/*
    * 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;
  
  import java.nio.charset.Charset;
  import java.util.Arrays;
  import java.util.Locale;
  
  import org.htmlunit.corejs.javascript.typedarrays.NativeArrayBuffer;
  import org.htmlunit.corejs.javascript.typedarrays.NativeArrayBufferView;
  import org.htmlunit.cyberneko.xerces.util.StandardEncodingTranslator;
  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.util.XUserDefinedCharset;
  
  /**
   * JavaScript host object for {@code TextDecoder}.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   *
   * @see <a href="https://developer.mozilla.org/en-US/docs/Web/API/TextDecoder">MDN Documentation</a>
   */
  @JsxClass
  public class TextDecoder extends HtmlUnitScriptable {
      private String whatwgEncoding_ = "utf-8";
  
      /**
       * Creates an instance of this object.
       *
       * @param encodingLabel the encoding label to use; defaults to {@code "utf-8"} if not specified
       */
      @JsxConstructor
      public void jsConstructor(final Object encodingLabel) {
          if (JavaScriptEngine.isUndefined(encodingLabel)) {
              return;
          }
  
          String enc = JavaScriptEngine.toString(encodingLabel);
          enc = enc.trim().toLowerCase(Locale.ROOT);
          final String whatwgEncoding = StandardEncodingTranslator.ENCODING_FROM_LABEL.get(enc);
  
          if (whatwgEncoding == null
                  || StandardEncodingTranslator.REPLACEMENT.equalsIgnoreCase(whatwgEncoding)) {
              throw JavaScriptEngine.rangeError("Failed to construct 'TextDecoder': The encoding label provided ('"
                          + encodingLabel + "') is invalid.");
          }
  
          whatwgEncoding_ = whatwgEncoding;
      }
  
      /**
       * Returns the encoding label used by this decoder.
       *
       * @return the encoding label; defaults to {@code "utf-8"}
       */
      @JsxGetter
      public String getEncoding() {
          return whatwgEncoding_;
      }
  
      /**
       * Decodes the given buffer and returns the decoded string.
       *
       * @param buffer the buffer to decode
       * @return the decoded string
       */
      @JsxFunction
      public String decode(final Object buffer) {
          if (JavaScriptEngine.isUndefined(buffer)) {
              return "";
          }
  
          if (buffer instanceof NativeArrayBuffer arrayBuffer) {
              return new String(arrayBuffer.getBuffer(), getEncoding(whatwgEncoding_));
          }
  
          if (buffer instanceof NativeArrayBufferView arrayBufferView) {
              final NativeArrayBuffer arrayBuffer = arrayBufferView.getBuffer();
              if (arrayBuffer != null) {
                  final int byteLength = arrayBufferView.getByteLength();
                  final int byteOffset = arrayBufferView.getByteOffset();
                  final byte[] backedBytes = arrayBuffer.getBuffer();
                 final byte[] bytes = Arrays.copyOfRange(backedBytes, byteOffset, byteOffset + byteLength);
                 return new String(bytes, getEncoding(whatwgEncoding_));
             }
         }
 
         throw JavaScriptEngine.typeError("Argument 1 of TextDecoder.decode could not be"
                                 + " converted to any of: ArrayBufferView, ArrayBuffer.");
     }
 
     private Charset getEncoding(final String encodingLabel) {
         if (XUserDefinedCharset.NAME.equalsIgnoreCase(encodingLabel)) {
             return XUserDefinedCharset.INSTANCE;
         }
 
         final String ianaEncoding = StandardEncodingTranslator
                 .ENCODING_TO_IANA_ENCODING.getOrDefault(encodingLabel, encodingLabel);
         // Convert our IANA encoding names to Java charset names
         final String javaEncoding = StandardEncodingTranslator
                 .IANA_TO_JAVA_ENCODINGS.getOrDefault(ianaEncoding, ianaEncoding);
 
         return Charset.forName(javaEncoding);
     }
 }