/*
    * 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.html;
  
  import static org.htmlunit.BrowserVersionFeatures.FORM_IGNORE_REL_NOREFERRER;
  import static org.htmlunit.BrowserVersionFeatures.FORM_SUBMISSION_HEADER_CACHE_CONTROL_MAX_AGE;
  
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.nio.charset.Charset;
  import java.nio.charset.StandardCharsets;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Objects;
  import java.util.function.Predicate;
  import java.util.regex.Pattern;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.htmlunit.BrowserVersion;
  import org.htmlunit.ElementNotFoundException;
  import org.htmlunit.FormEncodingType;
  import org.htmlunit.HttpHeader;
  import org.htmlunit.HttpMethod;
  import org.htmlunit.Page;
  import org.htmlunit.ScriptResult;
  import org.htmlunit.SgmlPage;
  import org.htmlunit.WebAssert;
  import org.htmlunit.WebClient;
  import org.htmlunit.WebRequest;
  import org.htmlunit.WebWindow;
  import org.htmlunit.http.HttpUtils;
  import org.htmlunit.javascript.host.event.Event;
  import org.htmlunit.javascript.host.event.SubmitEvent;
  import org.htmlunit.protocol.javascript.JavaScriptURLConnection;
  import org.htmlunit.util.ArrayUtils;
  import org.htmlunit.util.EncodingSniffer;
  import org.htmlunit.util.NameValuePair;
  import org.htmlunit.util.StringUtils;
  import org.htmlunit.util.UrlUtils;
  
  /**
   * Wrapper for the HTML element "form".
   *
   * @author Mike Bowler
   * @author David K. Taylor
   * @author Brad Clarke
   * @author Christian Sell
   * @author Marc Guillemot
   * @author George Murnock
   * @author Kent Tong
   * @author Ahmed Ashour
   * @author Philip Graf
   * @author Ronald Brill
   * @author Frank Danek
   * @author Anton Demydenko
   * @author Lai Quang Duong
   */
  public class HtmlForm extends HtmlElement {
      private static final Log LOG = LogFactory.getLog(HtmlForm.class);
  
      /** The HTML tag represented by this element. */
      public static final String TAG_NAME = "form";
  
      /** The "novalidate" attribute name. */
      private static final String ATTRIBUTE_NOVALIDATE = "novalidate";
  
      /** The "formnovalidate" attribute name. */
      public static final String ATTRIBUTE_FORMNOVALIDATE = "formnovalidate";
  
      private static final HashSet<String> SUBMITTABLE_TAG_NAMES = new HashSet<>(Arrays.asList(HtmlInput.TAG_NAME,
          HtmlButton.TAG_NAME, HtmlSelect.TAG_NAME, HtmlTextArea.TAG_NAME));
  
      private static final Pattern SUBMIT_CHARSET_PATTERN = Pattern.compile("[ ,].*");
  
      private boolean isPreventDefault_;
  
      /**
       * A map that holds past names (name or id attribute) to elements belonging to this form.
       * @see <a href="https://html.spec.whatwg.org/multipage/forms.html#the-form-element:the-form-element-10">
       *     HTML spec - past names map</a>
      */
     private Map<String, HtmlElement> pastNamesMap_;
 
     /**
      * Creates an instance.
      *
      * @param qualifiedName the qualified name of the element type to instantiate
      * @param htmlPage the page that contains this element
      * @param attributes the initial attributes
      */
     HtmlForm(final String qualifiedName, final SgmlPage htmlPage,
             final Map<String, DomAttr> attributes) {
         super(qualifiedName, htmlPage, attributes);
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * <p>Submits this form to the server. If <code>submitElement</code> is {@code null}, then
      * the submission is treated as if it was triggered by JavaScript, and the <code>onsubmit</code>
      * handler will not be executed.</p>
      *
      * <p><b>IMPORTANT:</b> Using this method directly is not the preferred way of submitting forms.
      * Most consumers should emulate the user's actions instead, probably by using something like
      * {@link HtmlElement#click()} or {@link HtmlElement#dblClick()}.</p>
      *
      * @param submitElement the element that caused the submit to occur
      */
     public void submit(final SubmittableElement submitElement) {
         final HtmlPage htmlPage = (HtmlPage) getPage();
         final WebClient webClient = htmlPage.getWebClient();
 
         if (webClient.isJavaScriptEnabled()) {
             if (submitElement != null) {
                 isPreventDefault_ = false;
 
                 boolean validate = true;
                 if (submitElement instanceof HtmlSubmitInput input
                         && input.isFormNoValidate()) {
                     validate = false;
                 }
                 else if (submitElement instanceof HtmlButton htmlButton) {
                     if ("submit".equalsIgnoreCase(htmlButton.getType())
                             && htmlButton.isFormNoValidate()) {
                         validate = false;
                     }
                 }
 
                 if (validate
                         && getAttributeDirect(ATTRIBUTE_NOVALIDATE) != ATTRIBUTE_NOT_DEFINED) {
                     validate = false;
                 }
 
                 if (validate && !areChildrenValid()) {
                     return;
                 }
                 final ScriptResult scriptResult = fireEvent(new SubmitEvent(this,
                         ((HtmlElement) submitElement).getScriptableObject()));
                 if (isPreventDefault_) {
                     // null means 'nothing executed'
                     if (scriptResult == null) {
                         return;
                     }
                     return;
                 }
             }
 
             final String action = getActionAttribute().trim();
             if (StringUtils.startsWithIgnoreCase(action, JavaScriptURLConnection.JAVASCRIPT_PREFIX)) {
                 htmlPage.executeJavaScript(action, "Form action", getStartLineNumber());
                 return;
             }
         }
         else {
             if (StringUtils.startsWithIgnoreCase(getActionAttribute(), JavaScriptURLConnection.JAVASCRIPT_PREFIX)) {
                 // The action is JavaScript but JavaScript isn't enabled.
                 return;
             }
         }
 
         // html5 attribute's support
         if (submitElement != null) {
             updateHtml5Attributes(submitElement);
         }
 
         // dialog support
         final String methodAttribute = getMethodAttribute();
         if ("dialog".equalsIgnoreCase(methodAttribute)) {
             // find parent dialog
             final HtmlElement dialog = getEnclosingElement("dialog");
             if (dialog != null) {
                 ((HtmlDialog) dialog).close("");
             }
             return;
         }
 
         final WebRequest request = getWebRequest(submitElement);
         final String target = htmlPage.getResolvedTarget(getTargetAttribute());
 
         final WebWindow webWindow = htmlPage.getEnclosingWindow();
         // Calling form.submit() twice forces double download.
         webClient.download(webWindow, target, request, false, null, "JS form.submit()");
     }
 
     /**
      * Check if element which cause submit contains new html5 attributes
      * (formaction, formmethod, formtarget, formenctype)
      * and override existing values
      * @param submitElement the element to update
      */
     private void updateHtml5Attributes(final SubmittableElement submitElement) {
         if (submitElement instanceof HtmlElement element) {
 
             final String type = element.getAttributeDirect(TYPE_ATTRIBUTE);
             boolean typeImage = false;
             final boolean isInput = HtmlInput.TAG_NAME.equals(element.getTagName());
             if (isInput) {
                 typeImage = "image".equalsIgnoreCase(type);
             }
 
             // could be excessive validation but support of html5 fromxxx
             // attributes available for:
             // - input with 'submit' and 'image' types
             // - button with 'submit' or without type
             final boolean typeSubmit = "submit".equalsIgnoreCase(type);
             if (isInput && !typeSubmit && !typeImage) {
                 return;
             }
             else if (HtmlButton.TAG_NAME.equals(element.getTagName())
                 && !"submit".equals(((HtmlButton) element).getType())) {
                 return;
             }
 
             final String formaction = element.getAttributeDirect("formaction");
             if (ATTRIBUTE_NOT_DEFINED != formaction) {
                 setActionAttribute(formaction);
             }
             final String formmethod = element.getAttributeDirect("formmethod");
             if (ATTRIBUTE_NOT_DEFINED != formmethod) {
                 setMethodAttribute(formmethod);
             }
             final String formtarget = element.getAttributeDirect("formtarget");
             if (ATTRIBUTE_NOT_DEFINED != formtarget) {
                 setTargetAttribute(formtarget);
             }
             final String formenctype = element.getAttributeDirect("formenctype");
             if (ATTRIBUTE_NOT_DEFINED != formenctype) {
                 setEnctypeAttribute(formenctype);
             }
         }
     }
 
     private boolean areChildrenValid() {
         boolean valid = true;
         for (final HtmlElement element : getElements(htmlElement -> htmlElement instanceof HtmlInput)) {
             if (!element.isValid()) {
                 if (LOG.isInfoEnabled()) {
                     LOG.info("Form validation failed; element '" + element + "' was not valid. Submit cancelled.");
                 }
                 valid = false;
                 break;
             }
         }
         return valid;
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Gets the request for a submission of this form with the specified SubmittableElement.
      * @param submitElement the element that caused the submit to occur
      * @return the request
      */
     public WebRequest getWebRequest(final SubmittableElement submitElement) {
         final HttpMethod method;
         final String methodAttribute = getMethodAttribute();
         if ("post".equalsIgnoreCase(methodAttribute)) {
             method = HttpMethod.POST;
         }
         else {
             if (!"get".equalsIgnoreCase(methodAttribute) && StringUtils.isNotBlank(methodAttribute)) {
                 notifyIncorrectness("Incorrect submit method >" + getMethodAttribute() + "<. Using >GET<.");
             }
             method = HttpMethod.GET;
         }
 
         String actionUrl = getActionAttribute();
         String anchor = null;
         String queryFormFields = "";
         Charset enc = getSubmitCharset();
         if (StandardCharsets.UTF_16 == enc
                 || StandardCharsets.UTF_16BE == enc
                 || StandardCharsets.UTF_16LE == enc) {
             enc = StandardCharsets.UTF_8;
         }
 
         final List<NameValuePair> parameters = getParameterListForSubmit(submitElement);
         if (HttpMethod.GET == method) {
             if (actionUrl.contains("#")) {
                 anchor = StringUtils.substringAfter(actionUrl, "#");
             }
             queryFormFields = HttpUtils.toQueryFormFields(parameters, enc);
 
             // action may already contain some query parameters: they have to be removed
             actionUrl = StringUtils.substringBefore(actionUrl, "#");
             actionUrl = StringUtils.substringBefore(actionUrl, "?");
             parameters.clear(); // parameters have been added to query
         }
 
         final HtmlPage htmlPage = (HtmlPage) getPage();
         URL url;
         try {
             if (actionUrl.isEmpty()) {
                 url = WebClient.expandUrl(htmlPage.getUrl(), actionUrl);
             }
             else {
                 url = htmlPage.getFullyQualifiedUrl(actionUrl);
             }
 
             if (!queryFormFields.isEmpty()) {
                 url = UrlUtils.getUrlWithNewQuery(url, queryFormFields);
             }
 
             if (anchor != null && UrlUtils.URL_ABOUT_BLANK != url) {
                 url = UrlUtils.getUrlWithNewRef(url, anchor);
             }
         }
         catch (final MalformedURLException e) {
             throw new IllegalArgumentException("Not a valid url: " + actionUrl, e);
         }
 
         final BrowserVersion browser = htmlPage.getWebClient().getBrowserVersion();
         final WebRequest request = new WebRequest(url, browser.getHtmlAcceptHeader(),
                                                         browser.getAcceptEncodingHeader());
         request.setHttpMethod(method);
         request.setRequestParameters(parameters);
         if (HttpMethod.POST == method) {
             request.setEncodingType(FormEncodingType.getInstance(getEnctypeAttribute()));
         }
         request.setCharset(enc);
 
         // forms are ignoring the rel='noreferrer'
         if (browser.hasFeature(FORM_IGNORE_REL_NOREFERRER)
                 || !relContainsNoreferrer()) {
             request.setRefererHeader(htmlPage.getUrl());
         }
 
         if (HttpMethod.POST == method) {
             try {
                 request.setAdditionalHeader(HttpHeader.ORIGIN,
                         UrlUtils.getUrlWithProtocolAndAuthority(htmlPage.getUrl()).toExternalForm());
             }
             catch (final MalformedURLException e) {
                 if (LOG.isInfoEnabled()) {
                     LOG.info("Invalid origin url '" + htmlPage.getUrl() + "'");
                 }
             }
         }
         if (HttpMethod.POST == method) {
             if (browser.hasFeature(FORM_SUBMISSION_HEADER_CACHE_CONTROL_MAX_AGE)) {
                 request.setAdditionalHeader(HttpHeader.CACHE_CONTROL, "max-age=0");
             }
         }
 
         return request;
     }
 
     private boolean relContainsNoreferrer() {
         String rel = getRelAttribute();
         if (rel != null) {
             rel = rel.toLowerCase(Locale.ROOT);
             return ArrayUtils.contains(StringUtils.splitAtBlank(rel), "noreferrer");
         }
         return false;
     }
 
     /**
      * Returns the charset to use for the form submission. This is the first one
      * from the list provided in {@link #getAcceptCharsetAttribute()} if any
      * or the page's charset else
      * @return the charset to use for the form submission
      */
     private Charset getSubmitCharset() {
         String charset = getAcceptCharsetAttribute();
         if (!charset.isEmpty()) {
             charset = charset.trim();
             return EncodingSniffer.toCharset(
                     SUBMIT_CHARSET_PATTERN.matcher(charset).replaceAll("").toUpperCase(Locale.ROOT));
         }
         return getPage().getCharset();
     }
 
     /**
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span><br>
      *
      * Returns a list of {@link NameValuePair}s that represent the data that will be
      * sent to the server when this form is submitted. This is primarily intended to aid
      * debugging.
      *
      * @param submitElement the element used to submit the form, or {@code null} if the
      *        form was submitted by JavaScript
      * @return the list of {@link NameValuePair}s that represent that data that will be sent
      *         to the server when this form is submitted
      */
     public List<NameValuePair> getParameterListForSubmit(final SubmittableElement submitElement) {
         final Collection<SubmittableElement> submittableElements = getSubmittableElements(submitElement);
 
         final List<NameValuePair> parameterList = new ArrayList<>(submittableElements.size());
         for (final SubmittableElement element : submittableElements) {
             parameterList.addAll(Arrays.asList(element.getSubmitNameValuePairs()));
         }
 
         return parameterList;
     }
 
     /**
      * Resets this form to its initial values, returning the page contained by this form's window after the
      * reset. Note that the returned page may or may not be the same as the original page, based on JavaScript
      * event handlers, etc.
      *
      * @return the page contained by this form's window after the reset
      */
     public Page reset() {
         final SgmlPage sgmlPage = getPage();
         final ScriptResult scriptResult = fireEvent(Event.TYPE_RESET);
         if (ScriptResult.isFalse(scriptResult)) {
             return sgmlPage.getWebClient().getCurrentWindow().getEnclosedPage();
         }
 
         for (final HtmlElement next : getHtmlElementDescendants()) {
             if (next instanceof SubmittableElement element) {
                 element.reset();
             }
         }
 
         return sgmlPage;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public boolean isValid() {
         for (final HtmlElement element : getFormElements()) {
             if (!element.isValid()) {
                 return false;
             }
         }
         return super.isValid();
     }
 
     /**
      * Returns a collection of elements that represent all the "submittable" elements in this form,
      * assuming that the specified element is used to submit the form.
      *
      * @param submitElement the element used to submit the form, or {@code null} if the
      *        form is submitted by JavaScript
      * @return a collection of elements that represent all the "submittable" elements in this form
      */
     Collection<SubmittableElement> getSubmittableElements(final SubmittableElement submitElement) {
         final List<SubmittableElement> submittableElements = new ArrayList<>();
 
         for (final HtmlElement element : getElements(htmlElement -> isSubmittable(htmlElement, submitElement))) {
             submittableElements.add((SubmittableElement) element);
         }
 
         return submittableElements;
     }
 
     private static boolean isValidForSubmission(final HtmlElement element, final SubmittableElement submitElement) {
         final String tagName = element.getTagName();
         if (!SUBMITTABLE_TAG_NAMES.contains(tagName)) {
             return false;
         }
         if (element.isDisabledElementAndDisabled()) {
             return false;
         }
         // clicked input type="image" is submitted even if it hasn't a name
         if (element == submitElement && element instanceof HtmlImageInput) {
             return true;
         }
 
         if (!element.hasAttribute(NAME_ATTRIBUTE)) {
             return false;
         }
 
         if (StringUtils.isEmptyString(element.getAttributeDirect(NAME_ATTRIBUTE))) {
             return false;
         }
 
         if (element instanceof HtmlInput input) {
             if (input.isCheckable()) {
                 return input.isChecked();
             }
         }
         if (element instanceof HtmlSelect select) {
             return select.isValidForSubmission();
         }
         return true;
     }
 
     /**
      * Returns {@code true} if the specified element gets submitted when this form is submitted,
      * assuming that the form is submitted using the specified submit element.
      *
      * @param element the element to check
      * @param submitElement the element used to submit the form, or {@code null} if the form is
      *        submitted by JavaScript
      * @return {@code true} if the specified element gets submitted when this form is submitted
      */
     private static boolean isSubmittable(final HtmlElement element, final SubmittableElement submitElement) {
         if (!isValidForSubmission(element, submitElement)) {
             return false;
         }
 
         // The one submit button that was clicked can be submitted but no other ones
         if (element == submitElement) {
             return true;
         }
         if (element instanceof HtmlInput input) {
             if (!input.isSubmitable()) {
                 return false;
             }
         }
 
         return !HtmlButton.TAG_NAME.equals(element.getTagName());
     }
 
     /**
      * Returns all input elements which are members of this form and have the specified name.
      *
      * @param name the input name to search for
      * @return all input elements which are members of this form and have the specified name
      */
     public List<HtmlInput> getInputsByName(final String name) {
         return getFormElementsByAttribute(HtmlInput.TAG_NAME, NAME_ATTRIBUTE, name);
     }
 
     /**
      * Same as {@link #getElementsByAttribute(String, String, String)} but
      * ignoring elements that are contained in a nested form.
      */
     @SuppressWarnings("unchecked")
     private <E extends HtmlElement> List<E> getFormElementsByAttribute(
             final String elementName,
             final String attributeName,
             final String attributeValue) {
 
         return (List<E>) getElements(htmlElement ->
                                 htmlElement.getTagName().equals(elementName)
                                 && htmlElement.getAttribute(attributeName).equals(attributeValue));
     }
 
     /**
      * @return A List containing all form controls in the form.
      *         The form controls in the returned collection are in the same order
      *         in which they appear in the form by following a preorder,
      *         depth-first traversal of the tree. This is called tree order.
      *         Only the following elements are returned:
      *         button, fieldset, input, object, output, select, textarea.
      */
     public List<HtmlElement> getFormElements() {
         return getElements(htmlElement -> {
             final String tagName = htmlElement.getTagName();
             return HtmlButton.TAG_NAME.equals(tagName)
                     || HtmlFieldSet.TAG_NAME.equals(tagName)
                     || HtmlInput.TAG_NAME.equals(tagName)
                     || HtmlObject.TAG_NAME.equals(tagName)
                     || HtmlOutput.TAG_NAME.equals(tagName)
                     || HtmlSelect.TAG_NAME.equals(tagName)
                     || HtmlTextArea.TAG_NAME.equals(tagName);
         });
     }
 
     /**
      * This is the backend for the getElements() javascript function of the form.
      * see https://developer.mozilla.org/en-US/docs/Web/API/HTMLFormElement/elements
      *
      * @return A List containing all non-image controls in the form.
      *         The form controls in the returned collection are in the same order
      *         in which they appear in the form by following a preorder,
      *         depth-first traversal of the tree. This is called tree order.
      *         Only the following elements are returned:
      *         button, fieldset,
      *         input (with the exception that any whose type is "image" are omitted for historical reasons),
      *         object, output, select, textarea.
      */
     public List<HtmlElement> getElementsJS() {
         return getElements(htmlElement -> {
             final String tagName = htmlElement.getTagName();
             if (HtmlInput.TAG_NAME.equals(tagName)) {
                 return !(htmlElement instanceof HtmlImageInput);
             }
 
             return HtmlButton.TAG_NAME.equals(tagName)
                     || HtmlFieldSet.TAG_NAME.equals(tagName)
                     || HtmlObject.TAG_NAME.equals(tagName)
                     || HtmlOutput.TAG_NAME.equals(tagName)
                     || HtmlSelect.TAG_NAME.equals(tagName)
                     || HtmlTextArea.TAG_NAME.equals(tagName);
         });
     }
 
     /**
      * @param filter a predicate to filter the element
      * @return all elements attached to this form and matching the filter predicate
      */
     public List<HtmlElement> getElements(final Predicate<HtmlElement> filter) {
         final List<HtmlElement> elements = new ArrayList<>();
 
         if (isAttachedToPage()) {
             for (final HtmlElement element : getPage().getDocumentElement().getHtmlElementDescendants()) {
                 if (filter.test(element)
                         && element.getEnclosingForm() == this) {
                     elements.add(element);
                 }
             }
         }
         else {
             for (final HtmlElement element : getHtmlElementDescendants()) {
                 if (filter.test(element)) {
                     elements.add(element);
                 }
             }
         }
 
         return elements;
     }
 
     /**
      * Returns the first input element which is a member of this form and has the specified name.
      *
      * @param name the input name to search for
      * @param <I> the input type
      * @return the first input element which is a member of this form and has the specified name
      * @throws ElementNotFoundException if there is no input in this form with the specified name
      */
     @SuppressWarnings("unchecked")
     public final <I extends HtmlInput> I getInputByName(final String name) throws ElementNotFoundException {
         final List<HtmlInput> inputs = getInputsByName(name);
 
         if (inputs.isEmpty()) {
             throw new ElementNotFoundException(HtmlInput.TAG_NAME, NAME_ATTRIBUTE, name);
         }
         return (I) inputs.get(0);
     }
 
     /**
      * Returns all the {@link HtmlSelect} elements in this form that have the specified name.
      *
      * @param name the name to search for
      * @return all the {@link HtmlSelect} elements in this form that have the specified name
      */
     public List<HtmlSelect> getSelectsByName(final String name) {
         return getFormElementsByAttribute(HtmlSelect.TAG_NAME, NAME_ATTRIBUTE, name);
     }
 
     /**
      * Returns the first {@link HtmlSelect} element in this form that has the specified name.
      *
      * @param name the name to search for
      * @return the first {@link HtmlSelect} element in this form that has the specified name
      * @throws ElementNotFoundException if this form does not contain a {@link HtmlSelect}
      *         element with the specified name
      */
     public HtmlSelect getSelectByName(final String name) throws ElementNotFoundException {
         final List<HtmlSelect> list = getSelectsByName(name);
         if (list.isEmpty()) {
             throw new ElementNotFoundException(HtmlSelect.TAG_NAME, NAME_ATTRIBUTE, name);
         }
         return list.get(0);
     }
 
     /**
      * Returns all the {@link HtmlButton} elements in this form that have the specified name.
      *
      * @param name the name to search for
      * @return all the {@link HtmlButton} elements in this form that have the specified name
      */
     public List<HtmlButton> getButtonsByName(final String name) {
         return getFormElementsByAttribute(HtmlButton.TAG_NAME, NAME_ATTRIBUTE, name);
     }
 
     /**
      * Returns the first {@link HtmlButton} element in this form that has the specified name.
      *
      * @param name the name to search for
      * @return the first {@link HtmlButton} element in this form that has the specified name
      * @throws ElementNotFoundException if this form does not contain a {@link HtmlButton}
      *         element with the specified name
      */
     public HtmlButton getButtonByName(final String name) throws ElementNotFoundException {
         final List<HtmlButton> list = getButtonsByName(name);
         if (list.isEmpty()) {
             throw new ElementNotFoundException(HtmlButton.TAG_NAME, NAME_ATTRIBUTE, name);
         }
         return list.get(0);
     }
 
     /**
      * Returns all the {@link HtmlTextArea} elements in this form that have the specified name.
      *
      * @param name the name to search for
      * @return all the {@link HtmlTextArea} elements in this form that have the specified name
      */
     public List<HtmlTextArea> getTextAreasByName(final String name) {
         return getFormElementsByAttribute(HtmlTextArea.TAG_NAME, NAME_ATTRIBUTE, name);
     }
 
     /**
      * Returns the first {@link HtmlTextArea} element in this form that has the specified name.
      *
      * @param name the name to search for
      * @return the first {@link HtmlTextArea} element in this form that has the specified name
      * @throws ElementNotFoundException if this form does not contain a {@link HtmlTextArea}
      *         element with the specified name
      */
     public HtmlTextArea getTextAreaByName(final String name) throws ElementNotFoundException {
         final List<HtmlTextArea> list = getTextAreasByName(name);
         if (list.isEmpty()) {
             throw new ElementNotFoundException(HtmlTextArea.TAG_NAME, NAME_ATTRIBUTE, name);
         }
         return list.get(0);
     }
 
     /**
      * Returns all the {@link HtmlRadioButtonInput} elements in this form that have the specified name.
      *
      * @param name the name to search for
      * @return all the {@link HtmlRadioButtonInput} elements in this form that have the specified name
      */
     public List<HtmlRadioButtonInput> getRadioButtonsByName(final String name) {
         WebAssert.notNull("name", name);
 
         final List<HtmlRadioButtonInput> results = new ArrayList<>();
 
         for (final HtmlElement element : getInputsByName(name)) {
             if (element instanceof HtmlRadioButtonInput input) {
                 results.add(input);
             }
         }
 
         return results;
     }
 
     /**
      * Selects the specified radio button in the form. Only a radio button that is actually contained
      * in the form can be selected.
      *
      * @param radioButtonInput the radio button to select
      */
     void setCheckedRadioButton(final HtmlRadioButtonInput radioButtonInput) {
         if (radioButtonInput.getEnclosingForm() == null) {
             throw new IllegalArgumentException("HtmlRadioButtonInput is not child of this HtmlForm");
         }
         final List<HtmlRadioButtonInput> radios = getRadioButtonsByName(radioButtonInput.getNameAttribute());
 
         for (final HtmlRadioButtonInput input : radios) {
             input.setCheckedInternal(input == radioButtonInput);
         }
     }
 
     /**
      * Returns the first checked radio button with the specified name. If none of
      * the radio buttons by that name are checked, this method returns {@code null}.
      *
      * @param name the name of the radio button
      * @return the first checked radio button with the specified name
      */
     public HtmlRadioButtonInput getCheckedRadioButton(final String name) {
         WebAssert.notNull("name", name);
 
         for (final HtmlRadioButtonInput input : getRadioButtonsByName(name)) {
             if (input.isChecked()) {
                 return input;
             }
         }
         return null;
     }
 
     /**
      * Returns the value of the attribute {@code action}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @return the value of the attribute {@code action} or an empty string if that attribute isn't defined
      */
     public final String getActionAttribute() {
         return getAttributeDirect("action");
     }
 
     /**
      * Sets the value of the attribute {@code action}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @param action the value of the attribute {@code action}
      */
     public final void setActionAttribute(final String action) {
         setAttribute("action", action);
     }
 
     /**
      * Returns the value of the attribute {@code method}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @return the value of the attribute {@code method} or an empty string if that attribute isn't defined
      */
     public final String getMethodAttribute() {
         return getAttributeDirect("method");
     }
 
     /**
      * Sets the value of the attribute {@code method}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @param method the value of the attribute {@code method}
      */
     public final void setMethodAttribute(final String method) {
         setAttribute("method", method);
     }
 
     /**
      * Returns the value of the attribute {@code name}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @return the value of the attribute {@code name} or an empty string if that attribute isn't defined
      */
     public final String getNameAttribute() {
         return getAttributeDirect(NAME_ATTRIBUTE);
     }
 
     /**
      * Sets the value of the attribute {@code name}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @param name the value of the attribute {@code name}
      */
     public final void setNameAttribute(final String name) {
         setAttribute(NAME_ATTRIBUTE, name);
     }
 
     /**
      * Returns the value of the attribute {@code enctype}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute. "Enctype" is the encoding type
      * used when submitting a form back to the server.
      *
      * @return the value of the attribute {@code enctype} or an empty string if that attribute isn't defined
      */
     public final String getEnctypeAttribute() {
         return getAttributeDirect("enctype");
     }
 
     /**
      * Sets the value of the attribute {@code enctype}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute. "Enctype" is the encoding type
      * used when submitting a form back to the server.
      *
      * @param encoding the value of the attribute {@code enctype}
      */
     public final void setEnctypeAttribute(final String encoding) {
         setAttribute("enctype", encoding);
     }
 
     /**
      * Returns the value of the attribute {@code onsubmit}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @return the value of the attribute {@code onsubmit} or an empty string if that attribute isn't defined
      */
     public final String getOnSubmitAttribute() {
         return getAttributeDirect("onsubmit");
     }
 
     /**
      * Returns the value of the attribute {@code onreset}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @return the value of the attribute {@code onreset} or an empty string if that attribute isn't defined
      */
     public final String getOnResetAttribute() {
         return getAttributeDirect("onreset");
     }
 
     /**
      * Returns the value of the attribute {@code accept}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @return the value of the attribute {@code accept} or an empty string if that attribute isn't defined
      */
     public final String getAcceptAttribute() {
         return getAttribute(HttpHeader.ACCEPT_LC);
     }
 
     /**
      * Returns the value of the attribute {@code accept-charset}. Refer to the <a
      * href='http://www.w3.org/TR/html401/interact/forms.html#adef-accept-charset'>
      * HTML 4.01</a> documentation for details on the use of this attribute.
      *
      * @return the value of the attribute {@code accept-charset} or an empty string if that attribute isn't defined
      */
     public final String getAcceptCharsetAttribute() {
         return getAttribute("accept-charset");
     }
 
     /**
      * Returns the value of the attribute {@code target}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @return the value of the attribute {@code target} or an empty string if that attribute isn't defined
      */
     public final String getTargetAttribute() {
         return getAttributeDirect("target");
     }
 
     /**
      * Sets the value of the attribute {@code target}. Refer to the <a
      * href='http://www.w3.org/TR/html401/'>HTML 4.01</a> documentation for
      * details on the use of this attribute.
      *
      * @param target the value of the attribute {@code target}
      */
     public final void setTargetAttribute(final String target) {
         setAttribute("target", target);
     }
 
     /**
      * Returns the value of the attribute {@code rel}. Refer to the
      * <a href="http://www.w3.org/TR/html401/">HTML 4.01</a>
      * documentation for details on the use of this attribute.
      *
      * @return the value of the attribute {@code rel} or an empty string if that attribute isn't defined
      */
     public final String getRelAttribute() {
         return getAttributeDirect("rel");
     }
 
     /**
      * Returns the first input in this form with the specified value.
      * @param value the value to search for
      * @param <I> the input type
      * @return the first input in this form with the specified value
      * @throws ElementNotFoundException if this form does not contain any inputs with the specified value
      */
     @SuppressWarnings("unchecked")
     public <I extends HtmlInput> I getInputByValue(final String value) throws ElementNotFoundException {
         final List<HtmlInput> list = getInputsByValue(value);
         if (list.isEmpty()) {
             throw new ElementNotFoundException(HtmlInput.TAG_NAME, VALUE_ATTRIBUTE, value);
         }
         return (I) list.get(0);
     }
 
     /**
      * Returns all the inputs in this form with the specified value.
      * @param value the value to search for
      * @return all the inputs in this form with the specified value
      */
     public List<HtmlInput> getInputsByValue(final String value) {
         final List<HtmlInput> results = new ArrayList<>();
 
         for (final HtmlElement element : getElements(htmlElement -> htmlElement instanceof HtmlInput)) {
             if (Objects.equals(((HtmlInput) element).getValue(), value)) {
                 results.add((HtmlInput) element);
             }
         }
 
         return results;
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     protected void preventDefault() {
         isPreventDefault_ = true;
     }
 
     /**
      * Browsers have problems with self closing form tags.
      */
     @Override
     protected boolean isEmptyXmlTagExpanded() {
         return true;
     }
 
     /**
      * @return the value of the attribute {@code novalidate} or an empty string if that attribute isn't defined
      */
     public final boolean isNoValidate() {
         return hasAttribute(ATTRIBUTE_NOVALIDATE);
     }
 
     /**
      * Sets the value of the attribute {@code novalidate}.
      *
      * @param noValidate the value of the attribute {@code novalidate}
      */
     public final void setNoValidate(final boolean noValidate) {
         if (noValidate) {
             setAttribute(ATTRIBUTE_NOVALIDATE, ATTRIBUTE_NOVALIDATE);
         }
         else {
             removeAttribute(ATTRIBUTE_NOVALIDATE);
         }
     }
 
     /**
      * Register an element to the past names map with the specified name.
      * @param name name or id attribute of the element
      * @param element the element to register
      */
     public void registerPastName(final String name, final HtmlElement element) {
         if (pastNamesMap_ == null) {
             pastNamesMap_ = new HashMap<>();
         }
         pastNamesMap_.put(name, element);
     }
 
     /**
      * Return the element registered in the past names map with the specified name.
      * If the element is no longer owned by this form, the entry is removed and null is returned.
      * @param name name or id attribute of the element
      * @return the element, or null if not found or no longer owned by this form
      */
     public HtmlElement getNamedElement(final String name) {
         if (pastNamesMap_ == null) {
             return null;
         }
         final HtmlElement element = pastNamesMap_.get(name);
         if (element != null && element.getEnclosingForm() != this) {
             pastNamesMap_.remove(name);
             return null;
         }
         return element;
     }
 }