// 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
//! @{

template <typename eT>
inline void op_sort::direct_sort(eT* X, const uword n_elem, const uword sort_type) {
  arma_debug_sigprint();

  if (sort_type == 0) {
    arma_lt_comparator<eT> comparator;

    std::sort(&X[0], &X[n_elem], comparator);
  } else {
    arma_gt_comparator<eT> comparator;

    std::sort(&X[0], &X[n_elem], comparator);
  }
}

template <typename eT>
inline void op_sort::direct_sort_ascending(eT* X, const uword n_elem) {
  arma_debug_sigprint();

  arma_lt_comparator<eT> comparator;

  std::sort(&X[0], &X[n_elem], comparator);
}

template <typename eT>
inline void op_sort::copy_row(eT* X, const Mat<eT>& A, const uword row) {
  const uword N = A.n_cols;

  uword i, j;

  for (i = 0, j = 1; j < N; i += 2, j += 2) {
    X[i] = A.at(row, i);
    X[j] = A.at(row, j);
  }

  if (i < N) {
    X[i] = A.at(row, i);
  }
}

template <typename eT>
inline void op_sort::copy_row(Mat<eT>& A, const eT* X, const uword row) {
  const uword N = A.n_cols;

  uword i, j;

  for (i = 0, j = 1; j < N; i += 2, j += 2) {
    A.at(row, i) = X[i];
    A.at(row, j) = X[j];
  }

  if (i < N) {
    A.at(row, i) = X[i];
  }
}

template <typename eT>
inline void op_sort::apply_noalias(Mat<eT>& out, const Mat<eT>& X, const uword sort_type,
                                   const uword dim) {
  arma_debug_sigprint();

  if ((X.n_rows * X.n_cols) <= 1) {
    out = X;
    return;
  }

  if (dim == 0)  // sort the contents of each column
  {
    arma_debug_print("op_sort::apply(): dim = 0");

    out = X;

    const uword n_rows = out.n_rows;
    const uword n_cols = out.n_cols;

    for (uword col = 0; col < n_cols; ++col) {
      op_sort::direct_sort(out.colptr(col), n_rows, sort_type);
    }
  } else if (dim == 1)  // sort the contents of each row
  {
    if (X.n_rows == 1)  // a row vector
    {
      arma_debug_print("op_sort::apply(): dim = 1, vector specific");

      out = X;
      op_sort::direct_sort(out.memptr(), out.n_elem, sort_type);
    } else  // not a row vector
    {
      arma_debug_print("op_sort::apply(): dim = 1, generic");

      out.copy_size(X);

      const uword n_rows = out.n_rows;
      const uword n_cols = out.n_cols;

      podarray<eT> tmp_array(n_cols);

      for (uword row = 0; row < n_rows; ++row) {
        op_sort::copy_row(tmp_array.memptr(), X, row);

        op_sort::direct_sort(tmp_array.memptr(), n_cols, sort_type);

        op_sort::copy_row(out, tmp_array.memptr(), row);
      }
    }
  }
}

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

  typedef typename T1::elem_type eT;

  const quasi_unwrap<T1> U(in.m);
  const Mat<eT>& X = U.M;

  const uword sort_type = in.aux_uword_a;
  const uword dim = in.aux_uword_b;

  arma_conform_check((sort_type > 1), "sort(): parameter 'sort_type' must be 0 or 1");
  arma_conform_check((dim > 1), "sort(): parameter 'dim' must be 0 or 1");
  arma_conform_check((X.internal_has_nan()), "sort(): detected NaN");

  if (U.is_alias(out)) {
    Mat<eT> tmp;

    op_sort::apply_noalias(tmp, X, sort_type, dim);

    out.steal_mem(tmp);
  } else {
    op_sort::apply_noalias(out, X, sort_type, dim);
  }
}

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

  typedef typename T1::elem_type eT;

  const unwrap<T1> U(
      in.m);  // not using quasi_unwrap, to ensure there is no aliasing with subviews
  const Mat<eT>& X = U.M;

  const uword sort_type = in.aux_uword_a;

  arma_conform_check((sort_type > 1), "sort(): parameter 'sort_type' must be 0 or 1");
  arma_conform_check((X.internal_has_nan()), "sort(): detected NaN");

  out = X;  // not checking for aliasing, to allow inplace sorting of vectors

  if (out.n_elem <= 1) {
    return;
  }

  eT* out_mem = out.memptr();

  eT* start_ptr = out_mem;
  eT* endp1_ptr = &out_mem[out.n_elem];

  if (sort_type == 0) {
    arma_lt_comparator<eT> comparator;

    std::sort(start_ptr, endp1_ptr, comparator);
  } else {
    arma_gt_comparator<eT> comparator;

    std::sort(start_ptr, endp1_ptr, comparator);
  }
}

//! @}
