#ifndef STAN_MATH_PRIM_SCAL_PROB_HYPERGEOMETRIC_LOG_HPP
#define STAN_MATH_PRIM_SCAL_PROB_HYPERGEOMETRIC_LOG_HPP

#include <stan/math/prim/scal/err/check_consistent_sizes.hpp>
#include <stan/math/prim/scal/err/check_bounded.hpp>
#include <stan/math/prim/scal/err/check_finite.hpp>
#include <stan/math/prim/scal/err/check_greater.hpp>
#include <stan/math/prim/scal/err/check_positive.hpp>
#include <stan/math/prim/scal/fun/binomial_coefficient_log.hpp>
#include <stan/math/prim/scal/meta/length.hpp>
#include <stan/math/prim/scal/meta/VectorView.hpp>
#include <stan/math/prim/scal/meta/VectorBuilder.hpp>
#include <stan/math/prim/scal/meta/return_type.hpp>
#include <stan/math/prim/scal/meta/include_summand.hpp>
#include <stan/math/prim/scal/fun/constants.hpp>
#include <boost/math/distributions.hpp>

namespace stan {
  namespace math {

    // Hypergeometric(n|N, a, b)  [0 <= n <= a;  0 <= N-n <= b;  0 <= N <= a+b]
    // n: #white balls drawn;  N: #balls drawn;
    // a: #white balls;  b: #black balls
    template <bool propto,
              typename T_n, typename T_N,
              typename T_a, typename T_b>
    double
    hypergeometric_log(const T_n& n, const T_N& N,
                       const T_a& a, const T_b& b) {
      static const char* function("hypergeometric_log");

      if (!(stan::length(n)
            && stan::length(N)
            && stan::length(a)
            && stan::length(b)))
        return 0.0;

      VectorView<const T_n> n_vec(n);
      VectorView<const T_N> N_vec(N);
      VectorView<const T_a> a_vec(a);
      VectorView<const T_b> b_vec(b);
      size_t size = max_size(n, N, a, b);

      double logp(0.0);
      check_bounded(function, "Successes variable", n, 0, a);
      check_greater(function, "Draws parameter", N, n);
      for (size_t i = 0; i < size; i++) {
        check_bounded(function, "Draws parameter minus successes variable",
                      N_vec[i]-n_vec[i], 0, b_vec[i]);
        check_bounded(function, "Draws parameter", N_vec[i], 0,
                      a_vec[i]+b_vec[i]);
      }
      check_consistent_sizes(function,
                             "Successes variable", n,
                             "Draws parameter", N,
                             "Successes in population parameter", a,
                             "Failures in population parameter", b);

      if (!include_summand<propto>::value)
        return 0.0;

      for (size_t i = 0; i < size; i++)
        logp += math::binomial_coefficient_log(a_vec[i], n_vec[i])
          + math::binomial_coefficient_log(b_vec[i], N_vec[i]-n_vec[i])
          - math::binomial_coefficient_log(a_vec[i]+b_vec[i], N_vec[i]);
      return logp;
    }

    template <typename T_n,
              typename T_N,
              typename T_a,
              typename T_b>
    inline
    double
    hypergeometric_log(const T_n& n,
                       const T_N& N,
                       const T_a& a,
                       const T_b& b) {
      return hypergeometric_log<false>(n, N, a, b);
    }

  }
}
#endif
