/*
    * 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.xml;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  
  import org.htmlunit.FormEncodingType;
  import org.htmlunit.WebRequest;
  import org.htmlunit.corejs.javascript.ClassDescriptor;
  import org.htmlunit.corejs.javascript.Context;
  import org.htmlunit.corejs.javascript.ES6Iterator;
  import org.htmlunit.corejs.javascript.Function;
  import org.htmlunit.corejs.javascript.Scriptable;
  import org.htmlunit.corejs.javascript.TopLevel;
  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.JsxSymbol;
  import org.htmlunit.javascript.host.file.Blob;
  import org.htmlunit.javascript.host.file.File;
  import org.htmlunit.javascript.host.html.HTMLFormElement;
  import org.htmlunit.util.NameValuePair;
  import org.htmlunit.util.StringUtils;
  
  /**
   * JavaScript host object for {@code FormData}.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   * @author Thorsten Wendelmuth
   *
   * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/FormData">MDN Documentation</a>
   */
  @JsxClass
  public class FormData extends HtmlUnitScriptable {
  
      /** Constant used to register the prototype in the context. */
      private static final String FORM_DATA_ITERATOR_TAG = "FormData Iterator";
  
      private final List<NameValuePair> requestParameters_ = new ArrayList<>();
  
      /**
       * Iterator support for {@code FormData}.
       */
      public static final class FormDataIterator extends ES6Iterator {
          private static final ClassDescriptor DESCRIPTOR =
                  ES6Iterator.makeDescriptor(FORM_DATA_ITERATOR_TAG, FORM_DATA_ITERATOR_TAG);
  
          enum Type { KEYS, VALUES, BOTH }
  
          private final Type type_;
          private final String className_;
          private final List<NameValuePair> nameValuePairList_;
          private int index_;
  
          /**
           * Initializes the iterator prototype.
           *
           * @param cx the {@link Context}
           * @param scope the scope
           * @param className the class name
           */
          public static void init(final Context cx, final TopLevel scope, final String className) {
              ES6Iterator.initialize(
                      DESCRIPTOR, cx, scope, new FormDataIterator(className), false, FORM_DATA_ITERATOR_TAG);
          }
  
          /**
           * Creates an instance with an empty list (used for prototype initialization).
           *
           * @param className the class name
           */
          public FormDataIterator(final String className) {
              super();
  
              type_ = Type.BOTH;
              index_ = 0;
              nameValuePairList_ = Collections.emptyList();
              className_ = className;
          }
  
         /**
          * Creates an instance for iterating over the given list of name-value pairs.
          *
          * @param scope the scope
          * @param className the class name
          * @param type the iteration type (keys, values, or both)
          * @param nameValuePairList the list of name-value pairs to iterate
          */
         public FormDataIterator(final VarScope scope, final String className, final Type type,
                 final List<NameValuePair> nameValuePairList) {
             super(scope, className);
             type_ = type;
             index_ = 0;
             nameValuePairList_ = nameValuePairList;
             className_ = className;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public String getClassName() {
             return className_;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         protected boolean isDone(final Context cx, final VarScope scope) {
             return index_ >= nameValuePairList_.size();
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         protected Object nextValue(final Context cx, final VarScope scope) {
             if (isDone(cx, scope)) {
                 return Context.getUndefinedValue();
             }
 
             final NameValuePair nextNameValuePair = nameValuePairList_.get(index_++);
             return switch (type_) {
                 case KEYS -> nextNameValuePair.getName();
                 case VALUES -> nextNameValuePair.getValue();
                 case BOTH ->
                     cx.newArray(scope, new Object[]{nextNameValuePair.getName(), nextNameValuePair.getValue()});
             };
         }
     }
 
     /**
      * Creates an instance of this object, optionally pre-populated from the given form.
      *
      * @param formObj an {@link HTMLFormElement} to initialize the data from, or {@code undefined}
      */
     @JsxConstructor
     public void jsConstructor(final Object formObj) {
         if (formObj instanceof HTMLFormElement form) {
             requestParameters_.addAll(form.getHtmlForm().getParameterListForSubmit(null));
         }
     }
 
     /**
      * Appends a new value for an existing key, or adds the key if it does not already exist.
      *
      * @param name the name of the field
      * @param value the field's value
      * @param filename the filename reported to the server (optional)
      */
     @JsxFunction
     public void append(final String name, final Object value, final Object filename) {
         if (value instanceof Blob blob) {
             String fileName = "blob";
             if (value instanceof File) {
                 fileName = null;
             }
             if (filename instanceof String string) {
                 fileName = string;
             }
             requestParameters_.add(blob.getKeyDataPair(name, fileName));
             return;
         }
         requestParameters_.add(new NameValuePair(name, JavaScriptEngine.toString(value)));
     }
 
     /**
      * Removes the entry with the given name, if it exists.
      *
      * @param name the name of the field to remove
      */
     @JsxFunction(functionName = "delete")
     public void delete_js(final String name) {
         if (StringUtils.isEmptyOrNull(name)) {
             return;
         }
 
         requestParameters_.removeIf(pair -> name.equals(pair.getName()));
     }
 
     /**
      * Returns the first value associated with the given name.
      *
      * @param name the name of the field to retrieve
      * @return the first value found, or {@code null} if not found
      */
     @JsxFunction
     public String get(final String name) {
         if (StringUtils.isEmptyOrNull(name)) {
             return null;
         }
 
         for (final NameValuePair pair : requestParameters_) {
             if (name.equals(pair.getName())) {
                 return pair.getValue();
             }
         }
         return null;
     }
 
     /**
      * Returns all values associated with the given name.
      *
      * @param name the name of the field to retrieve
      * @return an array of all values found for the given name
      */
     @JsxFunction
     public Scriptable getAll(final String name) {
         if (StringUtils.isEmptyOrNull(name)) {
             return JavaScriptEngine.newArray(getParentScope(), 0);
         }
 
         final List<Object> values = new ArrayList<>();
         for (final NameValuePair pair : requestParameters_) {
             if (name.equals(pair.getName())) {
                 values.add(pair.getValue());
             }
         }
 
         final Object[] stringValues = values.toArray(new Object[0]);
         return JavaScriptEngine.newArray(getParentScope(), stringValues);
     }
 
     /**
      * Returns whether an entry with the given name exists.
      *
      * @param name the name of the field to check
      * @return {@code true} if the name exists, {@code false} otherwise
      */
     @JsxFunction
     public boolean has(final String name) {
         if (StringUtils.isEmptyOrNull(name)) {
             return false;
         }
 
         for (final NameValuePair pair : requestParameters_) {
             if (name.equals(pair.getName())) {
                 return true;
             }
         }
         return false;
     }
 
     /**
      * Sets a new value for an existing key, replacing all existing values for that key,
      * or adds the key if it does not already exist.
      *
      * @param name the name of the field
      * @param value the field's value
      * @param filename the filename reported to the server (optional)
      */
     @JsxFunction
     public void set(final String name, final Object value, final Object filename) {
         if (StringUtils.isEmptyOrNull(name)) {
             return;
         }
 
         int pos = -1;
 
         final Iterator<NameValuePair> iter = requestParameters_.iterator();
         int idx = 0;
         while (iter.hasNext()) {
             final NameValuePair pair = iter.next();
             if (name.equals(pair.getName())) {
                 iter.remove();
                 if (pos < 0) {
                     pos = idx;
                 }
             }
             idx++;
         }
 
         if (pos < 0) {
             pos = requestParameters_.size();
         }
 
         if (value instanceof Blob blob) {
             String fileName = "blob";
             if (value instanceof File) {
                 fileName = null;
             }
             if (filename instanceof String string) {
                 fileName = string;
             }
             requestParameters_.add(pos, blob.getKeyDataPair(name, fileName));
         }
         else {
             requestParameters_.add(pos, new NameValuePair(name, JavaScriptEngine.toString(value)));
         }
     }
 
     /**
      * Returns an iterator over all name/value pairs contained in this {@code FormData}.
      *
      * @return an iterator of {@code [name, value]} arrays
      */
     @JsxFunction
     @JsxSymbol(symbolName = "iterator")
     public Scriptable entries() {
         return new FormDataIterator(getParentScope(),
                 FORM_DATA_ITERATOR_TAG, FormDataIterator.Type.BOTH, requestParameters_);
     }
 
     /**
      * Populates the given {@link WebRequest} with the parameters from this {@code FormData}.
      *
      * @param webRequest the web request to fill
      */
     public void fillRequest(final WebRequest webRequest) {
         webRequest.setEncodingType(FormEncodingType.MULTIPART);
         webRequest.setRequestParameters(requestParameters_);
     }
 
     /**
      * Iterates over all key/value pairs in this {@code FormData}, calling the given callback for each.
      *
      * @param callback the function to execute for each key/value pair
      */
     @JsxFunction
     public void forEach(final Object callback) {
         if (!(callback instanceof Function fun)) {
             throw JavaScriptEngine.typeError(
                     "Foreach callback '" + JavaScriptEngine.toString(callback) + "' is not a function");
         }
 
         // This must be indexes instead of iterator() for correct behavior when of list changes while iterating
         for (int i = 0;; i++) {
             if (i >= requestParameters_.size()) {
                 break;
             }
 
             final NameValuePair param = requestParameters_.get(i);
             fun.call(Context.getCurrentContext(), getParentScope(), this,
                         new Object[] {param.getValue(), param.getName(), this});
         }
     }
 
     /**
      * Returns an iterator over all keys in this {@code FormData}.
      *
      * @return an iterator of key strings
      */
     @JsxFunction
     public FormDataIterator keys() {
         return new FormDataIterator(getParentScope(),
                 FORM_DATA_ITERATOR_TAG, FormDataIterator.Type.KEYS, requestParameters_);
     }
 
     /**
      * Returns an iterator over all values in this {@code FormData}.
      *
      * @return an iterator of value strings
      */
     @JsxFunction
     public FormDataIterator values() {
         return new FormDataIterator(getParentScope(),
                 FORM_DATA_ITERATOR_TAG, FormDataIterator.Type.VALUES, requestParameters_);
     }
 }