// 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.

#ifndef MEDIA_GPU_IPC_SERVICE_VDA_VIDEO_DECODER_H_
#define MEDIA_GPU_IPC_SERVICE_VDA_VIDEO_DECODER_H_

#include <stdint.h>

#include <map>
#include <memory>

#include "base/callback_forward.h"
#include "base/containers/mru_cache.h"
#include "base/macros.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/shared_memory.h"
#include "base/memory/weak_ptr.h"
#include "base/single_thread_task_runner.h"
#include "base/time/time.h"
#include "media/base/video_decoder.h"
#include "media/gpu/command_buffer_helper.h"
#include "media/gpu/ipc/service/picture_buffer_manager.h"
#include "media/video/video_decode_accelerator.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gl/gl_bindings.h"

namespace gpu {
class CommandBufferStub;
class GpuDriverBugWorkarounds;
struct GpuPreferences;
}  // namespace gpu

namespace media {

// Implements the VideoDecoder interface backed by a VideoDecodeAccelerator.
// This class expects to run in the GPU process via MojoVideoDecoder.
class VdaVideoDecoder : public VideoDecoder,
                        public VideoDecodeAccelerator::Client {
 public:
  using GetStubCB = base::RepeatingCallback<gpu::CommandBufferStub*()>;
  using CreatePictureBufferManagerCB =
      base::OnceCallback<scoped_refptr<PictureBufferManager>(
          PictureBufferManager::ReusePictureBufferCB)>;
  using CreateCommandBufferHelperCB =
      base::OnceCallback<scoped_refptr<CommandBufferHelper>()>;
  using CreateAndInitializeVdaCB =
      base::OnceCallback<std::unique_ptr<VideoDecodeAccelerator>(
          scoped_refptr<CommandBufferHelper>,
          VideoDecodeAccelerator::Client*,
          const VideoDecodeAccelerator::Config&)>;
  using GetVdaCapabilitiesCB =
      base::OnceCallback<VideoDecodeAccelerator::Capabilities(
          const gpu::GpuPreferences&,
          const gpu::GpuDriverBugWorkarounds&)>;

  // Creates a VdaVideoDecoder. The returned unique_ptr can be safely upcast to
  // unique_ptr<VideoDecoder>.
  //
  // |get_stub_cb|: Callback to retrieve the CommandBufferStub that should be
  //     used for allocating textures and mailboxes. This callback will be
  //     called on the GPU thread.
  //
  // See VdaVideoDecoder() for other arguments.
  static std::unique_ptr<VdaVideoDecoder, std::default_delete<VideoDecoder>>
  Create(scoped_refptr<base::SingleThreadTaskRunner> parent_task_runner,
         scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner,
         const gpu::GpuPreferences& gpu_preferences,
         const gpu::GpuDriverBugWorkarounds& gpu_workarounds,
         GetStubCB get_stub_cb);

  // |parent_task_runner|: Task runner that |this| should operate on. All
  //     methods must be called on |parent_task_runner| (should be the Mojo
  //     MediaService task runner).
  // |gpu_task_runner|: Task runner that GPU command buffer methods must be
  //     called on (should be the GPU main thread).
  // |create_picture_buffer_manager_cb|: PictureBufferManager factory.
  // |create_command_buffer_helper_cb|: CommandBufferHelper factory.
  // |create_and_initialize_vda_cb|: VideoDecodeAccelerator factory.
  // |vda_capabilities|: Capabilities of the VDA that
  //     |create_and_initialize_vda_cb| will produce.
  VdaVideoDecoder(
      scoped_refptr<base::SingleThreadTaskRunner> parent_task_runner,
      scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner,
      CreatePictureBufferManagerCB create_picture_buffer_manager_cb,
      CreateCommandBufferHelperCB create_command_buffer_helper_cb,
      CreateAndInitializeVdaCB create_and_initialize_vda_cb,
      const VideoDecodeAccelerator::Capabilities& vda_capabilities);

  // media::VideoDecoder implementation.
  std::string GetDisplayName() const override;
  void Initialize(
      const VideoDecoderConfig& config,
      bool low_delay,
      CdmContext* cdm_context,
      const InitCB& init_cb,
      const OutputCB& output_cb,
      const WaitingForDecryptionKeyCB& waiting_for_decryption_key_cb) override;
  void Decode(scoped_refptr<DecoderBuffer> buffer,
              const DecodeCB& decode_cb) override;
  void Reset(const base::RepeatingClosure& reset_cb) override;
  bool NeedsBitstreamConversion() const override;
  bool CanReadWithoutStalling() const override;
  int GetMaxDecodeRequests() const override;

 private:
  void Destroy() override;

 protected:
  // Owners should call Destroy(). This is automatic via
  // std::default_delete<media::VideoDecoder> when held by a
  // std::unique_ptr<media::VideoDecoder>.
  ~VdaVideoDecoder() override;

 private:
  // media::VideoDecodeAccelerator::Client implementation.
  void NotifyInitializationComplete(bool success) override;
  void ProvidePictureBuffers(uint32_t requested_num_of_buffers,
                             VideoPixelFormat format,
                             uint32_t textures_per_buffer,
                             const gfx::Size& dimensions,
                             uint32_t texture_target) override;
  void DismissPictureBuffer(int32_t picture_buffer_id) override;
  void PictureReady(const Picture& picture) override;
  void NotifyEndOfBitstreamBuffer(int32_t bitstream_buffer_id) override;
  void NotifyFlushDone() override;
  void NotifyResetDone() override;
  void NotifyError(VideoDecodeAccelerator::Error error) override;

  // Tasks and thread hopping.
  void DestroyOnGpuThread();
  void InitializeOnGpuThread();
  void InitializeDone(bool status);
  void DecodeOnGpuThread(BitstreamBuffer bitstream_buffer);
  void PictureReadyOnParentThread(Picture picture);
  void NotifyEndOfBitstreamBufferOnParentThread(int32_t bitstream_buffer_id);
  void NotifyFlushDoneOnParentThread();
  void NotifyResetDoneOnParentThread();
  void ProvidePictureBuffersAsync(uint32_t count,
                                  VideoPixelFormat pixel_format,
                                  uint32_t planes,
                                  gfx::Size texture_size,
                                  GLenum texture_target);
  void ReusePictureBuffer(int32_t picture_buffer_id);

  // Error handling.
  void EnterErrorState();
  void DestroyCallbacks();

  //
  // Construction parameters.
  //
  scoped_refptr<base::SingleThreadTaskRunner> parent_task_runner_;
  scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner_;
  scoped_refptr<CommandBufferHelper> command_buffer_helper_;
  scoped_refptr<PictureBufferManager> picture_buffer_manager_;

  CreateCommandBufferHelperCB create_command_buffer_helper_cb_;
  CreateAndInitializeVdaCB create_and_initialize_vda_cb_;

  const VideoDecodeAccelerator::Capabilities vda_capabilities_;

  //
  // Parent thread state.
  //
  bool has_error_ = false;

  InitCB init_cb_;
  OutputCB output_cb_;
  DecodeCB flush_cb_;
  base::RepeatingClosure reset_cb_;

  int32_t bitstream_buffer_id_ = 0;
  std::map<int32_t, DecodeCB> decode_cbs_;
  // Records timestamps so that they can be mapped to output pictures. Must be
  // large enough to account for any amount of frame reordering.
  base::MRUCache<int32_t, base::TimeDelta> timestamps_;

  //
  // GPU thread state.
  //
  std::unique_ptr<VideoDecodeAccelerator> vda_;
  bool vda_initialized_ = false;

  //
  // Shared state.
  //
  VideoDecoderConfig config_;

  //
  // Weak pointers, prefixed by bound thread.
  //
  // |gpu_weak_vda_| is invalidated when the VDA has notified about an error, or
  //     has been destroyed. It is not valid to call VDA methods in those cases.
  base::WeakPtr<VideoDecodeAccelerator> gpu_weak_vda_;
  std::unique_ptr<base::WeakPtrFactory<VideoDecodeAccelerator>>
      gpu_weak_vda_factory_;

  // |gpu_weak_this_| is never explicitly invalidated.
  // |parent_weak_this_| is invalidated when the client calls Destroy(), and
  //     indicates that we should not make any new client callbacks.
  base::WeakPtr<VdaVideoDecoder> gpu_weak_this_;
  base::WeakPtr<VdaVideoDecoder> parent_weak_this_;
  base::WeakPtrFactory<VdaVideoDecoder> gpu_weak_this_factory_;
  base::WeakPtrFactory<VdaVideoDecoder> parent_weak_this_factory_;

  DISALLOW_COPY_AND_ASSIGN(VdaVideoDecoder);
};

}  // namespace media

#endif  // MEDIA_GPU_IPC_SERVICE_VDA_VIDEO_DECODER_H_