// Copyright (C) 2008-2015 National ICT Australia (NICTA)
// 
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
// -------------------------------------------------------------------
// 
// Written by Conrad Sanderson - http://conradsanderson.id.au
// Written by Ryan Curtin


//! \addtogroup fn_accu
//! @{



template<typename T1>
arma_hot
inline
typename T1::elem_type
accu_proxy_linear(const Proxy<T1>& P)
  {
  typedef typename T1::elem_type eT;
  
  const uword n_elem = P.get_n_elem();
  
  #if defined(__FINITE_MATH_ONLY__) && (__FINITE_MATH_ONLY__ > 0)
    {
    eT val = eT(0);
    
    if(P.is_aligned())
      {
      typename Proxy<T1>::aligned_ea_type A = P.get_aligned_ea();
      
      for(uword i=0; i<n_elem; ++i)  { val += A.at_alt(i); }
      }
    else
      {
      typename Proxy<T1>::ea_type A = P.get_ea();
      
      for(uword i=0; i<n_elem; ++i)  { val += A[i]; }
      }
    
    return val;
    }
  #else
    {
    eT val1 = eT(0);
    eT val2 = eT(0);
    
    typename Proxy<T1>::ea_type A = P.get_ea();
    
    uword i,j;
    for(i=0, j=1; j < n_elem; i+=2, j+=2)
      {
      val1 += A[i];
      val2 += A[j];
      }
    
    if(i < n_elem)
      {
      val1 += A[i];   // equivalent to: val1 += A[n_elem-1];
      }
    
    return (val1 + val2);
    }
  #endif
  }



template<typename T1>
arma_hot
inline
typename T1::elem_type
accu_proxy_mat(const Proxy<T1>& P)
  {
  const quasi_unwrap<typename Proxy<T1>::stored_type> tmp(P.Q);
  
  return arrayops::accumulate(tmp.M.memptr(), tmp.M.n_elem);
  }



template<typename T1>
arma_hot
inline
typename T1::elem_type
accu_proxy_at(const Proxy<T1>& P)
  {
  typedef typename T1::elem_type eT;
  
  const uword n_rows = P.get_n_rows();
  const uword n_cols = P.get_n_cols();
  
  eT val = eT(0);
  
  if(n_rows != 1)
    {
    eT val1 = eT(0);
    eT val2 = eT(0);
    
    for(uword col=0; col < n_cols; ++col)
      {
      uword i,j;
      for(i=0, j=1; j < n_rows; i+=2, j+=2)
        {
        val1 += P.at(i,col);
        val2 += P.at(j,col);
        }
      
      if(i < n_rows)
        {
        val1 += P.at(i,col);
        }
      }
    
    val = val1 + val2;
    }
  else
    {
    for(uword col=0; col < n_cols; ++col)
      {
      val += P.at(0,col);
      }
    }
  
  return val;
  }



//! accumulate the elements of a matrix
template<typename T1>
arma_hot
inline
typename enable_if2< is_arma_type<T1>::value, typename T1::elem_type >::result
accu(const T1& X)
  {
  arma_extra_debug_sigprint();
  
  const Proxy<T1> P(X);
  
  const bool have_direct_mem = (is_Mat<typename Proxy<T1>::stored_type>::value) || (is_subview_col<typename Proxy<T1>::stored_type>::value);
  
  return (Proxy<T1>::prefer_at_accessor) ? accu_proxy_at(P) : (have_direct_mem ? accu_proxy_mat(P) : accu_proxy_linear(P));
  }



//! explicit handling of Hamming norm (also known as zero norm)
template<typename T1>
inline
arma_warn_unused
uword
accu(const mtOp<uword,T1,op_rel_noteq>& X)
  {
  arma_extra_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const eT val = X.aux;
  
  const Proxy<T1> P(X.m);
  
  uword n_nonzero = 0;
  
  if(Proxy<T1>::prefer_at_accessor == false)
    {
    typedef typename Proxy<T1>::ea_type ea_type;
    
          ea_type A      = P.get_ea();
    const uword   n_elem = P.get_n_elem();
    
    for(uword i=0; i<n_elem; ++i)
      {
      n_nonzero += (A[i] != val) ? uword(1) : uword(0);
      }
    }
  else
    {
    const uword P_n_cols = P.get_n_cols();
    const uword P_n_rows = P.get_n_rows();
    
    if(P_n_rows == 1)
      {
      for(uword col=0; col < P_n_cols; ++col)
        {
        n_nonzero += (P.at(0,col) != val) ? uword(1) : uword(0);
        }
      }
    else
      {
      for(uword col=0; col < P_n_cols; ++col)
      for(uword row=0; row < P_n_rows; ++row)
        {
        n_nonzero += (P.at(row,col) != val) ? uword(1) : uword(0);
        }
      }
    }
  
  return n_nonzero;
  }



template<typename T1>
inline
arma_warn_unused
uword
accu(const mtOp<uword,T1,op_rel_eq>& X)
  {
  arma_extra_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const eT val = X.aux;
  
  const Proxy<T1> P(X.m);
  
  uword n_nonzero = 0;
  
  if(Proxy<T1>::prefer_at_accessor == false)
    {
    typedef typename Proxy<T1>::ea_type ea_type;
    
          ea_type A      = P.get_ea();
    const uword   n_elem = P.get_n_elem();
    
    for(uword i=0; i<n_elem; ++i)
      {
      n_nonzero += (A[i] == val) ? uword(1) : uword(0);
      }
    }
  else
    {
    const uword P_n_cols = P.get_n_cols();
    const uword P_n_rows = P.get_n_rows();
    
    if(P_n_rows == 1)
      {
      for(uword col=0; col < P_n_cols; ++col)
        {
        n_nonzero += (P.at(0,col) == val) ? uword(1) : uword(0);
        }
      }
    else
      {
      for(uword col=0; col < P_n_cols; ++col)
      for(uword row=0; row < P_n_rows; ++row)
        {
        n_nonzero += (P.at(row,col) == val) ? uword(1) : uword(0);
        }
      }
    }
  
  return n_nonzero;
  }



//! accumulate the elements of a subview (submatrix)
template<typename eT>
arma_hot
arma_pure
arma_warn_unused
inline
eT
accu(const subview<eT>& X)
  {
  arma_extra_debug_sigprint();  
  
  const uword X_n_rows = X.n_rows;
  const uword X_n_cols = X.n_cols;
  
  eT val = eT(0);
  
  if(X_n_rows == 1)
    {
    typedef subview_row<eT> sv_type;
    
    const sv_type& sv = reinterpret_cast<const sv_type&>(X);  // subview_row<eT> is a child class of subview<eT> and has no extra data
    
    const Proxy<sv_type> P(sv);
    
    val = accu_proxy_linear(P);
    }
  else
  if(X_n_cols == 1)
    {
    val = arrayops::accumulate( X.colptr(0), X_n_rows );
    }
  else
    {
    for(uword col=0; col < X_n_cols; ++col)
      {
      val += arrayops::accumulate( X.colptr(col), X_n_rows );
      }
    }
  
  return val;
  }



template<typename eT>
arma_hot
arma_pure
arma_warn_unused
inline
eT
accu(const subview_col<eT>& X)
  {
  arma_extra_debug_sigprint();  
  
  return arrayops::accumulate( X.colptr(0), X.n_rows );
  }



//! accumulate the elements of a cube
template<typename T1>
arma_hot
arma_warn_unused
inline
typename T1::elem_type
accu(const BaseCube<typename T1::elem_type,T1>& X)
  {
  arma_extra_debug_sigprint();
  
  typedef typename T1::elem_type          eT;
  typedef typename ProxyCube<T1>::ea_type ea_type;
  
  const ProxyCube<T1> A(X.get_ref());
  
  if(is_Cube<typename ProxyCube<T1>::stored_type>::value)
    {
    unwrap_cube<typename ProxyCube<T1>::stored_type> tmp(A.Q);
    
    return arrayops::accumulate(tmp.M.memptr(), tmp.M.n_elem);
    }
  
  
  if(ProxyCube<T1>::prefer_at_accessor == false)
    {
          ea_type P      = A.get_ea();
    const uword   n_elem = A.get_n_elem();
    
    eT val1 = eT(0);
    eT val2 = eT(0);
    
    uword i,j;
    
    for(i=0, j=1; j<n_elem; i+=2, j+=2)
      {
      val1 += P[i];
      val2 += P[j];
      }
    
    if(i < n_elem)
      {
      val1 += P[i];
      }
    
    return val1 + val2;
    }
  else
    {
    const uword n_rows   = A.get_n_rows();
    const uword n_cols   = A.get_n_cols();
    const uword n_slices = A.get_n_slices();
    
    eT val1 = eT(0);
    eT val2 = eT(0);
    
    for(uword slice=0; slice<n_slices; ++slice)
    for(uword col=0; col<n_cols; ++col)
      {
      uword i,j;
      for(i=0, j=1; j<n_rows; i+=2, j+=2)
        {
        val1 += A.at(i,col,slice);
        val2 += A.at(j,col,slice);
        }
      
      if(i < n_rows)
        {
        val1 += A.at(i,col,slice);
        }
      }
    
    return val1 + val2;
    }
  }



template<typename T>
arma_inline
arma_warn_unused
const typename arma_scalar_only<T>::result &
accu(const T& x)
  {
  return x;
  }



//! accumulate values in a sparse object
template<typename T1>
arma_hot
inline
arma_warn_unused
typename enable_if2<is_arma_sparse_type<T1>::value, typename T1::elem_type>::result
accu(const T1& x)
  {
  arma_extra_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const SpProxy<T1> p(x);
  
  if(SpProxy<T1>::must_use_iterator == false)
    {
    // direct counting
    return arrayops::accumulate(p.get_values(), p.get_n_nonzero());
    }
  else
    {
    typename SpProxy<T1>::const_iterator_type it     = p.begin();
    typename SpProxy<T1>::const_iterator_type it_end = p.end();
    
    eT result = eT(0);
    
    while(it != it_end)
      {
      result += (*it);
      ++it;
      }
    
    return result;
    }
  }



//! @}