#include "construction.hh"
#include <fstream>
#include <sstream>
#include <iostream>

MyDetectorConstruction::MyDetectorConstruction()
 : G4VUserDetectorConstruction(), solidWorld(nullptr), logicWorld(nullptr), physWorld(nullptr), worldMat(nullptr),
   fElectricField(nullptr), fFieldManager(nullptr), fChordFinder(nullptr)
{}

MyDetectorConstruction::~MyDetectorConstruction() 
{}

G4VPhysicalVolume *MyDetectorConstruction::Construct()
{
    G4NistManager *nist = G4NistManager::Instance();

    G4double atomicNumberVac = 1.;
    G4double massOfMole = 1.008*g/mole;
    G4double vacDensity = 1.e-25*g/cm3;
    G4double temperature = 293*kelvin;
    G4double pressure = 3.e-8*pascal; //typical pressure in an electron microscope
    
    worldMat = new G4Material("vaccum_microscope", atomicNumberVac, massOfMole, vacDensity, kStateGas, temperature, pressure); 
    
    solidWorld = new G4Box("solidWorld", 0.06*m, 0.06*m, 0.015*m);
    logicWorld = new G4LogicalVolume(solidWorld, worldMat,"logicWorld");
    physWorld = new G4PVPlacement(0, G4ThreeVector(0.,0.,0.), logicWorld, "physWorld", 0, false, 0, true);

    // specify the field file name here
    G4String fieldFilename = "uniform_field.txt";
    ConstructField(fieldFilename);

    return physWorld;
}

void MyDetectorConstruction::ConstructField(const G4String& fieldFilename)
{
    fElectricField = new MyElectricField(fieldFilename);
    G4EqMagElectricField* equation = new G4EqMagElectricField(fElectricField);
    G4MagIntegratorStepper* stepper = new G4ClassicalRK4(equation, 8);

    G4double minStep = 0.01*mm;
    G4MagInt_Driver* driver = new G4MagInt_Driver(minStep, stepper, stepper->GetNumberOfVariables());
    fChordFinder = new G4ChordFinder(driver);

    fFieldManager = new G4FieldManager(fElectricField);
    fFieldManager->SetChordFinder(fChordFinder);

    // assign the field manager to the logical volume
    logicWorld->SetFieldManager(fFieldManager, true);

    G4TransportationManager::GetTransportationManager()->GetFieldManager()->SetDetectorField(fElectricField);
    G4TransportationManager::GetTransportationManager()->GetFieldManager()->SetChordFinder(fChordFinder);

    // print field values at some random points for debugging
    std::vector<G4ThreeVector> debugPoints = 
    {
        G4ThreeVector(0, 0, 0),
        G4ThreeVector(1, 1, 1),
        G4ThreeVector(2, 2, 2)
    };
    fElectricField->PrintFieldValues(debugPoints);
    
    // verbosity commands
    G4UImanager* UImanager = G4UImanager::GetUIpointer();
    UImanager->ApplyCommand("/tracking/verbose 1");
    UImanager->ApplyCommand("/step/verbose 1");
}