/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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
   *
   *   http://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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.http.nio.entity;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.nio.channels.FileChannel;
  
  import org.apache.http.annotation.NotThreadSafe;
  import org.apache.http.entity.AbstractHttpEntity;
  import org.apache.http.entity.ContentType;
  import org.apache.http.nio.ContentEncoder;
  import org.apache.http.nio.ContentEncoderChannel;
  import org.apache.http.nio.FileContentEncoder;
  import org.apache.http.nio.IOControl;
  import org.apache.http.util.Args;
  
  /**
   * A self contained, repeatable non-blocking entity that retrieves its content
   * from a file. This class is mostly used to stream large files of different
   * types, so one needs to supply the content type of the file to make sure
   * the content can be correctly recognized and processed by the recipient.
   *
   * @since 4.0
   */
  @SuppressWarnings("deprecation")
  @NotThreadSafe
  public class NFileEntity extends AbstractHttpEntity
                           implements HttpAsyncContentProducer, ProducingNHttpEntity {
  
      private final File file;
      private FileChannel fileChannel;
      private long idx = -1;
      private boolean useFileChannels;
  
      /**
       * Creates new instance of NFileEntity from the given source {@link File}
       * with the given content type. If <code>useFileChannels</code> is set to
       * <code>true</code>, the entity will try to use {@link FileContentEncoder}
       * interface to stream file content directly from the file channel.
       *
       * @param file the source file.
       * @param contentType the content type of the file.
       * @param useFileChannels flag whether the direct transfer from the file
       *   channel should be attempted.
       *
       * @since 4.2
       */
      public NFileEntity(final File file, final ContentType contentType, final boolean useFileChannels) {
          Args.notNull(file, "File");
          this.file = file;
          this.useFileChannels = useFileChannels;
          if (contentType != null) {
              setContentType(contentType.toString());
          }
      }
  
      /**
       * @since 4.2
       */
      public NFileEntity(final File file) {
          Args.notNull(file, "File");
          this.file = file;
      }
      /**
       * Creates new instance of NFileEntity from the given source {@link File}
       * with the given content type.
       *
       * @param file the source file.
       * @param contentType the content type of the file.
       *
      * @since 4.2
      */
     public NFileEntity(final File file, final ContentType contentType) {
         this(file, contentType, true);
     }
 
     /**
      * @deprecated (4.2) use {@link #NFileEntity(File, ContentType, boolean)}
      */
     @Deprecated
     public NFileEntity(final File file, final String contentType, final boolean useFileChannels) {
         Args.notNull(file, "File");
         this.file = file;
         this.useFileChannels = useFileChannels;
         setContentType(contentType);
     }
 
     /**
      * @deprecated (4.2) use {@link #NFileEntity(File, ContentType)}
      */
     @Deprecated
     public NFileEntity(final File file, final String contentType) {
         this(file, contentType, true);
     }
 
     /**
      * {@inheritDoc}
      *
      * @since 4.2
      */
     public void close() throws IOException {
         final FileChannel local = fileChannel;
         fileChannel = null;
         if (local != null) {
             local.close();
         }
     }
 
     /**
      * {@inheritDoc}
      *
      * @deprecated (4.2) use {@link #close()}
      */
     @Deprecated
     public void finish() throws IOException {
         close();
     }
 
     public long getContentLength() {
         return file.length();
     }
 
     public boolean isRepeatable() {
         return true;
     }
 
     public void produceContent(final ContentEncoder encoder, final IOControl ioctrl)
             throws IOException {
         if (fileChannel == null) {
             final FileInputStream in = new FileInputStream(file);
             fileChannel = in.getChannel();
             idx = 0;
         }
 
         long transferred;
         if (useFileChannels && encoder instanceof FileContentEncoder) {
             transferred = ((FileContentEncoder)encoder)
                 .transfer(fileChannel, idx, Long.MAX_VALUE);
         } else {
             transferred = fileChannel.
                 transferTo(idx, Long.MAX_VALUE, new ContentEncoderChannel(encoder));
         }
         if (transferred > 0) {
             idx += transferred;
         }
         if (idx >= fileChannel.size()) {
             encoder.complete();
             close();
         }
     }
 
     public boolean isStreaming() {
         return false;
     }
 
     public InputStream getContent() throws IOException {
         return new FileInputStream(this.file);
     }
 
     public void writeTo(final OutputStream outstream) throws IOException {
         Args.notNull(outstream, "Output stream");
         final InputStream instream = new FileInputStream(this.file);
         try {
             final byte[] tmp = new byte[4096];
             int l;
             while ((l = instream.read(tmp)) != -1) {
                 outstream.write(tmp, 0, l);
             }
             outstream.flush();
         } finally {
             instream.close();
         }
     }
 
 }