// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef DEVICE_VR_UTIL_SAMPLE_QUEUE_H_
#define DEVICE_VR_UTIL_SAMPLE_QUEUE_H_

#include <cstddef>
#include <vector>

#include "base/component_export.h"

namespace device {

// Manages a fixed-size queue of samples including their current sum. Old
// samples are automatically dropped when an added sample would exceed the
// requested size.
class COMPONENT_EXPORT(DEVICE_VR_UTIL) SampleQueue {
 public:
  explicit SampleQueue(size_t window_size);

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

  ~SampleQueue();

  int64_t GetSum() const { return sum_; }

  void AddSample(int64_t value);

  size_t GetCount() const { return samples_.size(); }

  // Get sliding window size for tests.
  size_t GetWindowSize() const { return window_size_; }

 private:
  int64_t sum_ = 0;
  size_t current_index_ = 0;
  size_t window_size_;
  std::vector<int64_t> samples_;
};

}  // namespace device

#endif  // DEVICE_VR_UTIL_SAMPLE_QUEUE_H_