// Copyright 2011 Google Inc. 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.

#include "metrics.h"

#include <errno.h>
#include <stdio.h>
#include <string.h>

#ifndef _WIN32
#include <sys/time.h>
#else
#include <windows.h>
#endif

#include <algorithm>

#include "util.h"

Metrics* g_metrics = NULL;

namespace {

#ifndef _WIN32
/// Compute a platform-specific high-res timer value that fits into an int64.
int64_t HighResTimer() {
  timeval tv;
  if (gettimeofday(&tv, NULL) < 0)
    Fatal("gettimeofday: %s", strerror(errno));
  return (int64_t)tv.tv_sec * 1000*1000 + tv.tv_usec;
}

/// Convert a delta of HighResTimer() values to microseconds.
int64_t TimerToMicros(int64_t dt) {
  // No conversion necessary.
  return dt;
}
#else
int64_t LargeIntegerToInt64(const LARGE_INTEGER& i) {
  return ((int64_t)i.HighPart) << 32 | i.LowPart;
}

int64_t HighResTimer() {
  LARGE_INTEGER counter;
  if (!QueryPerformanceCounter(&counter))
    Fatal("QueryPerformanceCounter: %s", GetLastErrorString().c_str());
  return LargeIntegerToInt64(counter);
}

int64_t TimerToMicros(int64_t dt) {
  static int64_t ticks_per_sec = 0;
  if (!ticks_per_sec) {
    LARGE_INTEGER freq;
    if (!QueryPerformanceFrequency(&freq))
      Fatal("QueryPerformanceFrequency: %s", GetLastErrorString().c_str());
    ticks_per_sec = LargeIntegerToInt64(freq);
  }

  // dt is in ticks.  We want microseconds.
  return (dt * 1000000) / ticks_per_sec;
}
#endif

}  // anonymous namespace


ScopedMetric::ScopedMetric(Metric* metric) {
  metric_ = metric;
  if (!metric_)
    return;
  start_ = HighResTimer();
}
ScopedMetric::~ScopedMetric() {
  if (!metric_)
    return;
  metric_->count++;
  int64_t dt = TimerToMicros(HighResTimer() - start_);
  metric_->sum += dt;
}

Metric* Metrics::NewMetric(const string& name) {
  Metric* metric = new Metric;
  metric->name = name;
  metric->count = 0;
  metric->sum = 0;
  metrics_.push_back(metric);
  return metric;
}

void Metrics::Report() {
  int width = 0;
  for (vector<Metric*>::iterator i = metrics_.begin();
       i != metrics_.end(); ++i) {
    width = max((int)(*i)->name.size(), width);
  }

  printf("%-*s\t%-6s\t%-9s\t%s\n", width,
         "metric", "count", "avg (us)", "total (ms)");
  for (vector<Metric*>::iterator i = metrics_.begin();
       i != metrics_.end(); ++i) {
    Metric* metric = *i;
    double total = metric->sum / (double)1000;
    double avg = metric->sum / (double)metric->count;
    printf("%-*s\t%-6d\t%-8.1f\t%.1f\n", width, metric->name.c_str(),
           metric->count, avg, total);
  }
}

uint64_t Stopwatch::Now() const {
  return TimerToMicros(HighResTimer());
}

int64_t GetTimeMillis() {
  return TimerToMicros(HighResTimer()) / 1000;
}