/*
 *  Copyright (c) 2023 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#ifndef TEST_PC_E2E_ANALYZER_VIDEO_DVQA_FRAMES_STORAGE_H_
#define TEST_PC_E2E_ANALYZER_VIDEO_DVQA_FRAMES_STORAGE_H_

#include <cstddef>
#include <cstdint>
#include <optional>
#include <unordered_map>
#include <vector>

#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "api/video/video_frame.h"
#include "system_wrappers/include/clock.h"

namespace webrtc {

// Stores video frames for DefaultVideoQualityAnalyzer. Frames are cleaned up
// when the time elapsed from their capture time exceeds `max_storage_duration`.
class FramesStorage {
 public:
  FramesStorage(TimeDelta max_storage_duration, Clock* clock)
      : max_storage_duration_(max_storage_duration), clock_(clock) {}
  FramesStorage(const FramesStorage&) = delete;
  FramesStorage& operator=(const FramesStorage&) = delete;
  FramesStorage(FramesStorage&&) = default;
  FramesStorage& operator=(FramesStorage&&) = default;

  // Adds frame to the storage. It is guaranteed to be stored at least
  // `max_storage_duration` from `captured_time`.
  //
  // Complexity: O(log(n))
  void Add(const VideoFrame& frame, Timestamp captured_time);

  // Complexity: O(1)
  std::optional<VideoFrame> Get(uint16_t frame_id);

  // Removes the frame identified by `frame_id` from the storage. No error
  // happens in case there isn't a frame identified by `frame_id`.
  //
  // Complexity: O(log(n))
  void Remove(uint16_t frame_id);

 private:
  struct HeapNode {
    VideoFrame frame;
    Timestamp captured_time;
  };

  void RemoveInternal(uint16_t frame_id);

  void Heapify(size_t index);
  void HeapifyUp(size_t index);
  void HeapifyDown(size_t index);

  // Complexity: O(#(of too old frames) * log(n))
  void RemoveTooOldFrames();

  TimeDelta max_storage_duration_;
  Clock* clock_;

  std::unordered_map<uint16_t, size_t> frame_id_index_;
  // Min-heap based on HeapNode::captured_time.
  std::vector<HeapNode> heap_;
};

}  // namespace webrtc

#endif  // TEST_PC_E2E_ANALYZER_VIDEO_DVQA_FRAMES_STORAGE_H_