#include "DetectorConstruction.hh"
#include "PhotonHit.hh"
#include "OptFileManager.hh"
#include "SensitiveDetector.hh"
#include "G4LogicalBorderSurface.hh"
#include "G4RunManager.hh"
#include "G4NistManager.hh"
#include "G4Box.hh"
#include "G4LogicalVolume.hh"
#include "G4PVPlacement.hh"
#include "G4SystemOfUnits.hh"
#include "G4SDManager.hh"
#include "G4VisAttributes.hh"
#include "G4SubtractionSolid.hh"
#include "G4UnionSolid.hh"
#include "G4Tubs.hh"
#include <cmath>

// Option to switch on/off checking of volumes overlaps
G4bool checkOverlaps = true;

DetectorConstruction::DetectorConstruction() : G4VUserDetectorConstruction() {}
DetectorConstruction::~DetectorConstruction() {}

G4VPhysicalVolume* DetectorConstruction::Construct()
{
    // Define World Volume
    G4double world_size = 1.0 * m;
    G4Box* solidWorld = new G4Box("World", 0.5 * world_size, 0.5 * world_size, 0.5 * world_size);
    G4NistManager* nist = G4NistManager::Instance();
    G4Material* world_mat = nist->FindOrBuildMaterial("G4_AIR");
    G4LogicalVolume* logicWorld = new G4LogicalVolume(solidWorld, world_mat, "World");
    G4VPhysicalVolume* physWorld = new G4PVPlacement(0, G4ThreeVector(), logicWorld, "World", 0, false, 0, checkOverlaps);

    // Define LYSO material
    G4Element* Lu = new G4Element("Lutetium", "Lu", 71., 174.97 * g / mole);
    G4Element* Y = new G4Element("Yttrium", "Y", 39., 88.905 * g / mole);
    G4Element* Si = new G4Element("Silicon", "Si", 14., 28.085 * g / mole);
    G4Element* O = new G4Element("Oxygen", "O", 8., 16.00 * g / mole);

    G4Material* LYSO = new G4Material("LYSO", 7.1 * g / cm3, 4);
    LYSO->AddElement(Lu, 71.43 * perCent);
    LYSO->AddElement(Y, 4.03 * perCent);
    LYSO->AddElement(Si, 6.37 * perCent);
    LYSO->AddElement(O, 18.17 * perCent);

    G4Material* scint_mat = LYSO;

    // Define and Place the Scintillator
    G4double detector_x = 3 * mm;
    G4double detector_y = 3 * mm;
    G4double detector_z = 2 * cm;
    G4Box* solidDetector = new G4Box("Detector", detector_x / 2, detector_y / 2, detector_z / 2);
    G4LogicalVolume* logicDetector = new G4LogicalVolume(solidDetector, scint_mat, "Detector");
    G4VPhysicalVolume* physDetector = new G4PVPlacement(0, G4ThreeVector(), logicDetector, "Detector", logicWorld, false, 0, checkOverlaps);

    // Visualization
    G4VisAttributes* DetectorVis = new G4VisAttributes(G4Colour(0.9, 0.9, 0.9));
    DetectorVis->SetVisibility(true);
    DetectorVis->SetForceSolid(true);
    logicDetector->SetVisAttributes(DetectorVis);

    // Define and Place the PMT
    G4double pmt_radius = 1.5 * mm;
    G4double pmt_thickness = 1 * mm;
    G4Material* pmt_mat = nist->FindOrBuildMaterial("G4_Al");

    G4Tubs* solidPMT = new G4Tubs("PMT", 0., pmt_radius, pmt_thickness / 2, 0., 360. * deg);
    G4LogicalVolume* logicPMT = new G4LogicalVolume(solidPMT, pmt_mat, "PMT");
    
    // Position the PMT at the end of the scintillator
    G4ThreeVector pmt_pos(0, 0, detector_z / 2 + pmt_thickness / 2);
    G4VPhysicalVolume* physPMT = new G4PVPlacement(0, pmt_pos, logicPMT, "PMT", logicWorld, false, 0, checkOverlaps);

    // Visualization for PMT
    G4VisAttributes* PMTVis = new G4VisAttributes(G4Colour(0.0, 1.0, 0.0));
    PMTVis->SetVisibility(true);
    PMTVis->SetForceSolid(true);
    logicPMT->SetVisAttributes(PMTVis);

    // Sensitive Detector Setup
    G4SDManager* SD_manager = G4SDManager::GetSDMpointer();
    G4String SDModuleName = "/SensitiveDetector";

    // Check if the sensitive detector already exists
    SensitiveDetector* existingSD = dynamic_cast<SensitiveDetector*>(SD_manager->FindSensitiveDetector(SDModuleName));
    if (existingSD) {
        delete existingSD;
    }

    // Create a new sensitive detector
    G4String photonHitCollectionName = "PhotonHitCollection";
    SensitiveDetector* sensitiveModule = new SensitiveDetector(SDModuleName, "HitCollection", photonHitCollectionName);

    // Add the new sensitive detector to the SD manager
    SD_manager->AddNewDetector(sensitiveModule);

    // Set the sensitive detector to the logical volume of the scintillator
    logicDetector->SetSensitiveDetector(sensitiveModule);

    // Set the sensitive detector to the PMT as well
    logicPMT->SetSensitiveDetector(sensitiveModule);

    // Return the World Volume
    return physWorld;
}