/*
 * $Id: MessageOutputStream.java,v 1.3 2004/06/08 19:05:28 dog Exp $
 * Copyright (C) 2002 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.util;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * An output stream that escapes any dots on a line by themself with
 * another dot, for the purposes of sending messages to SMTP and NNTP
 * servers.
 *
 * @author <a href="mailto:dog@gnu.org">Chris Burdess</a>
 * @version $Revision: 1.3 $ $Date: 2004/06/08 19:05:28 $
 */
public class MessageOutputStream extends FilterOutputStream
{

  /**
   * The stream termination octet.
   */
  public static final int END = 46;

  /**
   * The line termination octet.
   */
  public static final int LF = 10;

  int[] last = { LF, LF };      // the last character written to the stream

  /**
   * Constructs a message output stream connected to the specified output stream.
   * @param out the target output stream
   */
  public MessageOutputStream (OutputStream out)
    {
      super (out);
    }

  /**
   * Character write.
   */
  public void write (int c) throws IOException
    {
      if (last[0] == LF && last[1] == END && c == LF)
        {
          out.write (END);
        }
      out.write (c);
      last[0] = last[1];
      last[1] = c;
    }

  public void write (byte[] bytes) throws IOException
    {
      write (bytes, 0, bytes.length);
    }

  /**
   * Block write.
   */
  public void write (byte[] bytes, int off, int len) throws IOException
    {
      for (int i = 0; i < len; i++)
        {
          int c = (int) bytes[off + i];
          if (last[0] == LF && last[1] == END && c == LF)
            {
              byte[] b2 = new byte[bytes.length + 1];
              System.arraycopy (bytes, off, b2, off, i);
              b2[off + i] = END;
              System.arraycopy (bytes, off + i, b2, off + i + 1, len - i);
              bytes = b2;
              i++;
              len++;
            }
          last[0] = last[1];
          last[1] = c;
        }
      out.write (bytes, off, len);
    }

}