// 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 diagview
//! @{

//! Class for storing data required to extract and set the diagonals of a matrix
template <typename eT>
class diagview : public Base<eT, diagview<eT> > {
 public:
  typedef eT elem_type;
  typedef typename get_pod_type<eT>::result pod_type;

  arma_aligned const Mat<eT>& m;

  static constexpr bool is_row = false;
  static constexpr bool is_col = true;
  static constexpr bool is_xvec = false;

  const uword row_offset;
  const uword col_offset;

  const uword n_rows;  // equal to n_elem
  const uword n_elem;

  static constexpr uword n_cols = 1;

 protected:
  arma_inline diagview(const Mat<eT>& in_m, const uword in_row_offset,
                       const uword in_col_offset, const uword len);

 public:
  inline ~diagview();
  inline diagview() = delete;

  inline diagview(const diagview& in);
  inline diagview(diagview&& in);

  inline void operator=(const diagview& x);

  inline void operator+=(const eT val);
  inline void operator-=(const eT val);
  inline void operator*=(const eT val);
  inline void operator/=(const eT val);

  template <typename T1>
  inline void operator=(const Base<eT, T1>& x);
  template <typename T1>
  inline void operator+=(const Base<eT, T1>& x);
  template <typename T1>
  inline void operator-=(const Base<eT, T1>& x);
  template <typename T1>
  inline void operator%=(const Base<eT, T1>& x);
  template <typename T1>
  inline void operator/=(const Base<eT, T1>& x);

  arma_inline eT at_alt(const uword ii) const;

  arma_inline eT& operator[](const uword ii);
  arma_inline eT operator[](const uword ii) const;

  arma_inline eT& at(const uword ii);
  arma_inline eT at(const uword ii) const;

  arma_inline eT& operator()(const uword ii);
  arma_inline eT operator()(const uword ii) const;

  arma_inline eT& at(const uword in_n_row, const uword);
  arma_inline eT at(const uword in_n_row, const uword) const;

  arma_inline eT& operator()(const uword in_n_row, const uword in_n_col);
  arma_inline eT operator()(const uword in_n_row, const uword in_n_col) const;

  inline void replace(const eT old_val, const eT new_val);

  inline void clean(const pod_type threshold);

  inline void clamp(const eT min_val, const eT max_val);

  inline void fill(const eT val);
  inline void zeros();
  inline void ones();
  inline void randu();
  inline void randn();

  inline static void extract(Mat<eT>& out, const diagview& in);

  inline static void plus_inplace(Mat<eT>& out, const diagview& in);
  inline static void minus_inplace(Mat<eT>& out, const diagview& in);
  inline static void schur_inplace(Mat<eT>& out, const diagview& in);
  inline static void div_inplace(Mat<eT>& out, const diagview& in);

  template <typename eT2>
  inline bool is_alias(const Mat<eT2>& X) const;

  friend class Mat<eT>;
  friend class subview<eT>;
};

//! @}
