// 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 glue_kron
//! @{

//! \brief
//! both input matrices have the same element type
template <typename eT>
inline void glue_kron::direct_kron(Mat<eT>& out, const Mat<eT>& A, const Mat<eT>& B) {
  arma_debug_sigprint();

  const uword A_rows = A.n_rows;
  const uword A_cols = A.n_cols;
  const uword B_rows = B.n_rows;
  const uword B_cols = B.n_cols;

  out.set_size(A_rows * B_rows, A_cols * B_cols);

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

  for (uword j = 0; j < A_cols; j++) {
    for (uword i = 0; i < A_rows; i++) {
      out.submat(i * B_rows, j * B_cols, (i + 1) * B_rows - 1, (j + 1) * B_cols - 1) =
          A.at(i, j) * B;
    }
  }
}

//! \brief
//! different types of input matrices
//! A -> complex, B -> basic element type
template <typename T>
inline void glue_kron::direct_kron(Mat<std::complex<T> >& out,
                                   const Mat<std::complex<T> >& A, const Mat<T>& B) {
  arma_debug_sigprint();

  typedef typename std::complex<T> eT;

  const uword A_rows = A.n_rows;
  const uword A_cols = A.n_cols;
  const uword B_rows = B.n_rows;
  const uword B_cols = B.n_cols;

  out.set_size(A_rows * B_rows, A_cols * B_cols);

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

  Mat<eT> tmp_B = conv_to<Mat<eT> >::from(B);

  for (uword j = 0; j < A_cols; j++) {
    for (uword i = 0; i < A_rows; i++) {
      out.submat(i * B_rows, j * B_cols, (i + 1) * B_rows - 1, (j + 1) * B_cols - 1) =
          A.at(i, j) * tmp_B;
    }
  }
}

//! \brief
//! different types of input matrices
//! A -> basic element type, B -> complex
template <typename T>
inline void glue_kron::direct_kron(Mat<std::complex<T> >& out, const Mat<T>& A,
                                   const Mat<std::complex<T> >& B) {
  arma_debug_sigprint();

  const uword A_rows = A.n_rows;
  const uword A_cols = A.n_cols;
  const uword B_rows = B.n_rows;
  const uword B_cols = B.n_cols;

  out.set_size(A_rows * B_rows, A_cols * B_cols);

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

  for (uword j = 0; j < A_cols; j++) {
    for (uword i = 0; i < A_rows; i++) {
      out.submat(i * B_rows, j * B_cols, (i + 1) * B_rows - 1, (j + 1) * B_cols - 1) =
          A.at(i, j) * B;
    }
  }
}

//! \brief
//! apply Kronecker product for two objects with same element type
template <typename T1, typename T2>
inline void glue_kron::apply(Mat<typename T1::elem_type>& out,
                             const Glue<T1, T2, glue_kron>& X) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  const quasi_unwrap<T1> UA(X.A);
  const quasi_unwrap<T2> UB(X.B);

  if (UA.is_alias(out) || UB.is_alias(out)) {
    Mat<eT> tmp;

    glue_kron::direct_kron(tmp, UA.M, UB.M);

    out.steal_mem(tmp);
  } else {
    glue_kron::direct_kron(out, UA.M, UB.M);
  }
}

//! @}
