/* Distributed under the Apache License, Version 2.0.
   See accompanying NOTICE file for details.*/

#include "stdafx.h"
#include "physiology/Energy.h"
#include "controller/Circuits.h"
#include "controller/Compartments.h"
#include "controller/Substances.h"
#include "PulseConfiguration.h"
// Conditions
#include "engine/SEConditionManager.h"
#include "patient/conditions/SEConsumeMeal.h"
// Actions
#include "engine/SEActionManager.h"
#include "engine/SEPatientActionCollection.h"
#include "patient/actions/SEExercise.h"
// Dependent Systems
#include "system/physiology/SEBloodChemistrySystem.h"
#include "system/physiology/SECardiovascularSystem.h"
// CDM
#include "patient/SEPatient.h"
#include "patient/SEMeal.h"
#include "patient/SENutrition.h"
#include "circuit/fluid/SEFluidCircuit.h"
#include "circuit/thermal/SEThermalCircuit.h"
#include "circuit/thermal/SEThermalCircuitNode.h"
#include "circuit/thermal/SEThermalCircuitPath.h"
#include "circuit/thermal/SEThermalCircuitCalculator.h"
#include "compartment/fluid/SELiquidCompartment.h"
#include "compartment/substances/SELiquidSubstanceQuantity.h"
#include "properties/SEScalar0To1.h"
#include "properties/SEScalarLength.h"
#include "properties/SEScalarMass.h"
#include "properties/SEScalarMassPerTime.h"
#include "properties/SEScalarPower.h"
#include "properties/SEScalarTemperature.h"
#include "properties/SEScalarArea.h"
#include "properties/SEScalarHeatCapacitancePerMass.h"
#include "properties/SEScalarHeatCapacitance.h"
#include "properties/SEScalarVolumePerTime.h"
#include "properties/SEScalarVolume.h"
#include "properties/SEScalarMassPerVolume.h"
#include "properties/SEScalarHeatResistance.h"
#include "properties/SEScalarHeatConductance.h"
#include "properties/SEScalarEnergyPerMass.h"
#include "properties/SEScalarEnergy.h"
#include "properties/SEScalar0To1.h"
#include "properties/SEScalarEnergyPerAmount.h"
#include "properties/SEScalarAmountPerVolume.h"
#include "properties/SEScalarAmountPerTime.h"
#include "properties/SEScalarPressure.h"
#include "properties/SEScalarFlowResistance.h"
#include "properties/SEScalarFlowCompliance.h"
#include "properties/SEScalarAmountPerTime.h"
#include "properties/SEScalarTime.h"
#include "properties/SEScalarVolumePerTimeMass.h"
#include "properties/SERunningAverage.h"

Energy::Energy(PulseController& data) : SEEnergySystem(data.GetLogger()), m_data(data)
{
  m_BloodpH = new SERunningAverage();
  m_BicarbonateMolarity_mmol_Per_L = new SERunningAverage();
  m_circuitCalculator = new SEThermalCircuitCalculator(GetLogger());
  Clear();
}

Energy::~Energy()
{
  Clear();
  delete m_BloodpH;
  delete m_BicarbonateMolarity_mmol_Per_L;
}

void Energy::Clear()
{
  SEEnergySystem::Clear();
  m_Patient = nullptr;
  m_AortaHCO3 = nullptr;
  m_coreNode = nullptr;
  m_skinNode = nullptr;
  m_temperatureGroundToCorePath = nullptr;
  m_coreToSkinPath = nullptr;
  m_skinExtravascularToSweatingGroundPath = nullptr;
  m_InternalTemperatureCircuit = nullptr;
  m_TemperatureCircuit = nullptr;

  m_BloodpH->Clear();
  m_BicarbonateMolarity_mmol_Per_L->Clear();
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Initializes system properties to valid homeostatic values.
//--------------------------------------------------------------------------------------------------
void Energy::Initialize()
{
  PulseSystem::Initialize();

  GetTotalMetabolicRate().Set(m_Patient->GetBasalMetabolicRate());
  //Initialization of other system variables
  /// \cite herman2008physics
  GetCoreTemperature().SetValue(37.0, TemperatureUnit::C);
  GetSkinTemperature().SetValue(33.0, TemperatureUnit::C);  
  /// \cite phypers2006lactate
  GetLactateProductionRate().SetValue(1.3, AmountPerTimeUnit::mol_Per_day);
  /// \cite garber1974ketone
  GetKetoneProductionRate().SetValue(300.0, AmountPerTimeUnit::umol_Per_min);
  /// \cite guyton2006medical
  GetExerciseMeanArterialPressureDelta().SetValue(0.0, PressureUnit::mmHg);
  GetTotalWorkRateLevel().SetValue(0.0);
  GetFatigueLevel().SetValue(0.0);

  //Running average quantities used to trigger events
  m_BloodpH->Sample(7.4); //Initialize
  m_BicarbonateMolarity_mmol_Per_L->Sample(24.0); //Initialize

  // Energy buckets for fatigue
  m_UsableEnergyStore_J = 2600.0;
  m_PeakPowerEnergyStore_J = 4200.0;
  m_MediumPowerEnergyStore_J = 35000.0;
  m_EnduranceEnergyStore_J = 400000.0;
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Initializes the energy specific quantities
///
/// \details
/// The energy local member variables, system level quantities, and metabolic-specific substance
/// quantities are initialized here. These variables are used in the numerous metabolic and thermal regulation
/// functions contained in the energy system. Encompassing them in this function allows for easy initialization
/// either at the beginning of a simulation or after a system crash
//--------------------------------------------------------------------------------------------------
void Energy::SetUp()
{
  m_dT_s = m_data.GetTimeStep().GetValue(TimeUnit::s);
  m_Patient = &m_data.GetPatient();

  m_AortaHCO3 = m_data.GetCompartments().GetLiquidCompartment(pulse::VascularCompartment::Aorta)->GetSubstanceQuantity(m_data.GetSubstances().GetHCO3());

  //Circuit elements
  //Circuits
  m_TemperatureCircuit = &m_data.GetCircuits().GetTemperatureCircuit();
  m_InternalTemperatureCircuit = &m_data.GetCircuits().GetInternalTemperatureCircuit();
  //Nodes
  m_coreNode = m_InternalTemperatureCircuit->GetNode(pulse::InternalTemperatureNode::InternalCore);
  m_skinNode = m_InternalTemperatureCircuit->GetNode(pulse::InternalTemperatureNode::InternalSkin);
  //Paths
  m_temperatureGroundToCorePath = m_InternalTemperatureCircuit->GetPath(pulse::InternalTemperaturePath::GroundToInternalCore);
  m_coreToSkinPath = m_InternalTemperatureCircuit->GetPath(pulse::InternalTemperaturePath::InternalCoreToInternalSkin);
  m_skinExtravascularToSweatingGroundPath = m_data.GetCircuits().GetActiveCardiovascularCircuit().GetPath(pulse::TissuePath::SkinSweating);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Applies an imposed dehydration time to the current fluid stores
///
/// \details
/// Starvation uses a coarse time-step approach with an assumed time-step of one day. This coarse time-step
/// is used to to manually decrement all of the fluid stores which represents the loss due to urination, sweating, and other mechanisms.
/// For time-steps longer than one day there is a reduced fluid loss.
//--------------------------------------------------------------------------------------------------
//void Energy::Dehydration(double time)
//{
//  Warning("Consume Dehydration is currently disabled.");
//  return;
//  //Fluid loss is approximately 2600 mL/day. Shirreffs SM. Markers of hydration status. J Sports Med Phys Fitness 2000;40:80-4. 
//  //After the first day without fluid intake, the renal loss decreases by 1000 mL leading to a total fluid loss of 1600 mL/day after day one.
//  double fluidLossRate_mL_Per_day = 2600;
//  double fluidLossRate_mL_Per_day2 = 1600;
//  double coarseTimeStep_days = time;
//  double fluidLoss_mL = 0.0;
//
//  if (coarseTimeStep_days<0.0)
//    /// \error Cannot specify elapsed time less than zero in the consume meal action.
//    Error("Cannot specify a negative time since last meal. Time since last meal is now set to zero.");
//
//  if (coarseTimeStep_days > 1.0)
//    fluidLoss_mL = fluidLossRate_mL_Per_day + fluidLossRate_mL_Per_day2*(coarseTimeStep_days - 1.0);
//  else
//    fluidLoss_mL = fluidLossRate_mL_Per_day*coarseTimeStep_days;
//
//  SEScalarVolume fluidDehydrated;
//  fluidDehydrated.SetValue(-fluidLoss_mL, VolumeUnit::mL);
//
//  // How do we take fluid from the body m_data.GetCircuits().DistributeVolume(fluidDehydrated);
//
//  //Patient weight decrease due to fluid mass lost
//  double patientMassLost_kg = m_data.GetConfiguration().GetWaterDensity(MassPerVolumeUnit::kg_Per_mL)*fluidLoss_mL;
//  m_Patient->GetWeight().IncrementValue(-patientMassLost_kg, MassUnit::kg);
//}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Applies an imposed starvation time to the current nutrient stores
///
/// \details
/// Starvation uses a coarse time-step approach with an assumed time-step of one day. This coarse time-step
/// is used to to manually decrement all of the nutrient stores which represents the loss due to metabolic consumption.
/// For time durations greater than one day, there is a decrease in the basal metabolic rate due to mass loss from increased
/// starvation times.
//--------------------------------------------------------------------------------------------------
// Starvation currently disabled
//void Energy::Starvation(double time)
//{
//  if (time < 1.0) //Less than one day without food. Decrement according to consumption/production methodology
//  {
//    //CalculateNutrientConsumptionAndProduction(Convert(time, TimeUnit::day, TimeUnit::s)); //TODO:: Add in clearances if they are needed
//    //BalanceSubstances();
//  }
//  else
//  {
//    unsigned int numTimeSteps = (int)time;
//    double deltaT_days = 1.0;
//    for (unsigned int iStep = 0; iStep < numTimeSteps; iStep++)
//    {
//      CalculateNutrientConsumptionAndProduction(Convert(deltaT_days, TimeUnit::day, TimeUnit::s));
//      CalculateBasalMetabolicRate();
//      GetTotalMetabolicRate().SetValue(m_PatientBMR_kcal_Per_day, PowerUnit::kcal_Per_day); //Metabolic rate decrease due to reduction in body mass
//      //BalanceSubstances();
//    }
//  }
//}


void Energy::AtSteadyState()
{
  if (m_data.GetState() == EngineState::AtInitialStableState)
  {
    //TODO: Get consume meal files
    // Consume meal condition currently disabled
    if (m_data.GetConditions().HasConsumeMeal())
    {
      Warning("Consume Meal Condition is currently disabled.");
    //  double elapsedTime = m_data.GetConditions().GetConsumeMeal()->GetMeal().GetElapsedTime(TimeUnit::day);
    //  Dehydration(elapsedTime);
    //  m_AdjustCO2 = false;// Don't mess with CO2 (in the blood) during this Starvation call
    //  Starvation(elapsedTime);
    //  m_AdjustCO2 = true;
    //  //Systemic clearance of calcium occurs over the elapsed time period
    //  double patientWeight_kg = m_Patient->GetWeight(MassUnit::kg);
    //  double renalVolumeCleared = m_calcium->GetClearance().GetRenalClearance(VolumePerTimeMassUnit::mL_Per_s_kg)*patientWeight_kg*elapsedTime;
    //  double systemicVolumeCleared = m_calcium->GetClearance().GetSystemicClearance(VolumePerTimeMassUnit::mL_Per_s_kg)*patientWeight_kg*elapsedTime - renalVolumeCleared;
    //  SEScalarVolume* integratedVolume = new SEScalarVolume();
    //  integratedVolume->SetValue(systemicVolumeCleared, VolumeUnit::mL);
    //  m_data.GetCircuits().BalanceBloodMassByClearedVolume(*m_calcium, *integratedVolume);
    }
  }
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Prepares the energy system for the circuit solver
///
/// \details
/// The PreProcess function performs function in preparation to update the thermal circuit.
/// It also processes energy-related actions (exercise) and computes a sweat rate.
//--------------------------------------------------------------------------------------------------
void Energy::PreProcess()
{
  CalculateMetabolicHeatGeneration();
  CalculateSweatRate();
  UpdateHeatResistance();
  Exercise();
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// The exercise function updates the patient's metabolic rate if the exercise action is present and
/// computes energy-store recovery post exercise.
///
/// \details
/// The exercise function adds to the body's basal metabolic rate a value that is specified by 
/// the exercise action. The metabolic rate set-point is specified by the action but limited by 
/// the amount of energy available. The energy limit is computed, and the actual metabolic rate is
/// ramped to the limited set-point. The body's actual work rate as a fraction of the total possible
/// work rate and the body's actual work rate as a fraction of the action-requested work rate are set
/// in this method.
//--------------------------------------------------------------------------------------------------
void Energy::Exercise()
{  
  // If there is no exercise action and no fatigue, then return.
  // Any exercise action will reduce energy stores and induce some fatigue, setting the fatigue event.
  // While the fatigue event is active, the exercise method will execute even if there is no exercise action.
  // This allows the energy stores to refill post-exercise.
  if (!m_data.GetActions().GetPatientActions().HasExercise() && !m_Patient->IsEventActive(ePatient_Event::Fatigue))
    return;

  double exerciseIntensity = 0.0;
  double currentMetabolicRate_kcal_Per_day = GetTotalMetabolicRate().GetValue(PowerUnit::kcal_Per_day);
  double basalMetabolicRate_kcal_Per_day = m_Patient->GetBasalMetabolicRate().GetValue(PowerUnit::kcal_Per_day);

  // Only try to get intensity if the exercise action is active. Otherwise, we are just refilling energy buckets post-exercise.
  if (m_data.GetActions().GetPatientActions().HasExercise())
  {
    if (m_data.GetActions().GetPatientActions().GetExercise()->HasIntensity())
    {
      exerciseIntensity = m_data.GetActions().GetPatientActions().GetExercise()->GetIntensity().GetValue();
    }    
    else
    {
      Warning("Exercise call with no severity. Action ignored.");
    }
  }
  
  if (exerciseIntensity > 0.5)
  {
    // Need to limit the exercise intensity due to current (as of 2/03/2016) engine limitations (CO2 solution error).
    Warning("Exercise intensity currently limited to 0.5. Setting intensity to 0.5.");
  }
  
  
  // Fatigue calculations
  double energyIncrement_J = 0.0;

  // There are four individual energy stores that comprise the fatigue system.
  // The usable and peak power stores together can be thought of as similar to the phosphagen energy system.
  // The medium power store can be thought of as similar to the glycogen-lactic acid energy system.
  // The endurance energy store can be thought of as similar to the aerobic energy system.
  // The energy store full levels and the maximum work rate are currently hard-coded, but will be a function of physical conditioning,
  // body composition, and starvation levels. See Future Work section in Pulse Energy documentation.
  double usableEnergyStoreFull_J = 2600.0;
  double peakPowerEnergyStoreFull_J = 4200.0;
  double mediumPowerEnergyStoreFull_J = 35000.0;
  double enduranceEnergyStoreFull_J = 400000.0;
  double maxWorkRate_W = 1200.0;
  // The maximum depletion rates will also scale with the body composition, physical conditioning, and
  // fed/starvation state of the Pulse body.
  double maxEnduranceOutRate_W = 240.0;
  double maxPeakOutRate_W = 621.0;
  double maxMediumOutRate_W = 420.0;

  // The following rates dictate the fill rate of the endurance energy store.
  // These rates are currently hard-coded, but will be tied to the concentration
  // of nutrient substances in the blood in the future. See Future Work section in Pulse Energy documentation.
  double glucoseConstant_W = 10.0;
  double lactateConstant_W = 10.0;
  double tristearinConstant_W = 10.0;

  double workRateDesired_W = exerciseIntensity*maxWorkRate_W;
  double workRate_W = 0.0;
  double normalizedUsableEnergyDeficit = (usableEnergyStoreFull_J - m_UsableEnergyStore_J) / usableEnergyStoreFull_J;
  double normalizedPeakEnergyDeficit = (peakPowerEnergyStoreFull_J - m_PeakPowerEnergyStore_J) / peakPowerEnergyStoreFull_J;
  double normalizedMediumEnergyDeficit = (mediumPowerEnergyStoreFull_J - m_MediumPowerEnergyStore_J) / mediumPowerEnergyStoreFull_J;
  double normalizedEnduranceEnergyDeficit = (enduranceEnergyStoreFull_J - m_EnduranceEnergyStore_J) / enduranceEnergyStoreFull_J;

  // Modify the rates based on the usable energy deficit.
  // This effectively creates piecewise rate functions so that all of the storage
  // outflow rates are zero until the immediate energy storage tank is almost depleted.
  double energyRateModifier = 6.0*normalizedUsableEnergyDeficit - 5.0;
  LLIM(energyRateModifier, 0.0);

  double glucoseRate_W = glucoseConstant_W*(normalizedUsableEnergyDeficit + normalizedPeakEnergyDeficit + normalizedMediumEnergyDeficit + normalizedEnduranceEnergyDeficit) / 4.0;
  double lactateRate_W = lactateConstant_W*(normalizedUsableEnergyDeficit + normalizedPeakEnergyDeficit + normalizedMediumEnergyDeficit + normalizedEnduranceEnergyDeficit) / 4.0;
  double tristearinRate_W = tristearinConstant_W*(normalizedUsableEnergyDeficit + normalizedPeakEnergyDeficit + normalizedMediumEnergyDeficit + normalizedEnduranceEnergyDeficit) / 4.0;

  energyIncrement_J = (glucoseRate_W + lactateRate_W + tristearinRate_W)*m_dT_s;

  if (m_EnduranceEnergyStore_J + energyIncrement_J > enduranceEnergyStoreFull_J){
    glucoseRate_W = lactateRate_W = tristearinRate_W = 0.0;
    energyIncrement_J = 0.0;
  }

  double enduranceOutRate_W = (normalizedUsableEnergyDeficit + normalizedPeakEnergyDeficit + normalizedMediumEnergyDeficit)*maxEnduranceOutRate_W;
  BLIM(enduranceOutRate_W, 0.0, maxEnduranceOutRate_W);
  if (m_EnduranceEnergyStore_J + energyIncrement_J < enduranceOutRate_W*m_dT_s){
    enduranceOutRate_W = (m_EnduranceEnergyStore_J + energyIncrement_J) / m_dT_s;
  }
  m_EnduranceEnergyStore_J += energyIncrement_J - enduranceOutRate_W*m_dT_s;

  // The aerobic store has multiple outflow paths. One path represents purely aerobic energy
  // usage, and the other paths represent the aerobic replenishment of the anaerobic stores. The following
  // algorithm computes the percent energy flow at the path junctions. There are two junctions.
  // First junction:
  double splitFraction = 1.0;
  if (normalizedUsableEnergyDeficit + normalizedPeakEnergyDeficit + normalizedMediumEnergyDeficit > 0.00000001){
    splitFraction = normalizedUsableEnergyDeficit / (normalizedUsableEnergyDeficit + (normalizedMediumEnergyDeficit + normalizedPeakEnergyDeficit) / 2.0);
  }
  double enduranceToUsableRate_W = splitFraction*enduranceOutRate_W;
  double enduranceToFillRate_W = (1.0 - splitFraction)*enduranceOutRate_W;
  // Second junction:
  splitFraction = 1.0;
  if (normalizedUsableEnergyDeficit + normalizedPeakEnergyDeficit + normalizedMediumEnergyDeficit > 0.00000001){
    if (normalizedPeakEnergyDeficit > 0.00000001)
    splitFraction = normalizedPeakEnergyDeficit / (normalizedPeakEnergyDeficit + normalizedMediumEnergyDeficit);
  }
  double peakFillRate_W = splitFraction*enduranceToFillRate_W;
  double mediumFillRate_W = (1.0 - splitFraction)*enduranceToFillRate_W;

  // Advance peak store state
  energyIncrement_J = peakFillRate_W*m_dT_s;
  double peakOutRate_W = normalizedUsableEnergyDeficit*maxPeakOutRate_W*energyRateModifier;
  BLIM(peakOutRate_W, 0.0, maxPeakOutRate_W);
  if (m_PeakPowerEnergyStore_J + energyIncrement_J < peakOutRate_W*m_dT_s){
    peakOutRate_W = (m_PeakPowerEnergyStore_J + energyIncrement_J) / m_dT_s;
  }
  m_PeakPowerEnergyStore_J += energyIncrement_J - peakOutRate_W*m_dT_s;
  // Advance medium store state
  energyIncrement_J = mediumFillRate_W*m_dT_s;
  double mediumOutRate_W = normalizedUsableEnergyDeficit*maxMediumOutRate_W*energyRateModifier;
  BLIM(mediumOutRate_W, 0.0, maxMediumOutRate_W);
  if (m_MediumPowerEnergyStore_J + energyIncrement_J < mediumOutRate_W*m_dT_s){
    mediumOutRate_W = (m_MediumPowerEnergyStore_J + energyIncrement_J) / m_dT_s;
  }
  m_MediumPowerEnergyStore_J += energyIncrement_J - mediumOutRate_W*m_dT_s;

  // Advance usable bucket state
  energyIncrement_J = (enduranceToUsableRate_W + mediumOutRate_W + peakOutRate_W)*m_dT_s;
  if (m_UsableEnergyStore_J + energyIncrement_J < workRateDesired_W*m_dT_s)
  {
    workRate_W = (m_UsableEnergyStore_J + energyIncrement_J) / m_dT_s;
  }
  else 
  {
    workRate_W = workRateDesired_W;
  }

  m_UsableEnergyStore_J += energyIncrement_J - workRate_W*m_dT_s;

  GetTotalWorkRateLevel().SetValue(workRate_W / maxWorkRate_W);
  double fatigue = (normalizedEnduranceEnergyDeficit + normalizedMediumEnergyDeficit + normalizedPeakEnergyDeficit + normalizedUsableEnergyDeficit) / 4.0;
  /// \event Patient: Fatigue - Energy stores are sub-maximal.
  if (fatigue > 0.0){
    m_Patient->SetEvent(ePatient_Event::Fatigue, true, m_data.GetSimulationTime());
  }
  else {
    m_Patient->SetEvent(ePatient_Event::Fatigue, false, m_data.GetSimulationTime());
  }
  GetFatigueLevel().SetValue(fatigue);

  double kcal_Per_day_Per_Watt = 20.6362855;

  if (exerciseIntensity > 0.0)
  {
    double  achievedExerciseFraction = GetTotalWorkRateLevel().GetValue() / exerciseIntensity;
    /// \todo Log an event or info message that available energy is insufficient to meet demand.
    //if (achievedExerciseFraction < 1.0)
    //  Info("Available energy insufficient to meet requested work rate.");
    GetAchievedExerciseLevel().SetValue(achievedExerciseFraction);
  }    
  else
    GetAchievedExerciseLevel().Clear();
  // End fatigue calculations
  
  double TotalMetabolicRateSetPoint_kcal_Per_day = basalMetabolicRate_kcal_Per_day + workRate_W*kcal_Per_day_Per_Watt;

  // The MetabolicRateGain is used to ramp the metabolic rate to the value specified by the user's exercise intensity.
  double MetabolicRateGain = 1.0;
  // We only let exercise control the metabolic rate if it is active, otherwise the heat generation method is in charge of the metabolic rate.
  if (m_data.GetActions().GetPatientActions().HasExercise())
  {
    double TotalMetabolicRateProduced_kcal_Per_day = currentMetabolicRate_kcal_Per_day + MetabolicRateGain*(TotalMetabolicRateSetPoint_kcal_Per_day - currentMetabolicRate_kcal_Per_day)*m_dT_s;
    GetTotalMetabolicRate().SetValue(TotalMetabolicRateProduced_kcal_Per_day, PowerUnit::kcal_Per_day);
  }
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Processes the temperature circuit and calculates extravascular transport
///
/// \details
/// The Process function solves the temperature circuit for all path heat transfer rates and nodal temperatures.
/// Additionally, the process function also initiates the flow transport of the metabolic substance quantities
/// from the vascular to extravascular space. After this is complete, the vital signs of the patient are updated
/// with regards to the new state.
//--------------------------------------------------------------------------------------------------
void Energy::Process()
{
  m_circuitCalculator->Process(*m_TemperatureCircuit, m_dT_s);
  CalculateVitalSigns();
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Updates the parameters for the temperature circuit
///
/// \details
/// Updates the resulting heat transfer rates, temperatures and nodal heat values; effectively moving
/// the next values to the current ones before time can be advanced.
//--------------------------------------------------------------------------------------------------
void Energy::PostProcess()
{
  m_circuitCalculator->PostProcess(*m_TemperatureCircuit);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Checks the patient's thermal and metabolic state
///
/// \details
/// The core and skin temperatures are recorded in this function. In addition, the current metabolic
/// state of the patient may trigger the following events: hypothermia, hyperthermia, dehydration, fasciculation
/// or fatigue. These events are only triggered if the current state falls within the criteria of the specific event
//--------------------------------------------------------------------------------------------------
void Energy::CalculateVitalSigns()
{
  double coreTemperature_degC = m_coreNode->GetTemperature(TemperatureUnit::C);
  double skinTemperature_degC = m_skinNode->GetTemperature(TemperatureUnit::C);
  GetCoreTemperature().SetValue(coreTemperature_degC, TemperatureUnit::C);
  GetSkinTemperature().SetValue(skinTemperature_degC, TemperatureUnit::C);
  std::stringstream ss; 

  //Hypothermia check
  double coreTempIrreversible_degC = 20.0;   /// \cite Stocks2004HumanPhysiologicalResponseCold
  if (coreTemperature_degC < 35.0) /// \cite mallet2001hypothermia
  {
    /// \event Patient: Core temperature has fallen below 35 degrees Celsius. Patient is hypothermic.
    m_Patient->SetEvent(ePatient_Event::Hypothermia, true, m_data.GetSimulationTime());

    /// \irreversible State: Core temperature has fallen below 20 degrees Celsius.
    if (coreTemperature_degC < coreTempIrreversible_degC)
    {
      ss << "Core temperature is " << coreTemperature_degC << ". This is below 20 degrees C, patient is experiencing extreme hypothermia and is in an irreversible state.";
      Warning(ss);
      m_Patient->SetEvent(ePatient_Event::IrreversibleState, true, m_data.GetSimulationTime());
    }

  }
  else if (m_Patient->IsEventActive(ePatient_Event::Hypothermia) && coreTemperature_degC>35.2)
  {
    m_Patient->SetEvent(ePatient_Event::Hypothermia, false, m_data.GetSimulationTime());
  }
  //Hyperthermia check
  if (coreTemperature_degC > 38.8) /// \cite mallet2001hypothermia
  {
    /// \event Patient: Core temperature has exceeded 38.3 degrees Celsius. Patient is hyperthermic.
    m_Patient->SetEvent(ePatient_Event::Hyperthermia, true, m_data.GetSimulationTime());
  }
  else if (m_Patient->IsEventActive(ePatient_Event::Hyperthermia) && coreTemperature_degC < 38.0)
  {
    m_Patient->SetEvent(ePatient_Event::Hyperthermia, false, m_data.GetSimulationTime());
  }

  /// \todo Move to blood chemistry
  // Although it is called metabolic acidosis/alkalosis, the detection and event setting is actually a part of the @ref BloodChemistrySystem
  // The terms "metabolic" and "respiratory" refer to the origin of the acid-base disturbance
  // The hydrogen ion concentration is a property of the blood
  // The events related to blood concentrations should be detected and set in blood chemistry.
  double highPh = 8.5;
  double lowPh = 6.5;   // \cite Edge2006AcidosisConscious
  m_BloodpH->Sample(m_data.GetBloodChemistry().GetBloodPH().GetValue());
  m_BicarbonateMolarity_mmol_Per_L->Sample(m_AortaHCO3->GetMolarity(AmountPerVolumeUnit::mmol_Per_L));
  //Only check these at the end of a cardiac cycle and reset at start of cardiac cycle 
  if (m_Patient->IsEventActive(ePatient_Event::StartOfCardiacCycle))
  {
    double bloodPH = m_BloodpH->Value();
    double bloodBicarbonate_mmol_Per_L = m_BicarbonateMolarity_mmol_Per_L->Value();

    if (m_data.GetState() > EngineState::InitialStabilization)
    {// Don't throw events if we are initializing
      if (bloodPH < 7.35 && bloodBicarbonate_mmol_Per_L < 22.0)
        /// \event The patient is in a state of metabolic acidosis
        m_Patient->SetEvent(ePatient_Event::MetabolicAcidosis, true, m_data.GetSimulationTime());

      /// \irreversible State: arterial blood pH has dropped below 6.5.
      if (bloodPH < lowPh)
      {
        ss << " Arterial blood PH is " << bloodPH << ". This is below 6.5, patient is experiencing extreme metabolic acidosis and is in an irreversible state.";
        Warning(ss);
        m_Patient->SetEvent(ePatient_Event::IrreversibleState, true, m_data.GetSimulationTime());
      }
      else if (bloodPH > 7.38 && bloodBicarbonate_mmol_Per_L > 23.0)
        /// \event The patient has exited the state state of metabolic acidosis
        m_Patient->SetEvent(ePatient_Event::MetabolicAcidosis, false, m_data.GetSimulationTime());

      if (bloodPH > 7.45 && bloodBicarbonate_mmol_Per_L > 26.0)
        /// \event The patient is in a state of metabolic alkalosis
        m_Patient->SetEvent(ePatient_Event::MetabolicAlkalosis, true, m_data.GetSimulationTime());

      /// \irreversible State: arterial blood pH has increased above 8.5.
      if (bloodPH > highPh)
      {
        ss << " Arterial blood PH is " << bloodPH << ". This is above 8.5, patient is experiencing extreme metabolic Alkalosis and is in an irreversible state.";
        Warning(ss);
        m_Patient->SetEvent(ePatient_Event::IrreversibleState, true, m_data.GetSimulationTime());
      }

      else if (bloodPH < 7.42 && bloodBicarbonate_mmol_Per_L < 25.0)
        /// \event The patient has exited the state of metabolic alkalosis
        m_Patient->SetEvent(ePatient_Event::MetabolicAlkalosis, false, m_data.GetSimulationTime());
    }
    // Reset the running averages. Why do we need running averages here? Does the aorta pH fluctuate that much? 
    m_BloodpH->Clear();
    m_BicarbonateMolarity_mmol_Per_L->Clear();
  }
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Calculates the metabolic rate, depending on the current state of the patient
///
/// \details
/// The metabolic rate is dictated by the current state of the core temperature. This function includes
/// states of increased metabolic rate due to shivering or severe hyperthermia. Additionally, an extreme
/// drop in core temperature leads to decreasing metabolic rate. If the core temperature does not meet any
/// of the criteria for increases/decreases, the metabolic rate will be calculated as the basal metabolic rate.
//--------------------------------------------------------------------------------------------------
void Energy::CalculateMetabolicHeatGeneration()
{
  const PulseConfiguration& config = m_data.GetConfiguration();
  double coreTemperature_degC = m_coreNode->GetTemperature(TemperatureUnit::C);
  double coreTemperatureLow_degC = config.GetCoreTemperatureLow(TemperatureUnit::C);
  double coreTemperatureLowDelta_degC = config.GetDeltaCoreTemperatureLow(TemperatureUnit::C);
  double coreTemperatureHigh_degC = 40.0; //TODO: This should use the config property why doesn't it?
  double totalMetabolicRateNew_Kcal_Per_day = 0.0;
  double totalMetabolicRateNew_W = 0.0;
  //The summit metabolism is the maximum amount of power the human body can generate due to shivering/response to the cold.
  double summitMetabolism_W = 21.0*pow(m_Patient->GetWeight(MassUnit::kg), 0.75); /// \cite herman2008physics
  double currentMetabolicRate_kcal_Per_day = GetTotalMetabolicRate().GetValue(PowerUnit::kcal_Per_day);
  double basalMetabolicRate_kcal_Per_day = m_Patient->GetBasalMetabolicRate().GetValue(PowerUnit::kcal_Per_day);

  if (coreTemperature_degC < 34.0) //Hypothermic state inducing metabolic depression (decline of metabolic heat generation)
  {
    totalMetabolicRateNew_W = summitMetabolism_W*pow(0.94, 34.0 - coreTemperature_degC); //The metabolic heat generated will drop by 6% for every degree below 34 C
    GetTotalMetabolicRate().SetValue(totalMetabolicRateNew_W, PowerUnit::W);     /// \cite mallet2002hypothermia
  }
  else if (coreTemperature_degC >= 34.0 && coreTemperature_degC < 36.8) //Patient is increasing heat generation via shivering. This caps out at the summit metabolism
  {
    //Add an event for shivering
    double basalMetabolicRate_W = m_Patient->GetBasalMetabolicRate(PowerUnit::W);
    totalMetabolicRateNew_W = basalMetabolicRate_W + (summitMetabolism_W - basalMetabolicRate_W)*(coreTemperatureLow_degC - coreTemperature_degC) / coreTemperatureLowDelta_degC;
    totalMetabolicRateNew_W = MIN(totalMetabolicRateNew_W, summitMetabolism_W); //Bounded at the summit metabolism so further heat generation doesn't continue for continue drops below 34 C.
    GetTotalMetabolicRate().SetValue(totalMetabolicRateNew_W, PowerUnit::W);
  }
  else if (coreTemperature_degC >= 36.8 && coreTemperature_degC < 42.5 && !m_data.GetActions().GetPatientActions().HasExercise()) //Basic Metabolic rate
  {
    double TotalMetabolicRateSetPoint_kcal_Per_day = basalMetabolicRate_kcal_Per_day;
    double MetabolicRateGain = 0.0001;  //Used to ramp the metabolic rate from its current value to the basal value if the patient meet's the basal criteria
    double TotalMetabolicRateProduced_kcal_Per_day = currentMetabolicRate_kcal_Per_day + MetabolicRateGain*(TotalMetabolicRateSetPoint_kcal_Per_day - currentMetabolicRate_kcal_Per_day);
    GetTotalMetabolicRate().SetValue(TotalMetabolicRateProduced_kcal_Per_day, PowerUnit::kcal_Per_day);
  }
  else if (coreTemperature_degC>40.0  && !m_data.GetActions().GetPatientActions().HasExercise()) //Core temperature greater than 40.0. If not exercising, then the hyperthermia leads to increased metabolism
  {
    totalMetabolicRateNew_Kcal_Per_day = basalMetabolicRate_kcal_Per_day*pow(1.11, coreTemperature_degC - coreTemperatureHigh_degC);  //The metabolic heat generated will increase by 11% for every degree above 40.0 C
    GetTotalMetabolicRate().SetValue(totalMetabolicRateNew_Kcal_Per_day, PowerUnit::kcal_Per_day);                  /// \cite pate2001thermal                  
  }

  m_temperatureGroundToCorePath->GetNextHeatSource().SetValue(GetTotalMetabolicRate(PowerUnit::W), PowerUnit::W);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Calculates the sweat rate if the core temperature is too high
///
/// \details
/// The sweat rate is calculated from a core temperature control function. The mass lost due to sweating is accounted for
/// and a flow source from the skin extravascular to ground path is updated to ensure fluid loss
//--------------------------------------------------------------------------------------------------
void Energy::CalculateSweatRate()
{
  const PulseConfiguration& config = m_data.GetConfiguration();
  double coreTemperature_degC = m_coreNode->GetTemperature(TemperatureUnit::C);
  double coreTemperatureHigh_degC = config.GetCoreTemperatureHigh(TemperatureUnit::C);
  double sweatHeatTranferCoefficient_W_Per_K = config.GetSweatHeatTransfer(HeatConductanceUnit::W_Per_K);
  double vaporizationEnergy_J_Per_kg = config.GetVaporizationEnergy(EnergyPerMassUnit::J_Per_kg);

  //Calculate sweat rate (in kg/s) from core temperature feedback.
  //The sweat rate heat transfer is determined from a control equation that attempts to keep the core temperature in line
  /// \cite herman2008physics
  double sweatRate_kg_Per_s = (0.25*sweatHeatTranferCoefficient_W_Per_K / vaporizationEnergy_J_Per_kg)*(coreTemperature_degC - coreTemperatureHigh_degC);
  sweatRate_kg_Per_s = MAX(sweatRate_kg_Per_s, 0.0);


  //Account for mass lost by substracting from the current patient mass
  double massLost_kg = sweatRate_kg_Per_s*m_dT_s;
  m_Patient->GetWeight().IncrementValue(-massLost_kg, MassUnit::kg);

  GetSweatRate().SetValue(sweatRate_kg_Per_s, MassPerTimeUnit::kg_Per_s);

  double sweatDensity_kg_Per_m3 = config.GetWaterDensity(MassPerVolumeUnit::kg_Per_m3); /// \todo Convert to sweat density once specific gravity calculation is in

  //Set the flow source on the extravascular circuit to begin removing the fluid that is excreted
  double sweatRate_mL_Per_s = sweatRate_kg_Per_s / sweatDensity_kg_Per_m3 * 1.e6;
  //m_data.GetDataTrack().Probe("sweatRate_mL_Per_s", sweatRate_mL_Per_s);
  //m_data.GetDataTrack().Probe("sweatRate_mg_Per_min", sweatRate_kg_Per_s*60.*1000.*1000.);
  m_skinExtravascularToSweatingGroundPath->GetNextFlowSource().SetValue(sweatRate_mL_Per_s, VolumePerTimeUnit::mL_Per_s);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Updates the variable core to skin heat transfer resistance
///
/// \details
/// The variable core to skin heat transfer resistance is updated here according to the  inverse 
/// of the skin blood flow.
//--------------------------------------------------------------------------------------------------
void Energy::UpdateHeatResistance()
{
  double skinBloodFlow_m3_Per_s = m_data.GetCardiovascular().GetMeanSkinFlow().GetValue(VolumePerTimeUnit::m3_Per_s);
  double bloodDensity_kg_Per_m3 = m_data.GetBloodChemistry().GetBloodDensity().GetValue(MassPerVolumeUnit::kg_Per_m3);
  double bloodSpecificHeat_J_Per_K_kg = m_data.GetBloodChemistry().GetBloodSpecificHeat().GetValue(HeatCapacitancePerMassUnit::J_Per_K_kg);

  double alphaScale = 0.5; //Scaling factor for convective heat transfer from core to skin

  //The heat transfer resistance from the core to the skin is inversely proportional to the skin blood flow.
  //When skin blood flow increases, then heat transfer resistance decreases leading to more heat transfer from core to skin. 
  //The opposite occurs for skin blood flow decrease.
  double coreToSkinResistance_K_Per_W = 1.0 / (alphaScale*bloodDensity_kg_Per_m3*bloodSpecificHeat_J_Per_K_kg*skinBloodFlow_m3_Per_s);
  
  coreToSkinResistance_K_Per_W = BLIM(coreToSkinResistance_K_Per_W, 0.0001, 20.0);
  m_coreToSkinPath->GetNextResistance().SetValue(coreToSkinResistance_K_Per_W, HeatResistanceUnit::K_Per_W);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Calculates the basal metabolic rate from the Harris-Benedict formula
///
///
/// \details
/// The Harris-Benedict formula uses the patient height, weight age and sex to determine
/// the basal metabolic requirements.
//--------------------------------------------------------------------------------------------------
void Energy::CalculateBasalMetabolicRate()
{
  SEPatient& patient = m_data.GetPatient();
  double PatientMass_kg = patient.GetWeight(MassUnit::kg);
  double PatientAge_yr = patient.GetAge(TimeUnit::yr);
  double PatientHeight_cm = patient.GetHeight(LengthUnit::cm);

  //The basal metabolic rate is determined from the Harris-Benedict formula, with differences dependent on sex, age, height and mass
  /// \cite roza1984metabolic
  double patientBMR_kcal_Per_day = 0.0;
  if (patient.GetSex() == ePatient_Sex::Male)
    patientBMR_kcal_Per_day = 88.632 + 13.397*PatientMass_kg + 4.799*PatientHeight_cm - 5.677*PatientAge_yr;
  else
    patientBMR_kcal_Per_day = 447.593 + 9.247*PatientMass_kg + 3.098*PatientHeight_cm - 4.330*PatientAge_yr;
  // Systems do their math with MetabolicRate in Watts, so let's make these consistent
  patient.GetBasalMetabolicRate().SetValue(patientBMR_kcal_Per_day, PowerUnit::kcal_Per_day);

  std::stringstream ss;
  ss << "Conditions applied homeostasis: " << "Patient basal metabolic rate = " << patientBMR_kcal_Per_day << " kcal/day";
  Info(ss);
}
