = require("../generated/utils");
  const conversions = require("webidl-conversions");
  
  // TODO: Once NodeFilter is ported to IDL method, use those instead.
  exports.FILTER_ACCEPT = 1; // NodeFilter.FILTER_ACCEPT
  exports.FILTER_REJECT = 2; // NodeFilter.FILTER_REJECT
  exports.FILTER_SKIP = 3; // NodeFilter.FILTER_SKIP
  
  exports.filter = (nodeIteratorOrTreeWalkerImpl, nodeImpl) => {
    if (nodeIteratorOrTreeWalkerImpl._active) {
      throw DOMException.create(nodeIteratorOrTreeWalkerImpl._globalObject, [
        "Recursive node filtering",
        "InvalidStateError"
      ]);
    }
  
    const n = nodeImpl.nodeType - 1;
  
    if (!((1 << n) & nodeIteratorOrTreeWalkerImpl.whatToShow)) {
      return exports.FILTER_SKIP;
    }
  
    // Saving in a variable is important so we don't accidentally call it as a method later.
    const { filter } = nodeIteratorOrTreeWalkerImpl;
  
    if (filter === null) {
      return exports.FILTER_ACCEPT;
    }
  
    nodeIteratorOrTreeWalkerImpl._active = true;
  
    let result;
  
    // https://github.com/whatwg/dom/issues/494
    try {
      if (typeof filter === "function") {
        result = filter(idlUtils.wrapperForImpl(nodeImpl));
      } else {
        result = filter.acceptNode(idlUtils.wrapperForImpl(nodeImpl));
      }
    } finally {
      nodeIteratorOrTreeWalkerImpl._active = false;
    }
  
    result = conversions["unsigned short"](result);
  
    return result;
  };