package gnu.crypto.assembly;

// ----------------------------------------------------------------------------
// $Id: CascadeTransformer.java,v 1.2 2005/10/06 04:24:13 rsdio Exp $
//
// Copyright (C) 2003, Free Software Foundation, Inc.
//
// This file is part of GNU Crypto.
//
// GNU Crypto 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, or (at your option)
// any later version.
//
// GNU Crypto 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 program; see the file COPYING.  If not, write to the
//
//    Free Software Foundation Inc.,
//    51 Franklin Street, Fifth Floor,
//    Boston, MA 02110-1301
//    USA
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give
// you permission to link this library with independent modules to
// produce an executable, regardless of the license terms of these
// independent modules, and to copy and distribute the resulting
// executable under terms of your choice, provided that you also meet,
// for each linked independent module, the terms and conditions of the
// license of that module.  An independent module is a module which is
// not derived from or based on this library.  If you modify this
// library, you may extend this exception to your version of the
// library, but you are not obligated to do so.  If you do not wish to
// do so, delete this exception statement from your version.
// ----------------------------------------------------------------------------

import java.security.InvalidKeyException;
import java.util.Map;

/**
 * An Adapter to use any {@link Cascade} as a {@link Transformer} in an
 * {@link Assembly}.
 *
 * @version $Revision: 1.2 $
 */
class CascadeTransformer extends Transformer {

   // Constants and variables
   // -------------------------------------------------------------------------

   private Cascade delegate;
   private int blockSize;

   // Constructor(s)
   // -------------------------------------------------------------------------

   CascadeTransformer(Cascade delegate) {
      super();

      this.delegate = delegate;
   }

   // Class methods
   // -------------------------------------------------------------------------

   // Instant methods
   // -------------------------------------------------------------------------

   void initDelegate(Map attributes) throws TransformerException {
      attributes.put(Cascade.DIRECTION, wired);
      try {
         delegate.init(attributes);
      } catch (InvalidKeyException x) {
         throw new TransformerException("initDelegate()", x);
      }
      blockSize = delegate.currentBlockSize();
   }

   int delegateBlockSize() {
      return blockSize;
   }

   void resetDelegate() {
      delegate.reset();
      blockSize = 0;
   }

   byte[] updateDelegate(byte[] in, int offset, int length) throws TransformerException {
      byte[] result = updateInternal(in, offset, length);
      return result;
   }

   byte[] lastUpdateDelegate() throws TransformerException {
      if (inBuffer.size() != 0) {
         throw new TransformerException("lastUpdateDelegate()",
               new IllegalStateException("Cascade transformer, after last "
               +"update, must be empty but isn't"));
      }
      return new byte[0];
   }

   private byte[] updateInternal(byte[] in, int offset, int length) {
      byte[] result;
      for (int i = 0; i < length; i++) {
         inBuffer.write(in[offset++] & 0xFF);
         if (inBuffer.size() >= blockSize) {
            result = inBuffer.toByteArray();
            inBuffer.reset();
            delegate.update(result, 0, result, 0);
            outBuffer.write(result, 0, blockSize);
         }
      }
      result = outBuffer.toByteArray();
      outBuffer.reset();
      return result;
   }
}
