// Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef timer_h
#define timer_h
#include <chrono>
#include <list>
class Timer final {
public:
  Timer() {}

  ~Timer() {}

  void clear() { ms_time.clear(); }

  void start() { tstart = std::chrono::system_clock::now(); }

  void end() {
    tend = std::chrono::system_clock::now();
    auto ts = std::chrono::duration_cast<std::chrono::microseconds>(tend - tstart);
    float elapse_ms =
        1000.f * float(ts.count()) * std::chrono::microseconds::period::num / std::chrono::microseconds::period::den;
    ms_time.push_back(elapse_ms);
  }

  float get_average_ms() {
    if (ms_time.size() == 0) {
      return 0.f;
    }
    float sum = 0.f;
    for (auto i : ms_time) {
      sum += i;
    }
    return sum / ms_time.size();
  }

  float get_sum_ms() {
    if (ms_time.size() == 0) {
      return 0.f;
    }
    float sum = 0.f;
    for (auto i : ms_time) {
      sum += i;
    }
    return sum;
  }

  // return tile (0-99) time.
  float get_tile_time(float tile) {
    if (tile < 0 || tile > 100) {
      return -1.f;
    }
    int total_items = (int)ms_time.size();
    if (total_items <= 0) {
      return -2.f;
    }
    ms_time.sort();
    int pos = (int)(tile * total_items / 100);
    auto it = ms_time.begin();
    for (int i = 0; i < pos; ++i) {
      ++it;
    }
    return *it;
  }

  const std::list<float> get_time_stat() { return ms_time; }

private:
  std::chrono::time_point<std::chrono::system_clock> tstart;
  std::chrono::time_point<std::chrono::system_clock> tend;
  std::list<float> ms_time;
};

#endif /* timer_h */