////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2017 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// 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.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Christoph Uhde
////////////////////////////////////////////////////////////////////////////////

#ifndef ARANGODB_BASICS_SCOPEDTIMER__H
#define ARANGODB_BASICS_SCOPEDTIMER__H 1

#include <lib/Logger/Logger.h>

#include <utility>
#include <vector>
#include <chrono>
#include <functional>
#include <iostream>
#include <sstream>
#include <iomanip>
namespace arangodb {


class ScopedTimer {
public:  // defines
    using hclock    = std::chrono::high_resolution_clock;
    using hrcStrVec = std::vector<std::pair<hclock::time_point,std::string>>;
    using intStrVec = std::vector<std::pair<int,std::string>>;

private:  // variables
    hrcStrVec _timePoints;
    std::function<void(intStrVec)> _callback;
    bool _enabled;
    bool _addDtorEntry;

public:  // functions
    ScopedTimer(ScopedTimer const&) = delete;
    ScopedTimer(ScopedTimer &&) = delete;

    ScopedTimer( std::function<void(intStrVec)> callback = &ScopedTimer::print)
        : _callback(callback)
        , _enabled(true)
        , _addDtorEntry(true) {
        _timePoints.reserve(10);  //if you want time more than 10 - add template param?
        _timePoints.emplace_back(hclock::time_point(),"");
        _timePoints.back().first=hclock::now(); //defeats the purpose of emplace a bit :/
    }

    ScopedTimer(std::string const& description
        , std::function<void(intStrVec)> callback = &ScopedTimer::print)
        : _callback(callback)
        , _enabled(true)
        , _addDtorEntry(true) {
        _timePoints.reserve(10);
        _timePoints.emplace_back(hclock::time_point(), description);
        _timePoints.back().first=hclock::now();
    }

    ScopedTimer(std::string&& description
        , std::function<void(intStrVec)> callback = &ScopedTimer::print)
        : _callback(callback)
        , _enabled(true)
        , _addDtorEntry(true) {
        _timePoints.reserve(10);
        _timePoints.emplace_back(hclock::time_point(), std::move(description));
        _timePoints.back().first=hclock::now();
    }

    ~ScopedTimer(void) {
        if(_addDtorEntry) {
            _timePoints.emplace_back(hclock::now(),"dtor");
        }
        if(_enabled) {
            _callback(calculate());
        }
    }

    void addStep(std::string const& str = "") {
        _timePoints.emplace_back(hclock::now(),str);
    }
    void addStep(std::string&& str = "") {
        _timePoints.emplace_back(hclock::now(),std::move(str));
    }

    void disableDtorEntry() {
        _addDtorEntry = false;
    }

    void runCallback(bool disable = true) {
        if (disable) {
          _enabled=false;
        }
        return _callback(calculate());
    }

    void set_description(std::string const& description) {
        _timePoints[0].second = description;
    }

    void set_description(std::string&& description) {
        _timePoints[0].second = description;
    }

private:  // functions
    static long int
    get_time_diff(hclock::time_point const& t0, hclock::time_point const& t1) {
        return std::chrono::duration_cast<std::chrono::nanoseconds>(t1-t0).count();
    }

    intStrVec calculate() {
        long int total_time = get_time_diff(_timePoints.front().first ,_timePoints.back().first);
        intStrVec times;
        times.emplace_back(std::make_pair(total_time ,_timePoints.front().second));
        if (_timePoints.size() > 2) {
            for (std::size_t i = 1; i < _timePoints.size(); i++) {
                times.emplace_back(std::make_pair(
                      get_time_diff(_timePoints[i-1].first ,_timePoints[i].first) ,_timePoints[i].second
                ));
            }
        }
        return times;
    }  // function - calculate

    static std::stringstream toStringStream(intStrVec const& times) {
        std::stringstream ss;
        int width = 15;
        ss << "total   : "
           << std::setw(width) << times[0].first << " ns - "
           << std::setprecision(8) << std::fixed << times[0].first / 1000.0 << " μs - "
           << std::setprecision(8) << std::fixed << times[0].first / 1000000.0 << " ms - "
           << std::setprecision(8) << std::fixed << times[0].first / 1000000000.0 << " s";

        if (!times[0].second.empty()) {
            ss << " - " << times[0].second;
        }
        ss << std::endl;

        if (times.size() > 1) {
            for (std::size_t i = 1; i < times.size(); i++) {
                ss << "step "  << std::setw(3) << i << ": "
                   << std::setw(width) << times[i].first << " ns"
                   << std::setprecision(1) << std::fixed
                   << " (" << std::setw(5) << 100*static_cast<float>(times[i].first)/static_cast<float>(times[0].first) << "%)";
                if (!times[i].second.empty()) {
                    ss << " - " << times[i].second;
                }
                ss << std::endl;
            }
        }
        return ss;
    }

    static std::string toString(intStrVec const& times) {
      return toStringStream(times).str();
    }

    static void print(intStrVec const& times) {
        std::string to;
        auto out = toStringStream(times);
        while(std::getline(out,to,'\n')) {
          LOG_TOPIC(ERR, Logger::FIXME) << to;
        }
    }
public:

    std::string str(bool disable = true) {
        if (disable) {
          _enabled=false;
        }
        return toString(calculate());
    }
} ;


}
#endif