#include "GCodeTimeEstimator.hpp"
#include <boost/bind.hpp>
#include <cmath>

#include <Shiny/Shiny.h>

static const float MMMIN_TO_MMSEC = 1.0f / 60.0f;
static const float MILLISEC_TO_SEC = 0.001f;
static const float INCHES_TO_MM = 25.4f;
static const float DEFAULT_FEEDRATE = 1500.0f; // from Prusa Firmware (Marlin_main.cpp)
static const float DEFAULT_ACCELERATION = 1500.0f; // Prusa Firmware 1_75mm_MK2
static const float DEFAULT_RETRACT_ACCELERATION = 1500.0f; // Prusa Firmware 1_75mm_MK2
static const float DEFAULT_AXIS_MAX_FEEDRATE[] = { 500.0f, 500.0f, 12.0f, 120.0f }; // Prusa Firmware 1_75mm_MK2
static const float DEFAULT_AXIS_MAX_ACCELERATION[] = { 9000.0f, 9000.0f, 500.0f, 10000.0f }; // Prusa Firmware 1_75mm_MK2
static const float DEFAULT_AXIS_MAX_JERK[] = { 10.0f, 10.0f, 0.2f, 2.5f }; // from Prusa Firmware (Configuration.h)
static const float DEFAULT_MINIMUM_FEEDRATE = 0.0f; // from Prusa Firmware (Configuration_adv.h)
static const float DEFAULT_MINIMUM_TRAVEL_FEEDRATE = 0.0f; // from Prusa Firmware (Configuration_adv.h)
static const float DEFAULT_EXTRUDE_FACTOR_OVERRIDE_PERCENTAGE = 1.0f; // 100 percent

static const float PREVIOUS_FEEDRATE_THRESHOLD = 0.0001f;

#if ENABLE_MOVE_STATS
static const std::string MOVE_TYPE_STR[Slic3r::GCodeTimeEstimator::Block::Num_Types] =
{
    "Noop",
    "Retract",
    "Unretract",
    "Tool_change",
    "Move",
    "Extrude"
};
#endif // ENABLE_MOVE_STATS

namespace Slic3r {

    void GCodeTimeEstimator::Feedrates::reset()
    {
        feedrate = 0.0f;
        safe_feedrate = 0.0f;
        ::memset(axis_feedrate, 0, Num_Axis * sizeof(float));
        ::memset(abs_axis_feedrate, 0, Num_Axis * sizeof(float));
    }

    float GCodeTimeEstimator::Block::Trapezoid::acceleration_time(float acceleration) const
    {
        return acceleration_time_from_distance(feedrate.entry, accelerate_until, acceleration);
    }

    float GCodeTimeEstimator::Block::Trapezoid::cruise_time() const
    {
        return (feedrate.cruise != 0.0f) ? cruise_distance() / feedrate.cruise : 0.0f;
    }

    float GCodeTimeEstimator::Block::Trapezoid::deceleration_time(float acceleration) const
    {
        return acceleration_time_from_distance(feedrate.cruise, (distance - decelerate_after), -acceleration);
    }

    float GCodeTimeEstimator::Block::Trapezoid::cruise_distance() const
    {
        return decelerate_after - accelerate_until;
    }

    float GCodeTimeEstimator::Block::Trapezoid::acceleration_time_from_distance(float initial_feedrate, float distance, float acceleration)
    {
        return (acceleration != 0.0f) ? (speed_from_distance(initial_feedrate, distance, acceleration) - initial_feedrate) / acceleration : 0.0f;
    }

    float GCodeTimeEstimator::Block::Trapezoid::speed_from_distance(float initial_feedrate, float distance, float acceleration)
    {
        // to avoid invalid negative numbers due to numerical imprecision 
        float value = std::max(0.0f, sqr(initial_feedrate) + 2.0f * acceleration * distance);
        return ::sqrt(value);
    }

    float GCodeTimeEstimator::Block::move_length() const
    {
        float length = ::sqrt(sqr(delta_pos[X]) + sqr(delta_pos[Y]) + sqr(delta_pos[Z]));
        return (length > 0.0f) ? length : std::abs(delta_pos[E]);
    }

    float GCodeTimeEstimator::Block::is_extruder_only_move() const
    {
        return (delta_pos[X] == 0.0f) && (delta_pos[Y] == 0.0f) && (delta_pos[Z] == 0.0f) && (delta_pos[E] != 0.0f);
    }

    float GCodeTimeEstimator::Block::is_travel_move() const
    {
        return delta_pos[E] == 0.0f;
    }

    float GCodeTimeEstimator::Block::acceleration_time() const
    {
        return trapezoid.acceleration_time(acceleration);
    }

    float GCodeTimeEstimator::Block::cruise_time() const
    {
        return trapezoid.cruise_time();
    }

    float GCodeTimeEstimator::Block::deceleration_time() const
    {
        return trapezoid.deceleration_time(acceleration);
    }

    float GCodeTimeEstimator::Block::cruise_distance() const
    {
        return trapezoid.cruise_distance();
    }

    void GCodeTimeEstimator::Block::calculate_trapezoid()
    {
        float distance = move_length();

        trapezoid.distance = distance;
        trapezoid.feedrate = feedrate;

        float accelerate_distance = estimate_acceleration_distance(feedrate.entry, feedrate.cruise, acceleration);
        float decelerate_distance = estimate_acceleration_distance(feedrate.cruise, feedrate.exit, -acceleration);
        float cruise_distance = distance - accelerate_distance - decelerate_distance;

        // Not enough space to reach the nominal feedrate.
        // This means no cruising, and we'll have to use intersection_distance() to calculate when to abort acceleration 
        // and start braking in order to reach the exit_feedrate exactly at the end of this block.
        if (cruise_distance < 0.0f)
        {
            accelerate_distance = clamp(0.0f, distance, intersection_distance(feedrate.entry, feedrate.exit, acceleration, distance));
            cruise_distance = 0.0f;
            trapezoid.feedrate.cruise = Trapezoid::speed_from_distance(feedrate.entry, accelerate_distance, acceleration);
        }

        trapezoid.accelerate_until = accelerate_distance;
        trapezoid.decelerate_after = accelerate_distance + cruise_distance;
    }

    float GCodeTimeEstimator::Block::max_allowable_speed(float acceleration, float target_velocity, float distance)
    {
        // to avoid invalid negative numbers due to numerical imprecision 
        float value = std::max(0.0f, sqr(target_velocity) - 2.0f * acceleration * distance);
        return ::sqrt(value);
    }

    float GCodeTimeEstimator::Block::estimate_acceleration_distance(float initial_rate, float target_rate, float acceleration)
    {
        return (acceleration == 0.0f) ? 0.0f : (sqr(target_rate) - sqr(initial_rate)) / (2.0f * acceleration);
    }

    float GCodeTimeEstimator::Block::intersection_distance(float initial_rate, float final_rate, float acceleration, float distance)
    {
        return (acceleration == 0.0f) ? 0.0f : (2.0f * acceleration * distance - sqr(initial_rate) + sqr(final_rate)) / (4.0f * acceleration);
    }

#if ENABLE_MOVE_STATS
    GCodeTimeEstimator::MoveStats::MoveStats()
        : count(0)
        , time(0.0f)
    {
    }
#endif // ENABLE_MOVE_STATS

    GCodeTimeEstimator::GCodeTimeEstimator()
    {
        reset();
        set_default();
    }

    void GCodeTimeEstimator::calculate_time_from_text(const std::string& gcode)
    {
        reset();

        _parser.parse_buffer(gcode,
            [this](GCodeReader &reader, const GCodeReader::GCodeLine &line)
        { this->_process_gcode_line(reader, line); });

        _calculate_time();

#if ENABLE_MOVE_STATS
        _log_moves_stats();
#endif // ENABLE_MOVE_STATS

        _reset_blocks();
        _reset();
    }

    void GCodeTimeEstimator::calculate_time_from_file(const std::string& file)
    {
        reset();

        _parser.parse_file(file, boost::bind(&GCodeTimeEstimator::_process_gcode_line, this, _1, _2));
        _calculate_time();

#if ENABLE_MOVE_STATS
        _log_moves_stats();
#endif // ENABLE_MOVE_STATS

        _reset_blocks();
        _reset();
    }

    void GCodeTimeEstimator::calculate_time_from_lines(const std::vector<std::string>& gcode_lines)
    {
        reset();

        auto action = [this](GCodeReader &reader, const GCodeReader::GCodeLine &line)
        { this->_process_gcode_line(reader, line); };
        for (const std::string& line : gcode_lines)
            _parser.parse_line(line, action);
        _calculate_time();

#if ENABLE_MOVE_STATS
        _log_moves_stats();
#endif // ENABLE_MOVE_STATS

        _reset_blocks();
        _reset();
    }

    void GCodeTimeEstimator::add_gcode_line(const std::string& gcode_line)
    {
        PROFILE_FUNC();
        _parser.parse_line(gcode_line, 
            [this](GCodeReader &reader, const GCodeReader::GCodeLine &line)
        { this->_process_gcode_line(reader, line); });
    }

    void GCodeTimeEstimator::add_gcode_block(const char *ptr)
    {
        PROFILE_FUNC();
        GCodeReader::GCodeLine gline;
        auto action = [this](GCodeReader &reader, const GCodeReader::GCodeLine &line)
        { this->_process_gcode_line(reader, line); };
        for (; *ptr != 0;) {
            gline.reset();
            ptr = _parser.parse_line(ptr, gline, action);
        }
    }

    void GCodeTimeEstimator::calculate_time()
    {
        PROFILE_FUNC();
        _calculate_time();

#if ENABLE_MOVE_STATS
        _log_moves_stats();
#endif // ENABLE_MOVE_STATS

        _reset_blocks();
        _reset();
    }

    void GCodeTimeEstimator::set_axis_position(EAxis axis, float position)
    {
        _state.axis[axis].position = position;
    }

    void GCodeTimeEstimator::set_axis_max_feedrate(EAxis axis, float feedrate_mm_sec)
    {
        _state.axis[axis].max_feedrate = feedrate_mm_sec;
    }

    void GCodeTimeEstimator::set_axis_max_acceleration(EAxis axis, float acceleration)
    {
        _state.axis[axis].max_acceleration = acceleration;
    }

    void GCodeTimeEstimator::set_axis_max_jerk(EAxis axis, float jerk)
    {
        _state.axis[axis].max_jerk = jerk;
    }

    float GCodeTimeEstimator::get_axis_position(EAxis axis) const
    {
        return _state.axis[axis].position;
    }

    float GCodeTimeEstimator::get_axis_max_feedrate(EAxis axis) const
    {
        return _state.axis[axis].max_feedrate;
    }

    float GCodeTimeEstimator::get_axis_max_acceleration(EAxis axis) const
    {
        return _state.axis[axis].max_acceleration;
    }

    float GCodeTimeEstimator::get_axis_max_jerk(EAxis axis) const
    {
        return _state.axis[axis].max_jerk;
    }

    void GCodeTimeEstimator::set_feedrate(float feedrate_mm_sec)
    {
        _state.feedrate = feedrate_mm_sec;
    }

    float GCodeTimeEstimator::get_feedrate() const
    {
        return _state.feedrate;
    }

    void GCodeTimeEstimator::set_acceleration(float acceleration_mm_sec2)
    {
        _state.acceleration = acceleration_mm_sec2;
    }

    float GCodeTimeEstimator::get_acceleration() const
    {
        return _state.acceleration;
    }

    void GCodeTimeEstimator::set_retract_acceleration(float acceleration_mm_sec2)
    {
        _state.retract_acceleration = acceleration_mm_sec2;
    }

    float GCodeTimeEstimator::get_retract_acceleration() const
    {
        return _state.retract_acceleration;
    }

    void GCodeTimeEstimator::set_minimum_feedrate(float feedrate_mm_sec)
    {
        _state.minimum_feedrate = feedrate_mm_sec;
    }

    float GCodeTimeEstimator::get_minimum_feedrate() const
    {
        return _state.minimum_feedrate;
    }

    void GCodeTimeEstimator::set_minimum_travel_feedrate(float feedrate_mm_sec)
    {
        _state.minimum_travel_feedrate = feedrate_mm_sec;
    }

    float GCodeTimeEstimator::get_minimum_travel_feedrate() const
    {
        return _state.minimum_travel_feedrate;
    }

    void GCodeTimeEstimator::set_extrude_factor_override_percentage(float percentage)
    {
        _state.extrude_factor_override_percentage = percentage;
    }

    float GCodeTimeEstimator::get_extrude_factor_override_percentage() const
    {
        return _state.extrude_factor_override_percentage;
    }

    void GCodeTimeEstimator::set_dialect(GCodeFlavor dialect)
    {
        _state.dialect = dialect;
    }

    GCodeFlavor GCodeTimeEstimator::get_dialect() const
    {
        return _state.dialect;
    }

    void GCodeTimeEstimator::set_units(GCodeTimeEstimator::EUnits units)
    {
        _state.units = units;
    }

    GCodeTimeEstimator::EUnits GCodeTimeEstimator::get_units() const
    {
        return _state.units;
    }

    void GCodeTimeEstimator::set_global_positioning_type(GCodeTimeEstimator::EPositioningType type)
    {
        _state.global_positioning_type = type;
    }

    GCodeTimeEstimator::EPositioningType GCodeTimeEstimator::get_global_positioning_type() const
    {
        return _state.global_positioning_type;
    }

    void GCodeTimeEstimator::set_e_local_positioning_type(GCodeTimeEstimator::EPositioningType type)
    {
        _state.e_local_positioning_type = type;
    }

    GCodeTimeEstimator::EPositioningType GCodeTimeEstimator::get_e_local_positioning_type() const
    {
        return _state.e_local_positioning_type;
    }

    void GCodeTimeEstimator::add_additional_time(float timeSec)
    {
        _state.additional_time += timeSec;
    }

    void GCodeTimeEstimator::set_additional_time(float timeSec)
    {
        _state.additional_time = timeSec;
    }

    float GCodeTimeEstimator::get_additional_time() const
    {
        return _state.additional_time;
    }

    void GCodeTimeEstimator::set_default()
    {
        set_units(Millimeters);
        set_dialect(gcfRepRap);
        set_global_positioning_type(Absolute);
        set_e_local_positioning_type(Absolute);

        set_feedrate(DEFAULT_FEEDRATE);
        set_acceleration(DEFAULT_ACCELERATION);
        set_retract_acceleration(DEFAULT_RETRACT_ACCELERATION);
        set_minimum_feedrate(DEFAULT_MINIMUM_FEEDRATE);
        set_minimum_travel_feedrate(DEFAULT_MINIMUM_TRAVEL_FEEDRATE);
        set_extrude_factor_override_percentage(DEFAULT_EXTRUDE_FACTOR_OVERRIDE_PERCENTAGE);

        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            EAxis axis = (EAxis)a;
            set_axis_max_feedrate(axis, DEFAULT_AXIS_MAX_FEEDRATE[a]);
            set_axis_max_acceleration(axis, DEFAULT_AXIS_MAX_ACCELERATION[a]);
            set_axis_max_jerk(axis, DEFAULT_AXIS_MAX_JERK[a]);
        }
    }

    void GCodeTimeEstimator::reset()
    {
        _time = 0.0f;
#if ENABLE_MOVE_STATS
        _moves_stats.clear();
#endif // ENABLE_MOVE_STATS
        _reset_blocks();
        _reset();
    }

    float GCodeTimeEstimator::get_time() const
    {
        return _time;
    }

    std::string GCodeTimeEstimator::get_time_hms() const
    {
        float timeinsecs = get_time();
        int hours = (int)(timeinsecs / 3600.0f);
        timeinsecs -= (float)hours * 3600.0f;
        int minutes = (int)(timeinsecs / 60.0f);
        timeinsecs -= (float)minutes * 60.0f;

        char buffer[64];
        if (hours > 0)
            ::sprintf(buffer, "%dh %dm %ds", hours, minutes, (int)timeinsecs);
        else if (minutes > 0)
            ::sprintf(buffer, "%dm %ds", minutes, (int)timeinsecs);
        else
            ::sprintf(buffer, "%ds", (int)timeinsecs);

        return buffer;
    }

    void GCodeTimeEstimator::_reset()
    {
        _curr.reset();
        _prev.reset();

        set_axis_position(X, 0.0f);
        set_axis_position(Y, 0.0f);
        set_axis_position(Z, 0.0f);

        set_additional_time(0.0f);
    }

    void GCodeTimeEstimator::_reset_blocks()
    {
        _blocks.clear();
    }

    void GCodeTimeEstimator::_calculate_time()
    {
        _forward_pass();
        _reverse_pass();
        _recalculate_trapezoids();

        _time += get_additional_time();

        for (const Block& block : _blocks)
        {
#if ENABLE_MOVE_STATS
            float block_time = 0.0f;
            block_time += block.acceleration_time();
            block_time += block.cruise_time();
            block_time += block.deceleration_time();
            _time += block_time;

            MovesStatsMap::iterator it = _moves_stats.find(block.move_type);
            if (it == _moves_stats.end())
                it = _moves_stats.insert(MovesStatsMap::value_type(block.move_type, MoveStats())).first;

            it->second.count += 1;
            it->second.time += block_time;
#else
            _time += block.acceleration_time();
            _time += block.cruise_time();
            _time += block.deceleration_time();
#endif // ENABLE_MOVE_STATS
        }
    }

    void GCodeTimeEstimator::_process_gcode_line(GCodeReader&, const GCodeReader::GCodeLine& line)
    {
        PROFILE_FUNC();
        std::string cmd = line.cmd();
        if (cmd.length() > 1)
        {
            switch (::toupper(cmd[0]))
            {
            case 'G':
                {
                    switch (::atoi(&cmd[1]))
                    {
                    case 1: // Move
                        {
                            _processG1(line);
                            break;
                        }
                    case 4: // Dwell
                        {
                            _processG4(line);
                            break;
                        }
                    case 20: // Set Units to Inches
                        {
                            _processG20(line);
                            break;
                        }
                    case 21: // Set Units to Millimeters
                        {
                            _processG21(line);
                            break;
                        }
                    case 28: // Move to Origin (Home)
                        {
                            _processG28(line);
                            break;
                        }
                    case 90: // Set to Absolute Positioning
                        {
                            _processG90(line);
                            break;
                        }
                    case 91: // Set to Relative Positioning
                        {
                            _processG91(line);
                            break;
                        }
                    case 92: // Set Position
                        {
                            _processG92(line);
                            break;
                        }
                    }

                    break;
                }
            case 'M':
                {
                    switch (::atoi(&cmd[1]))
                    {
                    case 1: // Sleep or Conditional stop
                        {
                            _processM1(line);
                            break;
                        }
                    case 82: // Set extruder to absolute mode
                        {
                            _processM82(line);
                            break;
                        }
                    case 83: // Set extruder to relative mode
                        {
                            _processM83(line);
                            break;
                        }
                    case 109: // Set Extruder Temperature and Wait
                        {
                            _processM109(line);
                            break;
                        }
                    case 201: // Set max printing acceleration
                        {
                            _processM201(line);
                            break;
                        }
                    case 203: // Set maximum feedrate
                        {
                            _processM203(line);
                            break;
                        }
                    case 204: // Set default acceleration
                        {
                            _processM204(line);
                            break;
                        }
                    case 205: // Advanced settings
                        {
                            _processM205(line);
                            break;
                        }
                    case 221: // Set extrude factor override percentage
                        {
                            _processM221(line);
                            break;
                        }
                    case 566: // Set allowable instantaneous speed change
                        {
                            _processM566(line);
                            break;
                        }
                    }

                    break;
                }
            }
        }
    }

    // Returns the new absolute position on the given axis in dependence of the given parameters
    float axis_absolute_position_from_G1_line(GCodeTimeEstimator::EAxis axis, const GCodeReader::GCodeLine& lineG1, GCodeTimeEstimator::EUnits units, bool is_relative, float current_absolute_position)
    {
        float lengthsScaleFactor = (units == GCodeTimeEstimator::Inches) ? INCHES_TO_MM : 1.0f;
        if (lineG1.has(Slic3r::Axis(axis)))
        {
            float ret = lineG1.value(Slic3r::Axis(axis)) * lengthsScaleFactor;
            return is_relative ? current_absolute_position + ret : ret;
        }
        else
            return current_absolute_position;
    }

    void GCodeTimeEstimator::_processG1(const GCodeReader::GCodeLine& line)
    {
        // updates axes positions from line
        EUnits units = get_units();
        float new_pos[Num_Axis];
        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            bool is_relative = (get_global_positioning_type() == Relative);
            if (a == E)
                is_relative |= (get_e_local_positioning_type() == Relative);

            new_pos[a] = axis_absolute_position_from_G1_line((EAxis)a, line, units, is_relative, get_axis_position((EAxis)a));
        }

        // updates feedrate from line, if present
        if (line.has_f())
            set_feedrate(std::max(line.f() * MMMIN_TO_MMSEC, get_minimum_feedrate()));

        // fills block data
        Block block;

        // calculates block movement deltas
        float max_abs_delta = 0.0f;
        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            block.delta_pos[a] = new_pos[a] - get_axis_position((EAxis)a);
            max_abs_delta = std::max(max_abs_delta, std::abs(block.delta_pos[a]));
        }

        // is it a move ?
        if (max_abs_delta == 0.0f)
            return;

        // calculates block feedrate
        _curr.feedrate = std::max(get_feedrate(), block.is_travel_move() ? get_minimum_travel_feedrate() : get_minimum_feedrate());

        float distance = block.move_length();
        float invDistance = 1.0f / distance;

        float min_feedrate_factor = 1.0f;
        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            _curr.axis_feedrate[a] = _curr.feedrate * block.delta_pos[a] * invDistance;
            if (a == E)
                _curr.axis_feedrate[a] *= get_extrude_factor_override_percentage();

            _curr.abs_axis_feedrate[a] = std::abs(_curr.axis_feedrate[a]);
            if (_curr.abs_axis_feedrate[a] > 0.0f)
                min_feedrate_factor = std::min(min_feedrate_factor, get_axis_max_feedrate((EAxis)a) / _curr.abs_axis_feedrate[a]);
        }
    
        block.feedrate.cruise = min_feedrate_factor * _curr.feedrate;

        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            _curr.axis_feedrate[a] *= min_feedrate_factor;
            _curr.abs_axis_feedrate[a] *= min_feedrate_factor;
        }

        // calculates block acceleration
        float acceleration = block.is_extruder_only_move() ? get_retract_acceleration() : get_acceleration();

        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            float axis_max_acceleration = get_axis_max_acceleration((EAxis)a);
            if (acceleration * std::abs(block.delta_pos[a]) * invDistance > axis_max_acceleration)
                acceleration = axis_max_acceleration;
        }

        block.acceleration = acceleration;

        // calculates block exit feedrate
        _curr.safe_feedrate = block.feedrate.cruise;

        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            float axis_max_jerk = get_axis_max_jerk((EAxis)a);
            if (_curr.abs_axis_feedrate[a] > axis_max_jerk)
                _curr.safe_feedrate = std::min(_curr.safe_feedrate, axis_max_jerk);
        }

        block.feedrate.exit = _curr.safe_feedrate;

        // calculates block entry feedrate
        float vmax_junction = _curr.safe_feedrate;
        if (!_blocks.empty() && (_prev.feedrate > PREVIOUS_FEEDRATE_THRESHOLD))
        {
            bool prev_speed_larger = _prev.feedrate > block.feedrate.cruise;
            float smaller_speed_factor = prev_speed_larger ? (block.feedrate.cruise / _prev.feedrate) : (_prev.feedrate / block.feedrate.cruise);
            // Pick the smaller of the nominal speeds. Higher speed shall not be achieved at the junction during coasting.
            vmax_junction = prev_speed_larger ? block.feedrate.cruise : _prev.feedrate;

            float v_factor = 1.0f;
            bool limited = false;

            for (unsigned char a = X; a < Num_Axis; ++a)
            {
                // Limit an axis. We have to differentiate coasting from the reversal of an axis movement, or a full stop.
                float v_exit = _prev.axis_feedrate[a];
                float v_entry = _curr.axis_feedrate[a];

                if (prev_speed_larger)
                    v_exit *= smaller_speed_factor;

                if (limited)
                {
                    v_exit *= v_factor;
                    v_entry *= v_factor;
                }

                // Calculate the jerk depending on whether the axis is coasting in the same direction or reversing a direction.
                float jerk =
                    (v_exit > v_entry) ?
                    (((v_entry > 0.0f) || (v_exit < 0.0f)) ?
                    // coasting
                    (v_exit - v_entry) :
                    // axis reversal
                    std::max(v_exit, -v_entry)) :
                    // v_exit <= v_entry
                    (((v_entry < 0.0f) || (v_exit > 0.0f)) ?
                    // coasting
                    (v_entry - v_exit) :
                    // axis reversal
                    std::max(-v_exit, v_entry));

                float axis_max_jerk = get_axis_max_jerk((EAxis)a);
                if (jerk > axis_max_jerk)
                {
                    v_factor *= axis_max_jerk / jerk;
                    limited = true;
                }
            }

            if (limited)
                vmax_junction *= v_factor;

            // Now the transition velocity is known, which maximizes the shared exit / entry velocity while
            // respecting the jerk factors, it may be possible, that applying separate safe exit / entry velocities will achieve faster prints.
            float vmax_junction_threshold = vmax_junction * 0.99f;

            // Not coasting. The machine will stop and start the movements anyway, better to start the segment from start.
            if ((_prev.safe_feedrate > vmax_junction_threshold) && (_curr.safe_feedrate > vmax_junction_threshold))
                vmax_junction = _curr.safe_feedrate;
        }

        float v_allowable = Block::max_allowable_speed(-acceleration, _curr.safe_feedrate, distance);
        block.feedrate.entry = std::min(vmax_junction, v_allowable);

        block.max_entry_speed = vmax_junction;
        block.flags.nominal_length = (block.feedrate.cruise <= v_allowable);
        block.flags.recalculate = true;
        block.safe_feedrate = _curr.safe_feedrate;

        // calculates block trapezoid
        block.calculate_trapezoid();

        // updates previous
        _prev = _curr;

        // updates axis positions
        for (unsigned char a = X; a < Num_Axis; ++a)
        {
            set_axis_position((EAxis)a, new_pos[a]);
        }

#if ENABLE_MOVE_STATS
        // detects block move type
        block.move_type = Block::Noop;

        if (block.delta_pos[E] < 0.0f)
        {
            if ((block.delta_pos[X] != 0.0f) || (block.delta_pos[Y] != 0.0f) || (block.delta_pos[Z] != 0.0f))
                block.move_type = Block::Move;
            else
                block.move_type = Block::Retract;
        }
        else if (block.delta_pos[E] > 0.0f)
        {
            if ((block.delta_pos[X] == 0.0f) && (block.delta_pos[Y] == 0.0f) && (block.delta_pos[Z] == 0.0f))
                block.move_type = Block::Unretract;
            else if ((block.delta_pos[X] != 0.0f) || (block.delta_pos[Y] != 0.0f))
                block.move_type = Block::Extrude;
        }
        else if ((block.delta_pos[X] != 0.0f) || (block.delta_pos[Y] != 0.0f) || (block.delta_pos[Z] != 0.0f))
            block.move_type = Block::Move;
#endif // ENABLE_MOVE_STATS

        // adds block to blocks list
        _blocks.emplace_back(block);
    }

    void GCodeTimeEstimator::_processG4(const GCodeReader::GCodeLine& line)
    {
        GCodeFlavor dialect = get_dialect();

        float value;
        if (line.has_value('P', value))
            add_additional_time(value * MILLISEC_TO_SEC);

        // see: http://reprap.org/wiki/G-code#G4:_Dwell
        if ((dialect == gcfRepetier) ||
            (dialect == gcfMarlin) ||
            (dialect == gcfSmoothie) ||
            (dialect == gcfRepRap))
        {
            if (line.has_value('S', value))
                add_additional_time(value);
        }

        _simulate_st_synchronize();
    }

    void GCodeTimeEstimator::_processG20(const GCodeReader::GCodeLine& line)
    {
        set_units(Inches);
    }

    void GCodeTimeEstimator::_processG21(const GCodeReader::GCodeLine& line)
    {
        set_units(Millimeters);
    }

    void GCodeTimeEstimator::_processG28(const GCodeReader::GCodeLine& line)
    {
        // TODO
    }

    void GCodeTimeEstimator::_processG90(const GCodeReader::GCodeLine& line)
    {
        set_global_positioning_type(Absolute);
    }

    void GCodeTimeEstimator::_processG91(const GCodeReader::GCodeLine& line)
    {
        set_global_positioning_type(Relative);
    }

    void GCodeTimeEstimator::_processG92(const GCodeReader::GCodeLine& line)
    {
        float lengthsScaleFactor = (get_units() == Inches) ? INCHES_TO_MM : 1.0f;
        bool anyFound = false;

        if (line.has_x())
        {
            set_axis_position(X, line.x() * lengthsScaleFactor);
            anyFound = true;
        }

        if (line.has_y())
        {
            set_axis_position(Y, line.y() * lengthsScaleFactor);
            anyFound = true;
        }

        if (line.has_z())
        {
            set_axis_position(Z, line.z() * lengthsScaleFactor);
            anyFound = true;
        }

        if (line.has_e())
        {
            set_axis_position(E, line.e() * lengthsScaleFactor);
            anyFound = true;
        }
        else
            _simulate_st_synchronize();

        if (!anyFound)
        {
            for (unsigned char a = X; a < Num_Axis; ++a)
            {
                set_axis_position((EAxis)a, 0.0f);
            }
        }
    }

    void GCodeTimeEstimator::_processM1(const GCodeReader::GCodeLine& line)
    {
        _simulate_st_synchronize();
    }

    void GCodeTimeEstimator::_processM82(const GCodeReader::GCodeLine& line)
    {
        set_e_local_positioning_type(Absolute);
    }

    void GCodeTimeEstimator::_processM83(const GCodeReader::GCodeLine& line)
    {
        set_e_local_positioning_type(Relative);
    }

    void GCodeTimeEstimator::_processM109(const GCodeReader::GCodeLine& line)
    {
        // TODO
    }

    void GCodeTimeEstimator::_processM201(const GCodeReader::GCodeLine& line)
    {
        GCodeFlavor dialect = get_dialect();

        // see http://reprap.org/wiki/G-code#M201:_Set_max_printing_acceleration
        float factor = ((dialect != gcfRepRap) && (get_units() == GCodeTimeEstimator::Inches)) ? INCHES_TO_MM : 1.0f;

        if (line.has_x())
            set_axis_max_acceleration(X, line.x() * factor);

        if (line.has_y())
            set_axis_max_acceleration(Y, line.y() * factor);

        if (line.has_z())
            set_axis_max_acceleration(Z, line.z() * factor);

        if (line.has_e())
            set_axis_max_acceleration(E, line.e() * factor);
    }

    void GCodeTimeEstimator::_processM203(const GCodeReader::GCodeLine& line)
    {
        GCodeFlavor dialect = get_dialect();

        // see http://reprap.org/wiki/G-code#M203:_Set_maximum_feedrate
        if (dialect == gcfRepetier)
            return;

        // see http://reprap.org/wiki/G-code#M203:_Set_maximum_feedrate
        float factor = (dialect == gcfMarlin) ? 1.0f : MMMIN_TO_MMSEC;

        if (line.has_x())
            set_axis_max_feedrate(X, line.x() * factor);

        if (line.has_y())
            set_axis_max_feedrate(Y, line.y() * factor);

        if (line.has_z())
            set_axis_max_feedrate(Z, line.z() * factor);

        if (line.has_e())
            set_axis_max_feedrate(E, line.e() * factor);
    }

    void GCodeTimeEstimator::_processM204(const GCodeReader::GCodeLine& line)
    {
        float value;
        if (line.has_value('S', value))
            set_acceleration(value);

        if (line.has_value('T', value))
            set_retract_acceleration(value);
    }

    void GCodeTimeEstimator::_processM205(const GCodeReader::GCodeLine& line)
    {
        if (line.has_x())
        {
            float max_jerk = line.x();
            set_axis_max_jerk(X, max_jerk);
            set_axis_max_jerk(Y, max_jerk);
        }

        if (line.has_y())
            set_axis_max_jerk(Y, line.y());

        if (line.has_z())
            set_axis_max_jerk(Z, line.z());

        if (line.has_e())
            set_axis_max_jerk(E, line.e());

        float value;
        if (line.has_value('S', value))
            set_minimum_feedrate(value);

        if (line.has_value('T', value))
            set_minimum_travel_feedrate(value);
    }

    void GCodeTimeEstimator::_processM221(const GCodeReader::GCodeLine& line)
    {
        float value_s;
        float value_t;
        if (line.has_value('S', value_s) && !line.has_value('T', value_t))
            set_extrude_factor_override_percentage(value_s * 0.01f);
    }

    void GCodeTimeEstimator::_processM566(const GCodeReader::GCodeLine& line)
    {
        if (line.has_x())
            set_axis_max_jerk(X, line.x() * MMMIN_TO_MMSEC);

        if (line.has_y())
            set_axis_max_jerk(Y, line.y() * MMMIN_TO_MMSEC);

        if (line.has_z())
            set_axis_max_jerk(Z, line.z() * MMMIN_TO_MMSEC);

        if (line.has_e())
            set_axis_max_jerk(E, line.e() * MMMIN_TO_MMSEC);
    }

    void GCodeTimeEstimator::_simulate_st_synchronize()
    {
        _calculate_time();
        _reset_blocks();
    }

    void GCodeTimeEstimator::_forward_pass()
    {
        if (_blocks.size() > 1)
        {
            for (unsigned int i = 0; i < (unsigned int)_blocks.size() - 1; ++i)
            {
                _planner_forward_pass_kernel(_blocks[i], _blocks[i + 1]);
            }
        }
    }

    void GCodeTimeEstimator::_reverse_pass()
    {
        if (_blocks.size() > 1)
        {
            for (int i = (int)_blocks.size() - 1; i >= 1;  --i)
            {
                _planner_reverse_pass_kernel(_blocks[i - 1], _blocks[i]);
            }
        }
    }

    void GCodeTimeEstimator::_planner_forward_pass_kernel(Block& prev, Block& curr)
    {
        // If the previous block is an acceleration block, but it is not long enough to complete the
        // full speed change within the block, we need to adjust the entry speed accordingly. Entry
        // speeds have already been reset, maximized, and reverse planned by reverse planner.
        // If nominal length is true, max junction speed is guaranteed to be reached. No need to recheck.
        if (!prev.flags.nominal_length)
        {
            if (prev.feedrate.entry < curr.feedrate.entry)
            {
                float entry_speed = std::min(curr.feedrate.entry, Block::max_allowable_speed(-prev.acceleration, prev.feedrate.entry, prev.move_length()));

                // Check for junction speed change
                if (curr.feedrate.entry != entry_speed)
                {
                    curr.feedrate.entry = entry_speed;
                    curr.flags.recalculate = true;
                }
            }
        }
    }

    void GCodeTimeEstimator::_planner_reverse_pass_kernel(Block& curr, Block& next)
    {
        // If entry speed is already at the maximum entry speed, no need to recheck. Block is cruising.
        // If not, block in state of acceleration or deceleration. Reset entry speed to maximum and
        // check for maximum allowable speed reductions to ensure maximum possible planned speed.
        if (curr.feedrate.entry != curr.max_entry_speed)
        {
            // If nominal length true, max junction speed is guaranteed to be reached. Only compute
            // for max allowable speed if block is decelerating and nominal length is false.
            if (!curr.flags.nominal_length && (curr.max_entry_speed > next.feedrate.entry))
                curr.feedrate.entry = std::min(curr.max_entry_speed, Block::max_allowable_speed(-curr.acceleration, next.feedrate.entry, curr.move_length()));
            else
                curr.feedrate.entry = curr.max_entry_speed;

            curr.flags.recalculate = true;
        }
    }

    void GCodeTimeEstimator::_recalculate_trapezoids()
    {
        Block* curr = nullptr;
        Block* next = nullptr;

        for (Block& b : _blocks)
        {
            curr = next;
            next = &b;

            if (curr != nullptr)
            {
                // Recalculate if current block entry or exit junction speed has changed.
                if (curr->flags.recalculate || next->flags.recalculate)
                {
                    // NOTE: Entry and exit factors always > 0 by all previous logic operations.
                    Block block = *curr;
                    block.feedrate.exit = next->feedrate.entry;
                    block.calculate_trapezoid();
                    curr->trapezoid = block.trapezoid;
                    curr->flags.recalculate = false; // Reset current only to ensure next trapezoid is computed
                }
            }
        }

        // Last/newest block in buffer. Always recalculated.
        if (next != nullptr)
        {
            Block block = *next;
            block.feedrate.exit = next->safe_feedrate;
            block.calculate_trapezoid();
            next->trapezoid = block.trapezoid;
            next->flags.recalculate = false;
        }
    }

#if ENABLE_MOVE_STATS
    void GCodeTimeEstimator::_log_moves_stats() const
    {
        float moves_count = 0.0f;
        for (const MovesStatsMap::value_type& move : _moves_stats)
        {
            moves_count += (float)move.second.count;
        }

        for (const MovesStatsMap::value_type& move : _moves_stats)
        {
            std::cout << MOVE_TYPE_STR[move.first];
            std::cout << ": count " << move.second.count << " (" << 100.0f * (float)move.second.count / moves_count << "%)";
            std::cout << " - time: " << move.second.time << "s (" << 100.0f * move.second.time / _time << "%)";
            std::cout << std::endl;
        }
        std::cout << std::endl;
    }
#endif // ENABLE_MOVE_STATS
}