// 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 SpSubview
//! @{


template<typename eT>
class SpSubview : public SpBase<eT, SpSubview<eT> >
  {
  public:
  
  const SpMat<eT>& m;
  
  typedef eT elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;
  
  static const bool is_row = false;
  static const bool is_col = false;
  
  const uword aux_row1;
  const uword aux_col1;
  const uword n_rows;
  const uword n_cols;
  const uword n_elem;
  const uword n_nonzero;
  
  friend class SpValProxy< SpSubview<eT> >;   // allow SpValProxy to call insert_element() and delete_element()
  
  protected:

  arma_inline SpSubview(const SpMat<eT>& in_m, const uword in_row1, const uword in_col1, const uword in_n_rows, const uword in_n_cols);
  arma_inline SpSubview(      SpMat<eT>& in_m, const uword in_row1, const uword in_col1, const uword in_n_rows, const uword in_n_cols);

  public:

  inline ~SpSubview();

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

  inline const SpSubview& operator=(const SpSubview& x);

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

  template<typename T1> inline const SpSubview& operator_equ_common(const SpBase<eT, T1>& x);
  
  template<typename T1> inline const SpSubview& operator= (const SpBase<eT, T1>& x);
  template<typename T1> inline const SpSubview& operator+=(const SpBase<eT, T1>& x);
  template<typename T1> inline const SpSubview& operator-=(const SpBase<eT, T1>& x);
  template<typename T1> inline const SpSubview& operator*=(const SpBase<eT, T1>& x);
  template<typename T1> inline const SpSubview& operator%=(const SpBase<eT, T1>& x);
  template<typename T1> inline const SpSubview& operator/=(const SpBase<eT, T1>& x);
  
  /*
  inline static void extract(SpMat<eT>& out, const SpSubview& 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);
  */

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

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

  arma_hot inline MapMat_svel<eT> operator[](const uword i);
  arma_hot inline eT              operator[](const uword i) const;

  arma_hot inline MapMat_svel<eT> operator()(const uword i);
  arma_hot inline eT              operator()(const uword i) const;

  arma_hot inline MapMat_svel<eT> operator()(const uword in_row, const uword in_col);
  arma_hot inline eT              operator()(const uword in_row, const uword in_col) const;

  arma_hot inline MapMat_svel<eT> at(const uword i);
  arma_hot inline eT              at(const uword i) const;

  arma_hot inline MapMat_svel<eT> at(const uword in_row, const uword in_col);
  arma_hot inline eT              at(const uword in_row, const uword in_col) const;

  inline bool check_overlap(const SpSubview& x) const;

  inline bool is_vec() const;

  inline       SpSubview row(const uword row_num);
  inline const SpSubview row(const uword row_num) const;

  inline       SpSubview col(const uword col_num);
  inline const SpSubview col(const uword col_num) const;

  inline       SpSubview rows(const uword in_row1, const uword in_row2);
  inline const SpSubview rows(const uword in_row1, const uword in_row2) const;

  inline       SpSubview cols(const uword in_col1, const uword in_col2);
  inline const SpSubview cols(const uword in_col1, const uword in_col2) const;

  inline       SpSubview submat(const uword in_row1, const uword in_col1, const uword in_row2, const uword in_col2);
  inline const SpSubview submat(const uword in_row1, const uword in_col1, const uword in_row2, const uword in_col2) const;

  inline       SpSubview submat(const span& row_span, const span& col_span);
  inline const SpSubview submat(const span& row_span, const span& col_span) const;

  inline       SpSubview operator()(const uword row_num, const span& col_span);
  inline const SpSubview operator()(const uword row_num, const span& col_span) const;

  inline       SpSubview operator()(const span& row_span, const uword col_num);
  inline const SpSubview operator()(const span& row_span, const uword col_num) const;

  inline       SpSubview operator()(const span& row_span, const span& col_span);
  inline const SpSubview operator()(const span& row_span, const span& col_span) 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);

  // Forward declarations.
  class iterator_base;
  class const_iterator;
  class iterator;
  class const_row_iterator;
  class row_iterator;

  // Similar to SpMat iterators but automatically iterates past and ignores values not in the subview.
  class iterator_base
    {
    public:

    inline iterator_base(const SpSubview& in_M);
    inline iterator_base(const SpSubview& in_M, const uword col, const uword pos, const uword skip_pos);

    arma_inline eT operator*() const;

    // Don't hold location internally; call "dummy" methods to get that information.
    arma_inline uword row() const { return M.m.row_indices[internal_pos + skip_pos] - M.aux_row1; }
    arma_inline uword col() const { return internal_col;                                          }
    arma_inline uword pos() const { return internal_pos;                                          }

    arma_aligned const SpSubview& M;
    arma_aligned       uword      internal_col;
    arma_aligned       uword      internal_pos;
    arma_aligned       uword      skip_pos; // not used in row_iterator or const_row_iterator

    typedef std::bidirectional_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;
    };

  class const_iterator : public iterator_base
    {
    public:

    inline const_iterator(const SpSubview& in_M, uword initial_pos = 0);
    inline const_iterator(const SpSubview& in_M, uword in_row, uword in_col);
    inline const_iterator(const SpSubview& in_M, uword in_row, uword in_col, uword in_pos, uword skip_pos);
    inline const_iterator(const const_iterator& other);

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

    inline const_iterator& operator--();
    inline const_iterator  operator--(int);

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

    inline bool operator!=(const typename SpMat<eT>::const_iterator& rhs) const;
    inline bool operator==(const typename SpMat<eT>::const_iterator& rhs) const;

    inline bool operator!=(const const_row_iterator& rhs) const;
    inline bool operator==(const const_row_iterator& rhs) const;

    inline bool operator!=(const typename SpMat<eT>::const_row_iterator& rhs) const;
    inline bool operator==(const typename SpMat<eT>::const_row_iterator& rhs) const;
    };

  class iterator : public const_iterator
    {
    public:

    inline iterator(SpSubview& in_M, const uword initial_pos = 0) : const_iterator(in_M, initial_pos) { }
    inline iterator(SpSubview& in_M, const uword in_row, const uword in_col) : const_iterator(in_M, in_row, in_col) { }
    inline iterator(SpSubview& in_M, const uword in_row, const uword in_col, const uword in_pos, const uword in_skip_pos) : const_iterator(in_M, in_row, in_col, in_pos, in_skip_pos) { }
    inline iterator(const iterator& other) : const_iterator(other) { }

    inline SpValProxy<SpSubview<eT> > operator*();

    // overloads needed for return type correctness
    inline iterator& operator++();
    inline iterator  operator++(int);

    inline iterator& operator--();
    inline iterator  operator--(int);

    // This has a different value_type than iterator_base.
    typedef SpValProxy<SpSubview<eT> >        value_type;
    typedef const SpValProxy<SpSubview<eT> >* pointer;
    typedef const SpValProxy<SpSubview<eT> >& reference;
    };

  class const_row_iterator : public iterator_base
    {
    public:

    inline const_row_iterator(const SpSubview& in_M, uword initial_pos = 0);
    inline const_row_iterator(const SpSubview& in_M, uword in_row, uword in_col);
    inline const_row_iterator(const const_row_iterator& other);

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

    inline const_row_iterator& operator--();
    inline const_row_iterator  operator--(int);

    uword internal_row; // Hold row internally because we use internal_pos differently.
    uword actual_pos; // Actual position in subview's parent matrix.

    arma_inline eT operator*() const { return iterator_base::M.m.values[actual_pos]; }

    arma_inline uword row() const { return internal_row; }

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

    inline bool operator!=(const typename SpMat<eT>::const_iterator& rhs) const;
    inline bool operator==(const typename SpMat<eT>::const_iterator& rhs) const;

    inline bool operator!=(const const_row_iterator& rhs) const;
    inline bool operator==(const const_row_iterator& rhs) const;

    inline bool operator!=(const typename SpMat<eT>::const_row_iterator& rhs) const;
    inline bool operator==(const typename SpMat<eT>::const_row_iterator& rhs) const;
    };

  class row_iterator : public const_row_iterator
    {
    public:

    inline row_iterator(SpSubview& in_M, uword initial_pos = 0) : const_row_iterator(in_M, initial_pos) { }
    inline row_iterator(SpSubview& in_M, uword in_row, uword in_col) : const_row_iterator(in_M, in_row, in_col) { }
    inline row_iterator(const row_iterator& other) : const_row_iterator(other) { }

    inline SpValProxy<SpSubview<eT> > operator*();

    // overloads needed for return type correctness
    inline row_iterator& operator++();
    inline row_iterator  operator++(int);

    inline row_iterator& operator--();
    inline row_iterator  operator--(int);

    // This has a different value_type than iterator_base.
    typedef SpValProxy<SpSubview<eT> >        value_type;
    typedef const SpValProxy<SpSubview<eT> >* pointer;
    typedef const SpValProxy<SpSubview<eT> >& reference;
    };

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

  inline iterator           begin_col(const uword col_num);
  inline const_iterator     begin_col(const uword col_num) const;

  inline row_iterator       begin_row(const uword row_num = 0);
  inline const_row_iterator begin_row(const uword row_num = 0) const;

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

  inline row_iterator       end_row();
  inline const_row_iterator end_row() const;

  inline row_iterator       end_row(const uword row_num = 0);
  inline const_row_iterator end_row(const uword row_num = 0) const;


  private:
  friend class SpMat<eT>;
  SpSubview();
  
  inline arma_warn_unused eT&  insert_element(const uword in_row, const uword in_col, const eT in_val = eT(0));
  inline                  void delete_element(const uword in_row, const uword in_col);
  
  inline void invalidate_cache() const;
  };

/*
template<typename eT>
class SpSubview_col : public SpSubview<eT>
  {
  public:

  typedef eT                                       elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

  inline void operator= (const SpSubview<eT>& x);
  inline void operator= (const SpSubview_col& x);

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

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

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


  protected:

  inline SpSubview_col(const Mat<eT>& in_m, const uword in_col);
  inline SpSubview_col(      Mat<eT>& in_m, const uword in_col);

  inline SpSubview_col(const Mat<eT>& in_m, const uword in_col, const uword in_row1, const uword in_n_rows);
  inline SpSubview_col(      Mat<eT>& in_m, const uword in_col, const uword in_row1, const uword in_n_rows);


  private:

  friend class Mat<eT>;
  friend class Col<eT>;
  friend class SpSubview<eT>;

  SpSubview_col();
  };

template<typename eT>
class SpSubview_row : public SpSubview<eT>
  {
  public:

  typedef eT                                       elem_type;
  typedef typename get_pod_type<elem_type>::result pod_type;

  inline void operator= (const SpSubview<eT>& x);
  inline void operator= (const SpSubview_row& x);

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

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

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


  protected:

  inline SpSubview_row(const Mat<eT>& in_m, const uword in_row);
  inline SpSubview_row(      Mat<eT>& in_m, const uword in_row);

  inline SpSubview_row(const Mat<eT>& in_m, const uword in_row, const uword in_col1, const uword in_n_cols);
  inline SpSubview_row(      Mat<eT>& in_m, const uword in_row, const uword in_col1, const uword in_n_cols);


  private:

  friend class Mat<eT>;
  friend class Row<eT>;
  friend class SpSubview<eT>;

  SpSubview_row();
  };
*/

//! @}
