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

#include "stdafx.h"
#include "physiology/Gastrointestinal.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/SEConsumeNutrients.h"
// Dependent Systems
#include "system/physiology/SEBloodChemistrySystem.h"
#include "system/physiology/SECardiovascularSystem.h"
#include "system/physiology/SETissueSystem.h"
// CDM
#include "patient/SEPatient.h"
#include "patient/SEMeal.h"
#include "patient/SENutrition.h"
#include "substance/SESubstance.h"
#include "circuit/fluid/SEFluidCircuit.h"
#include "compartment/fluid/SELiquidCompartment.h"
#include "compartment/substances/SELiquidSubstanceQuantity.h"
#include "properties/SEScalar.h"
#include "properties/SEScalar0To1.h"
#include "properties/SEScalarAmountPerVolume.h"
#include "properties/SEScalarMass.h"
#include "properties/SEScalarMassPerTime.h"
#include "properties/SEScalarMassPerVolume.h"
#include "properties/SEScalarMassPerAmount.h"
#include "properties/SEScalarPressure.h"
#include "properties/SEScalarVolume.h"
#include "properties/SEScalarVolumePerTime.h"
#include "properties/SEScalarTime.h"

#pragma warning(disable:4786)
#pragma warning(disable:4275)

//#define logMeal

Gastrointestinal::Gastrointestinal(PulseController& data) : SEGastrointestinalSystem(data.GetLogger()), m_data(data)
{
  Clear();
  m_CalciumDigestionRate = new SEScalarMassPerTime();
  m_WaterDigestionRate = new SEScalarVolumePerTime();
  /* Move to a unit test
  SENutrition one(m_Logger);
  SENutrition two(m_Logger);
  one.GetCarbohydrate()->SetValue(1, MassUnit::g);
  one.GetCarbohydrateDigestionRate()->SetValue(1, MassPerTimeUnit::g_Per_s);
  one.GetFat()->SetValue(2, MassUnit::g);
  one.GetFatDigestionRate()->SetValue(2, MassPerTimeUnit::g_Per_s);
  one.GetProtein()->SetValue(3, MassUnit::g);
  one.GetProteinDigestionRate()->SetValue(3, MassPerTimeUnit::g_Per_s);

  two.GetCarbohydrate()->SetValue(1, MassUnit::g);
  two.GetCarbohydrateDigestionRate()->SetValue(2, MassPerTimeUnit::g_Per_s);
  two.GetFat()->SetValue(2, MassUnit::g);
  two.GetFatDigestionRate()->SetValue(4, MassPerTimeUnit::g_Per_s);
  two.GetProtein()->SetValue(3, MassUnit::g);
  two.GetProteinDigestionRate()->SetValue(6, MassPerTimeUnit::g_Per_s);
  one.Increment(two);
  std::cout << "Carbo Rate: " << one.GetCarbohydrateDigestionRate() << std::endl;
  std::cout << "Fat Rate: " << one.GetFatDigestionRate() << std::endl;
  std::cout << "Protein Rate: " << one.GetProteinDigestionRate() << std::endl;
  */
}

Gastrointestinal::~Gastrointestinal()
{
  Clear();
  delete m_CalciumDigestionRate;
  delete m_WaterDigestionRate;
}

void Gastrointestinal::Clear()
{
  SEGastrointestinalSystem::Clear();
}

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

  m_DecrementNutrients = false;
  if (m_data.GetConfiguration().HasDefaultStomachContents())
  {
    // We are going to initialize the body with 2 meals so we process the default meal twice
    // 1 meal about 5hrs ago, and one meal at the start of the scenario
    GetStomachContents().Copy(*m_data.GetConfiguration().GetDefaultStomachContents());
    // Now digest the contents
    DigestStomachNutrients(5 * 60 * 60);//hrs to seconds (note decrement is off, so the stomach will stay full)    
                                        // TODO Should I be getting the weight here? After we digest?
  }
  // Cache off the initial Gut masses so we can reset back to them after stabilization
  m_InitialSubstanceMasses_ug.clear();
  m_InitialSubstanceMasses_ug[m_SmallIntestineChymeGlucose]    = m_SmallIntestineChymeGlucose->GetMass(MassUnit::ug);
  m_InitialSubstanceMasses_ug[m_SmallIntestineChymeTristearin] = m_SmallIntestineChymeTristearin->GetMass(MassUnit::ug);
  m_InitialSubstanceMasses_ug[m_SmallIntestineChymeCalcium]    = m_SmallIntestineChymeCalcium->GetMass(MassUnit::ug);
  m_InitialSubstanceMasses_ug[m_SmallIntestineChymeSodium]     = m_SmallIntestineChymeSodium->GetMass(MassUnit::ug);
  m_InitialSubstanceMasses_ug[m_SmallIntestineChymeUrea]       = m_SmallIntestineChymeUrea->GetMass(MassUnit::ug);

}

void Gastrointestinal::SetUp()
{
  m_ConsumeRate = false;
  m_WaterDigestionRate->SetValue(m_data.GetConfiguration().GetWaterDigestionRate(VolumePerTimeUnit::mL_Per_s), VolumePerTimeUnit::mL_Per_s);
  m_CalciumDigestionRate->SetValue(m_data.GetConfiguration().GetCalciumDigestionRate(MassPerTimeUnit::g_Per_s), MassPerTimeUnit::g_Per_s);

  m_GItoCVPath                    = m_data.GetCircuits().GetActiveCardiovascularCircuit().GetPath(pulse::ChymePath::SmallIntestineC1ToSmallIntestine1);
  m_GutT1ToGroundPath             = m_data.GetCircuits().GetActiveCardiovascularCircuit().GetPath(pulse::ChymePath::GutT1ToGround);

  m_SmallIntestineChyme           = m_data.GetCompartments().GetLiquidCompartment(pulse::ChymeCompartment::SmallIntestine);
  m_SmallIntestineChymeGlucose    = m_SmallIntestineChyme->GetSubstanceQuantity(m_data.GetSubstances().GetGlucose());
  m_SmallIntestineChymeTristearin = m_SmallIntestineChyme->GetSubstanceQuantity(m_data.GetSubstances().GetTristearin());
  m_SmallIntestineChymeCalcium    = m_SmallIntestineChyme->GetSubstanceQuantity(m_data.GetSubstances().GetCalcium());
  m_SmallIntestineChymeSodium     = m_SmallIntestineChyme->GetSubstanceQuantity(m_data.GetSubstances().GetSodium());
  m_SmallIntestineChymeUrea       = m_SmallIntestineChyme->GetSubstanceQuantity(m_data.GetSubstances().GetUrea());

  m_secretionRate_mL_Per_s = 0.041;// Average from daily secretion rates : Gastric (1500mL) ,Small Intestine(1800mL), Large Intestine (200mL) form Guyton p775
  m_dT_s = m_data.GetTimeStep().GetValue(TimeUnit::s);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Do anything needed between stabilization
///
/// \details
/// At the end of resting stabilization we apply a ConsumeMeal condition to modify the body state
/// if no condition is present we reset the body state substance levels to their original level
//--------------------------------------------------------------------------------------------------

void Gastrointestinal::AtSteadyState()
{
  if (m_data.GetState() == EngineState::AtInitialStableState)
  {// Apply our conditions    
    if (m_data.GetConditions().HasConsumeMeal())
    {
      SEMeal& meal = m_data.GetConditions().GetConsumeMeal()->GetMeal();
      DefaultNutritionRates(meal);// If no rates are provided, use the defaults
#ifdef logMeal
      m_ss << "Original Patient weight : " << m_data.GetPatient()->GetWeight();
      Info(m_ss);
      m_ss << "Original Stomach weight : " << m_StomachContents->GetWeight(MassUnit::g) << "(g)";
      Info(m_ss);
      m_ss << m_NutrientsInStomach;
      Info(m_ss);
#endif
      // Remove the default meal weight from the patient
      m_data.GetCurrentPatient().GetWeight().IncrementValue(-m_StomachContents->GetWeight(MassUnit::g), MassUnit::g);
      // Overwrite meal contents into our stomach
      GetStomachContents().Copy(meal);
      if (!m_StomachContents->HasWater() || m_StomachContents->GetWater().IsZero())
        m_StomachContents->GetWater().SetValue(m_secretionRate_mL_Per_s*m_dT_s, VolumeUnit::mL);//Add a time steps worth of water if empty
      // Increase our weight by the meal
      m_data.GetCurrentPatient().GetWeight().IncrementValue(m_StomachContents->GetWeight(MassUnit::g), MassUnit::g);
      // Empty out the gut
      m_SmallIntestineChyme->GetVolume().SetValue(0, VolumeUnit::mL);
      m_SmallIntestineChymeGlucose->GetMass().SetValue(0,MassUnit::ug);
      m_SmallIntestineChymeGlucose->Balance(BalanceLiquidBy::Mass);
      m_SmallIntestineChymeTristearin->GetMass().SetValue(0, MassUnit::ug);
      m_SmallIntestineChymeTristearin->Balance(BalanceLiquidBy::Mass);
      m_SmallIntestineChymeCalcium->GetMass().SetValue(0, MassUnit::ug);
      m_SmallIntestineChymeCalcium->Balance(BalanceLiquidBy::Mass);
      m_SmallIntestineChymeSodium->GetMass().SetValue(0, MassUnit::ug);
      m_SmallIntestineChymeSodium->Balance(BalanceLiquidBy::Mass);
      m_SmallIntestineChymeUrea->GetMass().SetValue(0, MassUnit::ug);
      m_SmallIntestineChymeUrea->Balance(BalanceLiquidBy::Mass);
#ifdef logMeal
      m_ss << "Stomach weight with meal : " << m_StomachContents->GetWeight(MassUnit::g) << "(g)";
      Info(m_ss);
      m_ss << m_NutrientsInStomach;
      Info(m_ss);
      m_ss << "New Patient weight : " << m_data.GetPatient()->GetWeight();
      Info(m_ss);
#endif
      // Flip flag in order for digestion to actually remove the proper amount from the stomach contents
      m_DecrementNutrients = true;
      // Digest for the elapsed time
#ifdef logMeal
      for (auto isub : m_InitialGutMasses_ug)
      {
        m_ss << "Predigestion Gut mass for " << isub.first->GetSubstance().GetName() << " : " << isub.first->GetMass();
        Info(m_ss);
      }
      m_ss << "Meal Elapsed time " << meal->GetElapsedTime();
      Info(m_ss);
#endif
      DigestStomachNutrients(meal.GetElapsedTime(TimeUnit::s));
#ifdef logMeal
      m_ss << "Stomach weight with digested meal : " << m_StomachContents->GetWeight(MassUnit::g) << "(g)";
      Info(m_ss);
      m_ss << m_NutrientsInStomach;
      Info(m_ss);
      for (auto isub : m_InitialGutMasses_ug)
      {
        m_ss << "Postdigestion Gut mass for " << isub.first->GetSubstance().GetName() << " : " << isub.first->GetMass();
        Info(m_ss);
      }
#endif
      // Flip it back to not decrement since we are still in stabilization 
      m_DecrementNutrients = false;
      // Based on flow, take off mass from GutChyme and put that mass throughout the body (CV/Tissues)
      AbsorbMeal(meal.GetElapsedTime(TimeUnit::min));
#ifdef logMeal
      for (auto isub : m_InitialGutMasses_ug)
      {
        m_ss << "Post-absorbed Gut mass for " << isub.first->GetSubstance().GetName() << " : " << isub.first->GetMass();
        Info(m_ss);
      }
#endif
      // Update our initial masses
      m_InitialSubstanceMasses_ug[m_SmallIntestineChymeGlucose]    = m_SmallIntestineChymeGlucose->GetMass(MassUnit::ug);
      m_InitialSubstanceMasses_ug[m_SmallIntestineChymeTristearin] = m_SmallIntestineChymeTristearin->GetMass(MassUnit::ug);
      m_InitialSubstanceMasses_ug[m_SmallIntestineChymeCalcium]    = m_SmallIntestineChymeCalcium->GetMass(MassUnit::ug);
      m_InitialSubstanceMasses_ug[m_SmallIntestineChymeSodium]     = m_SmallIntestineChymeSodium->GetMass(MassUnit::ug);
      m_InitialSubstanceMasses_ug[m_SmallIntestineChymeUrea]       = m_SmallIntestineChymeUrea->GetMass(MassUnit::ug);
    }
  }
  if (m_data.GetState() == EngineState::AtSecondaryStableState)
  {
    m_DecrementNutrients = true;
    // Reset the Gut Chyme substance to their original values
    for (auto i : m_InitialSubstanceMasses_ug)
    {
      i.first->GetMass().SetValue(i.second, MassUnit::ug);
      i.first->Balance(BalanceLiquidBy::Mass);
    }
    // We never decremented the volume so we are good there
  }
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Gastrointestinal Preprocess function
///
/// \details
/// Apply any meal consumtion actions
/// Absorb fluids from the tissues back into the stomach so it always has fluid in it
/// Digest substances based on our time step and transfer them to the Gut
/// Absorb substances from the gut into the vascular system via the small intestine 
//--------------------------------------------------------------------------------------------------

void Gastrointestinal::PreProcess()
{
  if (m_data.GetState() == EngineState::Active)
  {
    if (m_data.GetActions().GetPatientActions().HasConsumeNutrients())
    {
      // Use Default Rates if none provided
      SEConsumeNutrients* c = m_data.GetActions().GetPatientActions().GetConsumeNutrients();
      if (c->HasNutritionFile())
      {// Grab file, then load it (note GetNutrition will remove the file name, so get it first)
        std::string file = c->GetNutritionFile();
        if (!c->GetNutrition().SerializeFromFile(file,JSON))
        {
          /// \error Unable to read consume meal action file
          Error("Could not read provided nutrition file", "Gastrointestinal::PreProcess");
        }
      }
      DefaultNutritionRates(c->GetNutrition());
      m_StomachContents->Increment(c->GetNutrition());
      m_data.GetCurrentPatient().GetWeight().IncrementValue(c->GetNutrition().GetWeight(MassUnit::kg), MassUnit::kg);
      m_data.GetActions().GetPatientActions().RemoveConsumeNutrients();
    }
    GastricSecretion(m_dT_s); // Move some water from the Gut EV fluids to the Stomach
    DigestStomachNutrients(m_dT_s);
  }
  else
  {
    // Reset the Gut Chyme substance to their original values
    for (auto i : m_InitialSubstanceMasses_ug)
    {
      i.first->GetMass().SetValue(i.second, MassUnit::ug);
      i.first->Balance(BalanceLiquidBy::Mass);
    }
  }
  AbsorbNutrients(m_dT_s); // Absorb nutrients into the Blood from the small intestine chyme  
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Absorb fluids from the tissues back into the stomach so it always has fluid in it
///
/// \details
/// Fluid absorption is based on time step at a constant rate
//--------------------------------------------------------------------------------------------------
void Gastrointestinal::GastricSecretion(double duration_s)
{
  // Increase the water in the stomach by the flow rate
  // Take it out of the tissue at the same rate it's being added to the stomach
  //There is a compliance, so the volume will be modified accordingly
  m_GutT1ToGroundPath->GetNextFlowSource().SetValue(m_secretionRate_mL_Per_s, VolumePerTimeUnit::mL_Per_s);
  m_StomachContents->GetWater().IncrementValue(m_secretionRate_mL_Per_s * duration_s, VolumeUnit::mL);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Digest substances based on our time step and transfer them to the Gut
///
/// \details
/// Each substance can provide a digestion rate, if none is provided a default will be used
/// A portion of each substance is removed from the stomach based on time step and digestion rate
/// The substance is then incremented into the Gut. Each substance can have it's own movement logic
/// Water is also transfered to the Gut based on a constant rate
//--------------------------------------------------------------------------------------------------
void Gastrointestinal::DigestStomachNutrients(double duration_s)
{
  if (duration_s <= 0)
    return; // Nothing to do then
  if (!m_StomachContents->HasWater())
    Fatal("There is no water in the Stomach??");// This is not good... what is going on?  

  double digestedAmount;// either in g or mL

  if (m_StomachContents->HasSodium())
  {// Sodium rate is a function of the concentration of sodium in the stomach, so do this before we do water
    double totalNa_g = m_StomachContents->GetSodium(MassUnit::g);
    double digestedNa_g = (totalNa_g / m_StomachContents->GetWater(VolumeUnit::mL))
      * m_WaterDigestionRate->GetValue(VolumePerTimeUnit::mL_Per_s) * duration_s;
    if (totalNa_g <= digestedNa_g)
    {
      digestedNa_g = totalNa_g;
      if (m_DecrementNutrients)
      {
        m_StomachContents->GetSodium().Invalidate();
        Info("Stomach is out of Sodium");
      }
    }
    else
    {
      if (m_DecrementNutrients)
        m_StomachContents->GetSodium().IncrementValue(-digestedNa_g, MassUnit::g);
    }
#ifdef logDigest
    m_ss << "Digested " << digestedNa_g << "(g) of Sodium";
    Info(m_ss);
#endif
    m_SmallIntestineChymeSodium->GetMass().IncrementValue(digestedNa_g, MassUnit::g);
    // Wait till the water volume is corret on the chyme before we balance
  }

  digestedAmount = DigestNutrient(m_StomachContents->GetWater(), *m_WaterDigestionRate, false, duration_s);
  if (digestedAmount > 0)
  {
#ifdef logDigest
    m_ss << "Digested " << digestedAmount << "(mL) of Water";
    Info(m_ss);
#endif
    m_SmallIntestineChyme->GetVolume().IncrementValue(digestedAmount, VolumeUnit::mL);
  }
  // Balance Sodium, now that we have proper volume on the gut
  m_SmallIntestineChymeSodium->Balance(BalanceLiquidBy::Mass);

  m_ConsumeRate = true;// We are digesting nutrient rates provided by our consume action, if we run out of a substance, we invalidate this rate
  if (m_StomachContents->HasCarbohydrate())
  {
    digestedAmount = DigestNutrient(m_StomachContents->GetCarbohydrate(), m_StomachContents->GetCarbohydrateDigestionRate(), true, duration_s);
    digestedAmount *= m_data.GetConfiguration().GetCarbohydrateAbsorptionFraction(); // Take off percent that usually passes through the body
    if (digestedAmount != 0)
    {
#ifdef logDigest
      m_ss << "Digested " << digestedAmount << "(g) of Carbs";
      Info(m_ss);
#endif
      m_SmallIntestineChymeGlucose->GetMass().IncrementValue(digestedAmount, MassUnit::g);
      m_SmallIntestineChymeGlucose->Balance(BalanceLiquidBy::Mass);
    }
  }
  if (m_StomachContents->HasFat())
  {
    digestedAmount = DigestNutrient(m_StomachContents->GetFat(), m_StomachContents->GetFatDigestionRate(), true, duration_s);
    digestedAmount *= m_data.GetConfiguration().GetFatAbsorptionFraction(); // Take off percent that usually passes through the body
    if (digestedAmount != 0)
    {
#ifdef logDigest
      m_ss << "Digested " << digestedAmount << "(g) of Fat";
      Info(m_ss);
#endif
      m_SmallIntestineChymeTristearin->GetMass().IncrementValue(digestedAmount, MassUnit::g);
      m_SmallIntestineChymeTristearin->Balance(BalanceLiquidBy::Mass);
    }
  }
  if (m_StomachContents->HasProtein())
  {
    digestedAmount = DigestNutrient(m_StomachContents->GetProtein(), m_StomachContents->GetProteinDigestionRate(), true, duration_s);    
    digestedAmount *= m_data.GetConfiguration().GetProteinToUreaFraction(); // How much gets turned into Urea
    if (digestedAmount != 0)
    {      
#ifdef logDigest
      m_ss << "Digested " << digestedAmount << "(g) of Urea";
      Info(m_ss);
#endif
      double tuningFactor = 1.0; /// \todo Remove tuning factor and adjust protein to urea fraction following investigation
      m_SmallIntestineChymeUrea->GetMass().IncrementValue(digestedAmount * tuningFactor, MassUnit::g);
      m_SmallIntestineChymeUrea->Balance(BalanceLiquidBy::Mass);
    }
  }
  m_ConsumeRate = false; // Other rates are specified by configuration and should never be invalidated

  if (m_StomachContents->HasCalcium())
  {
    digestedAmount = DigestNutrient(m_StomachContents->GetCalcium(), *m_CalciumDigestionRate, true, duration_s);
    digestedAmount *= m_data.GetConfiguration().GetCalciumAbsorptionFraction(); // Take off percent that usually passes through the body
    if (digestedAmount != 0)
    {
#ifdef logDigest
      m_ss << "Digested " << digestedAmount << "(g) of Calcium";
      Info(m_ss);
#endif
      m_SmallIntestineChymeCalcium->GetMass().IncrementValue(digestedAmount, MassUnit::g);
      m_SmallIntestineChymeCalcium->Balance(BalanceLiquidBy::Mass);
    }
  }
}

// --------------------------------------------------------------------------------------------------
/// \brief
/// Generic code for removal of an amout of a substance from the stomach based on rate and duration
///
/// \details
//--------------------------------------------------------------------------------------------------
double Gastrointestinal::DigestNutrient(SEUnitScalar& totalAmt, SEUnitScalar& rate, bool mass, double duration_s)
{  
  double digestedAmt = 0;
  if (totalAmt.IsValid())
  {
    double t = totalAmt.GetValue(mass ? (const CCompoundUnit&)MassUnit::g : (const CCompoundUnit&)VolumeUnit::mL);
    digestedAmt = rate.GetValue(mass ? (const CCompoundUnit&)MassPerTimeUnit::g_Per_s : (const CCompoundUnit&)VolumePerTimeUnit::mL_Per_s)*duration_s;
    if (t <= digestedAmt)
    {
      digestedAmt = t;
      if (m_DecrementNutrients)
      {// Decrement stomach contents only if we are running (not stabilizing)
        totalAmt.Invalidate();
        if (m_ConsumeRate)// We keep this rate, it's a system parameter not a per nutrition rate as the masses are
          rate.Invalidate();
      }
    }
    else
    {
      if (m_DecrementNutrients)// Decrement stomach content only if we are running (not stabilizing)
        totalAmt.IncrementValue(-digestedAmt, mass ? (const CCompoundUnit&)MassUnit::g : (const CCompoundUnit&)VolumeUnit::mL);
    }
  }
  return digestedAmt;
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// If no substance rates are provided on meals (Action or Condition) use a default from configuration
///
/// \details
//--------------------------------------------------------------------------------------------------
void Gastrointestinal::DefaultNutritionRates(SENutrition& n)
{
  if (n.HasCarbohydrate() && !n.HasCarbohydrateDigestionRate())
    n.GetCarbohydrateDigestionRate().SetValue(m_data.GetConfiguration().GetDefaultCarbohydrateDigestionRate(MassPerTimeUnit::g_Per_min),MassPerTimeUnit::g_Per_min);
  if (n.HasFat() && !n.HasFatDigestionRate())
    n.GetFatDigestionRate().SetValue(m_data.GetConfiguration().GetDefaultFatDigestionRate(MassPerTimeUnit::g_Per_min),MassPerTimeUnit::g_Per_min);
  if (n.HasProtein() && !n.HasProteinDigestionRate())
    n.GetProteinDigestionRate().SetValue(m_data.GetConfiguration().GetDefaultProteinDigestionRate(MassPerTimeUnit::g_Per_min), MassPerTimeUnit::g_Per_min);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Absorb substances from the gut into the vascular system via the small intestine
///
/// \details
/// Move substances from the chyme system into the vascular system based on a rate that is a 
/// function of the sodium concentration in the body
//--------------------------------------------------------------------------------------------------
void Gastrointestinal::AbsorbNutrients(double duration_s)
{
  double absorptionRate_mL_Per_min = 3.3; // Average water absorption rate Peronnet

  double absorbedVolume_mL = absorptionRate_mL_Per_min * duration_s / 60;
  double siVolume_mL = m_SmallIntestineChyme->GetVolume().GetValue(VolumeUnit::mL);
  if (siVolume_mL <= 0)
  {
    absorptionRate_mL_Per_min = 0;// No volume, no flow
  }
  else if (absorbedVolume_mL > siVolume_mL)
  {//Only take what we have
    absorbedVolume_mL = siVolume_mL;
    absorptionRate_mL_Per_min = 60 * (absorbedVolume_mL / duration_s);
  }

  if (m_data.GetState() == EngineState::AtSecondaryStableState)
  {// Don't Remove volume while stabilizing
    m_SmallIntestineChyme->GetVolume().IncrementValue(-absorbedVolume_mL, VolumeUnit::mL);
    // Calculate new concentrations for everything based on new volume
    for (SELiquidSubstanceQuantity* subQ : m_SmallIntestineChyme->GetSubstanceQuantities())
    {
      if (subQ->HasMass())
        subQ->Balance(BalanceLiquidBy::Mass);
    }
  }
 
  GetChymeAbsorptionRate().SetValue(absorptionRate_mL_Per_min, VolumePerTimeUnit::mL_Per_min);
  //This will move substances
  m_GItoCVPath->GetNextFlowSource().SetValue(absorptionRate_mL_Per_min, VolumePerTimeUnit::mL_Per_min);
  //Need to manually remove volume, since there isn't a compliance
  m_GItoCVPath->GetSourceNode().GetNextVolume().IncrementValue(-absorptionRate_mL_Per_min / 60.0 * m_dT_s, VolumeUnit::mL);
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Absorb a meal over a specified lenth of time
///
/// \details
/// This method supports the ConsumeMeal Condition, it will move the provied meal into the stomach
/// Digest food for the specifed length of time and move it to the Gut, then calculate the amount
/// of substance that would then have been absorbed from the Gut and distributes that mass throughout
/// the body tissues
//--------------------------------------------------------------------------------------------------
void Gastrointestinal::AbsorbMeal(double duration_min)
{
  if (duration_min <= 0)
    return;

  // We use the default healthy flow rate throughout this absorption
  // We could step wise this and see if we can figure out how pH is changing
  // in order to change the flow rate, but that is a bit much for this model implementation
  double flowRate_mL_Per_min = 3.3;

  // Calculate the amount of fluid flow based on the elaspsed time 
  double absorbedVolume_mL = flowRate_mL_Per_min*duration_min;
  double siVolume_mL = m_SmallIntestineChyme->GetVolume().GetValue(VolumeUnit::mL);
  if (absorbedVolume_mL > siVolume_mL)
    absorbedVolume_mL = siVolume_mL;// Don't take off what we don't have
#ifdef logMeal
  double totVol_mL = m_data.GetBloodChemistry()->GetExtravascularFluidVolume()->GetValue(VolumeUnit::mL);
  totVol_mL += m_data.GetCardiovascular()->GetBloodVolume()->GetValue(VolumeUnit::mL);
  m_ss << "Blood Volume before absorption " << totVol_mL << "(mL)";
  Info(m_ss);
  m_ss << "Gut Volume before absorption: " << m_GutChyme->GetVolume();
  Info(m_ss);
  m_ss << "Absorbed Volume : " << absorbedVolume_mL << "(mL)";
  Info(m_ss);
#endif
  m_SmallIntestineChyme->GetVolume().IncrementValue(-absorbedVolume_mL, VolumeUnit::mL);

  SEScalarVolume absorbedVolume;
  absorbedVolume.SetValue(absorbedVolume_mL, VolumeUnit::mL);
//m_data.GetCircuits().DistributeVolume(absorbedVolume);
#ifdef logMeal
  double newtotVol_mL = m_data.GetBloodChemistry()->GetExtravascularFluidVolume()->GetValue(VolumeUnit::mL);
  newtotVol_mL += m_data.GetCardiovascular()->GetBloodVolume()->GetValue(VolumeUnit::mL);
  m_ss << "Blood Volume after absorption " << newtotVol_mL << "(mL), body absorbed : " << newtotVol_mL - totVol_mL;
  Info(m_ss);
  m_ss << "Gut Volume after absorption: " << m_GutChyme->GetVolume();
  Info(m_ss);
  if (newtotVol_mL - totVol_mL != absorbedVolume_mL)
    Error("Water volume is NOT conserved");
  else
    Info("Water volume is conserved");
#endif

  // Doing mass then volume, I don't think it matters which order this happens in since 
  // the amount of mass that goes on a compartment is the ratio of it volume over the total
  // and incrementing total volume via compartment should keep that same ratio

  double bloodVol_mL = m_data.GetCardiovascular().GetBloodVolume(VolumeUnit::mL);
  double tissueVol_mL = m_data.GetTissue().GetExtravascularFluidVolume(VolumeUnit::mL);

  SEScalarMass mass;
  double gutMass_g;
  double absorbedMass_g = 0;
  for (auto i : m_InitialSubstanceMasses_ug)
  {
    gutMass_g = i.first->GetMass().GetValue(MassUnit::g);
    if (gutMass_g == 0)
      continue;// Nothing to move!
    // Calculate the amout that absorbed over the elapsed duration time
    absorbedMass_g = flowRate_mL_Per_min * duration_min * i.first->GetConcentration(MassPerVolumeUnit::g_Per_mL);
    
    // Make sure we do not pull out more than we have in the Gut Chyme
    if (gutMass_g < absorbedMass_g)
      absorbedMass_g = gutMass_g;
    if (absorbedMass_g <= 0)
      continue;
    // Pull mass off the chyme
#ifdef logMeal
    m_ss << "Preabsortion Gut mass for " << i.first->GetSubstance().GetName() << " " << i.first->GetMass();
    Info(m_ss);
    m_ss << "Absorbing " << absorbedMass_g << " (g)";
    Info(m_ss);
#endif
    i.first->GetMass().IncrementValue(-absorbedMass_g, MassUnit::g);
    i.first->Balance(BalanceLiquidBy::Mass);
    m_InitialSubstanceMasses_ug[i.first] = i.first->GetMass(MassUnit::ug);
#ifdef logMeal
    m_ss << "Postabsorption Gut mass for " << i.first->GetSubstance().GetName() << " " << i.first->GetMass();
    Info(m_ss);

    // Add mass to the tissue
    double bPreAbsorbed_g = m_data.GetCircuits()->TotalSubstanceInBlood(i.first->GetSubstance(), MassUnit::g);
    double tPreAbsorbed_g = m_data.GetCircuits()->TotalSubstanceInTissue(i.first->GetSubstance(), MassUnit::g);
    m_ss << "Preabsorbed Total " << i.first->GetSubstance().GetName() << " in body : " << bPreAbsorbed_g + tPreAbsorbed_g << "(g) b(" << bPreAbsorbed_g << ") t(" << tPreAbsorbed_g << ")";
    Info(m_ss);
#endif
    // Distribute the mass over the body 
    mass.SetValue(absorbedMass_g, MassUnit::g);
//  m_data.GetCircuits().DistributeBloodAndTissueMass(i.first->GetSubstance(), mass);
#ifdef logMeal
    double bPostAbsorbed_g = m_data.GetCircuits()->TotalSubstanceInBlood(i.first->GetSubstance(), MassUnit::g);
    double tPostAbsorbed_g = m_data.GetCircuits()->TotalSubstanceInTissue(i.first->GetSubstance(), MassUnit::g);
    m_ss << "PostAbsorbed Total " << i.first->GetSubstance().GetName() << " in body : " << bPostAbsorbed_g + tPostAbsorbed_g << "(g), body absorbed : " << (bPostAbsorbed_g + tPostAbsorbed_g) - (bPreAbsorbed_g + tPreAbsorbed_g) << "(g) b(" << bPostAbsorbed_g << ") t(" << tPostAbsorbed_g << ")";
    Info(m_ss);
    double massDifference_g = (bPostAbsorbed_g + tPostAbsorbed_g) - (bPreAbsorbed_g + tPreAbsorbed_g);
    if (!SEScalar::IsZero(massDifference_g - absorbedMass_g))
      Error("Mass is NOT Conserved");
    else
      Info("Mass is conserved");
#endif
  }
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Gastrointestinal Preprocess function
///
/// \details
/// The current Pulse implementation has no functionality in the process function for Gastrointestinal.
//--------------------------------------------------------------------------------------------------
void Gastrointestinal::Process()
{
  
}

//--------------------------------------------------------------------------------------------------
/// \brief
/// Gastrointestinal postprocess function
///
/// \details
/// The current Pulse implementation has no specific postprocess functionality.
//--------------------------------------------------------------------------------------------------
void Gastrointestinal::PostProcess()
{
  
}