// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/filters/fuchsia/fuchsia_video_decoder.h"

#include <fuchsia/mediacodec/cpp/fidl.h>
#include <lib/sys/cpp/component_context.h>
#include <vulkan/vulkan.h>

#include "base/bind.h"
#include "base/bits.h"
#include "base/callback_helpers.h"
#include "base/command_line.h"
#include "base/fuchsia/fuchsia_logging.h"
#include "base/fuchsia/process_context.h"
#include "base/location.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/process/process_metrics.h"
#include "base/threading/sequenced_task_runner_handle.h"
#include "components/viz/common/gpu/raster_context_provider.h"
#include "gpu/command_buffer/client/context_support.h"
#include "gpu/command_buffer/client/shared_image_interface.h"
#include "gpu/command_buffer/common/shared_image_usage.h"
#include "gpu/ipc/common/gpu_memory_buffer_impl_native_pixmap.h"
#include "media/base/bind_to_current_loop.h"
#include "media/base/cdm_context.h"
#include "media/base/media_switches.h"
#include "media/base/video_aspect_ratio.h"
#include "media/base/video_frame.h"
#include "media/base/video_util.h"
#include "media/fuchsia/cdm/fuchsia_cdm_context.h"
#include "media/fuchsia/cdm/fuchsia_decryptor.h"
#include "media/fuchsia/cdm/fuchsia_stream_decryptor.h"
#include "media/fuchsia/common/decrypting_sysmem_buffer_stream.h"
#include "media/fuchsia/common/passthrough_sysmem_buffer_stream.h"
#include "media/fuchsia/common/stream_processor_helper.h"
#include "third_party/libyuv/include/libyuv/video_common.h"
#include "ui/gfx/buffer_types.h"
#include "ui/gfx/client_native_pixmap_factory.h"
#include "ui/ozone/public/client_native_pixmap_factory_ozone.h"

namespace media {

namespace {

// Number of output buffers allocated "for camping". This value is passed to
// sysmem to ensure that we get one output buffer for the frame currently
// displayed on the screen.
constexpr uint32_t kOutputBuffersForCamping = 1;

// Maximum number of frames we expect to have queued up while playing video.
// Higher values require more memory for output buffers. Lower values make it
// more likely that renderer will stall because decoded frames are not available
// on time.
constexpr uint32_t kMaxUsedOutputBuffers = 5;

// Use 2 buffers for decoder input. Allocating more than one buffers ensures
// that when the decoder is done working on one packet it will have another one
// waiting in the queue. Limiting number of buffers to 2 allows to minimize
// required memory, without significant effect on performance.
constexpr size_t kNumInputBuffers = 2;

// Some codecs do not support splitting video frames across multiple input
// buffers, so the buffers need to be large enough to fit all video frames. The
// buffer size is calculated to fit 1080p I420 frame with MinCR=2 (per H264
// spec), plus 128KiB for SEI/SPS/PPS. (note that the same size is used for all
// codecs, not just H264).
constexpr size_t kInputBufferSize = 1920 * 1080 * 3 / 2 / 2 + 128 * 1024;

}  // namespace

// Helper used to hold mailboxes for the output textures. OutputMailbox may
// outlive FuchsiaVideoDecoder if is referenced by a VideoFrame.
class FuchsiaVideoDecoder::OutputMailbox {
 public:
  OutputMailbox(
      scoped_refptr<viz::RasterContextProvider> raster_context_provider,
      std::unique_ptr<gfx::GpuMemoryBuffer> gmb)
      : raster_context_provider_(raster_context_provider), weak_factory_(this) {
    uint32_t usage = gpu::SHARED_IMAGE_USAGE_DISPLAY |
                     gpu::SHARED_IMAGE_USAGE_SCANOUT |
                     gpu::SHARED_IMAGE_USAGE_VIDEO_DECODE;
    mailbox_ =
        raster_context_provider_->SharedImageInterface()->CreateSharedImage(
            gmb.get(), nullptr, gfx::ColorSpace(), kTopLeft_GrSurfaceOrigin,
            kPremul_SkAlphaType, usage);
  }

  OutputMailbox(const OutputMailbox&) = delete;
  OutputMailbox& operator=(const OutputMailbox&) = delete;

  ~OutputMailbox() {
    raster_context_provider_->SharedImageInterface()->DestroySharedImage(
        sync_token_, mailbox_);
  }

  const gpu::Mailbox& mailbox() { return mailbox_; }

  // Create a new video frame that wraps the mailbox. |reuse_callback| will be
  // called when the mailbox can be reused.
  scoped_refptr<VideoFrame> CreateFrame(VideoPixelFormat pixel_format,
                                        const gfx::Size& coded_size,
                                        const gfx::Rect& visible_rect,
                                        const gfx::Size& natural_size,
                                        base::TimeDelta timestamp,
                                        base::OnceClosure reuse_callback) {
    DCHECK(!is_used_);
    is_used_ = true;
    reuse_callback_ = std::move(reuse_callback);

    gpu::MailboxHolder mailboxes[VideoFrame::kMaxPlanes];
    mailboxes[0].mailbox = mailbox_;
    mailboxes[0].sync_token = raster_context_provider_->SharedImageInterface()
                                  ->GenUnverifiedSyncToken();

    auto frame = VideoFrame::WrapNativeTextures(
        pixel_format, mailboxes,
        BindToCurrentLoop(base::BindOnce(&OutputMailbox::OnFrameDestroyed,
                                         base::Unretained(this))),
        coded_size, visible_rect, natural_size, timestamp);

    // Request a fence we'll wait on before reusing the buffer.
    frame->metadata().read_lock_fences_enabled = true;

    return frame;
  }

  // Called by FuchsiaVideoDecoder when it no longer needs this mailbox.
  void Release() {
    if (is_used_) {
      // The mailbox is referenced by a VideoFrame. It will be deleted  as soon
      // as the frame is destroyed.
      DCHECK(reuse_callback_);
      reuse_callback_ = base::OnceClosure();
    } else {
      delete this;
    }
  }

 private:
  void OnFrameDestroyed(const gpu::SyncToken& sync_token) {
    DCHECK(is_used_);
    is_used_ = false;
    sync_token_ = sync_token;

    if (!reuse_callback_) {
      // If the mailbox cannot be reused then we can just delete it.
      delete this;
      return;
    }

    raster_context_provider_->ContextSupport()->SignalSyncToken(
        sync_token_,
        BindToCurrentLoop(base::BindOnce(&OutputMailbox::OnSyncTokenSignaled,
                                         weak_factory_.GetWeakPtr())));
  }

  void OnSyncTokenSignaled() {
    sync_token_.Clear();
    std::move(reuse_callback_).Run();
  }

  const scoped_refptr<viz::RasterContextProvider> raster_context_provider_;

  gpu::Mailbox mailbox_;
  gpu::SyncToken sync_token_;

  // Set to true when the mailbox is referenced by a video frame.
  bool is_used_ = false;

  base::OnceClosure reuse_callback_;

  base::WeakPtrFactory<OutputMailbox> weak_factory_;
};

// static
std::unique_ptr<VideoDecoder> FuchsiaVideoDecoder::Create(
    scoped_refptr<viz::RasterContextProvider> raster_context_provider) {
  return std::make_unique<FuchsiaVideoDecoder>(
      std::move(raster_context_provider),
      /*enable_sw_decoding=*/false);
}

// static
std::unique_ptr<VideoDecoder> FuchsiaVideoDecoder::CreateForTests(
    scoped_refptr<viz::RasterContextProvider> raster_context_provider,
    bool enable_sw_decoding) {
  return std::make_unique<FuchsiaVideoDecoder>(
      std::move(raster_context_provider), enable_sw_decoding);
}

FuchsiaVideoDecoder::FuchsiaVideoDecoder(
    scoped_refptr<viz::RasterContextProvider> raster_context_provider,
    bool enable_sw_decoding)
    : raster_context_provider_(raster_context_provider),
      enable_sw_decoding_(enable_sw_decoding),
      use_overlays_for_video_(base::CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kUseOverlaysForVideo)),
      sysmem_allocator_("CrFuchsiaVideoDecoder"),
      client_native_pixmap_factory_(
          ui::CreateClientNativePixmapFactoryOzone()) {
  DCHECK(raster_context_provider_);
  weak_this_ = weak_factory_.GetWeakPtr();
}

FuchsiaVideoDecoder::~FuchsiaVideoDecoder() {
  // Reset SysmemBufferStream to ensure it doesn't try to send new packets when
  // the |decoder_| is destroyed.
  sysmem_buffer_stream_.reset();
  decoder_.reset();

  // Release mailboxes used for output frames.
  ReleaseOutputBuffers();
}

bool FuchsiaVideoDecoder::IsPlatformDecoder() const {
  return true;
}

bool FuchsiaVideoDecoder::SupportsDecryption() const {
  return true;
}

VideoDecoderType FuchsiaVideoDecoder::GetDecoderType() const {
  return VideoDecoderType::kFuchsia;
}

void FuchsiaVideoDecoder::Initialize(const VideoDecoderConfig& config,
                                     bool low_delay,
                                     CdmContext* cdm_context,
                                     InitCB init_cb,
                                     const OutputCB& output_cb,
                                     const WaitingCB& waiting_cb) {
  DCHECK(output_cb);
  DCHECK(waiting_cb);
  DCHECK(decode_callbacks_.empty());

  auto done_callback = BindToCurrentLoop(std::move(init_cb));

  // There should be no pending decode request, so DropInputQueue() is not
  // expected to fail.
  bool result = DropInputQueue(DecodeStatus::ABORTED);
  DCHECK(result);

  output_cb_ = output_cb;
  waiting_cb_ = waiting_cb;
  container_aspect_ratio_ = config.aspect_ratio();

  // Keep decoder and decryptor if the configuration hasn't changed.
  if (decoder_ && current_config_.codec() == config.codec() &&
      current_config_.is_encrypted() == config.is_encrypted()) {
    std::move(done_callback).Run(OkStatus());
    return;
  }

  sysmem_buffer_stream_.reset();
  decoder_.reset();

  // Initialize the stream.
  bool secure_mode = false;
  StatusCode status = InitializeSysmemBufferStream(config.is_encrypted(),
                                                   cdm_context, &secure_mode);
  if (status != StatusCode::kOk) {
    std::move(done_callback).Run(StatusCode::kOk);
    return;
  }

  // Reset output buffers since we won't be able to re-use them.
  ReleaseOutputBuffers();

  fuchsia::mediacodec::CreateDecoder_Params decoder_params;
  decoder_params.mutable_input_details()->set_format_details_version_ordinal(0);

  switch (config.codec()) {
    case VideoCodec::kH264:
      decoder_params.mutable_input_details()->set_mime_type("video/h264");
      break;
    case VideoCodec::kVP8:
      decoder_params.mutable_input_details()->set_mime_type("video/vp8");
      break;
    case VideoCodec::kVP9:
      decoder_params.mutable_input_details()->set_mime_type("video/vp9");
      break;
    case VideoCodec::kHEVC:
      decoder_params.mutable_input_details()->set_mime_type("video/hevc");
      break;
    case VideoCodec::kAV1:
      decoder_params.mutable_input_details()->set_mime_type("video/av1");
      break;

    default:
      std::move(done_callback).Run(StatusCode::kDecoderUnsupportedCodec);
      return;
  }

  if (secure_mode) {
    decoder_params.set_secure_input_mode(
        fuchsia::mediacodec::SecureMemoryMode::ON);
  }

  if (secure_mode || base::CommandLine::ForCurrentProcess()->HasSwitch(
                         switches::kForceProtectedVideoOutputBuffers)) {
    decoder_params.set_secure_output_mode(
        fuchsia::mediacodec::SecureMemoryMode::ON);
  }

  decoder_params.set_promise_separate_access_units_on_input(true);
  decoder_params.set_require_hw(!enable_sw_decoding_);

  auto decoder_factory = base::ComponentContextForProcess()
                             ->svc()
                             ->Connect<fuchsia::mediacodec::CodecFactory>();
  fuchsia::media::StreamProcessorPtr decoder;
  decoder_factory->CreateDecoder(std::move(decoder_params),
                                 decoder.NewRequest());
  decoder_ = std::make_unique<StreamProcessorHelper>(std::move(decoder), this);

  current_config_ = config;

  std::move(done_callback).Run(OkStatus());
}

void FuchsiaVideoDecoder::Decode(scoped_refptr<DecoderBuffer> buffer,
                                 DecodeCB decode_cb) {
  if (!decoder_) {
    // Post the callback to the current sequence as DecoderStream doesn't expect
    // Decode() to complete synchronously.
    base::SequencedTaskRunnerHandle::Get()->PostTask(
        FROM_HERE,
        base::BindOnce(std::move(decode_cb), DecodeStatus::DECODE_ERROR));
    return;
  }

  decode_callbacks_.push_back(std::move(decode_cb));

  sysmem_buffer_stream_->EnqueueBuffer(std::move(buffer));
}

void FuchsiaVideoDecoder::Reset(base::OnceClosure closure) {
  DropInputQueue(DecodeStatus::ABORTED);
  base::SequencedTaskRunnerHandle::Get()->PostTask(FROM_HERE,
                                                   std::move(closure));
}

bool FuchsiaVideoDecoder::NeedsBitstreamConversion() const {
  return true;
}

bool FuchsiaVideoDecoder::CanReadWithoutStalling() const {
  return num_used_output_buffers_ < kMaxUsedOutputBuffers;
}

int FuchsiaVideoDecoder::GetMaxDecodeRequests() const {
  return max_decoder_requests_;
}

StatusCode FuchsiaVideoDecoder::InitializeSysmemBufferStream(
    bool is_encrypted,
    CdmContext* cdm_context,
    bool* out_secure_mode) {
  DCHECK(!sysmem_buffer_stream_);

  *out_secure_mode = false;

  // By default queue as many decode requests as the input buffers available
  // with one extra request to be able to send a new InputBuffer immediately.
  max_decoder_requests_ = kNumInputBuffers + 1;

  if (is_encrypted) {
    // Caller makes sure |cdm_context| is available if the stream is encrypted.
    if (!cdm_context) {
      DLOG(ERROR) << "No cdm context for encrypted stream.";
      return StatusCode::kDecoderMissingCdmForEncryptedContent;
    }

    // Use FuchsiaStreamDecryptor with FuchsiaCdm (it doesn't support
    // media::Decryptor interface). Otherwise (e.g. for ClearKey CDM) use
    // DecryptingSysmemBufferStream.
    FuchsiaCdmContext* fuchsia_cdm = cdm_context->GetFuchsiaCdmContext();
    if (fuchsia_cdm) {
      *out_secure_mode = base::CommandLine::ForCurrentProcess()->HasSwitch(
          switches::kEnableProtectedVideoBuffers);
      sysmem_buffer_stream_ =
          fuchsia_cdm->CreateStreamDecryptor(*out_secure_mode);

      // For optimal performance allow more requests to fill the decryptor
      // queue.
      max_decoder_requests_ += FuchsiaStreamDecryptor::kInputBufferCount;
    } else {
      sysmem_buffer_stream_ = std::make_unique<DecryptingSysmemBufferStream>(
          &sysmem_allocator_, cdm_context, Decryptor::kVideo);
    }
  } else {
    sysmem_buffer_stream_ =
        std::make_unique<PassthroughSysmemBufferStream>(&sysmem_allocator_);
  }

  sysmem_buffer_stream_->Initialize(this, kInputBufferSize, kNumInputBuffers);

  return StatusCode::kOk;
}

void FuchsiaVideoDecoder::OnSysmemBufferStreamBufferCollectionToken(
    fuchsia::sysmem::BufferCollectionTokenPtr token) {
  DCHECK(decoder_);
  decoder_->SetInputBufferCollectionToken(std::move(token));
}

void FuchsiaVideoDecoder::OnSysmemBufferStreamOutputPacket(
    StreamProcessorHelper::IoPacket packet) {
  packet.AddOnDestroyClosure(
      base::BindOnce(&FuchsiaVideoDecoder::CallNextDecodeCallback,
                     decode_callbacks_weak_factory_.GetWeakPtr()));
  decoder_->Process(std::move(packet));
}

void FuchsiaVideoDecoder::OnSysmemBufferStreamEndOfStream() {
  decoder_->ProcessEos();
}

void FuchsiaVideoDecoder::OnSysmemBufferStreamError() {
  OnError();
}

void FuchsiaVideoDecoder::OnSysmemBufferStreamNoKey() {
  waiting_cb_.Run(WaitingReason::kNoDecryptionKey);
}

void FuchsiaVideoDecoder::OnStreamProcessorAllocateOutputBuffers(
    const fuchsia::media::StreamBufferConstraints& output_constraints) {
  ReleaseOutputBuffers();

  output_buffer_collection_ = sysmem_allocator_.AllocateNewCollection();

  output_buffer_collection_->CreateSharedToken(
      base::BindOnce(&StreamProcessorHelper::CompleteOutputBuffersAllocation,
                     base::Unretained(decoder_.get())),
      "codec");
  output_buffer_collection_->CreateSharedToken(
      base::BindOnce(&FuchsiaVideoDecoder::SetBufferCollectionTokenForGpu,
                     base::Unretained(this)),
      "gpu");

  fuchsia::sysmem::BufferCollectionConstraints buffer_constraints;
  buffer_constraints.usage.none = fuchsia::sysmem::noneUsage;
  buffer_constraints.min_buffer_count_for_camping = kOutputBuffersForCamping;
  buffer_constraints.min_buffer_count_for_shared_slack =
      kMaxUsedOutputBuffers - kOutputBuffersForCamping;
  output_buffer_collection_->Initialize(std::move(buffer_constraints),
                                        "ChromiumVideoDecoderOutput");
}

void FuchsiaVideoDecoder::OnStreamProcessorEndOfStream() {
  // Decode() is not supposed to be called again after EOF.
  DCHECK_EQ(decode_callbacks_.size(), 1U);
  CallNextDecodeCallback();
}

void FuchsiaVideoDecoder::OnStreamProcessorOutputFormat(
    fuchsia::media::StreamOutputFormat output_format) {
  auto* format = output_format.mutable_format_details();
  if (!format->has_domain() || !format->domain().is_video() ||
      !format->domain().video().is_uncompressed()) {
    DLOG(ERROR) << "Received OnOutputFormat() with invalid format.";
    OnError();
    return;
  }

  output_format_ = std::move(format->mutable_domain()->video().uncompressed());
}

void FuchsiaVideoDecoder::OnStreamProcessorOutputPacket(
    StreamProcessorHelper::IoPacket output_packet) {
  fuchsia::sysmem::PixelFormatType sysmem_pixel_format =
      output_format_.image_format.pixel_format.type;

  VideoPixelFormat pixel_format;
  gfx::BufferFormat buffer_format;
  VkFormat vk_format;
  switch (sysmem_pixel_format) {
    case fuchsia::sysmem::PixelFormatType::NV12:
      pixel_format = PIXEL_FORMAT_NV12;
      buffer_format = gfx::BufferFormat::YUV_420_BIPLANAR;
      vk_format = VK_FORMAT_G8_B8R8_2PLANE_420_UNORM;
      break;

    case fuchsia::sysmem::PixelFormatType::I420:
    case fuchsia::sysmem::PixelFormatType::YV12:
      pixel_format = PIXEL_FORMAT_I420;
      buffer_format = gfx::BufferFormat::YVU_420;
      vk_format = VK_FORMAT_G8_B8_R8_3PLANE_420_UNORM;
      break;

    default:
      DLOG(ERROR) << "Unsupported pixel format: "
                  << static_cast<int>(sysmem_pixel_format);
      OnError();
      return;
  }

  size_t buffer_index = output_packet.buffer_index();

  if (buffer_index >= output_mailboxes_.size())
    output_mailboxes_.resize(buffer_index + 1, nullptr);

  auto coded_size = gfx::Size(output_format_.primary_width_pixels,
                              output_format_.primary_height_pixels);

  if (!output_mailboxes_[buffer_index]) {
    gfx::GpuMemoryBufferHandle gmb_handle;
    gmb_handle.type = gfx::NATIVE_PIXMAP;
    gmb_handle.native_pixmap_handle.buffer_collection_id =
        output_buffer_collection_id_;
    gmb_handle.native_pixmap_handle.buffer_index = buffer_index;

    auto gmb = gpu::GpuMemoryBufferImplNativePixmap::CreateFromHandle(
        client_native_pixmap_factory_.get(), std::move(gmb_handle), coded_size,
        buffer_format, gfx::BufferUsage::GPU_READ,
        gpu::GpuMemoryBufferImpl::DestructionCallback());

    output_mailboxes_[buffer_index] =
        new OutputMailbox(raster_context_provider_, std::move(gmb));
  } else {
    raster_context_provider_->SharedImageInterface()->UpdateSharedImage(
        gpu::SyncToken(), output_mailboxes_[buffer_index]->mailbox());
  }

  auto display_rect = gfx::Rect(output_format_.primary_display_width_pixels,
                                output_format_.primary_display_height_pixels);

  VideoAspectRatio aspect_ratio = container_aspect_ratio_;
  if (!aspect_ratio.IsValid() && output_format_.has_pixel_aspect_ratio) {
    aspect_ratio =
        VideoAspectRatio::PAR(output_format_.pixel_aspect_ratio_width,
                              output_format_.pixel_aspect_ratio_height);
  }

  auto timestamp = output_packet.timestamp();

  // SendInputPacket() sets timestamp for all packets sent to the decoder, so we
  // expect to receive timestamp for all decoded frames. Missing timestamp
  // indicates a bug in the decoder implementation.
  if (timestamp == kNoTimestamp) {
    LOG(ERROR) << "Received frame without timestamp.";
    OnError();
    return;
  }

  num_used_output_buffers_++;

  auto frame = output_mailboxes_[buffer_index]->CreateFrame(
      pixel_format, coded_size, display_rect,
      aspect_ratio.GetNaturalSize(display_rect), timestamp,
      base::BindOnce(&FuchsiaVideoDecoder::ReleaseOutputPacket,
                     base::Unretained(this), std::move(output_packet)));

  // Currently sysmem doesn't specify location of chroma samples relative to
  // luma (see fxb/13677). Assume they are cosited with luma. YCbCr info here
  // must match the values passed for the same buffer in
  // ui::SysmemBufferCollection::CreateVkImage() (see
  // ui/ozone/platform/scenic/sysmem_buffer_collection.cc). |format_features|
  // are resolved later in the GPU process before this info is passed to Skia.
  frame->set_ycbcr_info(gpu::VulkanYCbCrInfo(
      vk_format, /*external_format=*/0,
      VK_SAMPLER_YCBCR_MODEL_CONVERSION_YCBCR_709,
      VK_SAMPLER_YCBCR_RANGE_ITU_NARROW, VK_CHROMA_LOCATION_COSITED_EVEN,
      VK_CHROMA_LOCATION_COSITED_EVEN, /*format_features=*/0));

  // Mark the frame as power-efficient when software decoders are disabled. The
  // codec may still decode on hardware even when |enable_sw_decoding_| is set
  // (i.e. power_efficient flag would not be set correctly in that case). It
  // doesn't matter because software decoders can be enabled only for tests.
  frame->metadata().power_efficient = !enable_sw_decoding_;

  // Allow this video frame to be promoted as an overlay, because it was
  // registered with an ImagePipe.
  frame->metadata().allow_overlay = use_overlays_for_video_;

  output_cb_.Run(std::move(frame));
}

void FuchsiaVideoDecoder::OnStreamProcessorNoKey() {
  // Decoder is not expected to produce NoKey() error.
  DLOG(ERROR) << "Video decoder failed with DECRYPTOR_NO_KEY expectedly";
  OnError();
}

void FuchsiaVideoDecoder::OnStreamProcessorError() {
  OnError();
}

void FuchsiaVideoDecoder::CallNextDecodeCallback() {
  DCHECK(!decode_callbacks_.empty());
  auto cb = std::move(decode_callbacks_.front());
  decode_callbacks_.pop_front();

  std::move(cb).Run(DecodeStatus::OK);
}

bool FuchsiaVideoDecoder::DropInputQueue(DecodeStatus status) {
  // Invalidate callbacks for CallNextDecodeCallback(), so the callbacks are not
  // called when the |decoder_| is dropped below. The callbacks are called
  // explicitly later.
  decode_callbacks_weak_factory_.InvalidateWeakPtrs();

  if (decoder_) {
    decoder_->Reset();
  }

  if (sysmem_buffer_stream_) {
    sysmem_buffer_stream_->Reset();
  }

  auto weak_this = weak_this_;

  for (auto& cb : decode_callbacks_) {
    std::move(cb).Run(status);

    // DecodeCB may destroy |this|.
    if (!weak_this)
      return false;
  }
  decode_callbacks_.clear();

  return true;
}

void FuchsiaVideoDecoder::OnError() {
  sysmem_buffer_stream_.reset();
  decoder_.reset();

  ReleaseOutputBuffers();

  DropInputQueue(DecodeStatus::DECODE_ERROR);
}

void FuchsiaVideoDecoder::SetBufferCollectionTokenForGpu(
    fuchsia::sysmem::BufferCollectionTokenPtr token) {
  // Register the new collection with the GPU process.
  DCHECK(!output_buffer_collection_id_);
  output_buffer_collection_id_ = gfx::SysmemBufferCollectionId::Create();
  raster_context_provider_->SharedImageInterface()
      ->RegisterSysmemBufferCollection(
          output_buffer_collection_id_, token.Unbind().TakeChannel(),
          gfx::BufferFormat::YUV_420_BIPLANAR, gfx::BufferUsage::GPU_READ,
          use_overlays_for_video_ /*register_with_image_pipe*/);

  // Exact number of buffers sysmem will allocate is unknown here.
  // |output_mailboxes_| is resized when we start receiving output frames.
  DCHECK(output_mailboxes_.empty());
}

void FuchsiaVideoDecoder::ReleaseOutputBuffers() {
  // Release the buffer collection.
  num_used_output_buffers_ = 0;
  if (output_buffer_collection_) {
    output_buffer_collection_.reset();
  }

  // Release all output mailboxes.
  for (OutputMailbox* mailbox : output_mailboxes_) {
    if (mailbox)
      mailbox->Release();
  }
  output_mailboxes_.clear();

  // Tell the GPU process to drop the buffer collection.
  if (output_buffer_collection_id_) {
    raster_context_provider_->SharedImageInterface()
        ->ReleaseSysmemBufferCollection(output_buffer_collection_id_);
    output_buffer_collection_id_ = {};
  }
}

void FuchsiaVideoDecoder::ReleaseOutputPacket(
    StreamProcessorHelper::IoPacket output_packet) {
  DCHECK_GT(num_used_output_buffers_, 0U);
  num_used_output_buffers_--;
}

}  // namespace media