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 // SPDX-License-Identifier: LGPL-3.0-or-later
 // Copyright (C) 2022 Chao Peng, Maria Zurek, Whitney Armstrong
 
 // Detector plugin to support a hybrid central barrel calorimeter
 // The detector consists of interlayers of Pb/ScFi (segmentation in global r, phi) and W/Si (segmentation in local x, y)
 // Assembly is used as the envelope so two different detectors can be interlayered with each other
 //
 //
 // 06/19/2021: Implementation of the Sci Fiber geometry. M. Żurek
 // 07/09/2021: Support interlayers between multiple detectors. C. Peng
 // 07/23/2021: Add assemblies as mother volumes of fibers to reduce the number of daughter volumes. C. Peng, M. Żurek
 //     Reference: TGeo performance issue with large number of daughter volumes
 //     https://indico.cern.ch/event/967418/contributions/4075358/attachments/2128099/3583278/201009_shKo_dd4hep.pdf
 // 07/24/2021: Changed support implementation to avoid too many uses of boolean geometries. DAWN view seems to have
 //     issue dealing with it. C. Peng
 
 #include "DD4hep/DetFactoryHelper.h"
 #include "Math/Point2D.h"
 #include "TGeoPolygon.h"
 #include "XML/Layering.h"
 #include <functional>
 
 using namespace dd4hep;
 
 typedef ROOT::Math::XYPoint Point;
 // fiber placement helpers, defined below
 struct FiberGrid {
   int ix = 0, iy = 0;
   std::vector<Point> points;
   Point mean_centroid    = Point(0., 0.);
   Assembly* assembly_ptr = nullptr;
 
   // initialize with grid id and points
   FiberGrid(int i, int j, const std::vector<Point>& pts) : ix(i), iy(j), points(pts) {
     if (pts.empty()) {
       return;
     }
 
     double mx = 0., my = 0.;
     for (auto& p : pts) {
       mx += p.x();
       my += p.y();
     }
     mx /= static_cast<double>(pts.size());
     my /= static_cast<double>(pts.size());
     mean_centroid = Point(mx, my);
   };
 };
 
 std::vector<Point> fiberPositions(double r, double sx, double sz, double trx, double trz,
                                   double phi, bool shift_first = false, double stol = 1e-2);
 std::vector<FiberGrid> gridPoints(int div_n_phi, double div_dr, double x, double z, double phi);
 
 // geometry helpers
 void buildFibers(Detector& desc, SensitiveDetector& sens, Volume& mother, int layer_nunber,
                  xml_comp_t x_fiber, const std::tuple<double, double, double, double>& dimensions);
 void buildSupport(Detector& desc, Volume& mother, xml_comp_t x_support,
                   const std::tuple<double, double, double, double>& dimensions);
 
 // barrel ecal layers contained in an assembly
 static Ref_t create_detector(Detector& desc, xml_h e, SensitiveDetector sens) {
   Layering layering(e);
   xml_det_t x_det      = e;
   Material air         = desc.air();
   int det_id           = x_det.id();
   double offset        = x_det.attr<double>(_Unicode(offset));
   xml_comp_t x_dim     = x_det.dimensions();
   int nsides           = x_dim.numsides();
   double inner_r       = x_dim.rmin();
   double dphi          = (2 * M_PI / nsides);
   double hphi          = dphi / 2;
   std::string det_name = x_det.nameStr();
 
   DetElement sdet(det_name, det_id);
   Volume motherVol = desc.pickMotherVolume(sdet);
 
   Assembly envelope(det_name);
   Transform3D tr_global = Translation3D(0, 0, offset) * RotationZ(hphi);
   PlacedVolume env_phv  = motherVol.placeVolume(envelope, tr_global);
   sens.setType("calorimeter");
 
   env_phv.addPhysVolID("system", det_id);
   sdet.setPlacement(env_phv);
 
   // build a single sector
   DetElement sector_det("sector0", det_id);
   Assembly mod_vol("sector");
 
   // keep tracking of the total thickness
   double l_pos_z = inner_r;
   { // =====  buildBarrelStave(desc, sens, module_volume) =====
     // Parameters for computing the layer X dimension:
     double tan_hphi = std::tan(hphi);
     double l_dim_y  = x_dim.z() / 2.;
 
     // Loop over the sets of layer elements in the detector.
     int l_num = 1;
     for (xml_coll_t li(x_det, _U(layer)); li; ++li) {
       xml_comp_t x_layer     = li;
       int repeat             = x_layer.repeat();
       double l_space_between = getAttrOrDefault(x_layer, _Unicode(space_between), 0.);
       double l_space_before  = getAttrOrDefault(x_layer, _Unicode(space_before), 0.);
       l_pos_z += l_space_before;
       // Loop over number of repeats for this layer.
       for (int j = 0; j < repeat; j++) {
         std::string l_name = Form("layer%d", l_num);
         double l_thickness = layering.layer(l_num - 1)->thickness(); // Layer's thickness.
         double l_dim_x     = tan_hphi * l_pos_z;
         l_pos_z += l_thickness;
 
         Position l_pos(0, 0, l_pos_z - l_thickness / 2.); // Position of the layer.
         double l_trd_x1 = l_dim_x;
         double l_trd_x2 = l_dim_x + l_thickness * tan_hphi;
         double l_trd_y1 = l_dim_y;
         double l_trd_y2 = l_trd_y1;
         double l_trd_z  = l_thickness / 2;
         Trapezoid l_shape(l_trd_x1, l_trd_x2, l_trd_y1, l_trd_y2, l_trd_z);
         Volume l_vol(l_name, l_shape, air);
         DetElement layer(sector_det, l_name, det_id);
 
         // Loop over the sublayers or slices for this layer.
         int s_num      = 1;
         double s_pos_z = -(l_thickness / 2.);
         for (xml_coll_t si(x_layer, _U(slice)); si; ++si) {
           xml_comp_t x_slice = si;
           std::string s_name = Form("slice%d", s_num);
           double s_thick     = x_slice.thickness();
           double s_trd_x1    = l_dim_x + (s_pos_z + l_thickness / 2) * tan_hphi;
           double s_trd_x2    = l_dim_x + (s_pos_z + l_thickness / 2 + s_thick) * tan_hphi;
           double s_trd_y1    = l_trd_y1;
           double s_trd_y2    = s_trd_y1;
           double s_trd_z     = s_thick / 2.;
           Trapezoid s_shape(s_trd_x1, s_trd_x2, s_trd_y1, s_trd_y2, s_trd_z);
           Volume s_vol(s_name, s_shape, desc.material(x_slice.materialStr()));
           DetElement slice(layer, s_name, det_id);
 
           // build fibers
           if (x_slice.hasChild(_Unicode(fiber))) {
             buildFibers(desc, sens, s_vol, l_num, x_slice.child(_Unicode(fiber)),
                         {s_trd_x1, s_thick, l_dim_y, hphi});
           }
 
           if (x_slice.isSensitive()) {
             s_vol.setSensitiveDetector(sens);
           }
           s_vol.setAttributes(desc, x_slice.regionStr(), x_slice.limitsStr(), x_slice.visStr());
 
           // Slice placement.
           PlacedVolume slice_phv = l_vol.placeVolume(s_vol, Position(0, 0, s_pos_z + s_thick / 2));
           slice_phv.addPhysVolID("slice", s_num);
           slice.setPlacement(slice_phv);
           // Increment Z position of slice.
           s_pos_z += s_thick;
           ++s_num;
         }
 
         // Set region, limitset, and vis of layer.
         l_vol.setAttributes(desc, x_layer.regionStr(), x_layer.limitsStr(), x_layer.visStr());
 
         PlacedVolume layer_phv = mod_vol.placeVolume(l_vol, l_pos);
         layer_phv.addPhysVolID("layer", l_num);
         layer.setPlacement(layer_phv);
         // Increment to next layer Z position. Do not add space_between for the last layer
         if (j < repeat - 1) {
           l_pos_z += l_space_between;
         }
         ++l_num;
       }
     }
   }
   // Phi start for a sector.
   double phi = M_PI / nsides;
   // Create nsides sectors.
   for (int i = 0; i < nsides; i++, phi -= dphi) { // i is module number
     // Compute the sector position
     Transform3D tr(RotationZYX(0, phi, M_PI * 0.5), Translation3D(0, 0, 0));
     PlacedVolume pv = envelope.placeVolume(mod_vol, tr);
     pv.addPhysVolID("sector", i + 1);
     DetElement sd = (i == 0) ? sector_det : sector_det.clone(Form("sector%d", i));
     sd.setPlacement(pv);
     sdet.add(sd);
   }
 
   // optional sector attributes
   if (x_det.hasChild(_Unicode(sectors))) {
     xml_comp_t x_sectors = x_det.child(_Unicode(sectors));
     mod_vol.setVisAttributes(desc.visAttributes(x_sectors.visStr()));
   }
   if (x_det.hasChild(_U(support))) {
     buildSupport(desc, mod_vol, x_det.child(_U(support)), {inner_r, l_pos_z, x_dim.z(), hphi});
   }
 
   // Set envelope volume attributes.
   envelope.setAttributes(desc, x_det.regionStr(), x_det.limitsStr(), x_det.visStr());
   return sdet;
 }
 
 void buildFibers(Detector& desc, SensitiveDetector& sens, Volume& s_vol, int layer_number,
                  xml_comp_t x_fiber, const std::tuple<double, double, double, double>& dimensions) {
   auto [s_trd_x1, s_thick, s_length, hphi] = dimensions;
   double f_radius                          = getAttrOrDefault(x_fiber, _U(radius), 0.1 * cm);
   double f_cladding_thickness = getAttrOrDefault(x_fiber, _Unicode(cladding_thickness), 0.0 * cm);
   double f_spacing_x          = getAttrOrDefault(x_fiber, _Unicode(spacing_x), 0.122 * cm);
   double f_spacing_z          = getAttrOrDefault(x_fiber, _Unicode(spacing_z), 0.134 * cm);
   int grid_n_phi              = getAttrOrDefault(x_fiber, _Unicode(grid_n_phi), 5);
   double grid_dr              = getAttrOrDefault(x_fiber, _Unicode(grid_dr), 2.0 * cm);
   std::string f_id_grid = getAttrOrDefault<std::string>(x_fiber, _Unicode(identifier_grid), "grid");
   std::string f_id_fiber =
       getAttrOrDefault<std::string>(x_fiber, _Unicode(identifier_fiber), "fiber");
 
   // Set up the readout grid for the fiber layers
   // Trapezoid is divided into segments with equal dz and equal number of divisions in x
   // Every segment is a polygon that can be attached later to the lightguide
   // The grid size is assumed to be ~2x2 cm (starting values). This is to be larger than
   // SiPM chip (for GlueX 13mmx13mm: 4x4 grid 3mmx3mm with 3600 50×50 μm pixels each)
   // See, e.g., https://arxiv.org/abs/1801.03088 Fig. 2d
 
   // fiber and its cladding
   double f_radius_core = f_radius - f_cladding_thickness;
   Tube f_tube_clad(0, f_radius, s_length);
   Volume f_vol_clad("fiber_vol", f_tube_clad, desc.material(x_fiber.materialStr()));
   Tube f_tube_core(0, f_radius_core, s_length);
   Volume f_vol_core("fiber_core_vol", f_tube_core, desc.material(x_fiber.materialStr()));
   if (x_fiber.isSensitive()) {
     f_vol_core.setSensitiveDetector(sens);
   }
   f_vol_core.setAttributes(desc, x_fiber.regionStr(), x_fiber.limitsStr(), x_fiber.visStr());
   f_vol_clad.placeVolume(f_vol_core);
 
   // calculate polygonal grid coordinates (vertices)
   auto grids = gridPoints(grid_n_phi, grid_dr, s_trd_x1, s_thick, hphi);
   std::vector<int> f_id_count(grids.size(), 0);
   // use layer_number % 2 to add correct shifts for the adjacent fibers at layer boundary
   auto f_pos = fiberPositions(f_radius, f_spacing_x, f_spacing_z, s_trd_x1, s_thick, hphi,
                               (layer_number % 2 == 0));
   // a helper struct to speed up searching
   struct Fiber {
     Point pos;
     bool assigned = false;
     Fiber(const Point& p) : pos(p) {};
   };
   std::vector<Fiber> fibers(f_pos.begin(), f_pos.end());
 
   // build assembly for each grid and put fibers in
   for (auto& gr : grids) {
     Assembly grid_vol(Form("fiber_grid_%i_%i", gr.ix, gr.iy));
 
     // loop over all fibers that are not assigned to a grid
     int f_id = 1;
     for (auto& fi : fibers) {
       if (fi.assigned) {
         continue;
       }
 
       // use TGeoPolygon to help check if fiber is inside a grid
       TGeoPolygon poly(gr.points.size());
       std::vector<double> vx, vy;
       std::transform(gr.points.begin(), gr.points.end(), back_inserter(vx), std::mem_fn(&Point::x));
       std::transform(gr.points.begin(), gr.points.end(), back_inserter(vy), std::mem_fn(&Point::y));
       poly.SetXY(vx.data(), vy.data());
       poly.FinishPolygon();
 
       double f_xy[2] = {fi.pos.x(), fi.pos.y()};
       if (not poly.Contains(f_xy)) {
         continue;
       }
 
       // place fiber in grid
       auto p        = fi.pos - gr.mean_centroid;
       auto clad_phv = grid_vol.placeVolume(f_vol_clad, Position(p.x(), p.y(), 0.));
       clad_phv.addPhysVolID(f_id_fiber, f_id);
       fi.assigned = true;
       f_id++;
     }
 
     // only add this if this grid has fibers
     if (f_id > 1) {
       // fiber is along y-axis of the layer volume, so grids are arranged on X-Z plane
       Transform3D gr_tr(RotationZYX(0., 0., M_PI * 0.5),
                         Position(gr.mean_centroid.x(), 0., gr.mean_centroid.y()));
       auto grid_phv = s_vol.placeVolume(grid_vol, gr_tr);
       grid_phv.addPhysVolID(f_id_grid, gr.ix + gr.iy * grid_n_phi + 1);
       grid_vol.ptr()->Voxelize("");
     }
   }
 
   /*
   // sanity check
   size_t missing_fibers = 0;
   for (auto &fi : fibers) {
     if (not fi.assigned) {
       missing_fibers++;
     }
   }
   std::cout << "built " << fibers.size() << " fibers, "
             << missing_fibers << " of them failed to find a grid" << std::endl;
   */
 }
 
 // simple aluminum sheet cover
 // dimensions: (inner r, position in z, length, phi)
 void buildSupport(Detector& desc, Volume& mod_vol, xml_comp_t x_support,
                   const std::tuple<double, double, double, double>& dimensions) {
   auto [inner_r, pos_z, sector_length, hphi] = dimensions;
   double support_thickness = getAttrOrDefault(x_support, _Unicode(thickness), 3. * cm);
   auto material            = desc.material(x_support.materialStr());
   double trd_y             = sector_length / 2.;
   double trd_x1_support    = std::tan(hphi) * pos_z;
   double trd_x2_support    = std::tan(hphi) * (pos_z + support_thickness);
 
   Trapezoid s_shape(trd_x1_support, trd_x2_support, trd_y, trd_y, support_thickness / 2.);
   Volume s_vol("support_layer", s_shape, material);
   s_vol.setVisAttributes(desc.visAttributes(x_support.visStr()));
   mod_vol.placeVolume(s_vol, Position(0.0, 0.0, pos_z + support_thickness / 2.));
 }
 
 // Fill fiber lattice into trapezoid starting from position (0,0) in x-z coordinate system
 std::vector<Point> fiberPositions(double r, double sx, double sz, double trx, double trz,
                                   double phi, bool shift, double stol) {
   // r      - fiber radius
   // sx, sz - spacing between fibers in x, z
   // trx    - half-length of the shorter (bottom) base of the trapezoid
   // trz    - height of the trapezoid
   // phi    - angle between z and trapezoid arm
   // stol   - spacing tolerance
 
   std::vector<Point> positions;
   int z_layers = floor((trz / 2 - r - stol) / sz); // number of layers that fits in half trapezoid-z
 
   double px = 0., pz = 0.;
   int start_line = shift ? 1 : 0;
 
   for (int l = -z_layers; l < z_layers + 1; l++) {
     std::vector<Point> xline;
     pz           = l * sz;
     double x_max = trx + (trz / 2. + pz) * tan(phi) - stol; // calculate max x at particular z_pos
     (abs(l) % 2 == start_line) ? px = 0. : px = sx / 2;     // account for spacing/2 shift
 
     while (px < (x_max - r)) {
       xline.push_back(Point(px, pz));
       if (px != 0.)
         xline.push_back(Point(-px, pz)); // using symmetry around x=0
       px += sx;
     }
 
     // Sort fiber IDs for a better organization
     sort(xline.begin(), xline.end(),
          [](const Point& p1, const Point& p2) { return p1.x() < p2.x(); });
     positions.insert(positions.end(), xline.begin(), xline.end());
   }
   return positions;
 }
 
 // Determine the number of divisions for the readout grid for the fiber layers
 // Calculate dimensions of the polygonal grid
 std::vector<FiberGrid> gridPoints(int div_n_phi, double div_dr, double trd_x1, double height,
                                   double phi) {
   /*
   // TODO: move this test to xml file
   double SiPMsize = 13.0 * mm;
   double grid_min = SiPMsize + 3.0 * mm;
 
   if (dz < grid_min) {
     dz = grid_min;
   }
 
   if (dx < grid_min) {
     dx = grid_min;
   }
   */
   // number of divisions
   int nph = div_n_phi;
   int nr  = floor(height / div_dr);
   if (nr == 0) {
     nr++;
   }
 
   // grid vertices
   std::vector<FiberGrid> results;
   double dr = height / nr;
 
   for (int ir = 0; ir <= nr; ir++) {
     for (int iph = 0; iph <= nph; iph++) {
       double A_y = -height / 2. + ir * dr;
       double B_y = -height / 2. + (ir + 1) * dr;
 
       double botl_dr = 2 * (trd_x1 + ir * dr * tan(phi));
       double topl_dr = 2 * (trd_x1 + (ir + 1) * dr * tan(phi));
 
       double botl_dph_dr = botl_dr / nph;
       double topl_dph_dr = topl_dr / nph;
 
       double A_x = -botl_dr / 2. + iph * botl_dph_dr;
       double B_x = -topl_dr / 2. + iph * topl_dph_dr;
 
       double C_y = B_y;
       double D_y = A_y;
       double C_x = B_x + topl_dph_dr;
       double D_x = A_x + botl_dph_dr;
 
       auto A = Point(A_x, A_y);
       auto B = Point(B_x, B_y);
       auto C = Point(C_x, C_y);
       auto D = Point(D_x, D_y);
 
       // vertex points filled in the clock-wise direction
       results.emplace_back(FiberGrid(iph, ir, {A, B, C, D}));
     }
   }
 
   return results;
 }
 
 DECLARE_DETELEMENT(epic_EcalBarrelScFi, create_detector)

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