package gnu.crypto.assembly;

// ----------------------------------------------------------------------------
// $Id: $
//
// 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.,
//    59 Temple Place - Suite 330,
//    Boston, MA 02111-1307
//    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.util.Map;

/**
 * @version $Revision: $
 */
public class Assembly {

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

   /** Flag that tells us if the instance is initialised or not; and if yes how. */
   private Direction wired;

   /** The first Transformer in the chain. */
   private Transformer head;

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

   public Assembly(Cascade cascade) {
      super();

      head = new CascadeTransformer(cascade);
   }

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

   // Instance methods
   // -------------------------------------------------------------------------

   public void addPreTransformer(Transformer t) {
      t.tail = head;
      head = t;
   }

   public void addPostTransformer(Transformer t) {
      t.tail = head.tail;
      head.tail = t;
   }

   public void init(Map attributes) throws TransformerException {
      if (wired != null) {
         throw new IllegalStateException();
      }
      Direction flow = (Direction) attributes.get(Transformer.DIRECTION);
      if (flow == null) {
         flow = Direction.FORWARD;
         attributes.put(Stage.DIRECTION, flow);
      }
      head.init(attributes);
      wired = flow;
   }

   public void reset() {
      head.reset();
      wired = null;
   }

   public int update(byte[] in, int offset, int length, byte[] out, int outOffset) {
      if (wired == null) {
         throw new IllegalStateException();
      }
      byte[] result = head.update(in, offset, length);
      System.arraycopy(result, 0, out, outOffset, result.length);
      return result.length;
   }

   public byte[] update(byte[] in, int offset, int length) {
      if (wired == null) {
         throw new IllegalStateException();
      }
      return head.update(in, offset, length);
   }

   public byte[] update(byte[] in) {
      return this.update(in, 0, in.length);
   }

   public byte[] lastUpdate(byte[] in, int offset, int length)
   throws TransformerException {
      if (wired == null) {
         throw new IllegalStateException();
      }
      byte[] result = head.lastUpdate(in, offset, length);
      this.reset();
      return result;
   }

   public byte[] lastUpdate(byte[] in) throws TransformerException {
      return this.lastUpdate(in, 0, in.length);
   }

   public byte[] lastUpdate() throws TransformerException {
      return this.lastUpdate(new byte[0], 0, 0);
   }
}