// 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 gmm_misc
//! @{

namespace gmm_priv {

template <typename eT>
inline running_mean_scalar<eT>::running_mean_scalar() : counter(uword(0)), r_mean(eT(0)) {
  arma_debug_sigprint_this(this);
}

template <typename eT>
inline running_mean_scalar<eT>::running_mean_scalar(const running_mean_scalar<eT>& in)
    : counter(in.counter), r_mean(in.r_mean) {
  arma_debug_sigprint_this(this);
}

template <typename eT>
inline const running_mean_scalar<eT>& running_mean_scalar<eT>::operator=(
    const running_mean_scalar<eT>& in) {
  arma_debug_sigprint();

  counter = in.counter;
  r_mean = in.r_mean;

  return *this;
}

template <typename eT>
inline void running_mean_scalar<eT>::operator()(const eT X) {
  arma_debug_sigprint();

  counter++;

  if (counter > 1) {
    const eT old_r_mean = r_mean;

    r_mean = old_r_mean + (X - old_r_mean) / counter;
  } else {
    r_mean = X;
  }
}

template <typename eT>
inline void running_mean_scalar<eT>::reset() {
  arma_debug_sigprint();

  counter = 0;
  r_mean = eT(0);
}

template <typename eT>
inline uword running_mean_scalar<eT>::count() const {
  return counter;
}

template <typename eT>
inline eT running_mean_scalar<eT>::mean() const {
  return r_mean;
}

//
//
//

template <typename eT>
arma_inline eT distance<eT, uword(1)>::eval(const uword N, const eT* A, const eT* B,
                                            const eT*) {
  eT acc1 = eT(0);
  eT acc2 = eT(0);

  uword i, j;
  for (i = 0, j = 1; j < N; i += 2, j += 2) {
    eT tmp_i = A[i];
    eT tmp_j = A[j];

    tmp_i -= B[i];
    tmp_j -= B[j];

    acc1 += tmp_i * tmp_i;
    acc2 += tmp_j * tmp_j;
  }

  if (i < N) {
    const eT tmp_i = A[i] - B[i];

    acc1 += tmp_i * tmp_i;
  }

  return (acc1 + acc2);
}

template <typename eT>
arma_inline eT distance<eT, uword(2)>::eval(const uword N, const eT* A, const eT* B,
                                            const eT* C) {
  eT acc1 = eT(0);
  eT acc2 = eT(0);

  uword i, j;
  for (i = 0, j = 1; j < N; i += 2, j += 2) {
    eT tmp_i = A[i];
    eT tmp_j = A[j];

    tmp_i -= B[i];
    tmp_j -= B[j];

    acc1 += (tmp_i * tmp_i) * C[i];
    acc2 += (tmp_j * tmp_j) * C[j];
  }

  if (i < N) {
    const eT tmp_i = A[i] - B[i];

    acc1 += (tmp_i * tmp_i) * C[i];
  }

  return (acc1 + acc2);
}

}  // namespace gmm_priv

//! @}
