//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.client.util;
  
  import java.io.IOException;
  import java.nio.ByteBuffer;
  import java.nio.channels.SeekableByteChannel;
  import java.nio.file.AccessDeniedException;
  import java.nio.file.Files;
  import java.nio.file.NoSuchFileException;
  import java.nio.file.Path;
  import java.nio.file.StandardOpenOption;
  import java.util.Iterator;
  import java.util.NoSuchElementException;
  
  import org.eclipse.jetty.client.api.ContentProvider;
  
  /**
   * A {@link ContentProvider} for files using JDK 7's {@code java.nio.file} APIs.
   * <p />
   * It is possible to specify, at the constructor, a buffer size used to read content from the
   * stream, by default 4096 bytes.
   */
  public class PathContentProvider implements ContentProvider
  {
      private final Path filePath;
      private final long fileSize;
      private final int bufferSize;
  
      public PathContentProvider(Path filePath) throws IOException
      {
          this(filePath, 4096);
      }
  
      public PathContentProvider(Path filePath, int bufferSize) throws IOException
      {
          if (!Files.isRegularFile(filePath))
              throw new NoSuchFileException(filePath.toString());
          if (!Files.isReadable(filePath))
              throw new AccessDeniedException(filePath.toString());
          this.filePath = filePath;
          this.fileSize = Files.size(filePath);
          this.bufferSize = bufferSize;
      }
  
      @Override
      public long getLength()
      {
          return fileSize;
      }
  
      @Override
      public Iterator<ByteBuffer> iterator()
      {
          return new Iterator<ByteBuffer>()
          {
              private final ByteBuffer buffer = ByteBuffer.allocateDirect(bufferSize);
              private SeekableByteChannel channel;
              private long position;
  
              @Override
              public boolean hasNext()
              {
                  return position < getLength();
              }
  
              @Override
              public ByteBuffer next()
              {
                  try
                  {
                      if (channel == null)
                          channel = Files.newByteChannel(filePath, StandardOpenOption.READ);
  
                      buffer.clear();
                      int read = channel.read(buffer);
                      if (read < 0)
                          throw new NoSuchElementException();
  
                      position += read;
                      buffer.flip();
                      return buffer;
                  }
                 catch (IOException x)
                 {
                     throw (NoSuchElementException)new NoSuchElementException().initCause(x);
                 }
             }
 
             @Override
             public void remove()
             {
                 throw new UnsupportedOperationException();
             }
         };
     }
 }