/*
    * Copyright (c) 2002-2026 Gargoyle Software Inc.
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    * https://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.htmlunit.javascript.host.draganddrop;
  
  import java.util.ArrayList;
  
  import org.htmlunit.corejs.javascript.Context;
  import org.htmlunit.corejs.javascript.Function;
  import org.htmlunit.corejs.javascript.Scriptable;
  import org.htmlunit.corejs.javascript.VarScope;
  import org.htmlunit.javascript.HtmlUnitScriptable;
  import org.htmlunit.javascript.JavaScriptEngine;
  import org.htmlunit.javascript.configuration.JsxClass;
  import org.htmlunit.javascript.configuration.JsxConstructor;
  import org.htmlunit.javascript.configuration.JsxFunction;
  import org.htmlunit.javascript.configuration.JsxGetter;
  import org.htmlunit.javascript.configuration.JsxSymbol;
  import org.htmlunit.javascript.host.file.File;
  import org.htmlunit.javascript.host.file.FileList;
  
  /**
   * A JavaScript object for {@code DataTransferItemList}.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   */
  @JsxClass
  public class DataTransferItemList extends HtmlUnitScriptable {
  
      private ArrayList<DataTransferItem> items_;
      private FileList fileList_;
  
      /**
       * JavaScript constructor.
       */
      @JsxConstructor
      public void jsConstructor() {
          // nothing to do
      }
  
      /**
       * Returns the {@code length} property.
       *
       * @return the {@code length} property
       */
      @JsxGetter
      public int getLength() {
          if (items_ == null) {
              return 0;
          }
          return items_.size();
      }
  
      /**
       * Creates a new {@link DataTransferItem} using the specified data and adds it to the drag data list.
       * The item may be a {@link File} or a string of a given type. If the item is successfully added to the list,
       * the newly-created {@link DataTransferItem} object is returned.
       *
       * @param context the JavaScript context
       * @param scope the scope
       * @param thisObj the scriptable
       * @param args the arguments passed into the method
       * @param function the function
       * @return the newly-created {@link DataTransferItem} object
       * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/DataTransferItemList/add">MDN documentation</a>
       */
      @JsxFunction
      public static DataTransferItem add(final Context context, final VarScope scope,
              final Scriptable thisObj, final Object[] args, final Function function) {
          final DataTransferItemList itemList = (DataTransferItemList) thisObj;
          if (args.length == 1) {
              if (args[0] instanceof File file) {
                  final DataTransferItem item = DataTransferItem.buildFileItem(file);
                  item.setParentScope(scope);
                  item.setPrototype(itemList.getPrototype(item.getClass()));
  
                  if (itemList.items_ == null) {
                      itemList.items_ = new ArrayList<>();
                  }
                  itemList.items_.add(item);
                  itemList.updateFileList();
  
                  return item;
              }
              throw JavaScriptEngine.typeError(
                      "Failed to execute 'add' on 'DataTransferItemList': parameter 1 is not of type 'File'.");
          }
 
         if (args.length > 1) {
             final String data = JavaScriptEngine.toString(args[0]);
             final String type = JavaScriptEngine.toString(args[1]);
             final DataTransferItem item = DataTransferItem.buildStringItem(data, type);
             item.setParentScope(scope);
             item.setPrototype(itemList.getPrototype(item.getClass()));
 
             if (itemList.items_ == null) {
                 itemList.items_ = new ArrayList<>();
             }
             itemList.items_.add(item);
 
             return item;
         }
 
         throw JavaScriptEngine.typeError(
                 "Failed to execute 'add' on 'DataTransferItemList' - no args provided.");
     }
 
     /**
      * Removes all DataTransferItem objects from the drag data items list, leaving the list empty.
      */
     @JsxFunction
     public void clear() {
         if (items_ != null) {
             items_.clear();
             if (fileList_ != null) {
                 fileList_.updateFiles(new ArrayList<>());
             }
         }
     }
 
     /**
      * Removes the DataTransferItem at the specified index from the list. If the index is less
      * than zero or greater than one less than the length of the list, the list will not be changed.
      *
      * @param index the zero-based index number of the item in the drag data list to remove.
      *        If the index doesn't correspond to an existing item in the list, the list is left unchanged.
      */
     @JsxFunction
     public void remove(final int index) {
         if (items_ != null) {
             if (index >= 0 && index < items_.size()) {
                 items_.remove(index);
                 updateFileList();
             }
         }
     }
 
     /**
      * {@inheritDoc}
      */
     @Override
     public Object get(final int index, final Scriptable start) {
         if (this == start) {
             if (index >= 0 && index < items_.size()) {
                 return items_.get(index);
             }
         }
         return super.get(index, start);
     }
 
     /**
      * Returns an iterator over the values in this object.
      *
      * @return a native array iterator
      */
     @JsxSymbol(symbolName = "iterator")
     public Scriptable values() {
         return JavaScriptEngine.newArrayIteratorTypeValues(getParentScope(), this);
     }
 
     /**
      * Returns the file list for the parent {@code DataTransfer} object.
      * <span style="color:red">INTERNAL API - SUBJECT TO CHANGE AT ANY TIME - USE AT YOUR OWN RISK.</span>
      *
      * @return the {@code files} property
      */
     public FileList getFiles() {
         if (fileList_ == null) {
             final FileList list = new FileList(new java.io.File[0]);
             list.setParentScope(getParentScope());
             list.setPrototype(getPrototype(list.getClass()));
             fileList_ = list;
 
             if (items_ != null) {
                 updateFileList();
             }
         }
         return fileList_;
     }
 
     private void updateFileList() {
         if (fileList_ != null) {
             final ArrayList<File> files = new ArrayList<>();
             for (final DataTransferItem item : items_) {
                 if (item.isFile()) {
                     files.add(item.getAsFile());
                 }
             }
             fileList_.updateFiles(files);
         }
     }
 }