// 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 spop_reverse
//! @{

template <typename eT>
inline void spop_reverse::apply_spmat(SpMat<eT>& out, const SpMat<eT>& X,
                                      const uword dim) {
  arma_extra_debug_sigprint();

  const uword X_n_rows = X.n_rows;
  const uword X_n_cols = X.n_cols;

  const uword X_n_rows_m1 = X_n_rows - 1;
  const uword X_n_cols_m1 = X_n_cols - 1;

  const uword N = X.n_nonzero;

  if (N == uword(0)) {
    out.zeros(X_n_rows, X_n_cols);
    return;
  }

  umat locs(2, N, arma_nozeros_indicator());

  uword* locs_mem = locs.memptr();

  typename SpMat<eT>::const_iterator it = X.begin();

  if (dim == 0) {
    for (uword i = 0; i < N; ++i) {
      const uword row = it.row();
      const uword col = it.col();

      (*locs_mem) = X_n_rows_m1 - row;
      locs_mem++;
      (*locs_mem) = col;
      locs_mem++;

      ++it;
    }
  } else if (dim == 1) {
    for (uword i = 0; i < N; ++i) {
      const uword row = it.row();
      const uword col = it.col();

      (*locs_mem) = row;
      locs_mem++;
      (*locs_mem) = X_n_cols_m1 - col;
      locs_mem++;

      ++it;
    }
  }

  const Col<eT> vals(const_cast<eT*>(X.values), N, false);

  SpMat<eT> tmp(locs, vals, X_n_rows, X_n_cols, true, false);

  out.steal_mem(tmp);
}

template <typename T1>
inline void spop_reverse::apply_proxy(SpMat<typename T1::elem_type>& out, const T1& X,
                                      const uword dim) {
  arma_extra_debug_sigprint();

  typedef typename T1::elem_type eT;

  const SpProxy<T1> P(X);

  const uword P_n_rows = P.get_n_rows();
  const uword P_n_cols = P.get_n_cols();

  const uword P_n_rows_m1 = P_n_rows - 1;
  const uword P_n_cols_m1 = P_n_cols - 1;

  const uword N = P.get_n_nonzero();

  if (N == uword(0)) {
    out.zeros(P_n_rows, P_n_cols);
    return;
  }

  umat locs(2, N, arma_nozeros_indicator());
  Col<eT> vals(N, arma_nozeros_indicator());

  uword* locs_mem = locs.memptr();
  eT* vals_mem = vals.memptr();

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

  if (dim == 0) {
    for (uword i = 0; i < N; ++i) {
      const uword row = it.row();
      const uword col = it.col();

      (*locs_mem) = P_n_rows_m1 - row;
      locs_mem++;
      (*locs_mem) = col;
      locs_mem++;

      (*vals_mem) = (*it);
      vals_mem++;

      ++it;
    }
  } else if (dim == 1) {
    for (uword i = 0; i < N; ++i) {
      const uword row = it.row();
      const uword col = it.col();

      (*locs_mem) = row;
      locs_mem++;
      (*locs_mem) = P_n_cols_m1 - col;
      locs_mem++;

      (*vals_mem) = (*it);
      vals_mem++;

      ++it;
    }
  }

  SpMat<eT> tmp(locs, vals, P_n_rows, P_n_cols, true, false);

  out.steal_mem(tmp);
}

template <typename T1>
inline void spop_reverse::apply(SpMat<typename T1::elem_type>& out,
                                const SpOp<T1, spop_reverse>& in) {
  arma_extra_debug_sigprint();

  const uword dim = in.aux_uword_a;

  arma_debug_check((dim > 1), "reverse(): parameter 'dim' must be 0 or 1");

  if (is_SpMat<T1>::value) {
    const unwrap_spmat<T1> tmp(in.m);

    spop_reverse::apply_spmat(out, tmp.M, dim);
  } else {
    spop_reverse::apply_proxy(out, in.m, dim);
  }
}

//! @}
