// SPDX-License-Identifier: Apache-2.0
// 
// Copyright 2008-2016 Conrad Sanderson (https://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
// https://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_sp_min
//! @{



template<typename T1>
inline
void
op_sp_min::apply(Mat<typename T1::elem_type>& out, const mtSpReduceOp<typename T1::elem_type, T1, op_sp_min>& in)
  {
  arma_debug_sigprint();
  
  const uword dim = in.aux_uword_a;
  
  arma_conform_check( (dim > 1), "min(): parameter 'dim' must be 0 or 1" );
  
  const SpProxy<T1> p(in.m);
  
  const uword p_n_rows = p.get_n_rows();
  const uword p_n_cols = p.get_n_cols();
  
  if( (p_n_rows == 0) || (p_n_cols == 0) || (p.get_n_nonzero() == 0) )
    {
    if(dim == 0)  { out.zeros((p_n_rows > 0) ? 1 : 0, p_n_cols); }
    if(dim == 1)  { out.zeros(p_n_rows, (p_n_cols > 0) ? 1 : 0); }
    
    return;
    }
  
  op_sp_min::apply_proxy(out, p, dim);
  }



template<typename T1>
inline
void
op_sp_min::apply_proxy
  (
        Mat<typename T1::elem_type>& out,
  const SpProxy<T1>&                 p,
  const uword                        dim,
  const typename arma_not_cx<typename T1::elem_type>::result* junk
  )
  {
  arma_debug_sigprint();
  arma_ignore(junk);
  
  typedef typename T1::elem_type eT;
  
  typename SpProxy<T1>::const_iterator_type it     = p.begin();
  typename SpProxy<T1>::const_iterator_type it_end = p.end();
  
  const uword p_n_cols = p.get_n_cols();
  const uword p_n_rows = p.get_n_rows();
  
  if(dim == 0) // find the minimum in each column
    {
    out.zeros(1, p_n_cols);
    
    urowvec count(p_n_cols, arma_zeros_indicator());
    
    while(it != it_end)
      {
      const uword col = it.col();
      
        out[col] = (count[col] == 0) ? (*it) : (std::min)(out[col], (*it));
      count[col]++;
      ++it;
      }
    
    for(uword col=0; col<p_n_cols; ++col)
      {
      if(count[col] < p_n_rows)  { out[col] = (std::min)(out[col], eT(0)); }
      }
    }
  else
  if(dim == 1)  // find the minimum in each row
    {
    out.zeros(p_n_rows, 1);
    
    ucolvec count(p_n_rows, arma_zeros_indicator());
    
    while(it != it_end)
      {
      const uword row = it.row();
      
        out[row] = (count[row] == 0) ? (*it) : (std::min)(out[row], (*it));
      count[row]++;
      ++it;
      }
    
    for(uword row=0; row<p_n_rows; ++row)
      {
      if(count[row] < p_n_cols)  { out[row] = (std::min)(out[row], eT(0)); }
      }
    }
  }



template<typename T1>
inline
typename T1::elem_type
op_sp_min::vector_min
  (
  const T1& x,
  const typename arma_not_cx<typename T1::elem_type>::result* junk
  )
  {
  arma_debug_sigprint();
  arma_ignore(junk);
  
  typedef typename T1::elem_type eT;
  
  const SpProxy<T1> p(x);
  
  if(p.get_n_elem() == 0)
    {
    arma_conform_check(true, "min(): object has no elements");
    
    return Datum<eT>::nan;
    }
  
  if(p.get_n_nonzero() == 0)  { return eT(0); }
  
  if(SpProxy<T1>::use_iterator == false)
    {
    // direct access of values
    if(p.get_n_nonzero() == p.get_n_elem())
      {
      return op_min::direct_min(p.get_values(), p.get_n_nonzero());
      }
    else
      {
      return (std::min)(eT(0), op_min::direct_min(p.get_values(), p.get_n_nonzero()));
      }
    }
  else
    {
    // use iterator
    typename SpProxy<T1>::const_iterator_type it     = p.begin();
    typename SpProxy<T1>::const_iterator_type it_end = p.end();
    
    eT result = (*it);
    ++it;
    
    while(it != it_end)
      {
      if((*it) < result)  { result = (*it); }
      
      ++it;
      }
    
    if(p.get_n_nonzero() == p.get_n_elem())
      {
      return result;
      }
    else
      {
      return (std::min)(eT(0), result);
      }
    }
  }



template<typename T1>
inline
typename arma_not_cx<typename T1::elem_type>::result
op_sp_min::min(const SpBase<typename T1::elem_type, T1>& X)
  {
  arma_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const SpProxy<T1> P(X.get_ref());
  
  const uword n_elem    = P.get_n_elem();
  const uword n_nonzero = P.get_n_nonzero();
  
  if(n_elem == 0)
    {
    arma_conform_check(true, "min(): object has no elements");
    
    return Datum<eT>::nan;
    }
  
  eT min_val = priv::most_pos<eT>();
  
  if(SpProxy<T1>::use_iterator)
    {
    // We have to iterate over the elements.
    typedef typename SpProxy<T1>::const_iterator_type it_type;
    
    it_type it     = P.begin();
    it_type it_end = P.end();
    
    while(it != it_end)
      {
      if((*it) < min_val)  { min_val = *it; }
      
      ++it;
      }
    }
  else
    {
    // We can do direct access of the values, row_indices, and col_ptrs.
    // We don't need the location of the min value, so we can just call out to
    // other functions...
    min_val = op_min::direct_min(P.get_values(), n_nonzero);
    }
  
  if(n_elem == n_nonzero)
    {
    return min_val;
    }
  else
    {
    return (std::min)(eT(0), min_val);
    }
  }



template<typename T1>
inline
typename arma_not_cx<typename T1::elem_type>::result
op_sp_min::min_with_index(const SpProxy<T1>& P, uword& index_of_min_val)
  {
  arma_debug_sigprint();
  
  typedef typename T1::elem_type eT;
  
  const uword n_elem    = P.get_n_elem();
  const uword n_nonzero = P.get_n_nonzero();
  const uword n_rows    = P.get_n_rows();
  
  if(n_elem == 0)
    {
    arma_conform_check(true, "min(): object has no elements");
    
    index_of_min_val = uword(0);
    
    return Datum<eT>::nan;
    }
  
  eT min_val = priv::most_pos<eT>();
  
  if(SpProxy<T1>::use_iterator)
    {
    // We have to iterate over the elements.
    typedef typename SpProxy<T1>::const_iterator_type it_type;
    
    it_type it     = P.begin();
    it_type it_end = P.end();
    
    while(it != it_end)
      {
      if((*it) < min_val)
        {
        min_val = *it;
        index_of_min_val = it.row() + it.col() * n_rows;
        }
      
      ++it;
      }
    }
  else
    {
    // We can do direct access.
    min_val = op_min::direct_min(P.get_values(), n_nonzero, index_of_min_val);
    
    // Convert to actual position in matrix.
    const uword row = P.get_row_indices()[index_of_min_val];
    uword col = 0;
    while(P.get_col_ptrs()[++col] < index_of_min_val + 1) { }
    index_of_min_val = (col - 1) * n_rows + row;
    }
  
  
  if(n_elem != n_nonzero)
    {
    min_val = (std::min)(eT(0), min_val);
    
    // If the min_val is a nonzero element, we need its actual position in the matrix.
    if(min_val == eT(0))
      {
      // Find first zero element.
      uword last_row = 0;
      uword last_col = 0;
      
      typedef typename SpProxy<T1>::const_iterator_type it_type;
      
      it_type it     = P.begin();
      it_type it_end = P.end();
      
      while(it != it_end)
        {
        // Have we moved more than one position from the last place?
        if((it.col() == last_col) && (it.row() - last_row > 1))
          {
          index_of_min_val = it.col() * n_rows + last_row + 1;
          break;
          }
        else if((it.col() >= last_col + 1) && (last_row < n_rows - 1))
          {
          index_of_min_val = last_col * n_rows + last_row + 1;
          break;
          }
        else if((it.col() == last_col + 1) && (it.row() > 0))
          {
          index_of_min_val = it.col() * n_rows;
          break;
          }
        else if(it.col() > last_col + 1)
          {
          index_of_min_val = (last_col + 1) * n_rows;
          break;
          }
        
        last_row = it.row();
        last_col = it.col();
        ++it;
        }
      }
    }
  
  return min_val;
  }



template<typename T1>
inline
void
op_sp_min::apply_proxy
  (
        Mat<typename T1::elem_type>& out,
  const SpProxy<T1>&                 p,
  const uword                        dim,
  const typename arma_cx_only<typename T1::elem_type>::result* junk
  )
  {
  arma_debug_sigprint();
  arma_ignore(junk);
  
  typedef typename T1::elem_type            eT;
  typedef typename get_pod_type<eT>::result  T;
  
  typename SpProxy<T1>::const_iterator_type it     = p.begin();
  typename SpProxy<T1>::const_iterator_type it_end = p.end();
  
  const uword p_n_cols = p.get_n_cols();
  const uword p_n_rows = p.get_n_rows();
  
  if(dim == 0) // find the minimum in each column
    {
    out.zeros(1, p_n_cols);
    
    Row<T>  absval(p_n_cols, arma_zeros_indicator());
    urowvec  count(p_n_cols, arma_zeros_indicator());
    
    while(it != it_end)
      {
      const uword col = it.col();
      
      const eT& v = (*it);
      const  T  a = std::abs(v);
      
      if(count[col] == 0)
        {
        absval[col] = a;
           out[col] = v;
        }
      else
        {
        if(a < absval[col])
          {
          absval[col] = a;
             out[col] = v;
          }
        }
      
      count[col]++;
      ++it;
      }
    
    for(uword col=0; col < p_n_cols; ++col)
      {
      if(count[col] < p_n_rows)
        {
        if(T(0) < absval[col])  { out[col] = eT(0); }
        }
      }
    }
  else
  if(dim == 1)  // find the minimum in each row
    {
    out.zeros(p_n_rows, 1);
    
    Col<T>  absval(p_n_rows, arma_zeros_indicator());
    ucolvec  count(p_n_rows, arma_zeros_indicator());
    
    while(it != it_end)
      {
      const uword row = it.row();
      
      const eT& v = (*it);
      const  T  a = std::abs(v);
      
      if(count[row] == 0)
        {
        absval[row] = a;
           out[row] = v;
        }
      else
        {
        if(a < absval[row])
          {
          absval[row] = a;
             out[row] = v;
          }
        }
      
      count[row]++;
      ++it;
      }
    
    for(uword row=0; row < p_n_rows; ++row)
      {
      if(count[row] < p_n_cols)
        {
        if(T(0) < absval[row])  { out[row] = eT(0); }
        }
      }
    }
  }



template<typename T1>
inline
typename T1::elem_type
op_sp_min::vector_min
  (
  const T1& x,
  const typename arma_cx_only<typename T1::elem_type>::result* junk
  )
  {
  arma_debug_sigprint();
  arma_ignore(junk);
  
  typedef typename T1::elem_type            eT;
  typedef typename get_pod_type<eT>::result  T;
  
  const SpProxy<T1> p(x);
  
  if(p.get_n_elem() == 0)
    {
    arma_conform_check(true, "min(): object has no elements");
    
    return Datum<eT>::nan;
    }
  
  if(p.get_n_nonzero() == 0)  { return eT(0); }
  
  if(SpProxy<T1>::use_iterator == false)
    {
    // direct access of values
    if(p.get_n_nonzero() == p.get_n_elem())
      {
      return op_min::direct_min(p.get_values(), p.get_n_nonzero());
      }
    else
      {
      const eT val1 = eT(0);
      const eT val2 = op_min::direct_min(p.get_values(), p.get_n_nonzero());
      
      return ( std::abs(val1) < std::abs(val2) ) ? val1 : val2;
      }
    }
  else
    {
    // use iterator
    typename SpProxy<T1>::const_iterator_type it     = p.begin();
    typename SpProxy<T1>::const_iterator_type it_end = p.end();

    eT best_val_orig = *it;
     T best_val_abs  = std::abs(best_val_orig);
    
    ++it;
    
    while(it != it_end)
      {
      eT val_orig = *it;
       T val_abs  = std::abs(val_orig);
      
      if(val_abs < best_val_abs)
        {
        best_val_abs  = val_abs;
        best_val_orig = val_orig;
        }

      ++it;
      }

    if(p.get_n_nonzero() == p.get_n_elem())
      {
      return best_val_orig;
      }
    else
      {
      const eT val1 = eT(0);
      
      return ( std::abs(val1) < best_val_abs ) ? val1 : best_val_orig;
      }
    }
  }



template<typename T1>
inline
typename arma_cx_only<typename T1::elem_type>::result
op_sp_min::min(const SpBase<typename T1::elem_type, T1>& X)
  {
  arma_debug_sigprint();

  typedef typename T1::elem_type            eT;
  typedef typename get_pod_type<eT>::result  T;

  const SpProxy<T1> P(X.get_ref());

  const uword n_elem    = P.get_n_elem();
  const uword n_nonzero = P.get_n_nonzero();

  if(n_elem == 0)
    {
    arma_conform_check(true, "min(): object has no elements");
    
    return Datum<eT>::nan;
    }
  
   T min_val = priv::most_pos<T>();
  eT ret_val;
  
  if(SpProxy<T1>::use_iterator)
    {
    // We have to iterate over the elements.
    typedef typename SpProxy<T1>::const_iterator_type it_type;
    
    it_type it     = P.begin();
    it_type it_end = P.end();
    
    while(it != it_end)
      {
      const T tmp_val = std::abs(*it);
      
      if(tmp_val < min_val)
        {
        min_val = tmp_val;
        ret_val = *it;
        }
      
      ++it;
      }
    }
  else
    {
    // We can do direct access of the values, row_indices, and col_ptrs.
    // We don't need the location of the min value, so we can just call out to
    // other functions...
    ret_val = op_min::direct_min(P.get_values(), n_nonzero);
    min_val = std::abs(ret_val);
    }

  if(n_elem == n_nonzero)
    {
    return ret_val;
    }
  else
    {
    return (T(0) < min_val) ? eT(0) : ret_val;
    }
  }



template<typename T1>
inline
typename arma_cx_only<typename T1::elem_type>::result
op_sp_min::min_with_index(const SpProxy<T1>& P, uword& index_of_min_val)
  {
  arma_debug_sigprint();
  
  typedef typename T1::elem_type            eT;
  typedef typename get_pod_type<eT>::result  T;
  
  const uword n_elem    = P.get_n_elem();
  const uword n_nonzero = P.get_n_nonzero();
  const uword n_rows    = P.get_n_rows();
  
  if(n_elem == 0)
    {
    arma_conform_check(true, "min(): object has no elements");
    
    index_of_min_val = uword(0);
    
    return Datum<eT>::nan;
    }
  
  T min_val = priv::most_pos<T>();
  
  if(SpProxy<T1>::use_iterator)
    {
    // We have to iterate over the elements.
    typedef typename SpProxy<T1>::const_iterator_type it_type;
    
    it_type it     = P.begin();
    it_type it_end = P.end();
    
    while(it != it_end)
      {
      const T tmp_val = std::abs(*it);
      
      if(tmp_val < min_val)
        {
                 min_val = tmp_val;
        index_of_min_val = it.row() + it.col() * n_rows;
        }
      
      ++it;
      }
    }
  else
    {
    // We can do direct access.
    min_val = std::abs(op_min::direct_min(P.get_values(), n_nonzero, index_of_min_val));

    // Convert to actual position in matrix.
    const uword row = P.get_row_indices()[index_of_min_val];
    uword col = 0;
    while(P.get_col_ptrs()[++col] < index_of_min_val + 1) { }
    index_of_min_val = (col - 1) * n_rows + row;
    }
  
  
  if(n_elem != n_nonzero)
    {
    min_val = (std::min)(T(0), min_val);

    // If the min_val is a nonzero element, we need its actual position in the matrix.
    if(min_val == T(0))
      {
      // Find first zero element.
      uword last_row = 0;
      uword last_col = 0;
      
      typedef typename SpProxy<T1>::const_iterator_type it_type;
      
      it_type it     = P.begin();
      it_type it_end = P.end();
      
      while(it != it_end)
        {
        // Have we moved more than one position from the last place?
        if((it.col() == last_col) && (it.row() - last_row > 1))
          {
          index_of_min_val = it.col() * n_rows + last_row + 1;
          break;
          }
        else if((it.col() >= last_col + 1) && (last_row < n_rows - 1))
          {
          index_of_min_val = last_col * n_rows + last_row + 1;
          break;
          }
        else if((it.col() == last_col + 1) && (it.row() > 0))
          {
          index_of_min_val = it.col() * n_rows;
          break;
          }
        else if(it.col() > last_col + 1)
          {
          index_of_min_val = (last_col + 1) * n_rows;
          break;
          }

        last_row = it.row();
        last_col = it.col();
        ++it;
        }
      }
    }

  return P[index_of_min_val];
  }



//! @}
