/*
  *  MoMEMta: a modular implementation of the Matrix Element Method
  *  Copyright (C) 2016  Universite catholique de Louvain (UCL), Belgium
  *
  *  This program is free software: you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation, either version 3 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 
 #include <momemta/ParameterSet.h>
 #include <momemta/Module.h>
 
 #include <cmath>
 
 class BreitWignerGenerator: public Module {
     public:
 
         BreitWignerGenerator(PoolPtr pool, const ParameterSet& parameters): Module(pool, parameters.getModuleName()),
             mass(parameters.get<double>("mass")),
             width(parameters.get<double>("width")) {
 
             m_ps_point = get<double>(parameters.get<InputTag>("ps_point"));
         };
 
         virtual Status work() override {
 
             double psPoint = *m_ps_point;
             const double range = M_PI / 2. + std::atan(mass / width);
             const double y = - std::atan(mass / width) + range * psPoint;
 
             *s = mass * width * std::tan(y) + (mass * mass);
             *jacobian = range * mass * width / (std::cos(y) * std::cos(y));
 
             return Status::OK;
         }
 
     private:
         const double mass;
         const double width;
 
         // Inputs
         Value<double> m_ps_point;
 
         // Outputs
         std::shared_ptr<double> s = produce<double>("s");
         std::shared_ptr<double> jacobian = produce<double>("jacobian");
 
 
 };
 
 REGISTER_MODULE(BreitWignerGenerator)
         .Input("ps_point")
         .Output("s")
         .Output("jacobian")
         .Attr("mass:double")
         .Attr("width:double");