/*
    * 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.dom;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.commons.lang3.StringUtils;
  import org.htmlunit.WebClient;
  import org.htmlunit.corejs.javascript.Context;
  import org.htmlunit.corejs.javascript.ContextAction;
  import org.htmlunit.corejs.javascript.Function;
  import org.htmlunit.corejs.javascript.Scriptable;
  import org.htmlunit.corejs.javascript.VarScope;
  import org.htmlunit.html.DomAttr;
  import org.htmlunit.html.DomElement;
  import org.htmlunit.html.DomNode;
  import org.htmlunit.javascript.HtmlUnitContextFactory;
  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.configuration.JsxSetter;
  import org.htmlunit.javascript.configuration.JsxSymbol;
  
  /**
   * A JavaScript object for {@code DOMTokenList}.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   * @author Marek Gawlicki
   * @author Markus Winter
   *
   * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/DOMTokenList">MDN Documentation</a>
   */
  @JsxClass
  public class DOMTokenList extends HtmlUnitScriptable {
  
      private static final String WHITESPACE_CHARS = " \t\r\n\u000C";
  
      private String attributeName_;
  
      /**
       * Creates an instance.
       */
      public DOMTokenList() {
          super();
      }
  
      /**
       * JavaScript constructor.
       */
      @JsxConstructor
      public void jsConstructor() {
          // nothing to do
      }
  
      /**
       * Creates an instance.
       * @param node the node which contains the underlying string
       * @param attributeName the attribute name of the DomElement of the specified node
       */
      public DOMTokenList(final Node node, final String attributeName) {
          super();
          setDomNode(node.getDomNodeOrDie(), false);
          setParentScope(node.getParentScope());
          setPrototype(getPrototype(getClass()));
          attributeName_ = attributeName;
      }
  
      /**
       * Returns the {@code value} property.
       * @return the value
       */
      @JsxGetter
      public String getValue() {
          final DomNode node = getDomNodeOrNull();
          if (node != null) {
              final DomAttr attr = (DomAttr) node.getAttributes().getNamedItem(attributeName_);
              if (attr != null) {
                  return attr.getValue();
              }
          }
          return null;
      }
 
     /**
      * Sets the {@code value} property.
      * @param value the new value
      */
     @JsxSetter
     public void setValue(final String value) {
         final DomNode node = getDomNodeOrNull();
         if (node != null) {
             updateAttribute(value);
         }
     }
 
     /**
      * Returns the length property.
      * @return the length
      */
     @JsxGetter
     public int getLength() {
         final String value = getValue();
         if (org.htmlunit.util.StringUtils.isBlank(value)) {
             return 0;
         }
 
         return split(value).size();
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public String getDefaultValue(final Class<?> hint) {
         if (getPrototype() == null) {
             return (String) super.getDefaultValue(hint);
         }
 
         final String value = getValue();
         if (value != null) {
             return String.join(" ", StringUtils.split(value, WHITESPACE_CHARS));
         }
         return "";
     }
 
     /**
      * Adds the given tokens to the list, omitting any that are already present.
      *
      * @param context the JavaScript context
      * @param scope the scope
      * @param thisObj the scriptable
      * @param args the arguments passed into the method
      * @param function the function
      */
     @JsxFunction
     public static void add(final Context context, final VarScope scope,
             final Scriptable thisObj, final Object[] args, final Function function) {
         if (args.length > 0) {
             final DOMTokenList list = (DOMTokenList) thisObj;
             final List<String> parts = split(list.getValue());
 
             for (final Object arg : args) {
                 final String token = JavaScriptEngine.toString(arg);
 
                 if (org.htmlunit.util.StringUtils.isEmptyOrNull(token)) {
                     throw JavaScriptEngine.asJavaScriptException(
                             (HtmlUnitScriptable) getTopLevelScope(scope).getGlobalThis(),
                             "DOMTokenList: add() does not support empty tokens",
                             DOMException.SYNTAX_ERR);
                 }
                 if (StringUtils.containsAny(token, WHITESPACE_CHARS)) {
                     throw JavaScriptEngine.asJavaScriptException(
                             (HtmlUnitScriptable) getTopLevelScope(scope).getGlobalThis(),
                             "DOMTokenList: add() does not support whitespace chars in tokens",
                             DOMException.INVALID_CHARACTER_ERR);
                 }
 
                 if (!parts.contains(token)) {
                     parts.add(token);
                 }
             }
             list.updateAttribute(String.join(" ", parts));
         }
     }
 
     /**
      * Removes the specified tokens from the underlying string.
      *
      * @param context the JavaScript context
      * @param scope the scope
      * @param thisObj the scriptable
      * @param args the arguments passed into the method
      * @param function the function
      */
     @JsxFunction
     public static void remove(final Context context, final VarScope scope,
             final Scriptable thisObj, final Object[] args, final Function function) {
         final DOMTokenList list = (DOMTokenList) thisObj;
 
         final String value = list.getValue();
         if (value == null) {
             return;
         }
 
         if (args.length > 0) {
             final List<String> parts = split(list.getValue());
 
             for (final Object arg : args) {
                 final String token = JavaScriptEngine.toString(arg);
 
                 if (org.htmlunit.util.StringUtils.isEmptyOrNull(token)) {
                     throw JavaScriptEngine.asJavaScriptException(
                             (HtmlUnitScriptable) getTopLevelScope(scope).getGlobalThis(),
                             "DOMTokenList: remove() does not support empty tokens",
                             DOMException.SYNTAX_ERR);
                 }
                 if (StringUtils.containsAny(token, WHITESPACE_CHARS)) {
                     throw JavaScriptEngine.asJavaScriptException(
                             (HtmlUnitScriptable) getTopLevelScope(scope).getGlobalThis(),
                             "DOMTokenList: remove() does not support whitespace chars in tokens",
                             DOMException.INVALID_CHARACTER_ERR);
                 }
 
                 parts.remove(token);
             }
             list.updateAttribute(String.join(" ", parts));
         }
     }
 
     /**
      * Replaces an existing token with a new token. If the first token doesn't exist, replace()
      * returns false immediately, without adding the new token to the token list.
      * @param oldToken a string representing the token you want to replace
      * @param newToken a string representing the token you want to replace oldToken with
      * @return true if oldToken was successfully replaced, or false if not
      */
     @JsxFunction
     public boolean replace(final String oldToken, final String newToken) {
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(oldToken)) {
             throw JavaScriptEngine.asJavaScriptException(
                     getWindow(),
                     "Empty oldToken not allowed",
                     DOMException.SYNTAX_ERR);
         }
         if (StringUtils.containsAny(oldToken, WHITESPACE_CHARS)) {
             throw JavaScriptEngine.asJavaScriptException(
                     getWindow(),
                     "DOMTokenList: replace() oldToken contains whitespace",
                     DOMException.INVALID_CHARACTER_ERR);
         }
 
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(newToken)) {
             throw JavaScriptEngine.asJavaScriptException(
                     getWindow(),
                     "Empty newToken not allowed",
                     DOMException.SYNTAX_ERR);
         }
         if (StringUtils.containsAny(newToken, WHITESPACE_CHARS)) {
             throw JavaScriptEngine.asJavaScriptException(
                     getWindow(),
                     "DOMTokenList: replace() newToken contains whitespace",
                     DOMException.INVALID_CHARACTER_ERR);
         }
 
         final String value = getValue();
         if (value == null) {
             return false;
         }
         final List<String> parts = split(value);
         final int pos = parts.indexOf(oldToken);
         if (pos == -1) {
             return false;
         }
 
         parts.set(pos, newToken);
         updateAttribute(String.join(" ", parts));
         return true;
     }
 
     /**
      * Toggles the token, adding or removing it.
      * @param token the token to add or remove
      * @return whether the string now contains the token or not
      */
     @JsxFunction
     public boolean toggle(final String token) {
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(token)) {
             throw JavaScriptEngine.asJavaScriptException(
                     getWindow(),
                     "DOMTokenList: toggle() does not support empty tokens",
                     DOMException.SYNTAX_ERR);
         }
         if (StringUtils.containsAny(token, WHITESPACE_CHARS)) {
             throw JavaScriptEngine.asJavaScriptException(
                     getWindow(),
                     "DOMTokenList: toggle() does not support whitespace chars in tokens",
                     DOMException.INVALID_CHARACTER_ERR);
         }
 
         final List<String> parts = split(getValue());
         if (parts.contains(token)) {
             parts.remove(token);
             updateAttribute(String.join(" ", parts));
             return false;
         }
 
         parts.add(token);
         updateAttribute(String.join(" ", parts));
         return true;
     }
 
     /**
      * Checks if the specified token is contained in the underlying string.
      * @param token the token to add
      * @return true if the underlying string contains token, otherwise false
      */
     @JsxFunction
     public boolean contains(final String token) {
         if (org.htmlunit.util.StringUtils.isBlank(token)) {
             return false;
         }
 
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(token)) {
             throw JavaScriptEngine.reportRuntimeError("DOMTokenList: contains() does not support empty tokens");
         }
         if (StringUtils.containsAny(token, WHITESPACE_CHARS)) {
             throw JavaScriptEngine.reportRuntimeError(
                     "DOMTokenList: contains() does not support whitespace chars in tokens");
         }
 
         final List<String> parts = split(getValue());
         return parts.contains(token);
     }
 
     /**
      * Returns the item at the specified index.
      * @param index the index of the item
      * @return the item
      */
     @JsxFunction
     public String item(final int index) {
         if (index < 0) {
             return null;
         }
 
         final String value = getValue();
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(value)) {
             return null;
         }
 
         final List<String> parts = split(value);
         if (index < parts.size()) {
             return parts.get(index);
         }
 
         return null;
     }
 
     /**
      * Returns an Iterator allowing to go through all keys contained in this object.
      * @return a NativeArrayIterator
      */
     @JsxFunction
     public Scriptable keys() {
         return JavaScriptEngine.newArrayIteratorTypeKeys(getParentScope(), this);
     }
 
     /**
      * {@inheritDoc}.
      */
     @Override
     public Object[] getIds() {
         final Object[] normalIds = super.getIds();
 
         final String value = getValue();
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(value)) {
             return normalIds;
         }
 
         final List<String> parts = split(getValue());
         final Object[] ids = new Object[parts.size() + normalIds.length];
         final int size = parts.size();
         for (int i = 0; i < size; i++) {
             ids[i] = i;
         }
         System.arraycopy(normalIds, 0, ids, parts.size(), normalIds.length);
 
         return ids;
     }
 
     /**
      * Returns an Iterator allowing to go through all keys contained in this object.
      * @return a NativeArrayIterator
      */
     @JsxFunction
     @JsxSymbol(symbolName = "iterator")
     public Scriptable values() {
         return JavaScriptEngine.newArrayIteratorTypeValues(getParentScope(), this);
     }
 
     /**
      * Returns an Iterator allowing to go through all key/value pairs contained in this object.
      * @return a NativeArrayIterator
      */
     @JsxFunction
     public Scriptable entries() {
         return JavaScriptEngine.newArrayIteratorTypeEntries(getParentScope(), this);
     }
 
     /**
      * Calls the {@code callback} given in parameter once for each value in the list.
      * @param callback function to execute for each element
      */
     @JsxFunction
     public void forEach(final Object callback) {
         if (!(callback instanceof Function function)) {
             throw JavaScriptEngine.typeError(
                     "Foreach callback '" + JavaScriptEngine.toString(callback) + "' is not a function");
         }
 
         final String value = getValue();
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(value)) {
             return;
         }
 
         final WebClient client = getWindow().getWebWindow().getWebClient();
         final HtmlUnitContextFactory cf = client.getJavaScriptEngine().getContextFactory();
 
         final ContextAction<Object> contextAction = cx -> {
             final VarScope scope = getParentScope();
 
             List<String> parts = split(value);
             final int size = parts.size();
             int i = 0;
             while (i < size && i < parts.size()) {
                 function.call(cx, scope, this, new Object[] {parts.get(i), i, this});
 
                 // refresh
                 parts = split(getValue());
                 i++;
             }
             return null;
         };
         cf.call(contextAction);
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Object get(final int index, final Scriptable start) {
         final Object value = item(index);
         if (value == null) {
             return JavaScriptEngine.UNDEFINED;
         }
         return value;
     }
 
     private void updateAttribute(final String value) {
         final DomElement domNode = (DomElement) getDomNodeOrDie();
 
         // always create a new one because the old one is used later for the mutation observer
         // to get the old value from
         final DomAttr attr = domNode.getPage().createAttribute(attributeName_);
         attr.setValue(value);
         domNode.setAttributeNode(attr);
     }
 
     private static List<String> split(final String value) {
         if (org.htmlunit.util.StringUtils.isEmptyOrNull(value)) {
             return new ArrayList<>();
         }
 
         final String[] parts = StringUtils.split(value, WHITESPACE_CHARS);
 
         // usually a short list, no index needed
         final List<String> result = new ArrayList<>();
         for (final String part : parts) {
             if (!result.contains(part)) {
                 result.add(part);
             }
         }
         return result;
     }
 }