// 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_nonzeros
//! @{

template <typename T1>
inline void op_nonzeros::apply_noalias(Mat<typename T1::elem_type>& out,
                                       const Proxy<T1>& P) {
  arma_extra_debug_sigprint();

  typedef typename T1::elem_type eT;

  const uword N_max = P.get_n_elem();

  Mat<eT> tmp(N_max, 1, arma_nozeros_indicator());

  eT* tmp_mem = tmp.memptr();

  uword N_nz = 0;

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

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

      if (val != eT(0)) {
        tmp_mem[N_nz] = val;
        ++N_nz;
      }
    }
  } else {
    const uword n_rows = P.get_n_rows();
    const uword n_cols = P.get_n_cols();

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

        if (val != eT(0)) {
          tmp_mem[N_nz] = val;
          ++N_nz;
        }
      }
  }

  out.steal_mem_col(tmp, N_nz);
}

template <typename T1>
inline void op_nonzeros::apply(Mat<typename T1::elem_type>& out,
                               const Op<T1, op_nonzeros>& X) {
  arma_extra_debug_sigprint();

  typedef typename T1::elem_type eT;

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

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

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

    op_nonzeros::apply_noalias(out2, P);

    out.steal_mem(out2);
  } else {
    op_nonzeros::apply_noalias(out, P);
  }
}

template <typename T1>
inline void op_nonzeros_spmat::apply(Mat<typename T1::elem_type>& out,
                                     const SpToDOp<T1, op_nonzeros_spmat>& X) {
  arma_extra_debug_sigprint();

  typedef typename T1::elem_type eT;

  const SpProxy<T1> P(X.m);

  const uword N = P.get_n_nonzero();

  out.set_size(N, 1);

  if (N == 0) {
    return;
  }

  if (is_SpMat<typename SpProxy<T1>::stored_type>::value) {
    const unwrap_spmat<typename SpProxy<T1>::stored_type> U(P.Q);

    arrayops::copy(out.memptr(), U.M.values, N);

    return;
  }

  if (is_SpSubview<typename SpProxy<T1>::stored_type>::value) {
    const SpSubview<eT>& sv = reinterpret_cast<const SpSubview<eT>&>(P.Q);

    if (sv.n_rows == sv.m.n_rows) {
      const SpMat<eT>& m = sv.m;
      const uword col = sv.aux_col1;

      arrayops::copy(out.memptr(), &(m.values[m.col_ptrs[col]]), N);

      return;
    }
  }

  eT* out_mem = out.memptr();

  typename SpProxy<T1>::const_iterator_type it = P.begin();

  for (uword i = 0; i < N; ++i) {
    out_mem[i] = (*it);
    ++it;
  }
}

//! @}
