// Copyright 2016 Google Inc. All Rights Reserved.

#ifndef WVCDM_METRICS_METRICS_FRONT_END_H_
#define WVCDM_METRICS_METRICS_FRONT_END_H_

#include <map>

#include "report.h"
#include "timer_metric.h" /* needed for the macro */

namespace wvcdm {
namespace metrics {

class MetricsFrontEnd {

 public:

  MetricsFrontEnd(Report* root);

  MetricNotification* CreateSubscriber();

  static MetricsFrontEnd& Instance();
  static void OverrideInstance(MetricsFrontEnd* instance);

 private:

  static MetricsFrontEnd* instance_;

  Report* root_;

  /* Disallow copy and assign. */
  MetricsFrontEnd(const MetricsFrontEnd&);
  void operator=(const MetricsFrontEnd&);
};

} // namespace metrics
} // namespace wvcdm

#define MFE wvcdm::metrics::MetricsFrontEnd::Instance()

#define NO_TIME 0

#define M_RECORD(GROUP, METRIC, TIME, ...) \
  if ( GROUP ) { \
    ( GROUP ) -> METRIC . Record( TIME, ##__VA_ARGS__ ); \
  }

#define M_TIME(CALL, GROUP, METRIC, ...) \
  if ( GROUP ) { \
    wvcdm::metrics::TimerMetric timer; \
    timer.Start(); \
    CALL; \
    ( GROUP ) -> METRIC . Record(timer.AsUs(), ##__VA_ARGS__ ); \
  } else { \
    CALL; \
  }

#endif