// 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 op_sort_index
//! @{

template <typename T1, bool sort_stable>
inline bool arma_sort_index_helper(Mat<uword>& out, const Proxy<T1>& P,
                                   const uword sort_type) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  const uword n_elem = P.get_n_elem();

  out.set_size(n_elem, 1);

  std::vector<arma_sort_index_packet<eT> > packet_vec(n_elem);

  if (Proxy<T1>::use_at == false) {
    for (uword i = 0; i < n_elem; ++i) {
      const eT val = P[i];

      if (arma_isnan(val)) {
        out.soft_reset();
        return false;
      }

      packet_vec[i].val = val;
      packet_vec[i].index = i;
    }
  } else {
    const uword n_rows = P.get_n_rows();
    const uword n_cols = P.get_n_cols();

    uword i = 0;

    for (uword col = 0; col < n_cols; ++col)
      for (uword row = 0; row < n_rows; ++row) {
        const eT val = P.at(row, col);

        if (arma_isnan(val)) {
          out.soft_reset();
          return false;
        }

        packet_vec[i].val = val;
        packet_vec[i].index = i;

        ++i;
      }
  }

  if (sort_type == 0) {
    // ascend

    arma_sort_index_helper_ascend<eT> comparator;

    if (sort_stable == false) {
      std::sort(packet_vec.begin(), packet_vec.end(), comparator);
    } else {
      std::stable_sort(packet_vec.begin(), packet_vec.end(), comparator);
    }
  } else {
    // descend

    arma_sort_index_helper_descend<eT> comparator;

    if (sort_stable == false) {
      std::sort(packet_vec.begin(), packet_vec.end(), comparator);
    } else {
      std::stable_sort(packet_vec.begin(), packet_vec.end(), comparator);
    }
  }

  uword* out_mem = out.memptr();

  for (uword i = 0; i < n_elem; ++i) {
    out_mem[i] = packet_vec[i].index;
  }

  return true;
}

template <typename T1>
inline bool op_sort_index::apply_noalias(Mat<uword>& out, const Proxy<T1>& P,
                                         const uword sort_type) {
  arma_debug_sigprint();

  return arma_sort_index_helper<T1, false>(out, P, sort_type);
}

template <typename T1>
inline void op_sort_index::apply(Mat<uword>& out,
                                 const mtOp<uword, T1, op_sort_index>& in) {
  arma_debug_sigprint();

  const Proxy<T1> P(in.m);

  if (P.get_n_elem() == 0) {
    out.set_size(0, 1);
    return;
  }

  const uword sort_type = in.aux_uword_a;

  bool all_non_nan = false;

  if (P.is_alias(out)) {
    Mat<uword> out2;

    all_non_nan = op_sort_index::apply_noalias(out2, P, sort_type);

    out.steal_mem(out2);
  } else {
    all_non_nan = op_sort_index::apply_noalias(out, P, sort_type);
  }

  arma_conform_check((all_non_nan == false), "sort_index(): detected NaN");
}

template <typename T1>
inline bool op_stable_sort_index::apply_noalias(Mat<uword>& out, const Proxy<T1>& P,
                                                const uword sort_type) {
  arma_debug_sigprint();

  return arma_sort_index_helper<T1, true>(out, P, sort_type);
}

template <typename T1>
inline void op_stable_sort_index::apply(Mat<uword>& out,
                                        const mtOp<uword, T1, op_stable_sort_index>& in) {
  arma_debug_sigprint();

  const Proxy<T1> P(in.m);

  if (P.get_n_elem() == 0) {
    out.set_size(0, 1);
    return;
  }

  const uword sort_type = in.aux_uword_a;

  bool all_non_nan = false;

  if (P.is_alias(out)) {
    Mat<uword> out2;

    all_non_nan = op_stable_sort_index::apply_noalias(out2, P, sort_type);

    out.steal_mem(out2);
  } else {
    all_non_nan = op_stable_sort_index::apply_noalias(out, P, sort_type);
  }

  arma_conform_check((all_non_nan == false), "stable_sort_index(): detected NaN");
}

//! @}
