// Arguments: Ints, Doubles, Doubles
#include <stan/math/prim.hpp>

using stan::math::var;
using std::numeric_limits;
using std::vector;

class AgradDistributionsNegBinomial2 : public AgradDistributionTest {
 public:
  void valid_values(vector<vector<double> >& parameters,
                    vector<double>& log_prob) {
    vector<double> param(3);

    param[0] = 10;   // n
    param[1] = 2.0;  // mu
    param[2] = 1.5;  // phi
    parameters.push_back(param);
    log_prob.push_back(-5.55873452880806);  // expected log_prob

    param[0] = 100;  // n
    param[1] = 3.0;  // mu
    param[2] = 3.5;  // phi
    parameters.push_back(param);
    log_prob.push_back(-69.1303554183435);  // expected log_prob

    param[0] = 100;  // n
    param[1] = 4;    // mu
    param[2] = 200;  // phi
    parameters.push_back(param);
    log_prob.push_back(-209.614066642678);  // expected log_prob
  }

  void invalid_values(vector<size_t>& index, vector<double>& value) {
    // n
    index.push_back(0U);
    value.push_back(-1);

    // mu
    index.push_back(1U);
    value.push_back(-1);

    // phi
    index.push_back(2U);
    value.push_back(-1);
  }

  template <class T_n, class T_location, class T_inv_scale, typename T3,
            typename T4, typename T5>
  stan::return_type_t<T_location, T_inv_scale> log_prob(const T_n& n,
                                                        const T_location& mu,
                                                        const T_inv_scale& phi,
                                                        const T3&, const T4&,
                                                        const T5&) {
    return stan::math::neg_binomial_2_log(n, mu, phi);
  }

  template <bool propto, class T_n, class T_location, class T_inv_scale,
            typename T3, typename T4, typename T5>
  stan::return_type_t<T_location, T_inv_scale> log_prob(const T_n& n,
                                                        const T_location& mu,
                                                        const T_inv_scale& phi,
                                                        const T3&, const T4&,
                                                        const T5&) {
    return stan::math::neg_binomial_2_log<propto>(n, mu, phi);
  }

  template <class T_n, class T_location, class T_inv_scale, typename T3,
            typename T4, typename T5>
  stan::return_type_t<T_location, T_inv_scale> log_prob_function(
      const T_n& n, const T_location& mu, const T_inv_scale& phi, const T3&,
      const T4&, const T5&) {
    using stan::math::binomial_coefficient_log;
    using stan::math::multiply_log;
    using std::log;

    if (n != 0)
      return binomial_coefficient_log<
                 typename stan::scalar_type<T_inv_scale>::type>(n + phi - 1.0,
                                                                n)
             + multiply_log(n, mu) + multiply_log(phi, phi)
             - (n + phi) * log(mu + phi);
    return log(0.0);
  }
};
