/*
* (C) 2018 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/internal/timer.h>
#include <botan/internal/os_utils.h>
#include <algorithm>
#include <sstream>
#include <iomanip>

namespace Botan {

void Timer::start()
   {
   stop();
   m_timer_start = OS::get_system_timestamp_ns();
   m_cpu_cycles_start = OS::get_cpu_cycle_counter();
   }

void Timer::stop()
   {
   if(m_timer_start)
      {
      if(m_cpu_cycles_start != 0)
         {
         const uint64_t cycles_taken = OS::get_cpu_cycle_counter() - m_cpu_cycles_start;
         if(cycles_taken > 0)
            {
            m_cpu_cycles_used += static_cast<size_t>(cycles_taken * m_clock_cycle_ratio);
            }
         }

      const uint64_t now = OS::get_system_timestamp_ns();

      if(now > m_timer_start)
         {
         const uint64_t dur = now - m_timer_start;

         m_time_used += dur;

         if(m_event_count == 0)
            {
            m_min_time = m_max_time = dur;
            }
         else
            {
            m_max_time = std::max(m_max_time, dur);
            m_min_time = std::min(m_min_time, dur);
            }
         }

      m_timer_start = 0;
      ++m_event_count;
      }
   }

bool Timer::operator<(const Timer& other) const
   {
   if(this->doing() != other.doing())
      return (this->doing() < other.doing());

   return (this->get_name() < other.get_name());
   }

std::string Timer::to_string() const
   {
   if(m_custom_msg.size() > 0)
      {
      return m_custom_msg;
      }
   else if(this->buf_size() == 0)
      {
      return result_string_ops();
      }
   else
      {
      return result_string_bps();
      }
   }

std::string Timer::result_string_bps() const
   {
   const size_t MiB = 1024 * 1024;

   const double MiB_total = static_cast<double>(events()) / MiB;
   const double MiB_per_sec = MiB_total / seconds();

   std::ostringstream oss;
   oss << get_name();

   if(!doing().empty())
      {
      oss << " " << doing();
      }

   if(buf_size() > 0)
      {
      oss << " buffer size " << buf_size() << " bytes:";
      }

   if(events() == 0)
      oss << " " << "N/A";
   else
      oss << " " << std::fixed << std::setprecision(3) << MiB_per_sec << " MiB/sec";

   if(cycles_consumed() != 0)
      {
      const double cycles_per_byte = static_cast<double>(cycles_consumed()) / events();
      oss << " " << std::fixed << std::setprecision(2) << cycles_per_byte << " cycles/byte";
      }

   oss << " (" << MiB_total << " MiB in " << milliseconds() << " ms)\n";

   return oss.str();
   }

std::string Timer::result_string_ops() const
   {
   std::ostringstream oss;

   oss << get_name() << " ";

   if(events() == 0)
      {
      oss << "no events\n";
      }
   else
      {
      oss << static_cast<uint64_t>(events_per_second())
          << ' ' << doing() << "/sec; "
          << std::setprecision(2) << std::fixed
          << ms_per_event() << " ms/op";

      if(cycles_consumed() != 0)
         {
         const double cycles_per_op = static_cast<double>(cycles_consumed()) / events();
         const size_t precision = (cycles_per_op < 10000) ? 2 : 0;
         oss << " " << std::fixed << std::setprecision(precision) << cycles_per_op << " cycles/op";
         }

      oss << " (" << events() << " " << (events() == 1 ? "op" : "ops")
          << " in " << milliseconds() << " ms)\n";
      }

   return oss.str();
   }

}