/*
    * 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.javascript.host.dom;
  
  import java.util.ArrayList;
  import java.util.List;
  
  import org.htmlunit.html.HtmlPage;
  import org.htmlunit.html.impl.SimpleRange;
  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;
  
  /**
   * A JavaScript object for {@code Selection}.
   *
   * @see <a href="http://msdn2.microsoft.com/en-us/library/ms535869.aspx">MSDN Documentation</a>
   * @see <a href="https://developer.mozilla.org/en/DOM/Selection">Gecko DOM Reference</a>
   * @author Ahmed Ashour
   * @author Daniel Gredler
   * @author Frank Danek
   * @author Ronald Brill
   */
  @JsxClass
  public class Selection extends HtmlUnitScriptable {
      private static final String TYPE_NONE = "None";
      private static final String TYPE_CARET = "Caret";
      private static final String TYPE_RANGE = "Range";
  
      private String type_ = TYPE_NONE;
  
      /**
       * JavaScript constructor.
       */
      @JsxConstructor
      public void jsConstructor() {
          // nothing to do
      }
  
      /**
       * @return a string currently being represented by the selection object,
       *         i.e. the currently selected text.
       */
      @JsxFunction(functionName = "toString")
      public String jsToString() {
          final StringBuilder sb = new StringBuilder();
          for (final SimpleRange r : getRanges()) {
              sb.append(r.toString());
          }
          return sb.toString();
      }
  
      /**
       * {@inheritDoc}
       */
      @Override
      public Object getDefaultValue(final Class<?> hint) {
          if (getPrototype() != null && (String.class.equals(hint) || hint == null)) {
              return jsToString();
          }
          return super.getDefaultValue(hint);
      }
  
      /**
       * Returns the node in which the selection begins.
       * @return the node in which the selection begins
       */
      @JsxGetter
      public Node getAnchorNode() {
          final SimpleRange last = getLastRange();
          if (last == null) {
              return null;
          }
          return (Node) getScriptableNullSafe(last.getStartContainer());
      }
  
      /**
       * Returns the number of characters that the selection's anchor is offset within the anchor node.
       * @return the number of characters that the selection's anchor is offset within the anchor node
       */
      @JsxGetter
      public int getAnchorOffset() {
          final SimpleRange last = getLastRange();
          if (last == null) {
             return 0;
         }
         return last.getStartOffset();
     }
 
     /**
      * Returns the node in which the selection ends.
      * @return the node in which the selection ends
      */
     @JsxGetter
     public Node getFocusNode() {
         final SimpleRange last = getLastRange();
         if (last == null) {
             return null;
         }
         return (Node) getScriptableNullSafe(last.getEndContainer());
     }
 
     /**
      * Returns the number of characters that the selection's focus is offset within the focus node.
      * @return the number of characters that the selection's focus is offset within the focus node
      */
     @JsxGetter
     public int getFocusOffset() {
         final SimpleRange last = getLastRange();
         if (last == null) {
             return 0;
         }
         return last.getEndOffset();
     }
 
     /**
      * Returns a boolean indicating whether the selection's start and end points are at the same position.
      * @return a boolean indicating whether the selection's start and end points are at the same position
      */
     @JsxGetter
     public boolean isIsCollapsed() {
         final List<SimpleRange> ranges = getRanges();
         return ranges.isEmpty() || (ranges.size() == 1 && ranges.get(0).isCollapsed());
     }
 
     /**
      * Returns the number of ranges in the selection.
      * @return the number of ranges in the selection
      */
     @JsxGetter
     public int getRangeCount() {
         return getRanges().size();
     }
 
     /**
      * Returns the type of selection (IE only).
      * @return the type of selection
      */
     @JsxGetter
     public String getType() {
         return type_;
     }
 
     /**
      * Adds a range to the selection.
      * @param range the range to add
      */
     @JsxFunction
     public void addRange(final Range range) {
         final SimpleRange rg = range.getSimpleRange();
         getRanges().add(rg);
 
         if (TYPE_CARET.equals(type_) && rg.isCollapsed()) {
             return;
         }
         type_ = TYPE_RANGE;
     }
 
     /**
      * Removes a range from the selection.
      * @param range the range to remove
      */
     @JsxFunction
     public void removeRange(final Range range) {
         getRanges().remove(range.getSimpleRange());
 
         if (getRangeCount() < 1) {
             type_ = TYPE_NONE;
         }
     }
 
     /**
      * Removes all ranges from the selection.
      */
     @JsxFunction
     public void removeAllRanges() {
         getRanges().clear();
 
         type_ = TYPE_NONE;
     }
 
     /**
      * Returns the range at the specified index.
      *
      * @param index the index of the range to return
      * @return the range at the specified index
      */
     @JsxFunction
     public Range getRangeAt(final int index) {
         final List<SimpleRange> ranges = getRanges();
         if (index < 0 || index >= ranges.size()) {
             throw JavaScriptEngine.asJavaScriptException(
                     getWindow(), "Invalid range index: " + index, DOMException.INDEX_SIZE_ERR);
         }
         final SimpleRange range = ranges.get(index);
         final Range jsRange = new Range(range);
         jsRange.setParentScope(getWindow());
         jsRange.setPrototype(getPrototype(Range.class));
 
         return jsRange;
     }
 
     /**
      * Collapses the current selection to a single point. The document is not modified.
      * @param parentNode the caret location will be within this node
      * @param offset the caret will be placed this number of characters from the beginning of the parentNode's text
      */
     @JsxFunction
     public void collapse(final Node parentNode, final int offset) {
         final List<SimpleRange> ranges = getRanges();
         ranges.clear();
         ranges.add(new SimpleRange(parentNode.getDomNodeOrDie(), offset));
 
         type_ = TYPE_CARET;
     }
 
     /**
      * Moves the anchor of the selection to the same point as the focus. The focus does not move.
      */
     @JsxFunction
     public void collapseToEnd() {
         final SimpleRange last = getLastRange();
         if (last != null) {
             final List<SimpleRange> ranges = getRanges();
             ranges.clear();
             ranges.add(last);
             last.collapse(false);
         }
 
         type_ = TYPE_CARET;
     }
 
     /**
      * Moves the focus of the selection to the same point at the anchor. The anchor does not move.
      */
     @JsxFunction
     public void collapseToStart() {
         final SimpleRange first = getFirstRange();
         if (first != null) {
             final List<SimpleRange> ranges = getRanges();
             ranges.clear();
             ranges.add(first);
             first.collapse(true);
         }
 
         type_ = TYPE_CARET;
     }
 
     /**
      * Cancels the current selection, sets the selection type to none.
      */
     @JsxFunction
     public void empty() {
         removeAllRanges();
     }
 
     /**
      * Moves the focus of the selection to a specified point. The anchor of the selection does not move.
      * @param parentNode the node within which the focus will be moved
      * @param offset the number of characters from the beginning of parentNode's text the focus will be placed
      */
     @JsxFunction
     public void extend(final Node parentNode, final int offset) {
         final SimpleRange last = getLastRange();
         if (last != null) {
             last.setEnd(parentNode.getDomNodeOrDie(), offset);
 
             type_ = TYPE_RANGE;
         }
     }
 
     /**
      * Adds all the children of the specified node to the selection. The previous selection is lost.
      * @param parentNode all children of parentNode will be selected; parentNode itself is not part of the selection
      */
     @JsxFunction
     public void selectAllChildren(final Node parentNode) {
         final List<SimpleRange> ranges = getRanges();
         ranges.clear();
         final SimpleRange simpleRange = new SimpleRange(parentNode.getDomNodeOrDie());
         ranges.add(simpleRange);
 
         if (simpleRange.isCollapsed()) {
             type_ = TYPE_CARET;
         }
         else {
             type_ = TYPE_RANGE;
         }
     }
 
     /**
      * Returns the current HtmlUnit DOM selection ranges.
      * @return the current HtmlUnit DOM selection ranges
      */
     private List<SimpleRange> getRanges() {
         final HtmlPage page = (HtmlPage) getWindow().getDomNodeOrDie();
         return page.getSelectionRanges();
     }
 
     /**
      * Returns the first selection range in the current document, by document position.
      * @return the first selection range in the current document, by document position
      */
     private SimpleRange getFirstRange() {
         // avoid concurrent modification exception
         final List<SimpleRange> ranges = new ArrayList<>(getRanges());
 
         SimpleRange first = null;
         for (final SimpleRange range : ranges) {
             if (first == null) {
                 first = range;
             }
             else {
                 final org.w3c.dom.Node firstStart = first.getStartContainer();
                 final org.w3c.dom.Node rangeStart = range.getStartContainer();
                 if ((firstStart.compareDocumentPosition(rangeStart) & Node.DOCUMENT_POSITION_PRECEDING) != 0) {
                     first = range;
                 }
             }
         }
         return first;
     }
 
     /**
      * Returns the last selection range in the current document, by document position.
      * @return the last selection range in the current document, by document position
      */
     private SimpleRange getLastRange() {
         // avoid concurrent modification exception
         final List<SimpleRange> ranges = new ArrayList<>(getRanges());
 
         SimpleRange last = null;
         for (final SimpleRange range : ranges) {
             if (last == null) {
                 last = range;
             }
             else {
                 final org.w3c.dom.Node lastStart = last.getStartContainer();
                 final org.w3c.dom.Node rangeStart = range.getStartContainer();
                 if ((lastStart.compareDocumentPosition(rangeStart) & Node.DOCUMENT_POSITION_FOLLOWING) != 0) {
                     last = range;
                 }
             }
         }
         return last;
     }
 
     /**
      * Returns the scriptable object corresponding to the specified HtmlUnit DOM object.
      * @param object the HtmlUnit DOM object whose scriptable object is to be returned (may be {@code null})
      * @return the scriptable object corresponding to the specified HtmlUnit DOM object, or {@code null} if
      *         <code>object</code> was {@code null}
      */
     private HtmlUnitScriptable getScriptableNullSafe(final Object object) {
         final HtmlUnitScriptable scriptable;
         if (object != null) {
             scriptable = getScriptableFor(object);
         }
         else {
             scriptable = null;
         }
         return scriptable;
     }
 }