/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "PartiallySeekableInputStream.h"
#include "mozilla/ipc/InputStreamUtils.h"
#include "nsISeekableStream.h"
#include "nsStreamUtils.h"

namespace mozilla {
namespace net {

NS_IMPL_ADDREF(PartiallySeekableInputStream);
NS_IMPL_RELEASE(PartiallySeekableInputStream);

NS_INTERFACE_MAP_BEGIN(PartiallySeekableInputStream)
  NS_INTERFACE_MAP_ENTRY(nsIInputStream)
  NS_INTERFACE_MAP_ENTRY(nsISeekableStream)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsICloneableInputStream,
                                     mWeakCloneableInputStream)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIIPCSerializableInputStream,
                                     mWeakIPCSerializableInputStream)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIAsyncInputStream,
                                     mWeakAsyncInputStream)
  NS_INTERFACE_MAP_ENTRY_CONDITIONAL(nsIInputStreamCallback,
                                     mWeakAsyncInputStream)
  NS_INTERFACE_MAP_ENTRY_AMBIGUOUS(nsISupports, nsIInputStream)
NS_INTERFACE_MAP_END

PartiallySeekableInputStream::PartiallySeekableInputStream(already_AddRefed<nsIInputStream> aInputStream,
                                                           uint64_t aBufferSize)
  : mInputStream(std::move(aInputStream))
  , mWeakCloneableInputStream(nullptr)
  , mWeakIPCSerializableInputStream(nullptr)
  , mWeakAsyncInputStream(nullptr)
  , mBufferSize(aBufferSize)
  , mPos(0)
  , mClosed(false)
{
  Init();
}

PartiallySeekableInputStream::PartiallySeekableInputStream(already_AddRefed<nsIInputStream> aClonedBaseStream,
                                                           PartiallySeekableInputStream* aClonedFrom)
  : mInputStream(std::move(aClonedBaseStream))
  , mWeakCloneableInputStream(nullptr)
  , mWeakIPCSerializableInputStream(nullptr)
  , mWeakAsyncInputStream(nullptr)
  , mCachedBuffer(aClonedFrom->mCachedBuffer)
  , mBufferSize(aClonedFrom->mBufferSize)
  , mPos(aClonedFrom->mPos)
  , mClosed(aClonedFrom->mClosed)
{
  Init();
}

void
PartiallySeekableInputStream::Init()
{
  MOZ_ASSERT(mInputStream);

#ifdef DEBUG
  nsCOMPtr<nsISeekableStream> seekableStream = do_QueryInterface(mInputStream);
  MOZ_ASSERT(!seekableStream);
#endif

  nsCOMPtr<nsICloneableInputStream> cloneableStream =
    do_QueryInterface(mInputStream);
  if (cloneableStream && SameCOMIdentity(mInputStream, cloneableStream)) {
    mWeakCloneableInputStream = cloneableStream;
  }

  nsCOMPtr<nsIIPCSerializableInputStream> serializableStream =
    do_QueryInterface(mInputStream);
  if (serializableStream &&
      SameCOMIdentity(mInputStream, serializableStream)) {
    mWeakIPCSerializableInputStream = serializableStream;
  }

  nsCOMPtr<nsIAsyncInputStream> asyncInputStream =
    do_QueryInterface(mInputStream);
  if (asyncInputStream && SameCOMIdentity(mInputStream, asyncInputStream)) {
    mWeakAsyncInputStream = asyncInputStream;
  }
}

NS_IMETHODIMP
PartiallySeekableInputStream::Close()
{
  mInputStream->Close();
  mCachedBuffer.Clear();
  mPos = 0;
  mClosed = true;
  return NS_OK;
}

// nsIInputStream interface

NS_IMETHODIMP
PartiallySeekableInputStream::Available(uint64_t* aLength)
{
  if (mClosed) {
    return NS_BASE_STREAM_CLOSED;
  }

  nsresult rv = mInputStream->Available(aLength);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  if (mPos < mCachedBuffer.Length()) {
    *aLength += mCachedBuffer.Length() - mPos;
  }

  return NS_OK;
}

NS_IMETHODIMP
PartiallySeekableInputStream::Read(char* aBuffer, uint32_t aCount,
                                   uint32_t* aReadCount)
{
  *aReadCount = 0;

  if (mClosed) {
    return NS_OK;
  }

  uint32_t byteRead = 0;

  if (mPos < mCachedBuffer.Length()) {
    // We are reading from the cached buffer.
    byteRead = XPCOM_MIN(mCachedBuffer.Length() - mPos, (uint64_t)aCount);
    memcpy(aBuffer, mCachedBuffer.Elements() + mPos, byteRead);
    *aReadCount = byteRead;
    mPos += byteRead;
  }

  if (byteRead < aCount) {
    MOZ_ASSERT(mPos >= mCachedBuffer.Length());
    MOZ_ASSERT_IF(mPos > mCachedBuffer.Length(),
                  mCachedBuffer.Length() == mBufferSize);

    // We can read from the stream.
    uint32_t byteWritten;
    nsresult rv = mInputStream->Read(aBuffer + byteRead, aCount - byteRead,
                                     &byteWritten);
    if (NS_WARN_IF(NS_FAILED(rv)) || byteWritten == 0) {
      return rv;
    }

    *aReadCount += byteWritten;

    // Maybe we have to cache something.
    if (mPos < mBufferSize) {
      uint32_t size = XPCOM_MIN(mPos + byteWritten, mBufferSize);
      mCachedBuffer.SetLength(size);
      memcpy(mCachedBuffer.Elements() + mPos, aBuffer + byteRead, size - mPos);
    }

    mPos += byteWritten;
  }

  return NS_OK;
}

NS_IMETHODIMP
PartiallySeekableInputStream::ReadSegments(nsWriteSegmentFun aWriter, void* aClosure,
                                           uint32_t aCount, uint32_t *aResult)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
PartiallySeekableInputStream::IsNonBlocking(bool* aNonBlocking)
{
  return mInputStream->IsNonBlocking(aNonBlocking);
}

// nsICloneableInputStream interface

NS_IMETHODIMP
PartiallySeekableInputStream::GetCloneable(bool* aCloneable)
{
  NS_ENSURE_STATE(mWeakCloneableInputStream);

  return mWeakCloneableInputStream->GetCloneable(aCloneable);
}

NS_IMETHODIMP
PartiallySeekableInputStream::Clone(nsIInputStream** aResult)
{
  NS_ENSURE_STATE(mWeakCloneableInputStream);

  nsCOMPtr<nsIInputStream> clonedStream;
  nsresult rv = mWeakCloneableInputStream->Clone(getter_AddRefs(clonedStream));
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return rv;
  }

  nsCOMPtr<nsIInputStream> stream =
    new PartiallySeekableInputStream(clonedStream.forget(), this);

  stream.forget(aResult);
  return NS_OK;
}

// nsIAsyncInputStream interface

NS_IMETHODIMP
PartiallySeekableInputStream::CloseWithStatus(nsresult aStatus)
{
  NS_ENSURE_STATE(mWeakAsyncInputStream);

  return mWeakAsyncInputStream->CloseWithStatus(aStatus);
}

NS_IMETHODIMP
PartiallySeekableInputStream::AsyncWait(nsIInputStreamCallback* aCallback,
                                        uint32_t aFlags,
                                        uint32_t aRequestedCount,
                                        nsIEventTarget* aEventTarget)
{
  if (mClosed) {
    return NS_BASE_STREAM_CLOSED;
  }

  NS_ENSURE_STATE(mWeakAsyncInputStream);

  if (mAsyncWaitCallback && aCallback) {
    return NS_ERROR_FAILURE;
  }

  mAsyncWaitCallback = aCallback;

  if (!mAsyncWaitCallback) {
    return NS_OK;
  }

  return mWeakAsyncInputStream->AsyncWait(this, aFlags, aRequestedCount,
                                          aEventTarget);
}

// nsIInputStreamCallback

NS_IMETHODIMP
PartiallySeekableInputStream::OnInputStreamReady(nsIAsyncInputStream* aStream)
{
  MOZ_ASSERT(mWeakAsyncInputStream);
  MOZ_ASSERT(mWeakAsyncInputStream == aStream);

  // We have been canceled in the meanwhile.
  if (!mAsyncWaitCallback) {
    return NS_OK;
  }

  nsCOMPtr<nsIInputStreamCallback> callback = mAsyncWaitCallback;

  mAsyncWaitCallback = nullptr;

  return callback->OnInputStreamReady(this);
}

// nsIIPCSerializableInputStream

void
PartiallySeekableInputStream::Serialize(mozilla::ipc::InputStreamParams& aParams,
                                        FileDescriptorArray& aFileDescriptors)
{
  MOZ_ASSERT(mWeakIPCSerializableInputStream);
  MOZ_DIAGNOSTIC_ASSERT(mCachedBuffer.IsEmpty());
  mozilla::ipc::InputStreamHelper::SerializeInputStream(mInputStream, aParams,
                                                        aFileDescriptors);
}

bool
PartiallySeekableInputStream::Deserialize(const mozilla::ipc::InputStreamParams& aParams,
                                          const FileDescriptorArray& aFileDescriptors)
{
  MOZ_CRASH("This method should never be called!");
  return false;
}

mozilla::Maybe<uint64_t>
PartiallySeekableInputStream::ExpectedSerializedLength()
{
  if (!mWeakIPCSerializableInputStream) {
    return mozilla::Nothing();
  }

  return mWeakIPCSerializableInputStream->ExpectedSerializedLength();
}

// nsISeekableStream

NS_IMETHODIMP
PartiallySeekableInputStream::Seek(int32_t aWhence, int64_t aOffset)
{
  if (mClosed) {
    return NS_BASE_STREAM_CLOSED;
  }

  int64_t offset;

  switch (aWhence) {
    case NS_SEEK_SET:
      offset = aOffset;
      break;
    case NS_SEEK_CUR:
      offset = mPos + aOffset;
      break;
    case NS_SEEK_END: {
      return NS_ERROR_NOT_IMPLEMENTED;
    }
    default:
      return NS_ERROR_ILLEGAL_VALUE;
  }

  if (offset < 0) {
    return NS_ERROR_ILLEGAL_VALUE;
  }

  if ((uint64_t)offset >= mCachedBuffer.Length() || mPos > mBufferSize) {
    return NS_ERROR_NOT_IMPLEMENTED;
  }

  mPos = offset;
  return NS_OK;
}

NS_IMETHODIMP
PartiallySeekableInputStream::Tell(int64_t *aResult)
{
  if (mClosed) {
    return NS_BASE_STREAM_CLOSED;
  }

  *aResult = mPos;
  return NS_OK;
}

NS_IMETHODIMP
PartiallySeekableInputStream::SetEOF()
{
  return Close();
}

} // net namespace
} // mozilla namespace
