/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "IpcResourceUpdateQueue.h"
#include <string.h>
#include <algorithm>
#include "mozilla/Maybe.h"
#include "mozilla/ipc/SharedMemory.h"
#include "mozilla/layers/PTextureChild.h"
#include "mozilla/layers/WebRenderBridgeChild.h"

namespace mozilla {
namespace wr {

using namespace mozilla::layers;

ShmSegmentsWriter::ShmSegmentsWriter(layers::WebRenderBridgeChild* aAllocator,
                                     size_t aChunkSize)
    : mShmAllocator(aAllocator), mCursor(0), mChunkSize(aChunkSize) {
  MOZ_ASSERT(mShmAllocator);
}

ShmSegmentsWriter::~ShmSegmentsWriter() { Clear(); }

ShmSegmentsWriter::ShmSegmentsWriter(ShmSegmentsWriter&& aOther) noexcept
    : mSmallAllocs(std::move(aOther.mSmallAllocs)),
      mLargeAllocs(std::move(aOther.mLargeAllocs)),
      mShmAllocator(aOther.mShmAllocator),
      mCursor(aOther.mCursor),
      mChunkSize(aOther.mChunkSize) {
  aOther.mCursor = 0;
}

ShmSegmentsWriter& ShmSegmentsWriter::operator=(
    ShmSegmentsWriter&& aOther) noexcept {
  MOZ_ASSERT(IsEmpty(), "Will forget existing updates!");
  Clear();
  mSmallAllocs = std::move(aOther.mSmallAllocs);
  mLargeAllocs = std::move(aOther.mLargeAllocs);
  mShmAllocator = aOther.mShmAllocator;
  mCursor = aOther.mCursor;
  mChunkSize = aOther.mChunkSize;
  aOther.mCursor = 0;
  return *this;
}

layers::OffsetRange ShmSegmentsWriter::Write(Range<uint8_t> aBytes) {
  const size_t start = mCursor;
  const size_t length = aBytes.length();

  if (length >= mChunkSize * 4) {
    auto range = AllocLargeChunk(length);
    if (range.length()) {
      // Allocation was successful
      uint8_t* dstPtr = mLargeAllocs.LastElement().get<uint8_t>();
      memcpy(dstPtr, aBytes.begin().get(), length);
    }
    return range;
  }

  int remainingBytesToCopy = length;

  size_t srcCursor = 0;
  size_t dstCursor = mCursor;
  size_t currAllocLen = mSmallAllocs.Length();

  while (remainingBytesToCopy > 0) {
    if (dstCursor >= mSmallAllocs.Length() * mChunkSize) {
      if (!AllocChunk()) {
        // Allocation failed, so roll back to the state at the start of this
        // Write() call and abort.
        while (mSmallAllocs.Length() > currAllocLen) {
          RefCountedShmem shm = mSmallAllocs.PopLastElement();
          RefCountedShm::Dealloc(mShmAllocator, shm);
        }
        MOZ_ASSERT(mSmallAllocs.Length() == currAllocLen);
        return layers::OffsetRange(0, start, 0);
      }
      // Allocation succeeded, so dstCursor should now be pointing to
      // something inside the allocation buffer
      MOZ_ASSERT(dstCursor < (mSmallAllocs.Length() * mChunkSize));
    }

    const size_t dstMaxOffset = mChunkSize * mSmallAllocs.Length();
    const size_t dstBaseOffset = mChunkSize * (mSmallAllocs.Length() - 1);

    MOZ_ASSERT(dstCursor >= dstBaseOffset);
    MOZ_ASSERT(dstCursor <= dstMaxOffset);

    size_t availableRange = dstMaxOffset - dstCursor;
    size_t copyRange = std::min<int>(availableRange, remainingBytesToCopy);

    uint8_t* srcPtr = &aBytes[srcCursor];
    uint8_t* dstPtr = RefCountedShm::GetBytes(mSmallAllocs.LastElement()) +
                      (dstCursor - dstBaseOffset);

    memcpy(dstPtr, srcPtr, copyRange);

    srcCursor += copyRange;
    dstCursor += copyRange;
    remainingBytesToCopy -= copyRange;

    // sanity check
    MOZ_ASSERT(remainingBytesToCopy >= 0);
  }

  mCursor += length;

  return layers::OffsetRange(0, start, length);
}

bool ShmSegmentsWriter::AllocChunk() {
  RefCountedShmem shm;
  if (!mShmAllocator->AllocResourceShmem(mChunkSize, shm)) {
    gfxCriticalNote << "ShmSegmentsWriter failed to allocate chunk #"
                    << mSmallAllocs.Length();
    MOZ_ASSERT(false, "ShmSegmentsWriter fails to allocate chunk");
    return false;
  }
  RefCountedShm::AddRef(shm);
  mSmallAllocs.AppendElement(shm);
  return true;
}

layers::OffsetRange ShmSegmentsWriter::AllocLargeChunk(size_t aSize) {
  ipc::Shmem shm;
  if (!mShmAllocator->AllocShmem(aSize, &shm)) {
    gfxCriticalNote
        << "ShmSegmentsWriter failed to allocate large chunk of size " << aSize;
    MOZ_ASSERT(false, "ShmSegmentsWriter fails to allocate large chunk");
    return layers::OffsetRange(0, 0, 0);
  }
  mLargeAllocs.AppendElement(shm);

  return layers::OffsetRange(mLargeAllocs.Length(), 0, aSize);
}

void ShmSegmentsWriter::Flush(nsTArray<RefCountedShmem>& aSmallAllocs,
                              nsTArray<ipc::Shmem>& aLargeAllocs) {
  MOZ_ASSERT(aSmallAllocs.IsEmpty());
  MOZ_ASSERT(aLargeAllocs.IsEmpty());
  aSmallAllocs = std::move(mSmallAllocs);
  aLargeAllocs = std::move(mLargeAllocs);
  mCursor = 0;
}

bool ShmSegmentsWriter::IsEmpty() const { return mCursor == 0; }

void ShmSegmentsWriter::Clear() {
  if (mShmAllocator) {
    IpcResourceUpdateQueue::ReleaseShmems(mShmAllocator, mSmallAllocs);
    IpcResourceUpdateQueue::ReleaseShmems(mShmAllocator, mLargeAllocs);
  }
  mCursor = 0;
}

ShmSegmentsReader::ShmSegmentsReader(
    const nsTArray<RefCountedShmem>& aSmallShmems,
    const nsTArray<ipc::Shmem>& aLargeShmems)
    : mSmallAllocs(aSmallShmems), mLargeAllocs(aLargeShmems), mChunkSize(0) {
  if (mSmallAllocs.IsEmpty()) {
    return;
  }

  mChunkSize = RefCountedShm::GetSize(mSmallAllocs[0]);

  // Check that all shmems are readable and have the same size. If anything
  // isn't right, set mChunkSize to zero which signifies that the reader is
  // in an invalid state and Read calls will return false;
  for (const auto& shm : mSmallAllocs) {
    if (!RefCountedShm::IsValid(shm) ||
        RefCountedShm::GetSize(shm) != mChunkSize ||
        RefCountedShm::GetBytes(shm) == nullptr) {
      mChunkSize = 0;
      return;
    }
  }

  for (const auto& shm : mLargeAllocs) {
    if (!shm.IsReadable() || shm.get<uint8_t>() == nullptr) {
      mChunkSize = 0;
      return;
    }
  }
}

bool ShmSegmentsReader::ReadLarge(const layers::OffsetRange& aRange,
                                  wr::Vec<uint8_t>& aInto) {
  // source = zero is for small allocs.
  MOZ_RELEASE_ASSERT(aRange.source() != 0);
  if (aRange.source() > mLargeAllocs.Length()) {
    return false;
  }
  size_t id = aRange.source() - 1;
  const ipc::Shmem& shm = mLargeAllocs[id];
  if (shm.Size<uint8_t>() < aRange.length()) {
    return false;
  }

  uint8_t* srcPtr = shm.get<uint8_t>();
  aInto.PushBytes(Range<uint8_t>(srcPtr, aRange.length()));

  return true;
}

bool ShmSegmentsReader::Read(const layers::OffsetRange& aRange,
                             wr::Vec<uint8_t>& aInto) {
  if (aRange.length() == 0) {
    return true;
  }

  if (aRange.source() != 0) {
    return ReadLarge(aRange, aInto);
  }

  if (mChunkSize == 0) {
    return false;
  }

  if (aRange.start() + aRange.length() > mChunkSize * mSmallAllocs.Length()) {
    return false;
  }

  size_t initialLength = aInto.Length();

  size_t srcCursor = aRange.start();
  size_t remainingBytesToCopy = aRange.length();
  while (remainingBytesToCopy > 0) {
    const size_t shm_idx = srcCursor / mChunkSize;
    const size_t ptrOffset = srcCursor % mChunkSize;
    const size_t copyRange =
        std::min(remainingBytesToCopy, mChunkSize - ptrOffset);
    uint8_t* srcPtr =
        RefCountedShm::GetBytes(mSmallAllocs[shm_idx]) + ptrOffset;

    aInto.PushBytes(Range<uint8_t>(srcPtr, copyRange));

    srcCursor += copyRange;
    remainingBytesToCopy -= copyRange;
  }

  return aInto.Length() - initialLength == aRange.length();
}

Maybe<Range<uint8_t>> ShmSegmentsReader::GetReadPointerLarge(
    const layers::OffsetRange& aRange) {
  // source = zero is for small allocs.
  MOZ_RELEASE_ASSERT(aRange.source() != 0);
  if (aRange.source() > mLargeAllocs.Length()) {
    return Nothing();
  }
  size_t id = aRange.source() - 1;
  const ipc::Shmem& shm = mLargeAllocs[id];
  if (shm.Size<uint8_t>() < aRange.length()) {
    return Nothing();
  }

  uint8_t* srcPtr = shm.get<uint8_t>();
  return Some(Range<uint8_t>(srcPtr, aRange.length()));
}

Maybe<Range<uint8_t>> ShmSegmentsReader::GetReadPointer(
    const layers::OffsetRange& aRange) {
  if (aRange.length() == 0) {
    return Some(Range<uint8_t>());
  }

  if (aRange.source() != 0) {
    return GetReadPointerLarge(aRange);
  }

  if (mChunkSize == 0 ||
      aRange.start() + aRange.length() > mChunkSize * mSmallAllocs.Length()) {
    return Nothing();
  }

  size_t srcCursor = aRange.start();
  size_t remainingBytesToCopy = aRange.length();
  const size_t shm_idx = srcCursor / mChunkSize;
  const size_t ptrOffset = srcCursor % mChunkSize;
  // Return nothing if we can't return a pointer to the full range
  if (mChunkSize - ptrOffset < remainingBytesToCopy) {
    return Nothing();
  }
  uint8_t* srcPtr = RefCountedShm::GetBytes(mSmallAllocs[shm_idx]) + ptrOffset;
  return Some(Range<uint8_t>(srcPtr, remainingBytesToCopy));
}

IpcResourceUpdateQueue::IpcResourceUpdateQueue(
    layers::WebRenderBridgeChild* aAllocator, size_t aChunkSize)
    : mWriter(aAllocator, aChunkSize) {}

IpcResourceUpdateQueue::IpcResourceUpdateQueue(
    IpcResourceUpdateQueue&& aOther) noexcept
    : mWriter(std::move(aOther.mWriter)),
      mUpdates(std::move(aOther.mUpdates)) {}

IpcResourceUpdateQueue& IpcResourceUpdateQueue::operator=(
    IpcResourceUpdateQueue&& aOther) noexcept {
  MOZ_ASSERT(IsEmpty(), "Will forget existing updates!");
  mWriter = std::move(aOther.mWriter);
  mUpdates = std::move(aOther.mUpdates);
  return *this;
}

void IpcResourceUpdateQueue::ReplaceResources(IpcResourceUpdateQueue&& aOther) {
  MOZ_ASSERT(IsEmpty(), "Will forget existing updates!");
  mWriter = std::move(aOther.mWriter);
  mUpdates = std::move(aOther.mUpdates);
}

bool IpcResourceUpdateQueue::AddImage(ImageKey key,
                                      const ImageDescriptor& aDescriptor,
                                      Range<uint8_t> aBytes) {
  auto bytes = mWriter.Write(aBytes);
  if (!bytes.length()) {
    return false;
  }
  mUpdates.AppendElement(layers::OpAddImage(aDescriptor, bytes, 0, key));
  return true;
}

bool IpcResourceUpdateQueue::AddBlobImage(BlobImageKey key,
                                          const ImageDescriptor& aDescriptor,
                                          Range<uint8_t> aBytes,
                                          ImageIntRect aVisibleRect) {
  MOZ_RELEASE_ASSERT(aDescriptor.width > 0 && aDescriptor.height > 0);
  auto bytes = mWriter.Write(aBytes);
  if (!bytes.length()) {
    return false;
  }
  mUpdates.AppendElement(
      layers::OpAddBlobImage(aDescriptor, bytes, aVisibleRect, 0, key));
  return true;
}

void IpcResourceUpdateQueue::AddSharedExternalImage(wr::ExternalImageId aExtId,
                                                    wr::ImageKey aKey) {
  mUpdates.AppendElement(layers::OpAddSharedExternalImage(aExtId, aKey));
}

void IpcResourceUpdateQueue::PushExternalImageForTexture(
    wr::ExternalImageId aExtId, wr::ImageKey aKey,
    layers::TextureClient* aTexture, bool aIsUpdate) {
  MOZ_ASSERT(aTexture);
  MOZ_ASSERT(aTexture->GetIPDLActor());
  MOZ_RELEASE_ASSERT(aTexture->GetIPDLActor()->GetIPCChannel() ==
                     mWriter.WrBridge()->GetIPCChannel());
  mUpdates.AppendElement(layers::OpPushExternalImageForTexture(
      aExtId, aKey, nullptr, aTexture->GetIPDLActor(), aIsUpdate));
}

bool IpcResourceUpdateQueue::UpdateImageBuffer(
    ImageKey aKey, const ImageDescriptor& aDescriptor, Range<uint8_t> aBytes) {
  auto bytes = mWriter.Write(aBytes);
  if (!bytes.length()) {
    return false;
  }
  mUpdates.AppendElement(layers::OpUpdateImage(aDescriptor, bytes, aKey));
  return true;
}

bool IpcResourceUpdateQueue::UpdateBlobImage(BlobImageKey aKey,
                                             const ImageDescriptor& aDescriptor,
                                             Range<uint8_t> aBytes,
                                             ImageIntRect aVisibleRect,
                                             ImageIntRect aDirtyRect) {
  MOZ_ASSERT(aVisibleRect.width > 0 && aVisibleRect.height > 0);

  auto bytes = mWriter.Write(aBytes);
  if (!bytes.length()) {
    return false;
  }
  mUpdates.AppendElement(layers::OpUpdateBlobImage(aDescriptor, bytes, aKey,
                                                   aVisibleRect, aDirtyRect));
  return true;
}

void IpcResourceUpdateQueue::UpdateSharedExternalImage(
    wr::ExternalImageId aExtId, wr::ImageKey aKey, ImageIntRect aDirtyRect) {
  mUpdates.AppendElement(
      layers::OpUpdateSharedExternalImage(aExtId, aKey, aDirtyRect));
}

void IpcResourceUpdateQueue::SetBlobImageVisibleArea(
    wr::BlobImageKey aKey, const ImageIntRect& aArea) {
  mUpdates.AppendElement(layers::OpSetBlobImageVisibleArea(aArea, aKey));
}

void IpcResourceUpdateQueue::DeleteImage(ImageKey aKey) {
  mUpdates.AppendElement(layers::OpDeleteImage(aKey));
}

void IpcResourceUpdateQueue::DeleteBlobImage(BlobImageKey aKey) {
  mUpdates.AppendElement(layers::OpDeleteBlobImage(aKey));
}

bool IpcResourceUpdateQueue::AddRawFont(wr::FontKey aKey, Range<uint8_t> aBytes,
                                        uint32_t aIndex) {
  auto bytes = mWriter.Write(aBytes);
  if (!bytes.length()) {
    return false;
  }
  mUpdates.AppendElement(layers::OpAddRawFont(bytes, aIndex, aKey));
  return true;
}

bool IpcResourceUpdateQueue::AddFontDescriptor(wr::FontKey aKey,
                                               Range<uint8_t> aBytes,
                                               uint32_t aIndex) {
  auto bytes = mWriter.Write(aBytes);
  if (!bytes.length()) {
    return false;
  }
  mUpdates.AppendElement(layers::OpAddFontDescriptor(bytes, aIndex, aKey));
  return true;
}

void IpcResourceUpdateQueue::DeleteFont(wr::FontKey aKey) {
  mUpdates.AppendElement(layers::OpDeleteFont(aKey));
}

void IpcResourceUpdateQueue::AddFontInstance(
    wr::FontInstanceKey aKey, wr::FontKey aFontKey, float aGlyphSize,
    const wr::FontInstanceOptions* aOptions,
    const wr::FontInstancePlatformOptions* aPlatformOptions,
    Range<const gfx::FontVariation> aVariations) {
  auto bytes = mWriter.WriteAsBytes(aVariations);
  mUpdates.AppendElement(layers::OpAddFontInstance(
      aOptions ? Some(*aOptions) : Nothing(),
      aPlatformOptions ? Some(*aPlatformOptions) : Nothing(), bytes, aKey,
      aFontKey, aGlyphSize));
}

void IpcResourceUpdateQueue::DeleteFontInstance(wr::FontInstanceKey aKey) {
  mUpdates.AppendElement(layers::OpDeleteFontInstance(aKey));
}

void IpcResourceUpdateQueue::Flush(
    nsTArray<layers::OpUpdateResource>& aUpdates,
    nsTArray<layers::RefCountedShmem>& aSmallAllocs,
    nsTArray<ipc::Shmem>& aLargeAllocs) {
  aUpdates = std::move(mUpdates);
  mWriter.Flush(aSmallAllocs, aLargeAllocs);
}

bool IpcResourceUpdateQueue::IsEmpty() const {
  if (mUpdates.Length() == 0) {
    MOZ_ASSERT(mWriter.IsEmpty());
    return true;
  }
  return false;
}

void IpcResourceUpdateQueue::Clear() {
  mWriter.Clear();
  mUpdates.Clear();
}

// static
void IpcResourceUpdateQueue::ReleaseShmems(
    ipc::IProtocol* aShmAllocator, nsTArray<layers::RefCountedShmem>& aShms) {
  for (auto& shm : aShms) {
    if (RefCountedShm::IsValid(shm) && RefCountedShm::Release(shm) == 0) {
      RefCountedShm::Dealloc(aShmAllocator, shm);
    }
  }
  aShms.Clear();
}

// static
void IpcResourceUpdateQueue::ReleaseShmems(ipc::IProtocol* aShmAllocator,
                                           nsTArray<ipc::Shmem>& aShms) {
  for (auto& shm : aShms) {
    aShmAllocator->DeallocShmem(shm);
  }
  aShms.Clear();
}

}  // namespace wr
}  // namespace mozilla