#pragma once

#include "envoy/common/time.h"

#include "envoy/stats/histogram.h"

#include "envoy/stats/stats.h"

#include "envoy/stats/timespan.h"

namespace Envoy {

namespace Stats {

/**

 * An individual timespan that flushes its measured value to the histogram on completion.

 * The start time is captured on construction. The timespan must be

 * completed via complete() for it to be stored. If the timespan is deleted this will be treated as

 * a cancellation. The target histogram must represent a quantity of time.

 */

class HistogramCompletableTimespanImpl : public CompletableTimespan {

public:

  HistogramCompletableTimespanImpl(Histogram& histogram, TimeSource& time_source);

  // Stats::CompletableTimespan

  std::chrono::milliseconds elapsed() const override;

  void complete() override;

private:

  void ensureTimeHistogram(const Histogram& histogram) const;

  uint64_t tickCount() const;

  TimeSource& time_source_;

  Histogram& histogram_;

  const MonotonicTime start_;

};

} // namespace Stats

} // namespace Envoy