/*
    * Copyright (c) 2002-2026 Gargoyle Software Inc.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * https://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.htmlunit.javascript.host.css;
  
  import java.io.Serializable;
  import java.util.function.Predicate;
  
  import org.htmlunit.WebClient;
  import org.htmlunit.WebWindow;
  import org.htmlunit.corejs.javascript.Scriptable;
  import org.htmlunit.corejs.javascript.WithScope;
  import org.htmlunit.html.DomNode;
  import org.htmlunit.html.HtmlAttributeChangeEvent;
  import org.htmlunit.html.HtmlElement;
  import org.htmlunit.html.HtmlLink;
  import org.htmlunit.html.HtmlStyle;
  import org.htmlunit.javascript.HtmlUnitScriptable;
  import org.htmlunit.javascript.JavaScriptEngine;
  import org.htmlunit.javascript.configuration.JsxClass;
  import org.htmlunit.javascript.configuration.JsxConstructor;
  import org.htmlunit.javascript.configuration.JsxFunction;
  import org.htmlunit.javascript.configuration.JsxGetter;
  import org.htmlunit.javascript.host.dom.AbstractList.EffectOnCache;
  import org.htmlunit.javascript.host.dom.Document;
  import org.htmlunit.javascript.host.html.HTMLCollection;
  import org.htmlunit.javascript.host.html.HTMLElement;
  import org.htmlunit.javascript.host.html.HTMLLinkElement;
  import org.htmlunit.javascript.host.html.HTMLStyleElement;
  
  /**
   * <p>An ordered list of stylesheets, accessible via <code>document.styleSheets</code>, as specified by the
   * <a href="http://www.w3.org/TR/DOM-Level-2-Style/stylesheets.html#StyleSheets-StyleSheetList">DOM
   * Level 2 Style spec</a> and the <a href="https://developer.mozilla.org/en-US/docs/DOM/document.styleSheets">Gecko
   * DOM Guide</a>.</p>
   *
   * <p>If CSS is disabled via {@link org.htmlunit.WebClientOptions#setCssEnabled(boolean)}, instances
   * of this class will always be empty. This allows us to check for CSS enablement/disablement in a single
   * location, without having to sprinkle checks throughout the code.</p>
   *
   * @author Daniel Gredler
   * @author Ahmed Ashour
   * @author Ronald Brill
   * @author Frank Danek
   * @author Carsten Steul
   */
  @JsxClass
  public class StyleSheetList extends HtmlUnitScriptable {
  
      /**
       * We back the stylesheet list with an {@link HTMLCollection} of styles/links because this list must be "live".
       */
      private HTMLCollection nodes_;
  
      /**
       * Creates an instance.
       */
      public StyleSheetList() {
          super();
      }
  
      /**
       * JavaScript constructor.
       */
      @JsxConstructor
      public void jsConstructor() {
          // nothing to do
      }
  
      /**
       * Creates a new style sheet list owned by the specified document.
       *
       * @param document the owning document
       */
      public StyleSheetList(final Document document) {
          super();
  
          final WebWindow webWindow = document.getWindow().getWebWindow();
          setParentScope(new WithScope(getTopLevelScope(document.getParentScope()), document));
          setPrototype(getPrototype(getClass()));
  
          final WebClient webClient = webWindow.getWebClient();
  
          if (webClient.getOptions().isCssEnabled()) {
              nodes_ = new HTMLCollection(document.getDomNodeOrDie(), true);
  
              nodes_.setEffectOnCacheFunction(
                      (java.util.function.Function<HtmlAttributeChangeEvent, EffectOnCache> & Serializable)
                     event -> {
                         final HtmlElement node = event.getHtmlElement();
                         if (node instanceof HtmlLink && "rel".equalsIgnoreCase(event.getName())) {
                             return EffectOnCache.RESET;
                         }
                         return EffectOnCache.NONE;
                     });
 
             nodes_.setIsMatchingPredicate(
                     (Predicate<DomNode> & Serializable)
                     node -> {
                         if (node instanceof HtmlStyle) {
                             return true;
                         }
                         if (node instanceof HtmlLink link) {
                             return link.isActiveStyleSheetLink();
                         }
                         return false;
                     });
         }
         else {
             nodes_ = HTMLCollection.emptyCollection(getWindow().getDomNodeOrDie());
         }
     }
 
     /**
      * Returns the list's length.
      *
      * @return the list's length
      */
     @JsxGetter
     public int getLength() {
         return nodes_.getLength();
     }
 
     /**
      * Returns the style sheet at the specified index.
      *
      * @param index the index of the style sheet to return
      * @return the style sheet at the specified index
      */
     @JsxFunction
     public Object item(final int index) {
         final Object item = get(index, this);
         if (JavaScriptEngine.UNDEFINED == item) {
             return null;
         }
         return item;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Object get(final int index, final Scriptable start) {
         if (this == start) {
             if (nodes_ == null || index < 0 || index >= nodes_.getLength()) {
                 return JavaScriptEngine.UNDEFINED;
             }
 
             final HTMLElement element = (HTMLElement) nodes_.item(Integer.valueOf(index));
 
             // <style type="text/css"> ... </style>
             if (element instanceof HTMLStyleElement styleElement) {
                 return styleElement.getSheet();
             }
             // <link rel="stylesheet" type="text/css" href="..." />
             return ((HTMLLinkElement) element).getSheet();
         }
         return super.get(index, start);
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     protected Object equivalentValues(final Object value) {
         return value != null
                 && getClass() == value.getClass()
                 && getDomNodeOrNull() == ((StyleSheetList) value).getDomNodeOrNull();
     }
 }