// 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_strans
//! @{

//! for tiny square matrices (size <= 4x4)
template <typename eT, typename TA>
inline void op_strans::apply_mat_noalias_tinysq(Mat<eT>& out, const TA& A) {
  const eT* Am = A.memptr();
  eT* outm = out.memptr();

  switch (A.n_rows) {
    case 1: {
      outm[0] = Am[0];
    } break;

    case 2: {
      outm[pos<false, 0, 0>::n2] = Am[pos<true, 0, 0>::n2];
      outm[pos<false, 1, 0>::n2] = Am[pos<true, 1, 0>::n2];

      outm[pos<false, 0, 1>::n2] = Am[pos<true, 0, 1>::n2];
      outm[pos<false, 1, 1>::n2] = Am[pos<true, 1, 1>::n2];
    } break;

    case 3: {
      outm[pos<false, 0, 0>::n3] = Am[pos<true, 0, 0>::n3];
      outm[pos<false, 1, 0>::n3] = Am[pos<true, 1, 0>::n3];
      outm[pos<false, 2, 0>::n3] = Am[pos<true, 2, 0>::n3];

      outm[pos<false, 0, 1>::n3] = Am[pos<true, 0, 1>::n3];
      outm[pos<false, 1, 1>::n3] = Am[pos<true, 1, 1>::n3];
      outm[pos<false, 2, 1>::n3] = Am[pos<true, 2, 1>::n3];

      outm[pos<false, 0, 2>::n3] = Am[pos<true, 0, 2>::n3];
      outm[pos<false, 1, 2>::n3] = Am[pos<true, 1, 2>::n3];
      outm[pos<false, 2, 2>::n3] = Am[pos<true, 2, 2>::n3];
    } break;

    case 4: {
      outm[pos<false, 0, 0>::n4] = Am[pos<true, 0, 0>::n4];
      outm[pos<false, 1, 0>::n4] = Am[pos<true, 1, 0>::n4];
      outm[pos<false, 2, 0>::n4] = Am[pos<true, 2, 0>::n4];
      outm[pos<false, 3, 0>::n4] = Am[pos<true, 3, 0>::n4];

      outm[pos<false, 0, 1>::n4] = Am[pos<true, 0, 1>::n4];
      outm[pos<false, 1, 1>::n4] = Am[pos<true, 1, 1>::n4];
      outm[pos<false, 2, 1>::n4] = Am[pos<true, 2, 1>::n4];
      outm[pos<false, 3, 1>::n4] = Am[pos<true, 3, 1>::n4];

      outm[pos<false, 0, 2>::n4] = Am[pos<true, 0, 2>::n4];
      outm[pos<false, 1, 2>::n4] = Am[pos<true, 1, 2>::n4];
      outm[pos<false, 2, 2>::n4] = Am[pos<true, 2, 2>::n4];
      outm[pos<false, 3, 2>::n4] = Am[pos<true, 3, 2>::n4];

      outm[pos<false, 0, 3>::n4] = Am[pos<true, 0, 3>::n4];
      outm[pos<false, 1, 3>::n4] = Am[pos<true, 1, 3>::n4];
      outm[pos<false, 2, 3>::n4] = Am[pos<true, 2, 3>::n4];
      outm[pos<false, 3, 3>::n4] = Am[pos<true, 3, 3>::n4];
    } break;

    default:;
  }
}

template <typename eT>
inline void op_strans::block_worker(eT* Y, const eT* X, const uword X_n_rows,
                                    const uword Y_n_rows, const uword n_rows,
                                    const uword n_cols) {
  for (uword row = 0; row < n_rows; ++row) {
    const uword Y_offset = row * Y_n_rows;

    for (uword col = 0; col < n_cols; ++col) {
      const uword X_offset = col * X_n_rows;

      Y[col + Y_offset] = X[row + X_offset];
    }
  }
}

template <typename eT>
inline void op_strans::apply_mat_noalias_large(Mat<eT>& out, const Mat<eT>& A) {
  arma_extra_debug_sigprint();

  const uword n_rows = A.n_rows;
  const uword n_cols = A.n_cols;

  const uword block_size = 64;

  const uword n_rows_base = block_size * (n_rows / block_size);
  const uword n_cols_base = block_size * (n_cols / block_size);

  const uword n_rows_extra = n_rows - n_rows_base;
  const uword n_cols_extra = n_cols - n_cols_base;

  const eT* X = A.memptr();
  eT* Y = out.memptr();

  for (uword row = 0; row < n_rows_base; row += block_size) {
    const uword Y_offset = row * n_cols;

    for (uword col = 0; col < n_cols_base; col += block_size) {
      const uword X_offset = col * n_rows;

      op_strans::block_worker(&Y[col + Y_offset], &X[row + X_offset], n_rows, n_cols,
                              block_size, block_size);
    }

    const uword X_offset = n_cols_base * n_rows;

    op_strans::block_worker(&Y[n_cols_base + Y_offset], &X[row + X_offset], n_rows,
                            n_cols, block_size, n_cols_extra);
  }

  if (n_rows_extra == 0) {
    return;
  }

  const uword Y_offset = n_rows_base * n_cols;

  for (uword col = 0; col < n_cols_base; col += block_size) {
    const uword X_offset = col * n_rows;

    op_strans::block_worker(&Y[col + Y_offset], &X[n_rows_base + X_offset], n_rows,
                            n_cols, n_rows_extra, block_size);
  }

  const uword X_offset = n_cols_base * n_rows;

  op_strans::block_worker(&Y[n_cols_base + Y_offset], &X[n_rows_base + X_offset], n_rows,
                          n_cols, n_rows_extra, n_cols_extra);
}

//! Immediate transpose of a dense matrix
template <typename eT, typename TA>
inline void op_strans::apply_mat_noalias(Mat<eT>& out, const TA& A) {
  arma_extra_debug_sigprint();

  const uword A_n_cols = A.n_cols;
  const uword A_n_rows = A.n_rows;

  out.set_size(A_n_cols, A_n_rows);

  if ((TA::is_row) || (TA::is_col) || (A_n_cols == 1) || (A_n_rows == 1)) {
    arrayops::copy(out.memptr(), A.memptr(), A.n_elem);
  } else {
    if ((A_n_rows <= 4) && (A_n_rows == A_n_cols)) {
      op_strans::apply_mat_noalias_tinysq(out, A);
    } else if ((A_n_rows >= 512) && (A_n_cols >= 512)) {
      op_strans::apply_mat_noalias_large(out, A);
    } else {
      eT* outptr = out.memptr();

      for (uword k = 0; k < A_n_rows; ++k) {
        const eT* Aptr = &(A.at(k, 0));

        uword j;
        for (j = 1; j < A_n_cols; j += 2) {
          const eT tmp_i = (*Aptr);
          Aptr += A_n_rows;
          const eT tmp_j = (*Aptr);
          Aptr += A_n_rows;

          (*outptr) = tmp_i;
          outptr++;
          (*outptr) = tmp_j;
          outptr++;
        }

        if ((j - 1) < A_n_cols) {
          (*outptr) = (*Aptr);
          outptr++;
          ;
        }
      }
    }
  }
}

template <typename eT>
inline void op_strans::apply_mat_inplace(Mat<eT>& out) {
  arma_extra_debug_sigprint();

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

  if (n_rows == n_cols) {
    arma_extra_debug_print(
        "op_strans::apply(): doing in-place transpose of a square matrix");

    const uword N = n_rows;

    for (uword k = 0; k < N; ++k) {
      eT* colptr = &(out.at(k, k));
      eT* rowptr = colptr;

      colptr++;
      rowptr += N;

      uword j;

      for (j = (k + 2); j < N; j += 2) {
        std::swap((*rowptr), (*colptr));
        rowptr += N;
        colptr++;
        std::swap((*rowptr), (*colptr));
        rowptr += N;
        colptr++;
      }

      if ((j - 1) < N) {
        std::swap((*rowptr), (*colptr));
      }
    }
  } else {
    Mat<eT> tmp;

    op_strans::apply_mat_noalias(tmp, out);

    out.steal_mem(tmp);
  }
}

template <typename eT, typename TA>
inline void op_strans::apply_mat(Mat<eT>& out, const TA& A) {
  arma_extra_debug_sigprint();

  if (&out != &A) {
    op_strans::apply_mat_noalias(out, A);
  } else {
    op_strans::apply_mat_inplace(out);
  }
}

template <typename T1>
inline void op_strans::apply_proxy(Mat<typename T1::elem_type>& out, const Proxy<T1>& P) {
  arma_extra_debug_sigprint();

  typedef typename T1::elem_type eT;

  const uword n_rows = P.get_n_rows();
  const uword n_cols = P.get_n_cols();

  if ((resolves_to_vector<T1>::yes) && (Proxy<T1>::use_at == false)) {
    out.set_size(n_cols, n_rows);

    eT* out_mem = out.memptr();

    const uword n_elem = P.get_n_elem();

    typename Proxy<T1>::ea_type Pea = P.get_ea();

    uword i, j;
    for (i = 0, j = 1; j < n_elem; i += 2, j += 2) {
      const eT tmp_i = Pea[i];
      const eT tmp_j = Pea[j];

      out_mem[i] = tmp_i;
      out_mem[j] = tmp_j;
    }

    if (i < n_elem) {
      out_mem[i] = Pea[i];
    }
  } else  // general matrix transpose
  {
    out.set_size(n_cols, n_rows);

    eT* outptr = out.memptr();

    for (uword k = 0; k < n_rows; ++k) {
      uword j;
      for (j = 1; j < n_cols; j += 2) {
        const uword i = j - 1;

        const eT tmp_i = P.at(k, i);
        const eT tmp_j = P.at(k, j);

        (*outptr) = tmp_i;
        outptr++;
        (*outptr) = tmp_j;
        outptr++;
      }

      const uword i = j - 1;

      if (i < n_cols) {
        (*outptr) = P.at(k, i);
        outptr++;
      }
    }
  }
}

template <typename T1>
inline void op_strans::apply_direct(Mat<typename T1::elem_type>& out, const T1& X) {
  arma_extra_debug_sigprint();

  typedef typename T1::elem_type eT;

  // allow detection of in-place transpose
  if (is_Mat<T1>::value || (arma_config::openmp && Proxy<T1>::use_mp)) {
    const unwrap<T1> U(X);

    op_strans::apply_mat(out, U.M);
  } else {
    const Proxy<T1> P(X);

    const bool is_alias = P.is_alias(out);

    if (is_Mat<typename Proxy<T1>::stored_type>::value) {
      const quasi_unwrap<typename Proxy<T1>::stored_type> U(P.Q);

      if (is_alias) {
        Mat<eT> tmp;

        op_strans::apply_mat_noalias(tmp, U.M);

        out.steal_mem(tmp);
      } else {
        op_strans::apply_mat_noalias(out, U.M);
      }
    } else {
      if (is_alias) {
        Mat<eT> tmp;

        op_strans::apply_proxy(tmp, P);

        out.steal_mem(tmp);
      } else {
        op_strans::apply_proxy(out, P);
      }
    }
  }
}

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

  op_strans::apply_direct(out, in.m);
}

//
//
//

template <typename eT>
inline void op_strans_cube::apply_noalias(Cube<eT>& out, const Cube<eT>& X) {
  out.set_size(X.n_cols, X.n_rows, X.n_slices);

  for (uword s = 0; s < X.n_slices; ++s) {
    Mat<eT> out_slice(out.slice_memptr(s), X.n_cols, X.n_rows, false, true);

    const Mat<eT> X_slice(const_cast<eT*>(X.slice_memptr(s)), X.n_rows, X.n_cols, false,
                          true);

    op_strans::apply_mat_noalias(out_slice, X_slice);
  }
}

//! @}
