/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim:set ts=2 sw=2 sts=2 et cindent: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "SimpleBuffer.h"

#include <algorithm>

namespace mozilla {

namespace net {

SimpleBuffer::SimpleBuffer()

  : mStatus(NS_OK)

  , mAvailable(0)

{

}

nsresult SimpleBuffer::Write(char *src, size_t len)

{

  NS_ASSERT_OWNINGTHREAD(SimpleBuffer);

  if (NS_FAILED(mStatus)) {

    return mStatus;

  }

  while (len > 0) {

    SimpleBufferPage *p = mBufferList.getLast();

    if (p && (p->mWriteOffset == SimpleBufferPage::kSimpleBufferPageSize)) {

      // no room.. make a new page

      p = nullptr;

    }

    if (!p) {

      p = new (fallible) SimpleBufferPage();

      if (!p) {

        mStatus = NS_ERROR_OUT_OF_MEMORY;

        return mStatus;

      }

      mBufferList.insertBack(p);

    }

    size_t roomOnPage = SimpleBufferPage::kSimpleBufferPageSize - p->mWriteOffset;

    size_t toWrite = std::min(roomOnPage, len);

    memcpy(p->mBuffer + p->mWriteOffset, src, toWrite);

    src += toWrite;

    len -= toWrite;

    p->mWriteOffset += toWrite;

    mAvailable += toWrite;

  }

  return NS_OK;

}

size_t SimpleBuffer::Read(char *dest, size_t maxLen)

{

  NS_ASSERT_OWNINGTHREAD(SimpleBuffer);

  if (NS_FAILED(mStatus)) {

    return 0;

  }

  size_t rv = 0;

  for (SimpleBufferPage *p = mBufferList.getFirst();

       p && (rv < maxLen); p = mBufferList.getFirst()) {

    size_t avail = p->mWriteOffset - p->mReadOffset;

    size_t toRead = std::min(avail, (maxLen - rv));

    memcpy(dest + rv, p->mBuffer + p->mReadOffset, toRead);

    rv += toRead;

    p->mReadOffset += toRead;

    if (p->mReadOffset == p->mWriteOffset) {

      p->remove();

      delete p;

    }

  }

  MOZ_ASSERT(mAvailable >= rv);

  mAvailable -= rv;

  return rv;

}

size_t SimpleBuffer::Available()

{

  NS_ASSERT_OWNINGTHREAD(SimpleBuffer);

  return NS_SUCCEEDED(mStatus) ? mAvailable : 0;

}

void SimpleBuffer::Clear()

{

  NS_ASSERT_OWNINGTHREAD(SimpleBuffer);

  SimpleBufferPage *p;

  while ((p = mBufferList.popFirst())) {

    delete p;

  }

  mAvailable = 0;

}

} // namespace net

} // namespace mozilla