/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * The contents of this file are subject to the Netscape Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/NPL/
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is Netscape
 * Communications Corporation.  Portions created by Netscape are
 * Copyright (C) 1998 Netscape Communications Corporation. All
 * Rights Reserved.
 *
 * Contributor(s): 
 */

#include "nsBasicStreamGenerator.h"

const char * nsBasicStreamGenerator::mSignature = "Basic Keyed Stream Generator";

NS_IMPL_ISUPPORTS1(nsBasicStreamGenerator, nsIKeyedStreamGenerator)

nsBasicStreamGenerator::nsBasicStreamGenerator()
    : mLevel(NS_SECURITY_LEVEL), mSalt(0), mPassword(), mState(0) {
  NS_INIT_ISUPPORTS();
}

nsBasicStreamGenerator::~nsBasicStreamGenerator() {
}


NS_IMETHODIMP nsBasicStreamGenerator::GetSignature(char **signature) {
  NS_ENSURE_ARG_POINTER(signature);
  *signature = nsCRT::strdup(mSignature);
  return NS_OK;
}

NS_IMETHODIMP nsBasicStreamGenerator::Setup(PRUint32 salt, nsISupports *consumer) {
  nsresult rv = NS_OK;

  /* forget about previous setup */
  mWeakPasswordSink = nsnull;
  mPassword.Truncate(0);

  /* reestablish setup */
  if (consumer) {
    mWeakPasswordSink = getter_AddRefs(NS_GetWeakReference(consumer, &rv));
    if (NS_FAILED(rv)) return rv;
  }
  mSalt = salt;
  return NS_OK;
}

NS_IMETHODIMP nsBasicStreamGenerator::GetLevel(float *aLevel) {
  NS_ENSURE_ARG_POINTER(aLevel);
  *aLevel = mLevel;
  return NS_OK;
}

NS_IMETHODIMP nsBasicStreamGenerator::GetByte(PRUint32 offset, PRUint8 *retval) {
  NS_ENSURE_ARG_POINTER(retval);
  nsresult rv = NS_OK;
  if (mPassword.Length() == 0) {
    /* this is the first time, so we need to get the password */
    nsCOMPtr<nsIPasswordSink> weakPasswordSink = do_QueryReferent(mWeakPasswordSink);
    if (!weakPasswordSink) {
      return NS_ERROR_FAILURE;
    }
    PRUnichar *aPassword;
    rv = weakPasswordSink->GetPassword(&aPassword);
    if (NS_FAILED(rv)) {
      return rv;
    }
    mPassword = aPassword;
    nsAllocator::Free(aPassword);
    mState = 0;
  }

  /*
   * Get the offset byte from the stream. Our stream is just our password
   * repeating itself infinite times.
   *
   * Since mPassword is an nsString, its elements are PRUnichars.
   * We want to return either the high-order or low-order 8 bits of the PRUnichar
   * depending on whether or not this routine was called an odd or an even number of times
   */
  PRUnichar ret16 = mPassword.CharAt((mState>>1) % mPassword.Length());
  if (!((mState++) & 1)) {
    ret16 = ret16>>8;
  }
  *retval = (PRUint8)(ret16 & 0xff);
  return rv;
}
