// 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_find_unique
//! @{

template <typename T1>
inline bool op_find_unique::apply_helper(Mat<uword>& out, const Proxy<T1>& P,
                                         const bool ascending_indices) {
  arma_extra_debug_sigprint();

  typedef typename T1::elem_type eT;

  const uword n_elem = P.get_n_elem();

  if (n_elem == 0) {
    out.set_size(0, 1);
    return true;
  }
  if (n_elem == 1) {
    out.set_size(1, 1);
    out[0] = 0;
    return true;
  }

  uvec indices(n_elem, arma_nozeros_indicator());

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

  if (Proxy<T1>::use_at == false) {
    typename Proxy<T1>::ea_type Pea = P.get_ea();

    for (uword i = 0; i < n_elem; ++i) {
      const eT val = Pea[i];

      if (arma_isnan(val)) {
        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)) {
          return false;
        }

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

        ++i;
      }
  }

  arma_find_unique_comparator<eT> comparator;

  std::sort(packet_vec.begin(), packet_vec.end(), comparator);

  uword* indices_mem = indices.memptr();

  indices_mem[0] = packet_vec[0].index;

  uword count = 1;

  for (uword i = 1; i < n_elem; ++i) {
    const eT diff = packet_vec[i - 1].val - packet_vec[i].val;

    if (diff != eT(0)) {
      indices_mem[count] = packet_vec[i].index;
      ++count;
    }
  }

  out.steal_mem_col(indices, count);

  if (ascending_indices) {
    std::sort(out.begin(), out.end());
  }

  return true;
}

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

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

  const bool ascending_indices = (in.aux_uword_a == uword(1));

  const bool all_non_nan = op_find_unique::apply_helper(out, P, ascending_indices);

  if (all_non_nan == false) {
    arma_debug_check(true, "find_unique(): detected NaN");

    out.reset();
  }
}

//! @}
