//
   //  ========================================================================
   //  Copyright (c) 1995-2014 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.Closeable;
  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;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  
  /**
   * 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 static final Logger LOG = Log.getLogger(PathContentProvider.class);
  
      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 PathIterator();
      }
  
      private class PathIterator implements Iterator<ByteBuffer>, Closeable
      {
          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);
                      LOG.debug("Opened file {}", filePath);
                 }
 
                 buffer.clear();
                 int read = channel.read(buffer);
                 if (read < 0)
                     throw new NoSuchElementException();
 
                 if (LOG.isDebugEnabled())
                     LOG.debug("Read {} bytes from {}", read, filePath);
 
                 position += read;
 
                 if (!hasNext())
                     close();
 
                 buffer.flip();
                 return buffer;
             }
             catch (NoSuchElementException x)
             {
                 close();
                 throw x;
             }
             catch (Exception x)
             {
                 close();
                 throw (NoSuchElementException)new NoSuchElementException().initCause(x);
             }
         }
 
         @Override
         public void remove()
         {
             throw new UnsupportedOperationException();
         }
 
         @Override
         public void close()
         {
             try
             {
                 if (channel != null)
                     channel.close();
             }
             catch (Exception x)
             {
                 LOG.ignore(x);
             }
         }
     }
 }