"use strict";
  const cssom = require("cssom");
  const cssstyle = require("cssstyle");
  
  // http://dev.w3.org/csswg/cssom/#stylesheetlist
  // TODO: implement using webidl2js
  function StyleSheetList() {}
  
  Object.setPrototypeOf(StyleSheetList.prototype, Array.prototype);
  
  StyleSheetList.prototype.item = function item(i) {
    return Object.prototype.hasOwnProperty.call(this, i) ? this[i] : null;
  };
  
  exports.StyleSheetList = StyleSheetList;
  
  exports.addToCore = core => {
    // What works now:
    // - Accessing the rules defined in individual stylesheets
    // - Modifications to style content attribute are reflected in style property
    // - Modifications to style property are reflected in style content attribute
    // TODO
    // - Modifications to style element's textContent are reflected in sheet property.
    // - Modifications to style element's sheet property are reflected in textContent.
    // - Modifications to link.href property are reflected in sheet property.
    // - Less-used features of link: disabled
    // - Less-used features of style: disabled, scoped, title
    // - CSSOM-View
    //   - getComputedStyle(): requires default stylesheet, cascading, inheritance,
    //     filtering by @media (screen? print?), layout for widths/heights
    // - Load events are not in the specs, but apparently some browsers
    //   implement something. Should onload only fire after all @imports have been
    //   loaded, or only the primary sheet?
  
    core.StyleSheet = cssom.StyleSheet;
    core.MediaList = cssom.MediaList;
    core.CSSStyleSheet = cssom.CSSStyleSheet;
    core.CSSRule = cssom.CSSRule;
    core.CSSStyleRule = cssom.CSSStyleRule;
    core.CSSMediaRule = cssom.CSSMediaRule;
    core.CSSImportRule = cssom.CSSImportRule;
    core.CSSStyleDeclaration = cssstyle.CSSStyleDeclaration;
    core.StyleSheetList = StyleSheetList;
  
    // Relavant specs
    // http://www.w3.org/TR/DOM-Level-2-Style (2000)
    // http://www.w3.org/TR/cssom-view/ (2008)
    // http://dev.w3.org/csswg/cssom/ (2010) Meant to replace DOM Level 2 Style
    // http://www.whatwg.org/specs/web-apps/current-work/multipage/ HTML5, of course
    // http://dev.w3.org/csswg/css-style-attr/  not sure what's new here
  
    // Objects that aren't in cssom library but should be:
    //   CSSRuleList  (cssom just uses array)
    //   CSSFontFaceRule
    //   CSSPageRule
  
    // These rules don't really make sense to implement, so CSSOM draft makes them
    // obsolete.
    //   CSSCharsetRule
    //   CSSUnknownRule
  
    // These objects are considered obsolete by CSSOM draft, although modern
    // browsers implement them.
    //   CSSValue
    //   CSSPrimitiveValue
    //   CSSValueList
    //   RGBColor
    //   Rect
    //   Counter
  };