/*
    * 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.file;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.Serializable;
  import java.nio.charset.Charset;
  import java.util.Locale;
  
  import org.htmlunit.BrowserVersion;
  import org.htmlunit.HttpHeader;
  import org.htmlunit.WebRequest;
  import org.htmlunit.corejs.javascript.NativeArray;
  import org.htmlunit.corejs.javascript.NativePromise;
  import org.htmlunit.corejs.javascript.Scriptable;
  import org.htmlunit.corejs.javascript.ScriptableObject;
  import org.htmlunit.corejs.javascript.typedarrays.NativeArrayBuffer;
  import org.htmlunit.corejs.javascript.typedarrays.NativeArrayBufferView;
  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.host.ReadableStream;
  import org.htmlunit.util.KeyDataPair;
  import org.htmlunit.util.MimeType;
  import org.htmlunit.util.StringUtils;
  
  /**
   * A JavaScript object for {@code Blob}.
   *
   * @author Ahmed Ashour
   * @author Ronald Brill
   * @author Lai Quang Duong
   */
  @JsxClass
  public class Blob extends HtmlUnitScriptable {
      private static final String OPTIONS_TYPE_NAME = "type";
      //default according to https://developer.mozilla.org/en-US/docs/Web/API/File/File
      private static final String OPTIONS_TYPE_DEFAULT = "";
      private static final String OPTIONS_LASTMODIFIED = "lastModified";
  
      private Backend backend_;
  
      /**
       * The backend used for saving the blob.
       */
      protected abstract static class Backend implements Serializable {
  
          /**
           * Returns the name.
           *
           * @return the name
           */
          abstract String getName();
  
          /**
           * Returns the last modified timestamp as long.
           *
           * @return the last modified timestamp as long
           */
          abstract long getLastModified();
  
          /**
           * Returns the size.
           *
           * @return the size
           */
          abstract long getSize();
  
          /**
           * Returns the type.
           *
           * @param browserVersion the {@link BrowserVersion}
           * @return the type
           */
          abstract String getType(BrowserVersion browserVersion);
  
          /**
           * Returns the text.
           *
           * @return the text
           * @throws IOException in case of error
          */
         abstract String getText() throws IOException;
 
         /**
          * Returns the bytes.
          *
          * @param start the start position
          * @param end the end position
          * @return the bytes
          */
         abstract byte[] getBytes(int start, int end);
 
         /**
          * Ctor.
          */
         Backend() {
             // to make it package protected
         }
 
         /**
          * Returns the KeyDataPair for this Blob/File.
          *
          * @param name the name
          * @param fileName the file name
          * @param contentType the content type
          * @return the KeyDataPair to hold the data
          */
         abstract KeyDataPair getKeyDataPair(String name, String fileName, String contentType);
     }
 
     /**
      * Implementation of the {@link Backend} that stores the bytes in memory.
      *
      */
     protected static class InMemoryBackend extends Backend {
         private final String fileName_;
         private final String type_;
         private final long lastModified_;
         private final byte[] bytes_;
 
         /**
          * Ctor.
          *
          * @param bytes the bytes
          * @param fileName the name
          * @param type the type
          * @param lastModified last modified
          */
         protected InMemoryBackend(final byte[] bytes, final String fileName,
                 final String type, final long lastModified) {
             super();
             fileName_ = fileName;
             type_ = type;
             lastModified_ = lastModified;
             bytes_ = bytes;
         }
 
         /**
          * Factory method to create an {@link InMemoryBackend} from an {@link NativeArray}.
          *
          * @param fileBits the bytes as {@link NativeArray}
          * @param fileName the name
          * @param type the type
          * @param lastModified last modified
          * @return the new {@link InMemoryBackend}
          */
         protected static InMemoryBackend create(final NativeArray fileBits, final String fileName,
                 final String type, final long lastModified) {
             if (fileBits == null) {
                 return new InMemoryBackend(new byte[0], fileName, type, lastModified);
             }
 
             final ByteArrayOutputStream out = new ByteArrayOutputStream();
             final long length = fileBits.getLength();
             for (long i = 0; i < length; i++) {
                 final Object fileBit = fileBits.get(i);
                 if (fileBit instanceof NativeArrayBuffer buffer) {
                     final byte[] bytes = buffer.getBuffer();
                     out.write(bytes, 0, bytes.length);
                 }
                 else if (fileBit instanceof NativeArrayBufferView view) {
                     final byte[] bytes = view.getBuffer().getBuffer();
                     out.write(bytes, 0, bytes.length);
                 }
                 else if (fileBit instanceof Blob blob) {
                     final byte[] bytes = blob.getBackend().getBytes(0, (int) blob.getSize());
                     out.write(bytes, 0, bytes.length);
                 }
                 else {
                     final String bits = JavaScriptEngine.toString(fileBits.get(i));
                     // Todo normalize line breaks
                     final byte[] bytes = bits.getBytes(UTF_8);
                     out.write(bytes, 0, bytes.length);
                 }
             }
             return new InMemoryBackend(out.toByteArray(), fileName, type, lastModified);
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public String getName() {
             return fileName_;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public long getLastModified() {
             return lastModified_;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public long getSize() {
             return bytes_.length;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public String getType(final BrowserVersion browserVersion) {
             return type_.toLowerCase(Locale.ROOT);
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public String getText() throws IOException {
             return new String(bytes_, UTF_8);
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public byte[] getBytes(final int start, final int end) {
             final byte[] result = new byte[end - start];
             System.arraycopy(bytes_, start, result, 0, result.length);
             return result;
         }
 
         /**
          * {@inheritDoc}
          */
         @Override
         public KeyDataPair getKeyDataPair(final String name, final String fileName, final String contentType) {
             String fname = fileName;
             if (fname == null) {
                 fname = getName();
             }
             final KeyDataPair data = new KeyDataPair(name, null, fname, contentType, (Charset) null);
             data.setData(bytes_);
             return data;
         }
     }
 
     protected static String extractFileTypeOrDefault(final ScriptableObject properties) {
         if (properties == null || JavaScriptEngine.isUndefined(properties)) {
             return OPTIONS_TYPE_DEFAULT;
         }
 
         final Object optionsType = properties.get(OPTIONS_TYPE_NAME, properties);
         if (optionsType != null && properties != Scriptable.NOT_FOUND
                 && !JavaScriptEngine.isUndefined(optionsType)) {
             return JavaScriptEngine.toString(optionsType);
         }
 
         return OPTIONS_TYPE_DEFAULT;
     }
 
     protected static long extractLastModifiedOrDefault(final ScriptableObject properties) {
         if (properties == null || JavaScriptEngine.isUndefined(properties)) {
             return System.currentTimeMillis();
         }
 
         final Object optionsType = properties.get(OPTIONS_LASTMODIFIED, properties);
         if (optionsType != null && optionsType != Scriptable.NOT_FOUND
                 && !JavaScriptEngine.isUndefined(optionsType)) {
             try {
                 return Long.parseLong(JavaScriptEngine.toString(optionsType));
             }
             catch (final NumberFormatException ignored) {
                 // fall back to default
             }
         }
 
         return System.currentTimeMillis();
     }
 
     /**
      * Creates an instance.
      */
     public Blob() {
         super();
     }
 
     /**
      * Creates an instance.
      * @param fileBits the bits
      * @param properties the properties
      */
     @JsxConstructor
     public void jsConstructor(final NativeArray fileBits, final ScriptableObject properties) {
         NativeArray nativeBits = fileBits;
         if (JavaScriptEngine.isUndefined(fileBits)) {
             nativeBits = null;
         }
 
         backend_ = InMemoryBackend.create(nativeBits, null,
                             extractFileTypeOrDefault(properties),
                             extractLastModifiedOrDefault(properties));
     }
 
     /**
      * Ctor.
      *
      * @param bytes the bytes
      * @param contentType the content type
      */
     public Blob(final byte[] bytes, final String contentType) {
         super();
         setBackend(new InMemoryBackend(bytes, null, contentType, -1));
     }
 
     /**
      * Returns the {@code size} property.
      *
      * @return the {@code size} property
      */
     @JsxGetter
     public long getSize() {
         return getBackend().getSize();
     }
 
     /**
      * Returns the {@code type} property.
      *
      * @return the {@code type} property
      */
     @JsxGetter
     public String getType() {
         return getBackend().getType(getBrowserVersion());
     }
 
     /**
      * Returns a Promise that resolves with an ArrayBuffer containing the
      *         data in binary form.
      *
      * @return a Promise that resolves with an ArrayBuffer containing the
      *         data in binary form.
      */
     @JsxFunction
     public NativePromise arrayBuffer() {
         return setupPromise(() -> {
             final byte[] bytes = getBytes();
             final NativeArrayBuffer buffer = new NativeArrayBuffer(bytes.length);
             System.arraycopy(bytes, 0, buffer.getBuffer(), 0, bytes.length);
             buffer.setParentScope(getParentScope());
             buffer.setPrototype(ScriptableObject.getClassPrototype(getParentScope(), buffer.getClassName()));
             return buffer;
         });
     }
 
     /**
      * Returns a new Blob object which contains data from a subset of the blob on which it's called.
      *
      * @param start An index into the Blob indicating the first byte to include in the new Blob. If you specify
      *        a negative value, it's treated as an offset from the end of the Blob toward the beginning.
      *        For example, -10 would be the 10th from last byte in the Blob. The default value is 0.
      *        If you specify a value for start that is larger than the size of the source Blob,
      *        the returned Blob has size 0 and contains no data.
      * @param end An index into the Blob indicating the first byte that will not be included in the
      *        new Blob (i.e. the byte exactly at this index is not included). If you specify a negative value,
      *        it's treated as an offset from the end of the Blob toward the beginning.
      *        For example, -10 would be the 10th from last byte in the Blob. The default value is size.
      * @param contentType The content type to assign to the new Blob; this will be the value of its type property. The default value is an empty string.
      * @return a new Blob object which contains data from a subset of the blob on which it's called.
      */
     @JsxFunction
     public Blob slice(final Object start, final Object end, final Object contentType) {
         final Blob blob = new Blob();
         blob.setParentScope(getParentScope());
         blob.setPrototype(getPrototype(Blob.class));
 
         final int size = (int) getSize();
         int usedStart = 0;
         int usedEnd = size;
         if (start != null && !JavaScriptEngine.isUndefined(start)) {
             usedStart = JavaScriptEngine.toInt32(start);
             if (usedStart < 0) {
                 usedStart = size + usedStart;
             }
             usedStart = Math.max(0, usedStart);
         }
 
         if (end != null && !JavaScriptEngine.isUndefined(end)) {
             usedEnd = JavaScriptEngine.toInt32(end);
             if (usedEnd < 0) {
                 usedEnd = size + usedEnd;
             }
             usedEnd = Math.min(size, usedEnd);
         }
 
         String usedContentType = "";
         if (contentType != null && !JavaScriptEngine.isUndefined(contentType)) {
             usedContentType = JavaScriptEngine.toString(contentType).toLowerCase(Locale.ROOT);
         }
 
         if (usedEnd <= usedStart || usedStart >= getSize()) {
             blob.setBackend(new InMemoryBackend(new byte[0], null, usedContentType, 0L));
             return blob;
         }
 
         blob.setBackend(new InMemoryBackend(getBackend().getBytes(usedStart, usedEnd), null, usedContentType, 0L));
         return blob;
     }
 
     /**
      * Returns a ReadableStream which, upon reading, returns the contents of the Blob.
      *
      * @return a ReadableStream which, upon reading, returns the contents of the Blob.
      */
     @JsxFunction
     public ReadableStream stream() {
         throw new UnsupportedOperationException("Blob.stream() is not yet implemented.");
     }
 
     /**
      * Returns a Promise that resolves with a string containing the
      *         contents of the blob, interpreted as UTF-8.
      *
      * @return a Promise that resolves with a string containing the
      *         contents of the blob, interpreted as UTF-8.
      */
     @JsxFunction
     public NativePromise text() {
         return setupPromise(() -> getBackend().getText());
     }
 
     /**
      * Returns the bytes of this blob.
      *
      * @return the bytes of this blob
      */
     public byte[] getBytes() {
         return getBackend().getBytes(0, (int) getBackend().getSize());
     }
 
     /**
      * Sets the specified request with the parameters in this {@code FormData}.
      * @param webRequest the web request to fill
      */
     public void fillRequest(final WebRequest webRequest) {
         webRequest.setRequestBody(new String(getBytes(), UTF_8));
 
         final boolean contentTypeDefinedByCaller = webRequest.getAdditionalHeader(HttpHeader.CONTENT_TYPE) != null;
         if (!contentTypeDefinedByCaller) {
             final String mimeType = getType();
             if (StringUtils.isNotBlank(mimeType)) {
                 webRequest.setAdditionalHeader(HttpHeader.CONTENT_TYPE, mimeType);
             }
             webRequest.setEncodingType(null);
         }
     }
 
     /**
      * Delegates the KeyDataPair construction to the backend.
      * @param name the name
      * @param fileName the filename
      * @return the constructed {@link KeyDataPair}
      */
     public KeyDataPair getKeyDataPair(final String name, final String fileName) {
         String contentType = getType();
         if (StringUtils.isEmptyOrNull(contentType)) {
             contentType = MimeType.APPLICATION_OCTET_STREAM;
         }
 
         return backend_.getKeyDataPair(name, fileName, contentType);
     }
 
     protected Backend getBackend() {
         return backend_;
     }
 
     protected void setBackend(final Backend backend) {
         backend_ = backend;
     }
 
 }