// Copyright 2014 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_FORMATS_MP2T_ES_ADAPTER_VIDEO_H_
#define MEDIA_FORMATS_MP2T_ES_ADAPTER_VIDEO_H_

#include <stdint.h>

#include <list>
#include <utility>

#include "base/callback.h"
#include "base/containers/circular_deque.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "media/base/media_export.h"
#include "media/base/stream_parser_buffer.h"

namespace media {

class VideoDecoderConfig;

namespace mp2t {

// Some constraints of the MSE spec are not necessarily met by video streams
// inside an Mpeg2 TS stream.
// The goal of the ES adapter is to modify the incoming buffers to meet these
// constraints, e.g.
// - get the frame duration,
// - replace the leading non-key frames by the first key frame to avoid
//   creating a hole in the video timeline.
class MEDIA_EXPORT EsAdapterVideo {
 public:
  using NewVideoConfigCB =
      base::RepeatingCallback<void(const VideoDecoderConfig&)>;
  using EmitBufferCB =
      base::RepeatingCallback<void(scoped_refptr<StreamParserBuffer>)>;

  EsAdapterVideo(NewVideoConfigCB new_video_config_cb,
                 EmitBufferCB emit_buffer_cb);

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

  ~EsAdapterVideo();

  // Force the emission of the pending video buffers.
  void Flush();

  // Reset the ES adapter to its initial state.
  void Reset();

  // Provide the configuration that applies to the upcoming video buffers.
  void OnConfigChanged(const VideoDecoderConfig& video_decoder_config);

  // Provide a new video buffer.
  // Returns true when successful.
  bool OnNewBuffer(scoped_refptr<StreamParserBuffer> stream_parser_buffer);

 private:
  using BufferQueue = base::circular_deque<scoped_refptr<StreamParserBuffer>>;
  using ConfigEntry = std::pair<int64_t, VideoDecoderConfig>;

  void ProcessPendingBuffers(bool flush);

  // Return the PTS of the frame that comes just after |current_pts| in
  // presentation order. Return kNoTimestamp if not found.
  base::TimeDelta GetNextFramePts(base::TimeDelta current_pts);

  // Replace the leading non key frames by |stream_parser_buffer|
  // (this one must be a key frame).
  void ReplaceDiscardedFrames(const StreamParserBuffer& stream_parser_buffer);

  const NewVideoConfigCB new_video_config_cb_;
  EmitBufferCB emit_buffer_cb_;

  bool has_valid_config_;
  bool has_valid_frame_;

  // Duration of the last video frame.
  base::TimeDelta last_frame_duration_;

  // Association between a video config and a buffer index.
  std::list<ConfigEntry> config_list_;

  // Global index of the first buffer in |buffer_list_|.
  int64_t buffer_index_;

  // List of buffer to be emitted and PTS of frames already emitted.
  BufferQueue buffer_list_;
  std::list<base::TimeDelta> emitted_pts_;

  // Minimum PTS/DTS since the last Reset.
  bool has_valid_initial_timestamp_;
  base::TimeDelta min_pts_;
  DecodeTimestamp min_dts_;

  // Number of frames to replace with the first valid key frame.
  int discarded_frame_count_;
};

}  // namespace mp2t
}  // namespace media

#endif  // MEDIA_FORMATS_MP2T_ES_ADAPTER_VIDEO_H_