// 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_shuffle
//! @{

template <typename eT>
inline void op_shuffle::apply_direct(Mat<eT>& out, const Mat<eT>& X, const uword dim) {
  arma_extra_debug_sigprint();

  if (X.is_empty()) {
    out.copy_size(X);
    return;
  }

  const uword N = (dim == 0) ? X.n_rows : X.n_cols;

  // see op_sort_index_bones.hpp for the definition of arma_sort_index_packet
  // and the associated comparison functor

  typedef arma_sort_index_packet<int> packet;

  std::vector<packet> packet_vec(N);

  for (uword i = 0; i < N; ++i) {
    packet_vec[i].val = int(arma_rng::randi<int>());
    packet_vec[i].index = i;
  }

  arma_sort_index_helper_ascend<int> comparator;

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

  const bool is_alias = (&out == &X);

  if (X.is_vec() == false) {
    if (is_alias == false) {
      arma_extra_debug_print("op_shuffle::apply(): matrix");

      out.copy_size(X);

      if (dim == 0) {
        for (uword i = 0; i < N; ++i) {
          out.row(i) = X.row(packet_vec[i].index);
        }
      } else {
        for (uword i = 0; i < N; ++i) {
          out.col(i) = X.col(packet_vec[i].index);
        }
      }
    } else  // in-place shuffle
    {
      arma_extra_debug_print("op_shuffle::apply(): in-place matrix");

      // reuse the val member variable of packet_vec
      // to indicate whether a particular row or column
      // has already been shuffled

      for (uword i = 0; i < N; ++i) {
        packet_vec[i].val = 0;
      }

      if (dim == 0) {
        for (uword i = 0; i < N; ++i) {
          if (packet_vec[i].val == 0) {
            const uword j = packet_vec[i].index;

            out.swap_rows(i, j);

            packet_vec[j].val = 1;
          }
        }
      } else {
        for (uword i = 0; i < N; ++i) {
          if (packet_vec[i].val == 0) {
            const uword j = packet_vec[i].index;

            out.swap_cols(i, j);

            packet_vec[j].val = 1;
          }
        }
      }
    }
  } else  // we're dealing with a vector
  {
    if (is_alias == false) {
      arma_extra_debug_print("op_shuffle::apply(): vector");

      out.copy_size(X);

      if (dim == 0) {
        if (X.n_rows > 1)  // ie. column vector
        {
          for (uword i = 0; i < N; ++i) {
            out[i] = X[packet_vec[i].index];
          }
        } else {
          out = X;
        }
      } else {
        if (X.n_cols > 1)  // ie. row vector
        {
          for (uword i = 0; i < N; ++i) {
            out[i] = X[packet_vec[i].index];
          }
        } else {
          out = X;
        }
      }
    } else  // in-place shuffle
    {
      arma_extra_debug_print("op_shuffle::apply(): in-place vector");

      // reuse the val member variable of packet_vec
      // to indicate whether a particular row or column
      // has already been shuffled

      for (uword i = 0; i < N; ++i) {
        packet_vec[i].val = 0;
      }

      if (dim == 0) {
        if (X.n_rows > 1)  // ie. column vector
        {
          for (uword i = 0; i < N; ++i) {
            if (packet_vec[i].val == 0) {
              const uword j = packet_vec[i].index;

              std::swap(out[i], out[j]);

              packet_vec[j].val = 1;
            }
          }
        }
      } else {
        if (X.n_cols > 1)  // ie. row vector
        {
          for (uword i = 0; i < N; ++i) {
            if (packet_vec[i].val == 0) {
              const uword j = packet_vec[i].index;

              std::swap(out[i], out[j]);

              packet_vec[j].val = 1;
            }
          }
        }
      }
    }
  }
}

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

  const unwrap<T1> U(in.m);

  const uword dim = in.aux_uword_a;

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

  op_shuffle::apply_direct(out, U.M, dim);
}

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

  const unwrap<T1> U(in.m);

  const uword dim =
      (T1::is_xvec) ? uword(U.M.is_rowvec() ? 1 : 0) : uword((T1::is_row) ? 1 : 0);

  op_shuffle::apply_direct(out, U.M, dim);
}

//! @}
