// 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 fn_fft2
//! @{

// 2D FFT & 2D IFFT

template <typename T1>
arma_warn_unused inline
    typename enable_if2<is_arma_type<T1>::value,
                        Mat<std::complex<typename T1::pod_type> > >::result
    fft2(const T1& A) {
  arma_debug_sigprint();

  // not exactly efficient, but "better-than-nothing" implementation

  typedef typename T1::pod_type T;

  Mat<std::complex<T> > B = fft(A);

  // for square matrices, strans() will work out that an inplace transpose can be done,
  // hence we can potentially avoid creating a temporary matrix

  B = strans(B);

  return strans(fft(B));
}

template <typename T1>
arma_warn_unused inline
    typename enable_if2<is_arma_type<T1>::value,
                        Mat<std::complex<typename T1::pod_type> > >::result
    fft2(const T1& A, const uword n_rows, const uword n_cols) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  const quasi_unwrap<T1> tmp(A);
  const Mat<eT>& B = tmp.M;

  const bool do_resize = (B.n_rows != n_rows) || (B.n_cols != n_cols);

  return (do_resize) ? fft2(resize(B, n_rows, n_cols)) : fft2(B);
}

template <typename T1>
arma_warn_unused inline
    typename enable_if2<(is_arma_type<T1>::value &&
                         (is_cx_float<typename T1::elem_type>::yes ||
                          is_cx_double<typename T1::elem_type>::yes)),
                        Mat<std::complex<typename T1::pod_type> > >::result
    ifft2(const T1& A) {
  arma_debug_sigprint();

  // not exactly efficient, but "better-than-nothing" implementation

  typedef typename T1::pod_type T;

  Mat<std::complex<T> > B = ifft(A);

  // for square matrices, strans() will work out that an inplace transpose can be done,
  // hence we can potentially avoid creating a temporary matrix

  B = strans(B);

  return strans(ifft(B));
}

template <typename T1>
arma_warn_unused inline
    typename enable_if2<(is_arma_type<T1>::value &&
                         (is_cx_float<typename T1::elem_type>::yes ||
                          is_cx_double<typename T1::elem_type>::yes)),
                        Mat<std::complex<typename T1::pod_type> > >::result
    ifft2(const T1& A, const uword n_rows, const uword n_cols) {
  arma_debug_sigprint();

  typedef typename T1::elem_type eT;

  const quasi_unwrap<T1> tmp(A);
  const Mat<eT>& B = tmp.M;

  const bool do_resize = (B.n_rows != n_rows) || (B.n_cols != n_cols);

  return (do_resize) ? ifft2(resize(B, n_rows, n_cols)) : ifft2(B);
}

//! @}
