/*
 * $Id: BlockInputStream.java,v 1.4 2004/06/08 19:05:27 dog Exp $
 * Copyright (C) 2003 The Free Software Foundation
 * 
 * This file is part of GNU inetlib, a library.
 * 
 * GNU inetlib is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * GNU inetlib is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * 
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License.
 */

package gnu.inet.ftp;

import java.io.FilterInputStream;
import java.io.InputStream;
import java.io.IOException;

/**
 * A DTP input stream that implements the FTP block transfer mode.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 * @version $Revision: 1.4 $ $Date: 2004/06/08 19:05:27 $
 */
class BlockInputStream extends DTPInputStream
{

  static final int EOF = 64;

  int descriptor;
  int max = -1;
  int count = -1;

  BlockInputStream (DTP dtp, InputStream in)
    {
      super (dtp, in);
    }

  public int read () throws IOException
    {
      if (transferComplete)
        {
          return -1;
        }
      if (count == -1)
        {
          readHeader ();
        }
      if (max < 1)
        {
          close ();
          return -1;
        }
      int c = in.read ();
      if (c == -1)
        {
          dtp.transferComplete ();
        }
      count++;
      if (count >= max)
        {
          count = -1;
          if (descriptor == EOF)
            {
              close ();
            }
        }
      return c;
    }

  public int read (byte[] buf) throws IOException
    {
      return read (buf, 0, buf.length);
    }

  public int read (byte[] buf, int off, int len) throws IOException
    {
      if (transferComplete)
        {
          return -1;
        }
      if (count == -1)
        {
          readHeader ();
        }
      if (max < 1)
        {
          close ();
          return -1;
        }
      int l = in.read (buf, off, len);
      if (l == -1)
        {
          dtp.transferComplete ();
        }
      count += l;
      if (count >= max)
        {
          count = -1;
          if (descriptor == EOF)
            {
              close ();
            }
        }
      return l;
    }

  /**
   * Reads the block header.
   */
  void readHeader () throws IOException
    {
      descriptor = in.read ();
      int max_hi = in.read ();
      int max_lo = in.read ();
      max = (max_hi << 8) | max_lo;
      count = 0;
    }

}