/*
    * Copyright (c) 2002-2025 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.serializer;
  
  import static org.htmlunit.css.CssStyleSheet.BLOCK;
  
  import java.util.List;
  
  import org.htmlunit.Page;
  import org.htmlunit.SgmlPage;
  import org.htmlunit.WebWindow;
  import org.htmlunit.css.ComputedCssStyleDeclaration;
  import org.htmlunit.css.StyleAttributes.Definition;
  import org.htmlunit.html.DomCDataSection;
  import org.htmlunit.html.DomComment;
  import org.htmlunit.html.DomElement;
  import org.htmlunit.html.DomNode;
  import org.htmlunit.html.DomText;
  import org.htmlunit.html.HtmlBody;
  import org.htmlunit.html.HtmlBreak;
  import org.htmlunit.html.HtmlCheckBoxInput;
  import org.htmlunit.html.HtmlDetails;
  import org.htmlunit.html.HtmlHiddenInput;
  import org.htmlunit.html.HtmlInlineFrame;
  import org.htmlunit.html.HtmlInput;
  import org.htmlunit.html.HtmlMenu;
  import org.htmlunit.html.HtmlNoFrames;
  import org.htmlunit.html.HtmlNoScript;
  import org.htmlunit.html.HtmlOption;
  import org.htmlunit.html.HtmlOrderedList;
  import org.htmlunit.html.HtmlPreformattedText;
  import org.htmlunit.html.HtmlRadioButtonInput;
  import org.htmlunit.html.HtmlResetInput;
  import org.htmlunit.html.HtmlScript;
  import org.htmlunit.html.HtmlSelect;
  import org.htmlunit.html.HtmlStyle;
  import org.htmlunit.html.HtmlSubmitInput;
  import org.htmlunit.html.HtmlSummary;
  import org.htmlunit.html.HtmlTable;
  import org.htmlunit.html.HtmlTableCell;
  import org.htmlunit.html.HtmlTableFooter;
  import org.htmlunit.html.HtmlTableHeader;
  import org.htmlunit.html.HtmlTableRow;
  import org.htmlunit.html.HtmlTextArea;
  import org.htmlunit.html.HtmlTitle;
  import org.htmlunit.html.HtmlUnorderedList;
  import org.htmlunit.html.TableRowGroup;
  import org.htmlunit.html.serializer.HtmlSerializerVisibleText.HtmlSerializerTextBuilder.Mode;
  import org.htmlunit.util.StringUtils;
  
  /**
   * Special serializer to generate the output we need
   * at least for selenium WebElement#getText().
   * <p>This is also used from estimations by ComputedCSSStyleDeclaration.</p>
   *
   * @author Ronald Brill
   * @author cd alexndr
   */
  public class HtmlSerializerVisibleText {
  
      /**
       * Converts an HTML node to text.
       * @param node a node
       * @return the text representation according to the setting of this serializer
       */
      public String asText(final DomNode node) {
          if (node instanceof HtmlBreak) {
              return "";
          }
          final HtmlSerializerTextBuilder builder = new HtmlSerializerTextBuilder();
          appendNode(builder, node, whiteSpaceStyle(node, Mode.WHITE_SPACE_NORMAL));
          return builder.getText();
      }
  
      /**
       * Iterate over all Children and call appendNode() for every.
       *
       * @param builder the StringBuilder to add to
       * @param node the node to process
       * @param mode the {@link Mode} to use for processing
       */
      protected void appendChildren(final HtmlSerializerTextBuilder builder, final DomNode node, final Mode mode) {
          for (final DomNode child : node.getChildren()) {
              appendNode(builder, child, updateWhiteSpaceStyle(node, mode));
          }
      }
  
     /**
      * The core distribution method call the different appendXXX
      * methods depending on the type of the given node.
      *
      * @param builder the StringBuilder to add to
      * @param node the node to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendNode(final HtmlSerializerTextBuilder builder, final DomNode node, final Mode mode) {
         if (node instanceof DomCDataSection) {
             // ignore
         }
         else if (node instanceof DomText) {
             appendText(builder, (DomText) node, mode);
         }
         else if (node instanceof DomComment) {
             appendComment(builder, (DomComment) node, mode);
         }
         else if (node instanceof HtmlBreak) {
             appendBreak(builder, (HtmlBreak) node, mode);
         }
         else if (node instanceof HtmlHiddenInput) {
             appendHiddenInput(builder, (HtmlHiddenInput) node, mode);
         }
         else if (node instanceof HtmlScript) {
             appendScript(builder, (HtmlScript) node, mode);
         }
         else if (node instanceof HtmlStyle) {
             appendStyle(builder, (HtmlStyle) node, mode);
         }
         else if (node instanceof HtmlNoFrames) {
             appendNoFrames(builder, (HtmlNoFrames) node, mode);
         }
         else if (node instanceof HtmlTextArea) {
             appendTextArea(builder, (HtmlTextArea) node, mode);
         }
         else if (node instanceof HtmlTitle) {
             appendTitle(builder, (HtmlTitle) node, mode);
         }
         else if (node instanceof HtmlTableRow) {
             appendTableRow(builder, (HtmlTableRow) node, mode);
         }
         else if (node instanceof HtmlSelect) {
             appendSelect(builder, (HtmlSelect) node, mode);
         }
         else if (node instanceof HtmlOption) {
             appendOption(builder, (HtmlOption) node, mode);
         }
         else if (node instanceof HtmlSubmitInput) {
             appendSubmitInput(builder, (HtmlSubmitInput) node, mode);
         }
         else if (node instanceof HtmlResetInput) {
             appendResetInput(builder, (HtmlResetInput) node, mode);
         }
         else if (node instanceof HtmlCheckBoxInput) {
             appendCheckBoxInput(builder, (HtmlCheckBoxInput) node, mode);
         }
         else if (node instanceof HtmlRadioButtonInput) {
             appendRadioButtonInput(builder, (HtmlRadioButtonInput) node, mode);
         }
         else if (node instanceof HtmlInput) {
             // nothing
         }
         else if (node instanceof HtmlTable) {
             appendTable(builder, (HtmlTable) node, mode);
         }
         else if (node instanceof HtmlOrderedList) {
             appendOrderedList(builder, (HtmlOrderedList) node, mode);
         }
         else if (node instanceof HtmlUnorderedList) {
             appendUnorderedList(builder, (HtmlUnorderedList) node, mode);
         }
         else if (node instanceof HtmlPreformattedText) {
             appendPreformattedText(builder, (HtmlPreformattedText) node, mode);
         }
         else if (node instanceof HtmlInlineFrame) {
             appendInlineFrame(builder, (HtmlInlineFrame) node, mode);
         }
         else if (node instanceof HtmlMenu) {
             appendMenu(builder, (HtmlMenu) node, mode);
         }
         else if (node instanceof HtmlDetails) {
             appendDetails(builder, (HtmlDetails) node, mode);
         }
         else if (node instanceof HtmlNoScript && node.getPage().getWebClient().isJavaScriptEnabled()) {
             appendNoScript(builder, (HtmlNoScript) node, mode);
         }
         else {
             appendDomNode(builder, node, mode);
         }
     }
 
     /**
      * Process {@link DomNode}.
      *
      * @param builder the StringBuilder to add to
      * @param domNode the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendDomNode(final HtmlSerializerTextBuilder builder,
             final DomNode domNode, final Mode mode) {
         final boolean block;
         if (domNode instanceof HtmlBody) {
             block = false;
         }
         else if (domNode instanceof DomElement) {
             final WebWindow window = domNode.getPage().getEnclosingWindow();
             final String display = window.getComputedStyle((DomElement) domNode, null).getDisplay();
             block = BLOCK.equals(display);
         }
         else {
             block = false;
         }
 
         if (block) {
             builder.appendBlockSeparator();
         }
         appendChildren(builder, domNode, mode);
         if (block) {
             builder.appendBlockSeparator();
         }
     }
 
     /**
      * Process {@link HtmlHiddenInput}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlHiddenInput the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendHiddenInput(final HtmlSerializerTextBuilder builder,
             final HtmlHiddenInput htmlHiddenInput, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlScript}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlScript the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendScript(final HtmlSerializerTextBuilder builder,
             final HtmlScript htmlScript, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlStyle}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlStyle the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendStyle(final HtmlSerializerTextBuilder builder,
             final HtmlStyle htmlStyle, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlNoScript}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlNoScript the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendNoScript(final HtmlSerializerTextBuilder builder,
             final HtmlNoScript htmlNoScript, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlNoFrames}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlNoFrames the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendNoFrames(final HtmlSerializerTextBuilder builder,
             final HtmlNoFrames htmlNoFrames, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlSubmitInput}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlSubmitInput the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendSubmitInput(final HtmlSerializerTextBuilder builder,
             final HtmlSubmitInput htmlSubmitInput, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlInput}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlInput the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendInput(final HtmlSerializerTextBuilder builder,
             final HtmlInput htmlInput, final Mode mode) {
         builder.append(htmlInput.getValueAttribute(), mode);
     }
 
     /**
      * Process {@link HtmlResetInput}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlResetInput the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendResetInput(final HtmlSerializerTextBuilder builder,
             final HtmlResetInput htmlResetInput, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlMenu}.
      * @param builder the StringBuilder to add to
      * @param htmlMenu the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendMenu(final HtmlSerializerTextBuilder builder,
                     final HtmlMenu htmlMenu, final Mode mode) {
         builder.appendBlockSeparator();
         boolean first = true;
         for (final DomNode item : htmlMenu.getChildren()) {
             if (!first) {
                 builder.appendBlockSeparator();
             }
             first = false;
             appendNode(builder, item, mode);
         }
         builder.appendBlockSeparator();
     }
 
     /**
      * Process {@link HtmlDetails}.
      * @param builder the StringBuilder to add to
      * @param htmlDetails the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendDetails(final HtmlSerializerTextBuilder builder,
                     final HtmlDetails htmlDetails, final Mode mode) {
         if (htmlDetails.isOpen()) {
             appendChildren(builder, htmlDetails, mode);
             return;
         }
 
         for (final DomNode child : htmlDetails.getChildren()) {
             if (child instanceof HtmlSummary) {
                 appendNode(builder, child, mode);
             }
         }
     }
 
     /**
      * Process {@link HtmlTitle}.
      * @param builder the StringBuilder to add to
      * @param htmlTitle the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendTitle(final HtmlSerializerTextBuilder builder,
             final HtmlTitle htmlTitle, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlTableRow}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlTableRow the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendTableRow(final HtmlSerializerTextBuilder builder,
             final HtmlTableRow htmlTableRow, final Mode mode) {
         boolean first = true;
         for (final HtmlTableCell cell : htmlTableRow.getCells()) {
             if (!first) {
                 builder.appendBlank();
             }
             else {
                 first = false;
             }
             appendChildren(builder, cell, mode); // trim?
         }
     }
 
     /**
      * Check domNode visibility.
      * @param domNode the node to check
      * @return true or false
      */
     protected boolean isDisplayed(final DomNode domNode) {
         return domNode.isDisplayed();
     }
 
     /**
      * Process {@link HtmlTextArea}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlTextArea the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendTextArea(final HtmlSerializerTextBuilder builder,
             final HtmlTextArea htmlTextArea, final Mode mode) {
         if (isDisplayed(htmlTextArea)) {
             builder.append(htmlTextArea.getDefaultValue(), whiteSpaceStyle(htmlTextArea, Mode.PRE));
             builder.trimRight(Mode.PRE);
         }
     }
 
     /**
      * Process {@link HtmlTable}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlTable the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendTable(final HtmlSerializerTextBuilder builder,
             final HtmlTable htmlTable, final Mode mode) {
         builder.appendBlockSeparator();
         final String caption = htmlTable.getCaptionText();
         if (caption != null) {
             builder.append(caption, mode);
             builder.appendBlockSeparator();
         }
 
         boolean first = true;
 
         // first thead has to be displayed first and first tfoot has to be displayed last
         final HtmlTableHeader tableHeader = htmlTable.getHeader();
         if (tableHeader != null) {
             first = appendTableRows(builder, mode, tableHeader.getRows(), true, null, null);
         }
         final HtmlTableFooter tableFooter = htmlTable.getFooter();
 
         final List<HtmlTableRow> tableRows = htmlTable.getRows();
         first = appendTableRows(builder, mode, tableRows, first, tableHeader, tableFooter);
 
         if (tableFooter != null) {
             first = appendTableRows(builder, mode, tableFooter.getRows(), first, null, null);
         }
         else if (tableRows.isEmpty()) {
             final DomNode firstChild = htmlTable.getFirstChild();
             if (firstChild != null) {
                 appendNode(builder, firstChild, mode);
             }
         }
 
         builder.appendBlockSeparator();
     }
 
     /**
      * Process {@link HtmlTableRow}.
      *
      * @param builder the StringBuilder to add to
      * @param mode the {@link Mode} to use for processing
      * @param rows the rows
      * @param first if true this is the first one
      * @param skipParent1 skip row if the parent is this
      * @param skipParent2 skip row if the parent is this
      * @return true if this was the first one
      */
     protected boolean appendTableRows(final HtmlSerializerTextBuilder builder, final Mode mode,
             final List<HtmlTableRow> rows, boolean first, final TableRowGroup skipParent1,
             final TableRowGroup skipParent2) {
         for (final HtmlTableRow row : rows) {
             if (row.getParentNode() == skipParent1 || row.getParentNode() == skipParent2) {
                 continue;
             }
             if (!first) {
                 builder.appendBlockSeparator();
             }
             first = false;
             appendTableRow(builder, row, mode);
         }
         return first;
     }
 
     /**
      * Process {@link HtmlSelect}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlSelect the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendSelect(final HtmlSerializerTextBuilder builder,
             final HtmlSelect htmlSelect, final Mode mode) {
         builder.appendBlockSeparator();
         boolean leadingNlPending = false;
         final Mode selectMode = whiteSpaceStyle(htmlSelect, mode);
         for (final DomNode item : htmlSelect.getChildren()) {
             if (leadingNlPending) {
                 builder.appendBlockSeparator();
                 leadingNlPending = false;
             }
 
             builder.resetContentAdded();
             appendNode(builder, item, whiteSpaceStyle(item, selectMode));
             if (!leadingNlPending && builder.contentAdded_) {
                 leadingNlPending = true;
             }
         }
         builder.appendBlockSeparator();
     }
 
     /**
      * Process {@link HtmlSelect}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlOption the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendOption(final HtmlSerializerTextBuilder builder,
             final HtmlOption htmlOption, final Mode mode) {
         appendChildren(builder, htmlOption, mode);
     }
 
     /**
      * Process {@link HtmlOrderedList}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlOrderedList the OL element
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendOrderedList(final HtmlSerializerTextBuilder builder,
             final HtmlOrderedList htmlOrderedList, final Mode mode) {
         builder.appendBlockSeparator();
         boolean leadingNlPending = false;
         final Mode olMode = whiteSpaceStyle(htmlOrderedList, mode);
         for (final DomNode item : htmlOrderedList.getChildren()) {
             if (leadingNlPending) {
                 builder.appendBlockSeparator();
                 leadingNlPending = false;
             }
 
             builder.resetContentAdded();
             appendNode(builder, item, whiteSpaceStyle(item, olMode));
             if (!leadingNlPending && builder.contentAdded_) {
                 leadingNlPending = true;
             }
         }
         builder.appendBlockSeparator();
     }
 
     /**
      * Process {@link HtmlUnorderedList}.
      * @param builder the StringBuilder to add to
      * @param htmlUnorderedList the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendUnorderedList(final HtmlSerializerTextBuilder builder,
                     final HtmlUnorderedList htmlUnorderedList, final Mode mode) {
         builder.appendBlockSeparator();
         boolean leadingNlPending = false;
         final Mode ulMode = whiteSpaceStyle(htmlUnorderedList, mode);
         for (final DomNode item : htmlUnorderedList.getChildren()) {
             if (leadingNlPending) {
                 builder.appendBlockSeparator();
                 leadingNlPending = false;
             }
 
             builder.resetContentAdded();
             appendNode(builder, item, whiteSpaceStyle(item, ulMode));
             if (!leadingNlPending && builder.contentAdded_) {
                 leadingNlPending = true;
             }
         }
         builder.appendBlockSeparator();
     }
 
     /**
      * Process {@link HtmlPreformattedText}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlPreformattedText the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendPreformattedText(final HtmlSerializerTextBuilder builder,
             final HtmlPreformattedText htmlPreformattedText, final Mode mode) {
         if (isDisplayed(htmlPreformattedText)) {
             builder.appendBlockSeparator();
             appendChildren(builder, htmlPreformattedText, whiteSpaceStyle(htmlPreformattedText, Mode.PRE));
             builder.appendBlockSeparator();
         }
     }
 
     /**
      * Process {@link HtmlInlineFrame}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlInlineFrame the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendInlineFrame(final HtmlSerializerTextBuilder builder,
             final HtmlInlineFrame htmlInlineFrame, final Mode mode) {
         if (isDisplayed(htmlInlineFrame)) {
             builder.appendBlockSeparator();
             final Page page = htmlInlineFrame.getEnclosedPage();
             if (page instanceof SgmlPage) {
                 builder.append(((SgmlPage) page).asNormalizedText(), mode);
             }
             builder.appendBlockSeparator();
         }
     }
 
     /**
      * Process {@link DomText}.
      *
      * @param builder the StringBuilder to add to
      * @param domText the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendText(final HtmlSerializerTextBuilder builder, final DomText domText, final Mode mode) {
         final DomNode parent = domText.getParentNode();
         if (parent instanceof HtmlTitle
                 || parent instanceof HtmlScript) {
             builder.append(domText.getData(), Mode.WHITE_SPACE_PRE_LINE);
         }
 
         if (parent == null
                 || parent instanceof HtmlTitle
                 || parent instanceof HtmlScript
                 || isDisplayed(parent)) {
             builder.append(domText.getData(), mode);
         }
     }
 
     /**
      * Process {@link DomComment}.
      *
      * @param builder the StringBuilder to add to
      * @param domComment the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendComment(final HtmlSerializerTextBuilder builder,
             final DomComment domComment, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlBreak}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlBreak the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendBreak(final HtmlSerializerTextBuilder builder,
             final HtmlBreak htmlBreak, final Mode mode) {
         builder.appendBreak(mode);
     }
 
     /**
      * Process {@link HtmlCheckBoxInput}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlCheckBoxInput the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendCheckBoxInput(final HtmlSerializerTextBuilder builder,
                     final HtmlCheckBoxInput htmlCheckBoxInput, final Mode mode) {
         // nothing to do
     }
 
     /**
      * Process {@link HtmlRadioButtonInput}.
      *
      * @param builder the StringBuilder to add to
      * @param htmlRadioButtonInput the target to process
      * @param mode the {@link Mode} to use for processing
      */
     protected void appendRadioButtonInput(final HtmlSerializerTextBuilder builder,
             final HtmlRadioButtonInput htmlRadioButtonInput, final Mode mode) {
         // nothing to do
     }
 
     protected Mode whiteSpaceStyle(final DomNode domNode, final Mode defaultMode) {
         final Page page = domNode.getPage();
         if (page != null) {
             final WebWindow window = page.getEnclosingWindow();
             if (window.getWebClient().getOptions().isCssEnabled()) {
                 DomNode node = domNode;
                 while (node != null) {
                     if (node instanceof DomElement) {
                         final ComputedCssStyleDeclaration style = window.getComputedStyle((DomElement) node, null);
                         final String value = style.getStyleAttribute(Definition.WHITE_SPACE, false);
                         if (!StringUtils.isEmptyOrNull(value)) {
                             if ("normal".equalsIgnoreCase(value)) {
                                 return Mode.WHITE_SPACE_NORMAL;
                             }
                             if ("nowrap".equalsIgnoreCase(value)) {
                                 return Mode.WHITE_SPACE_NORMAL;
                             }
                             if ("pre".equalsIgnoreCase(value)) {
                                 return Mode.WHITE_SPACE_PRE;
                             }
                             if ("pre-wrap".equalsIgnoreCase(value)) {
                                 return Mode.WHITE_SPACE_PRE;
                             }
                             if ("pre-line".equalsIgnoreCase(value)) {
                                 return Mode.WHITE_SPACE_PRE_LINE;
                             }
                         }
                     }
                     node = node.getParentNode();
                 }
             }
         }
         return defaultMode;
     }
 
     protected Mode updateWhiteSpaceStyle(final DomNode domNode, final Mode defaultMode) {
         final Page page = domNode.getPage();
         if (page != null) {
             final WebWindow window = page.getEnclosingWindow();
             if (window.getWebClient().getOptions().isCssEnabled()) {
                 if (domNode instanceof DomElement) {
                     final ComputedCssStyleDeclaration style = window.getComputedStyle((DomElement) domNode, null);
                     final String value = style.getStyleAttribute(Definition.WHITE_SPACE, false);
                     if (!StringUtils.isEmptyOrNull(value)) {
                         if ("normal".equalsIgnoreCase(value)) {
                             return Mode.WHITE_SPACE_NORMAL;
                         }
                         if ("nowrap".equalsIgnoreCase(value)) {
                             return Mode.WHITE_SPACE_NORMAL;
                         }
                         if ("pre".equalsIgnoreCase(value)) {
                             return Mode.WHITE_SPACE_PRE;
                         }
                         if ("pre-wrap".equalsIgnoreCase(value)) {
                             return Mode.WHITE_SPACE_PRE;
                         }
                         if ("pre-line".equalsIgnoreCase(value)) {
                             return Mode.WHITE_SPACE_PRE_LINE;
                         }
                     }
                 }
             }
         }
         return defaultMode;
     }
 
     /**
      * Helper to compose the text for the serializer based on several modes.
      */
     protected static class HtmlSerializerTextBuilder {
         /** Mode. */
         protected enum Mode {
             /**
              * The mode for the pre tag.
              */
             PRE,
 
             /**
              * Sequences of white space are collapsed. Newline characters
              * in the source are handled the same as other white space.
              * Lines are broken as necessary to fill line boxes.
              */
             WHITE_SPACE_NORMAL,
 
             /**
              * Sequences of white space are preserved. Lines are only broken
              * at newline characters in the source and at <br> elements.
              */
             WHITE_SPACE_PRE,
 
             /**
              * Sequences of white space are collapsed. Lines are broken
              * at newline characters, at <br>, and as necessary
              * to fill line boxes.
              */
             WHITE_SPACE_PRE_LINE
         }
 
         private enum State {
             DEFAULT,
             EMPTY,
             BLANK_AT_END,
             BLANK_AT_END_AFTER_NEWLINE,
             NEWLINE_AT_END,
             BREAK_AT_END,
             BLOCK_SEPARATOR_AT_END
         }
 
         private State state_;
         private final StringBuilder builder_;
         private int trimRightPos_;
         private boolean contentAdded_;
 
         /**
          * Ctor.
          */
         public HtmlSerializerTextBuilder() {
             builder_ = new StringBuilder();
             state_ = State.EMPTY;
             trimRightPos_ = 0;
         }
 
         /**
          * Append the provided content.
          * see https://drafts.csswg.org/css-text-3/#white-space
          *
          * @param content the content to add
          * @param mode the {@link Mode}
          */
         public void append(final String content, final Mode mode) {
             if (content == null) {
                 return;
             }
             int length = content.length();
             if (length == 0) {
                 return;
             }
 
             length--;
             final int contentLenght = content.length();
             for (int i = 0; i < contentLenght; i++) {
                 char c = content.charAt(i);
 
                 // handle \r
                 if (c == '\r') {
                     if (length != i) {
                         continue;
                     }
                     c = '\n';
                 }
 
                 if (c == '\n') {
                     if (mode == Mode.WHITE_SPACE_PRE) {
                         switch (state_) {
                             case EMPTY:
                             case BLOCK_SEPARATOR_AT_END:
                                 break;
                             default:
                                 builder_.append('\n');
                                 state_ = State.NEWLINE_AT_END;
                                 trimRightPos_ = builder_.length();
                                 break;
                         }
                         continue;
                     }
 
                     if (mode == Mode.PRE) {
                         builder_.append('\n');
                         state_ = State.NEWLINE_AT_END;
                         trimRightPos_ = builder_.length();
 
                         continue;
                     }
 
                     if (mode == Mode.WHITE_SPACE_PRE_LINE) {
                         switch (state_) {
                             case EMPTY:
                             case BLOCK_SEPARATOR_AT_END:
                                 break;
                             default:
                                 builder_.append('\n');
                                 state_ = State.NEWLINE_AT_END;
                                 trimRightPos_ = builder_.length();
                                 break;
                         }
                         continue;
                     }
 
                     switch (state_) {
                         case EMPTY:
                         case BLANK_AT_END:
                         case BLANK_AT_END_AFTER_NEWLINE:
                         case BLOCK_SEPARATOR_AT_END:
                         case NEWLINE_AT_END:
                         case BREAK_AT_END:
                             break;
                         default:
                             builder_.append(' ');
                             state_ = State.BLANK_AT_END;
                             break;
                     }
                     continue;
                 }
 
                 if (c == ' ' || c == '\t' || c == '\f') {
                     if (mode == Mode.WHITE_SPACE_PRE || mode == Mode.PRE) {
                         appendBlank();
                         continue;
                     }
 
                     if (mode == Mode.WHITE_SPACE_PRE_LINE) {
                         switch (state_) {
                             case EMPTY:
                             case BLANK_AT_END:
                             case BLANK_AT_END_AFTER_NEWLINE:
                             case BREAK_AT_END:
                                 break;
                             default:
                                 builder_.append(' ');
                                 state_ = State.BLANK_AT_END;
                                 break;
                         }
                         continue;
                     }
 
                     switch (state_) {
                         case EMPTY:
                         case BLANK_AT_END:
                         case BLANK_AT_END_AFTER_NEWLINE:
                         case BLOCK_SEPARATOR_AT_END:
                         case NEWLINE_AT_END:
                         case BREAK_AT_END:
                             break;
                         default:
                             builder_.append(' ');
                             state_ = State.BLANK_AT_END;
                             break;
                     }
                     continue;
                 }
 
                 if (c == (char) 160) {
                     appendBlank();
                     if (mode == Mode.WHITE_SPACE_NORMAL || mode == Mode.WHITE_SPACE_PRE_LINE) {
                         state_ = State.DEFAULT;
                     }
                     continue;
                 }
                 builder_.append(c);
                 state_ = State.DEFAULT;
                 trimRightPos_ = builder_.length();
                 contentAdded_ = true;
             }
         }
 
         /**
          * Append a block separator.
          */
         public void appendBlockSeparator() {
             switch (state_) {
                 case EMPTY:
                     break;
                 case BLANK_AT_END:
                     builder_.setLength(trimRightPos_);
                     if (builder_.length() == 0) {
                         state_ = State.EMPTY;
                     }
                     else {
                         builder_.append('\n');
                         state_ = State.BLOCK_SEPARATOR_AT_END;
                     }
                     break;
                 case BLANK_AT_END_AFTER_NEWLINE:
                     builder_.setLength(trimRightPos_ - 1);
                     if (builder_.length() == 0) {
                         state_ = State.EMPTY;
                     }
                     else {
                         builder_.append('\n');
                         state_ = State.BLOCK_SEPARATOR_AT_END;
                     }
                     break;
                 case BLOCK_SEPARATOR_AT_END:
                     break;
                 case NEWLINE_AT_END:
                 case BREAK_AT_END:
                     builder_.setLength(builder_.length() - 1);
                     trimRightPos_ = trimRightPos_ - 1;
                     if (builder_.length() == 0) {
                         state_ = State.EMPTY;
                     }
                     else {
                         builder_.append('\n');
                         state_ = State.BLOCK_SEPARATOR_AT_END;
                     }
                     break;
                 default:
                     builder_.append('\n');
                     state_ = State.BLOCK_SEPARATOR_AT_END;
                     break;
             }
         }
 
         /**
          * Append a break.
          *
          * @param mode the {@link Mode}
          */
         public void appendBreak(final Mode mode) {
             builder_.setLength(trimRightPos_);
 
             builder_.append('\n');
             state_ = State.BREAK_AT_END;
             trimRightPos_ = builder_.length();
         }
 
         /**
          * Append a blank.
          */
         public void appendBlank() {
             builder_.append(' ');
             state_ = State.BLANK_AT_END;
             trimRightPos_ = builder_.length();
         }
 
         /**
          * Remove all trailing whitespace from the end.
          *
          * @param mode the {@link Mode}
          */
         public void trimRight(final Mode mode) {
             if (mode == Mode.PRE) {
                 switch (state_) {
                     case BLOCK_SEPARATOR_AT_END:
                     case NEWLINE_AT_END:
                     case BREAK_AT_END:
                         if (trimRightPos_ == builder_.length()) {
                             trimRightPos_--;
                         }
                         break;
                     default:
                         break;
                 }
             }
 
             builder_.setLength(trimRightPos_);
             state_ = State.DEFAULT;
             if (builder_.length() == 0) {
                 state_ = State.EMPTY;
             }
         }
 
         /**
          * @return true if some content was already added
          */
         public boolean wasContentAdded() {
             return contentAdded_;
         }
 
         /**
          * Resets the contentAdded state to false.
          */
         public void resetContentAdded() {
             contentAdded_ = false;
         }
 
         /**
          * @return the constructed text.
          */
         public String getText() {
             return builder_.substring(0, trimRightPos_);
         }
     }
 }