#include <cmath>
#include <functional>
#include <numeric>

#include "Absorption.h"

using namespace std;

using namespace OscProb;

const double Absorption::kU = 1.660539066e-24; // atomic mass unit [g]

Absorption::Absorption() {}

Absorption::~Absorption() {}

//.............................................................................
double Absorption::Trans(double xsec)
{
  vector<double> p_trans_vec;

  for (int i = 0; i < int(fNuPaths.size()); i++) {
    double n       = fNuPaths[i].density / kU;
    double l       = fNuPaths[i].length * 1e5; // l in km -> cm
    double p_trans = exp(-l * n * xsec);
    p_trans_vec.push_back(p_trans); // probability of NO absorption!
  }

  // returns probability of transmission
  return accumulate(p_trans_vec.begin(), p_trans_vec.end(), 1.,
                    multiplies<double>());
}

//.............................................................................
void Absorption::SetPath(vector<NuPath> paths) { fNuPaths = paths; }