// SPDX-License-Identifier: Apache-2.0
//
// Copyright 2008-2016 Conrad Sanderson (http://conradsanderson.id.au)
// Copyright 2008-2016 National ICT Australia (NICTA)
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ------------------------------------------------------------------------

//! \addtogroup fn_normpdf
//! @{

template <typename T1, typename T2, typename T3>
inline typename enable_if2<(is_real<typename T1::elem_type>::value), void>::result
normpdf_helper(Mat<typename T1::elem_type>& out,
               const Base<typename T1::elem_type, T1>& X_expr,
               const Base<typename T1::elem_type, T2>& M_expr,
               const Base<typename T1::elem_type, T3>& S_expr) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  if (Proxy<T1>::use_at || Proxy<T2>::use_at || Proxy<T3>::use_at) {
    const quasi_unwrap<T1> UX(X_expr.get_ref());
    const quasi_unwrap<T2> UM(M_expr.get_ref());
    const quasi_unwrap<T3> US(S_expr.get_ref());

    normpdf_helper(out, UX.M, UM.M, US.M);

    return;
  }

  const Proxy<T1> PX(X_expr.get_ref());
  const Proxy<T2> PM(M_expr.get_ref());
  const Proxy<T3> PS(S_expr.get_ref());

  arma_conform_check(
      ((PX.get_n_rows() != PM.get_n_rows()) || (PX.get_n_cols() != PM.get_n_cols()) ||
       (PM.get_n_rows() != PS.get_n_rows()) || (PM.get_n_cols() != PS.get_n_cols())),
      "normpdf(): size mismatch");

  out.set_size(PX.get_n_rows(), PX.get_n_cols());

  eT* out_mem = out.memptr();

  const uword N = PX.get_n_elem();

  typename Proxy<T1>::ea_type X_ea = PX.get_ea();
  typename Proxy<T2>::ea_type M_ea = PM.get_ea();
  typename Proxy<T3>::ea_type S_ea = PS.get_ea();

  const bool use_mp = arma_config::openmp && mp_gate<eT, true>::eval(N);

  if (use_mp) {
#if defined(ARMA_USE_OPENMP)
    {
      const int n_threads = mp_thread_limit::get();
#pragma omp parallel for schedule(static) num_threads(n_threads)
      for (uword i = 0; i < N; ++i) {
        const eT sigma = S_ea[i];

        const eT tmp = (X_ea[i] - M_ea[i]) / sigma;

        out_mem[i] = std::exp(eT(-0.5) * (tmp * tmp)) / (sigma * Datum<eT>::sqrt2pi);
      }
    }
#endif
  } else {
    for (uword i = 0; i < N; ++i) {
      const eT sigma = S_ea[i];

      const eT tmp = (X_ea[i] - M_ea[i]) / sigma;

      out_mem[i] = std::exp(eT(-0.5) * (tmp * tmp)) / (sigma * Datum<eT>::sqrt2pi);
    }
  }
}

template <typename eT>
arma_warn_unused inline typename enable_if2<(is_real<eT>::value), eT>::result normpdf(
    const eT x) {
  const eT out = std::exp(eT(-0.5) * (x * x)) / Datum<eT>::sqrt2pi;

  return out;
}

template <typename eT>
arma_warn_unused inline typename enable_if2<(is_real<eT>::value), eT>::result normpdf(
    const eT x, const eT mu, const eT sigma) {
  const eT tmp = (x - mu) / sigma;

  const eT out = std::exp(eT(-0.5) * (tmp * tmp)) / (sigma * Datum<eT>::sqrt2pi);

  return out;
}

template <typename eT, typename T2, typename T3>
arma_warn_unused inline typename enable_if2<(is_real<eT>::value), Mat<eT> >::result
normpdf(const eT x, const Base<eT, T2>& M_expr, const Base<eT, T3>& S_expr) {
  arma_debug_sigprint();

  const quasi_unwrap<T2> UM(M_expr.get_ref());
  const Mat<eT>& M = UM.M;

  Mat<eT> out;

  normpdf_helper(out, x * ones<Mat<eT> >(arma::size(M)), M, S_expr.get_ref());

  return out;
}

template <typename T1>
arma_warn_unused inline typename enable_if2<(is_real<typename T1::elem_type>::value),
                                            Mat<typename T1::elem_type> >::result
normpdf(const Base<typename T1::elem_type, T1>& X_expr) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  const quasi_unwrap<T1> UX(X_expr.get_ref());
  const Mat<eT>& X = UX.M;

  Mat<eT> out;

  normpdf_helper(out, X, zeros<Mat<eT> >(arma::size(X)), ones<Mat<eT> >(arma::size(X)));

  return out;
}

template <typename T1>
arma_warn_unused inline typename enable_if2<(is_real<typename T1::elem_type>::value),
                                            Mat<typename T1::elem_type> >::result
normpdf(const Base<typename T1::elem_type, T1>& X_expr, const typename T1::elem_type mu,
        const typename T1::elem_type sigma) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  const quasi_unwrap<T1> UX(X_expr.get_ref());
  const Mat<eT>& X = UX.M;

  Mat<eT> out;

  normpdf_helper(out, X, mu * ones<Mat<eT> >(arma::size(X)),
                 sigma * ones<Mat<eT> >(arma::size(X)));

  return out;
}

template <typename T1, typename T2, typename T3>
arma_warn_unused inline typename enable_if2<(is_real<typename T1::elem_type>::value),
                                            Mat<typename T1::elem_type> >::result
normpdf(const Base<typename T1::elem_type, T1>& X_expr,
        const Base<typename T1::elem_type, T2>& M_expr,
        const Base<typename T1::elem_type, T3>& S_expr) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  Mat<eT> out;

  normpdf_helper(out, X_expr.get_ref(), M_expr.get_ref(), S_expr.get_ref());

  return out;
}

//! @}
