// 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 subview
//! @{

//! Class for storing data required to construct or apply operations to a submatrix
//! (ie. where the submatrix starts and ends as well as a reference/pointer to the
//! original matrix),
template <typename eT>
class subview : public Base<eT, subview<eT> > {
 public:
  typedef eT elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

  arma_aligned const Mat<eT>& m;

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

  const uword aux_row1;
  const uword aux_col1;

  const uword n_rows;
  const uword n_cols;
  const uword n_elem;

 protected:
  arma_inline subview(const Mat<eT>& in_m, const uword in_row1, const uword in_col1,
                      const uword in_n_rows, const uword in_n_cols);

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

  inline subview(const subview& in);
  inline subview(subview&& in);

  template <typename op_type>
  inline void inplace_op(const eT val);
  template <typename op_type, typename T1>
  inline void inplace_op(const Base<eT, T1>& x, const char* identifier);
  template <typename op_type>
  inline void inplace_op(const subview<eT>& x, const char* identifier);

  // deliberately returning void

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

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

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

  template <typename T1, typename gen_type>
  inline
      typename enable_if2<is_same_type<typename T1::elem_type, eT>::value, void>::result
      operator=(const Gen<T1, gen_type>& x);

  inline void operator=(const std::initializer_list<eT>& list);
  inline void operator=(const std::initializer_list<std::initializer_list<eT> >& list);

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

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

  template <typename functor>
  inline void for_each(functor F);
  template <typename functor>
  inline void for_each(functor F) const;

  template <typename functor>
  inline void transform(functor F);
  template <typename functor>
  inline void imbue(functor F);

  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 eye();
  inline void randu();
  inline void randn();

  arma_warn_unused inline eT at_alt(const uword ii) const;

  arma_warn_unused inline eT& operator[](const uword ii);
  arma_warn_unused inline eT operator[](const uword ii) const;

  arma_warn_unused inline eT& operator()(const uword ii);
  arma_warn_unused inline eT operator()(const uword ii) const;

  arma_warn_unused inline eT& operator()(const uword in_row, const uword in_col);
  arma_warn_unused inline eT operator()(const uword in_row, const uword in_col) const;

  arma_warn_unused inline eT& at(const uword in_row, const uword in_col);
  arma_warn_unused inline eT at(const uword in_row, const uword in_col) const;

  arma_warn_unused inline eT& front();
  arma_warn_unused inline eT front() const;

  arma_warn_unused inline eT& back();
  arma_warn_unused inline eT back() const;

  arma_inline eT* colptr(const uword in_col);
  arma_inline const eT* colptr(const uword in_col) const;

  template <typename eT2>
  inline bool check_overlap(const subview<eT2>& x) const;

  arma_warn_unused inline bool is_vec() const;
  arma_warn_unused inline bool is_finite() const;
  arma_warn_unused inline bool is_zero(const pod_type tol = 0) const;

  arma_warn_unused inline bool has_inf() const;
  arma_warn_unused inline bool has_nan() const;
  arma_warn_unused inline bool has_nonfinite() const;

  inline subview_row<eT> row(const uword row_num);
  inline const subview_row<eT> row(const uword row_num) const;

  inline subview_row<eT> operator()(const uword row_num, const span& col_span);
  inline const subview_row<eT> operator()(const uword row_num,
                                          const span& col_span) const;

  inline subview_col<eT> col(const uword col_num);
  inline const subview_col<eT> col(const uword col_num) const;

  inline subview_col<eT> operator()(const span& row_span, const uword col_num);
  inline const subview_col<eT> operator()(const span& row_span,
                                          const uword col_num) const;

  inline Col<eT> unsafe_col(const uword col_num);
  inline const Col<eT> unsafe_col(const uword col_num) const;

  inline subview<eT> rows(const uword in_row1, const uword in_row2);
  inline const subview<eT> rows(const uword in_row1, const uword in_row2) const;

  inline subview<eT> cols(const uword in_col1, const uword in_col2);
  inline const subview<eT> cols(const uword in_col1, const uword in_col2) const;

  inline subview<eT> submat(const uword in_row1, const uword in_col1, const uword in_row2,
                            const uword in_col2);
  inline const subview<eT> submat(const uword in_row1, const uword in_col1,
                                  const uword in_row2, const uword in_col2) const;

  inline subview<eT> submat(const span& row_span, const span& col_span);
  inline const subview<eT> submat(const span& row_span, const span& col_span) const;

  inline subview<eT> operator()(const span& row_span, const span& col_span);
  inline const subview<eT> operator()(const span& row_span, const span& col_span) const;

  inline subview_each1<subview<eT>, 0> each_col();
  inline subview_each1<subview<eT>, 1> each_row();

  template <typename T1>
  inline subview_each2<subview<eT>, 0, T1> each_col(const Base<uword, T1>& indices);
  template <typename T1>
  inline subview_each2<subview<eT>, 1, T1> each_row(const Base<uword, T1>& indices);

  inline void each_col(const std::function<void(Col<eT>&)>& F);
  inline void each_col(const std::function<void(const Col<eT>&)>& F) const;

  inline void each_row(const std::function<void(Row<eT>&)>& F);
  inline void each_row(const std::function<void(const Row<eT>&)>& F) const;

  inline diagview<eT> diag(const sword in_id = 0);
  inline const diagview<eT> diag(const sword in_id = 0) const;

  inline void swap_rows(const uword in_row1, const uword in_row2);
  inline void swap_cols(const uword in_col1, const uword in_col2);

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

  class const_iterator;

  class iterator {
   public:
    inline iterator();
    inline iterator(const iterator& X);
    inline iterator(subview<eT>& in_sv, const uword in_row, const uword in_col);

    arma_warn_unused inline eT& operator*();

    inline iterator& operator++();
    arma_warn_unused inline iterator operator++(int);

    arma_warn_unused inline bool operator==(const iterator& rhs) const;
    arma_warn_unused inline bool operator!=(const iterator& rhs) const;
    arma_warn_unused inline bool operator==(const const_iterator& rhs) const;
    arma_warn_unused inline bool operator!=(const const_iterator& rhs) const;

    typedef std::forward_iterator_tag iterator_category;
    typedef eT value_type;
    typedef std::ptrdiff_t difference_type;  // TODO: not certain on this one
    typedef eT* pointer;
    typedef eT& reference;

    arma_aligned Mat<eT>* M;
    arma_aligned eT* current_ptr;
    arma_aligned uword current_row;
    arma_aligned uword current_col;

    arma_aligned const uword aux_row1;
    arma_aligned const uword aux_row2_p1;
  };

  class const_iterator {
   public:
    inline const_iterator();
    inline const_iterator(const iterator& X);
    inline const_iterator(const const_iterator& X);
    inline const_iterator(const subview<eT>& in_sv, const uword in_row,
                          const uword in_col);

    arma_warn_unused inline const eT& operator*();

    inline const_iterator& operator++();
    arma_warn_unused inline const_iterator operator++(int);

    arma_warn_unused inline bool operator==(const iterator& rhs) const;
    arma_warn_unused inline bool operator!=(const iterator& rhs) const;
    arma_warn_unused inline bool operator==(const const_iterator& rhs) const;
    arma_warn_unused inline bool operator!=(const const_iterator& rhs) const;

    // So that we satisfy the STL iterator types.
    typedef std::forward_iterator_tag iterator_category;
    typedef eT value_type;
    typedef std::ptrdiff_t difference_type;  // TODO: not certain on this one
    typedef const eT* pointer;
    typedef const eT& reference;

    arma_aligned const Mat<eT>* M;
    arma_aligned const eT* current_ptr;
    arma_aligned uword current_row;
    arma_aligned uword current_col;

    arma_aligned const uword aux_row1;
    arma_aligned const uword aux_row2_p1;
  };

  class const_row_iterator;

  class row_iterator {
   public:
    inline row_iterator();
    inline row_iterator(const row_iterator& X);
    inline row_iterator(subview<eT>& in_sv, const uword in_row, const uword in_col);

    arma_warn_unused inline eT& operator*();

    inline row_iterator& operator++();
    arma_warn_unused inline row_iterator operator++(int);

    arma_warn_unused inline bool operator!=(const row_iterator& X) const;
    arma_warn_unused inline bool operator==(const row_iterator& X) const;
    arma_warn_unused inline bool operator!=(const const_row_iterator& X) const;
    arma_warn_unused inline bool operator==(const const_row_iterator& X) const;

    typedef std::forward_iterator_tag iterator_category;
    typedef eT value_type;
    typedef std::ptrdiff_t difference_type;  // TODO: not certain on this one
    typedef eT* pointer;
    typedef eT& reference;

    arma_aligned Mat<eT>* M;
    arma_aligned uword current_row;
    arma_aligned uword current_col;

    arma_aligned const uword aux_col1;
    arma_aligned const uword aux_col2_p1;
  };

  class const_row_iterator {
   public:
    inline const_row_iterator();
    inline const_row_iterator(const row_iterator& X);
    inline const_row_iterator(const const_row_iterator& X);
    inline const_row_iterator(const subview<eT>& in_sv, const uword in_row,
                              const uword in_col);

    arma_warn_unused inline const eT& operator*() const;

    inline const_row_iterator& operator++();
    arma_warn_unused inline const_row_iterator operator++(int);

    arma_warn_unused inline bool operator!=(const row_iterator& X) const;
    arma_warn_unused inline bool operator==(const row_iterator& X) const;
    arma_warn_unused inline bool operator!=(const const_row_iterator& X) const;
    arma_warn_unused inline bool operator==(const const_row_iterator& X) const;

    typedef std::forward_iterator_tag iterator_category;
    typedef eT value_type;
    typedef std::ptrdiff_t difference_type;  // TODO: not certain on this one
    typedef const eT* pointer;
    typedef const eT& reference;

    arma_aligned const Mat<eT>* M;
    arma_aligned uword current_row;
    arma_aligned uword current_col;

    arma_aligned const uword aux_col1;
    arma_aligned const uword aux_col2_p1;
  };

  inline iterator begin();
  inline const_iterator begin() const;
  inline const_iterator cbegin() const;

  inline iterator end();
  inline const_iterator end() const;
  inline const_iterator cend() const;

  friend class Mat<eT>;
};

template <typename eT>
class subview_col : public subview<eT> {
 public:
  typedef eT elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

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

  const eT* colmem;

  inline void operator=(const subview<eT>& x);
  inline void operator=(const subview_col& x);
  inline void operator=(const eT val);
  inline void operator=(const std::initializer_list<eT>& list);

  template <typename T1>
  inline void operator=(const Base<eT, T1>& x);
  template <typename T1>
  inline void operator=(const SpBase<eT, T1>& x);

  template <typename T1, typename gen_type>
  inline
      typename enable_if2<is_same_type<typename T1::elem_type, eT>::value, void>::result
      operator=(const Gen<T1, gen_type>& x);

  arma_warn_unused arma_inline const Op<subview_col<eT>, op_htrans> t() const;
  arma_warn_unused arma_inline const Op<subview_col<eT>, op_htrans> ht() const;
  arma_warn_unused arma_inline const Op<subview_col<eT>, op_strans> st() const;

  arma_warn_unused arma_inline const Op<subview_col<eT>, op_strans> as_row() const;

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

  arma_inline eT at_alt(const uword i) const;

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

  inline eT& operator()(const uword i);
  inline eT operator()(const uword i) const;

  inline eT& operator()(const uword in_row, const uword in_col);
  inline eT operator()(const uword in_row, const uword in_col) const;

  inline eT& at(const uword in_row, const uword in_col);
  inline eT at(const uword in_row, const uword in_col) const;

  arma_inline eT* colptr(const uword in_col);
  arma_inline const eT* colptr(const uword in_col) const;

  inline subview_col<eT> rows(const uword in_row1, const uword in_row2);
  inline const subview_col<eT> rows(const uword in_row1, const uword in_row2) const;

  inline subview_col<eT> subvec(const uword in_row1, const uword in_row2);
  inline const subview_col<eT> subvec(const uword in_row1, const uword in_row2) const;

  inline subview_col<eT> subvec(const uword start_row, const SizeMat& s);
  inline const subview_col<eT> subvec(const uword start_row, const SizeMat& s) const;

  inline subview_col<eT> head(const uword N);
  inline const subview_col<eT> head(const uword N) const;

  inline subview_col<eT> tail(const uword N);
  inline const subview_col<eT> tail(const uword N) const;

  arma_warn_unused inline eT min() const;
  arma_warn_unused inline eT max() const;

  arma_frown("use .index_min() instead") inline eT min(uword& index_of_min_val) const;
  arma_frown("use .index_max() instead") inline eT max(uword& index_of_max_val) const;

  arma_warn_unused inline uword index_min() const;
  arma_warn_unused inline uword index_max() const;

  inline subview_col(const subview_col& in);
  inline subview_col(subview_col&& in);

 protected:
  inline subview_col(const Mat<eT>& in_m, const uword in_col);
  inline subview_col(const Mat<eT>& in_m, const uword in_col, const uword in_row1,
                     const uword in_n_rows);
  inline subview_col() = delete;

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

template <typename eT>
class subview_cols : public subview<eT> {
 public:
  typedef eT elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

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

  inline subview_cols(const subview_cols& in);
  inline subview_cols(subview_cols&& in);

  inline void operator=(const subview<eT>& x);
  inline void operator=(const subview_cols& x);
  inline void operator=(const eT val);
  inline void operator=(const std::initializer_list<eT>& list);
  inline void operator=(const std::initializer_list<std::initializer_list<eT> >& list);

  template <typename T1>
  inline void operator=(const Base<eT, T1>& x);
  template <typename T1>
  inline void operator=(const SpBase<eT, T1>& x);

  template <typename T1, typename gen_type>
  inline
      typename enable_if2<is_same_type<typename T1::elem_type, eT>::value, void>::result
      operator=(const Gen<T1, gen_type>& x);

  arma_warn_unused arma_inline const Op<subview_cols<eT>, op_htrans> t() const;
  arma_warn_unused arma_inline const Op<subview_cols<eT>, op_htrans> ht() const;
  arma_warn_unused arma_inline const Op<subview_cols<eT>, op_strans> st() const;

  arma_warn_unused arma_inline const Op<subview_cols<eT>, op_vectorise_col> as_col()
      const;

  arma_warn_unused inline eT at_alt(const uword ii) const;

  arma_warn_unused inline eT& operator[](const uword ii);
  arma_warn_unused inline eT operator[](const uword ii) const;

  arma_warn_unused inline eT& operator()(const uword ii);
  arma_warn_unused inline eT operator()(const uword ii) const;

  arma_warn_unused inline eT& operator()(const uword in_row, const uword in_col);
  arma_warn_unused inline eT operator()(const uword in_row, const uword in_col) const;

  arma_warn_unused inline eT& at(const uword in_row, const uword in_col);
  arma_warn_unused inline eT at(const uword in_row, const uword in_col) const;

  arma_inline eT* colptr(const uword in_col);
  arma_inline const eT* colptr(const uword in_col) const;

 protected:
  inline subview_cols(const Mat<eT>& in_m, const uword in_col1, const uword in_n_cols);
  inline subview_cols() = delete;

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

template <typename eT>
class subview_row : public subview<eT> {
 public:
  typedef eT elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

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

  inline void operator=(const subview<eT>& x);
  inline void operator=(const subview_row& x);
  inline void operator=(const eT val);
  inline void operator=(const std::initializer_list<eT>& list);

  template <typename T1>
  inline void operator=(const Base<eT, T1>& x);
  template <typename T1>
  inline void operator=(const SpBase<eT, T1>& x);

  template <typename T1, typename gen_type>
  inline
      typename enable_if2<is_same_type<typename T1::elem_type, eT>::value, void>::result
      operator=(const Gen<T1, gen_type>& x);

  arma_warn_unused arma_inline const Op<subview_row<eT>, op_htrans> t() const;
  arma_warn_unused arma_inline const Op<subview_row<eT>, op_htrans> ht() const;
  arma_warn_unused arma_inline const Op<subview_row<eT>, op_strans> st() const;

  arma_warn_unused arma_inline const Op<subview_row<eT>, op_strans> as_col() const;

  inline eT at_alt(const uword i) const;

  inline eT& operator[](const uword i);
  inline eT operator[](const uword i) const;

  inline eT& operator()(const uword i);
  inline eT operator()(const uword i) const;

  inline eT& operator()(const uword in_row, const uword in_col);
  inline eT operator()(const uword in_row, const uword in_col) const;

  inline eT& at(const uword in_row, const uword in_col);
  inline eT at(const uword in_row, const uword in_col) const;

  inline subview_row<eT> cols(const uword in_col1, const uword in_col2);
  inline const subview_row<eT> cols(const uword in_col1, const uword in_col2) const;

  inline subview_row<eT> subvec(const uword in_col1, const uword in_col2);
  inline const subview_row<eT> subvec(const uword in_col1, const uword in_col2) const;

  inline subview_row<eT> subvec(const uword start_col, const SizeMat& s);
  inline const subview_row<eT> subvec(const uword start_col, const SizeMat& s) const;

  inline subview_row<eT> head(const uword N);
  inline const subview_row<eT> head(const uword N) const;

  inline subview_row<eT> tail(const uword N);
  inline const subview_row<eT> tail(const uword N) const;

  arma_warn_unused inline uword index_min() const;
  arma_warn_unused inline uword index_max() const;

  inline typename subview<eT>::row_iterator begin();
  inline typename subview<eT>::const_row_iterator begin() const;
  inline typename subview<eT>::const_row_iterator cbegin() const;

  inline typename subview<eT>::row_iterator end();
  inline typename subview<eT>::const_row_iterator end() const;
  inline typename subview<eT>::const_row_iterator cend() const;

  inline subview_row(const subview_row& in);
  inline subview_row(subview_row&& in);

 protected:
  inline subview_row(const Mat<eT>& in_m, const uword in_row);
  inline subview_row(const Mat<eT>& in_m, const uword in_row, const uword in_col1,
                     const uword in_n_cols);
  inline subview_row() = delete;

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

template <typename eT>
class subview_row_strans : public Base<eT, subview_row_strans<eT> > {
 public:
  typedef eT elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

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

  arma_aligned const subview_row<eT>& sv_row;

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

  static constexpr uword n_cols = 1;

  inline explicit subview_row_strans(const subview_row<eT>& in_sv_row);

  inline void extract(Mat<eT>& out) const;

  inline eT at_alt(const uword i) const;

  inline eT operator[](const uword i) const;
  inline eT operator()(const uword i) const;

  inline eT operator()(const uword in_row, const uword in_col) const;
  inline eT at(const uword in_row, const uword in_col) const;
};

template <typename eT>
class subview_row_htrans : public Base<eT, subview_row_htrans<eT> > {
 public:
  typedef eT elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

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

  arma_aligned const subview_row<eT>& sv_row;

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

  static constexpr uword n_cols = 1;

  inline explicit subview_row_htrans(const subview_row<eT>& in_sv_row);

  inline void extract(Mat<eT>& out) const;

  inline eT at_alt(const uword i) const;

  inline eT operator[](const uword i) const;
  inline eT operator()(const uword i) const;

  inline eT operator()(const uword in_row, const uword in_col) const;
  inline eT at(const uword in_row, const uword in_col) const;
};

//! @}
