/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: NPL 1.1/GPL 2.0/LGPL 2.1
 *
 * 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 the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
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#include "nsBasicStreamGenerator.h"
#include "nsCRT.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) {
}

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 = do_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.IsEmpty()) {
    /* 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;
    nsMemory::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;
}
