// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// Eigen is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// Alternatively, you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of
// the License, or (at your option) any later version.
//
// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License and a copy of the GNU General Public License along with
// Eigen. If not, see <http://www.gnu.org/licenses/>.

#ifndef EIGEN_SPARSE_CWISE_BINARY_OP_H
#define EIGEN_SPARSE_CWISE_BINARY_OP_H

// Here we have to handle 3 cases:
//  1 - sparse op dense
//  2 - dense op sparse
//  3 - sparse op sparse
// We also need to implement a 4th iterator for:
//  4 - dense op dense
// Finally, we also need to distinguish between the product and other operations :
//                configuration      returned mode
//  1 - sparse op dense    product      sparse
//                         generic      dense
//  2 - dense op sparse    product      sparse
//                         generic      dense
//  3 - sparse op sparse   product      sparse
//                         generic      sparse
//  4 - dense op dense     product      dense
//                         generic      dense

namespace internal {

template<> struct promote_storage_type<Dense,Sparse>
{ typedef Sparse ret; };

template<> struct promote_storage_type<Sparse,Dense>
{ typedef Sparse ret; };

template<typename BinaryOp, typename Lhs, typename Rhs, typename Derived,
  typename _LhsStorageMode = typename traits<Lhs>::StorageKind,
  typename _RhsStorageMode = typename traits<Rhs>::StorageKind>
class sparse_cwise_binary_op_inner_iterator_selector;

} // end namespace internal

template<typename BinaryOp, typename Lhs, typename Rhs>
class CwiseBinaryOpImpl<BinaryOp, Lhs, Rhs, Sparse>
  : public SparseMatrixBase<CwiseBinaryOp<BinaryOp, Lhs, Rhs> >
{
  public:
    class InnerIterator;
    typedef CwiseBinaryOp<BinaryOp, Lhs, Rhs> Derived;
    EIGEN_SPARSE_PUBLIC_INTERFACE(Derived)
};

template<typename BinaryOp, typename Lhs, typename Rhs>
class CwiseBinaryOpImpl<BinaryOp,Lhs,Rhs,Sparse>::InnerIterator
  : public internal::sparse_cwise_binary_op_inner_iterator_selector<BinaryOp,Lhs,Rhs,typename CwiseBinaryOpImpl<BinaryOp,Lhs,Rhs,Sparse>::InnerIterator>
{
  public:
    typedef typename Lhs::Index Index;
    typedef internal::sparse_cwise_binary_op_inner_iterator_selector<
      BinaryOp,Lhs,Rhs, InnerIterator> Base;

    EIGEN_STRONG_INLINE InnerIterator(const CwiseBinaryOpImpl& binOp, Index outer)
      : Base(binOp.derived(),outer)
    {}
};

/***************************************************************************
* Implementation of inner-iterators
***************************************************************************/

// template<typename T> struct internal::func_is_conjunction { enum { ret = false }; };
// template<typename T> struct internal::func_is_conjunction<internal::scalar_product_op<T> > { enum { ret = true }; };

// TODO generalize the internal::scalar_product_op specialization to all conjunctions if any !

namespace internal {

// sparse - sparse  (generic)
template<typename BinaryOp, typename Lhs, typename Rhs, typename Derived>
class sparse_cwise_binary_op_inner_iterator_selector<BinaryOp, Lhs, Rhs, Derived, Sparse, Sparse>
{
    typedef CwiseBinaryOp<BinaryOp, Lhs, Rhs> CwiseBinaryXpr;
    typedef typename traits<CwiseBinaryXpr>::Scalar Scalar;
    typedef typename traits<CwiseBinaryXpr>::_LhsNested _LhsNested;
    typedef typename traits<CwiseBinaryXpr>::_RhsNested _RhsNested;
    typedef typename _LhsNested::InnerIterator LhsIterator;
    typedef typename _RhsNested::InnerIterator RhsIterator;
    typedef typename Lhs::Index Index;

  public:

    EIGEN_STRONG_INLINE sparse_cwise_binary_op_inner_iterator_selector(const CwiseBinaryXpr& xpr, Index outer)
      : m_lhsIter(xpr.lhs(),outer), m_rhsIter(xpr.rhs(),outer), m_functor(xpr.functor())
    {
      this->operator++();
    }

    EIGEN_STRONG_INLINE Derived& operator++()
    {
      if (m_lhsIter && m_rhsIter && (m_lhsIter.index() == m_rhsIter.index()))
      {
        m_id = m_lhsIter.index();
        m_value = m_functor(m_lhsIter.value(), m_rhsIter.value());
        ++m_lhsIter;
        ++m_rhsIter;
      }
      else if (m_lhsIter && (!m_rhsIter || (m_lhsIter.index() < m_rhsIter.index())))
      {
        m_id = m_lhsIter.index();
        m_value = m_functor(m_lhsIter.value(), Scalar(0));
        ++m_lhsIter;
      }
      else if (m_rhsIter && (!m_lhsIter || (m_lhsIter.index() > m_rhsIter.index())))
      {
        m_id = m_rhsIter.index();
        m_value = m_functor(Scalar(0), m_rhsIter.value());
        ++m_rhsIter;
      }
      else
      {
        m_value = 0; // this is to avoid a compilation warning
        m_id = -1;
      }
      return *static_cast<Derived*>(this);
    }

    EIGEN_STRONG_INLINE Scalar value() const { return m_value; }

    EIGEN_STRONG_INLINE Index index() const { return m_id; }
    EIGEN_STRONG_INLINE Index row() const { return Lhs::IsRowMajor ? m_lhsIter.row() : index(); }
    EIGEN_STRONG_INLINE Index col() const { return Lhs::IsRowMajor ? index() : m_lhsIter.col(); }

    EIGEN_STRONG_INLINE operator bool() const { return m_id>=0; }

  protected:
    LhsIterator m_lhsIter;
    RhsIterator m_rhsIter;
    const BinaryOp& m_functor;
    Scalar m_value;
    Index m_id;
};

// sparse - sparse  (product)
template<typename T, typename Lhs, typename Rhs, typename Derived>
class sparse_cwise_binary_op_inner_iterator_selector<scalar_product_op<T>, Lhs, Rhs, Derived, Sparse, Sparse>
{
    typedef scalar_product_op<T> BinaryFunc;
    typedef CwiseBinaryOp<BinaryFunc, Lhs, Rhs> CwiseBinaryXpr;
    typedef typename CwiseBinaryXpr::Scalar Scalar;
    typedef typename traits<CwiseBinaryXpr>::_LhsNested _LhsNested;
    typedef typename _LhsNested::InnerIterator LhsIterator;
    typedef typename traits<CwiseBinaryXpr>::_RhsNested _RhsNested;
    typedef typename _RhsNested::InnerIterator RhsIterator;
    typedef typename Lhs::Index Index;
  public:

    EIGEN_STRONG_INLINE sparse_cwise_binary_op_inner_iterator_selector(const CwiseBinaryXpr& xpr, Index outer)
      : m_lhsIter(xpr.lhs(),outer), m_rhsIter(xpr.rhs(),outer), m_functor(xpr.functor())
    {
      while (m_lhsIter && m_rhsIter && (m_lhsIter.index() != m_rhsIter.index()))
      {
        if (m_lhsIter.index() < m_rhsIter.index())
          ++m_lhsIter;
        else
          ++m_rhsIter;
      }
    }

    EIGEN_STRONG_INLINE Derived& operator++()
    {
      ++m_lhsIter;
      ++m_rhsIter;
      while (m_lhsIter && m_rhsIter && (m_lhsIter.index() != m_rhsIter.index()))
      {
        if (m_lhsIter.index() < m_rhsIter.index())
          ++m_lhsIter;
        else
          ++m_rhsIter;
      }
      return *static_cast<Derived*>(this);
    }

    EIGEN_STRONG_INLINE Scalar value() const { return m_functor(m_lhsIter.value(), m_rhsIter.value()); }

    EIGEN_STRONG_INLINE Index index() const { return m_lhsIter.index(); }
    EIGEN_STRONG_INLINE Index row() const { return m_lhsIter.row(); }
    EIGEN_STRONG_INLINE Index col() const { return m_lhsIter.col(); }

    EIGEN_STRONG_INLINE operator bool() const { return (m_lhsIter && m_rhsIter); }

  protected:
    LhsIterator m_lhsIter;
    RhsIterator m_rhsIter;
    const BinaryFunc& m_functor;
};

// sparse - dense  (product)
template<typename T, typename Lhs, typename Rhs, typename Derived>
class sparse_cwise_binary_op_inner_iterator_selector<scalar_product_op<T>, Lhs, Rhs, Derived, Sparse, Dense>
{
    typedef scalar_product_op<T> BinaryFunc;
    typedef CwiseBinaryOp<BinaryFunc, Lhs, Rhs> CwiseBinaryXpr;
    typedef typename CwiseBinaryXpr::Scalar Scalar;
    typedef typename traits<CwiseBinaryXpr>::_LhsNested _LhsNested;
    typedef typename traits<CwiseBinaryXpr>::RhsNested RhsNested;
    typedef typename _LhsNested::InnerIterator LhsIterator;
    typedef typename Lhs::Index Index;
    enum { IsRowMajor = (int(Lhs::Flags)&RowMajorBit)==RowMajorBit };
  public:

    EIGEN_STRONG_INLINE sparse_cwise_binary_op_inner_iterator_selector(const CwiseBinaryXpr& xpr, Index outer)
      : m_rhs(xpr.rhs()), m_lhsIter(xpr.lhs(),outer), m_functor(xpr.functor()), m_outer(outer)
    {}

    EIGEN_STRONG_INLINE Derived& operator++()
    {
      ++m_lhsIter;
      return *static_cast<Derived*>(this);
    }

    EIGEN_STRONG_INLINE Scalar value() const
    { return m_functor(m_lhsIter.value(),
                       m_rhs.coeff(IsRowMajor?m_outer:m_lhsIter.index(),IsRowMajor?m_lhsIter.index():m_outer)); }

    EIGEN_STRONG_INLINE Index index() const { return m_lhsIter.index(); }
    EIGEN_STRONG_INLINE Index row() const { return m_lhsIter.row(); }
    EIGEN_STRONG_INLINE Index col() const { return m_lhsIter.col(); }

    EIGEN_STRONG_INLINE operator bool() const { return m_lhsIter; }

  protected:
    const RhsNested m_rhs;
    LhsIterator m_lhsIter;
    const BinaryFunc m_functor;
    const Index m_outer;
};

// sparse - dense  (product)
template<typename T, typename Lhs, typename Rhs, typename Derived>
class sparse_cwise_binary_op_inner_iterator_selector<scalar_product_op<T>, Lhs, Rhs, Derived, Dense, Sparse>
{
    typedef scalar_product_op<T> BinaryFunc;
    typedef CwiseBinaryOp<BinaryFunc, Lhs, Rhs> CwiseBinaryXpr;
    typedef typename CwiseBinaryXpr::Scalar Scalar;
    typedef typename traits<CwiseBinaryXpr>::_RhsNested _RhsNested;
    typedef typename _RhsNested::InnerIterator RhsIterator;
    typedef typename Lhs::Index Index;

    enum { IsRowMajor = (int(Rhs::Flags)&RowMajorBit)==RowMajorBit };
  public:

    EIGEN_STRONG_INLINE sparse_cwise_binary_op_inner_iterator_selector(const CwiseBinaryXpr& xpr, Index outer)
      : m_xpr(xpr), m_rhsIter(xpr.rhs(),outer), m_functor(xpr.functor()), m_outer(outer)
    {}

    EIGEN_STRONG_INLINE Derived& operator++()
    {
      ++m_rhsIter;
      return *static_cast<Derived*>(this);
    }

    EIGEN_STRONG_INLINE Scalar value() const
    { return m_functor(m_xpr.lhs().coeff(IsRowMajor?m_outer:m_rhsIter.index(),IsRowMajor?m_rhsIter.index():m_outer), m_rhsIter.value()); }

    EIGEN_STRONG_INLINE Index index() const { return m_rhsIter.index(); }
    EIGEN_STRONG_INLINE Index row() const { return m_rhsIter.row(); }
    EIGEN_STRONG_INLINE Index col() const { return m_rhsIter.col(); }

    EIGEN_STRONG_INLINE operator bool() const { return m_rhsIter; }

  protected:
    const CwiseBinaryXpr& m_xpr;
    RhsIterator m_rhsIter;
    const BinaryFunc& m_functor;
    const Index m_outer;
};

} // end namespace internal

/***************************************************************************
* Implementation of SparseMatrixBase and SparseCwise functions/operators
***************************************************************************/

// template<typename Derived>
// template<typename OtherDerived>
// EIGEN_STRONG_INLINE const CwiseBinaryOp<internal::scalar_difference_op<typename internal::traits<Derived>::Scalar>,
//                                  Derived, OtherDerived>
// SparseMatrixBase<Derived>::operator-(const SparseMatrixBase<OtherDerived> &other) const
// {
//   return CwiseBinaryOp<internal::scalar_difference_op<Scalar>,
//                        Derived, OtherDerived>(derived(), other.derived());
// }

template<typename Derived>
template<typename OtherDerived>
EIGEN_STRONG_INLINE Derived &
SparseMatrixBase<Derived>::operator-=(const SparseMatrixBase<OtherDerived> &other)
{
  return *this = derived() - other.derived();
}

// template<typename Derived>
// template<typename OtherDerived>
// EIGEN_STRONG_INLINE const CwiseBinaryOp<internal::scalar_sum_op<typename internal::traits<Derived>::Scalar>, Derived, OtherDerived>
// SparseMatrixBase<Derived>::operator+(const SparseMatrixBase<OtherDerived> &other) const
// {
//   return CwiseBinaryOp<internal::scalar_sum_op<Scalar>, Derived, OtherDerived>(derived(), other.derived());
// }

template<typename Derived>
template<typename OtherDerived>
EIGEN_STRONG_INLINE Derived &
SparseMatrixBase<Derived>::operator+=(const SparseMatrixBase<OtherDerived>& other)
{
  return *this = derived() + other.derived();
}

// template<typename ExpressionType>
// template<typename OtherDerived>
// EIGEN_STRONG_INLINE const EIGEN_SPARSE_CWISE_PRODUCT_RETURN_TYPE
// SparseCwise<ExpressionType>::operator*(const SparseMatrixBase<OtherDerived> &other) const
// {
//   return EIGEN_SPARSE_CWISE_PRODUCT_RETURN_TYPE(_expression(), other.derived());
// }

template<typename Derived>
template<typename OtherDerived>
EIGEN_STRONG_INLINE const EIGEN_SPARSE_CWISE_PRODUCT_RETURN_TYPE
SparseMatrixBase<Derived>::cwiseProduct(const MatrixBase<OtherDerived> &other) const
{
  return EIGEN_SPARSE_CWISE_PRODUCT_RETURN_TYPE(derived(), other.derived());
}

// template<typename ExpressionType>
// template<typename OtherDerived>
// EIGEN_STRONG_INLINE const EIGEN_SPARSE_CWISE_BINOP_RETURN_TYPE(internal::scalar_quotient_op)
// SparseCwise<ExpressionType>::operator/(const SparseMatrixBase<OtherDerived> &other) const
// {
//   return EIGEN_SPARSE_CWISE_BINOP_RETURN_TYPE(internal::scalar_quotient_op)(_expression(), other.derived());
// }
//
// template<typename ExpressionType>
// template<typename OtherDerived>
// EIGEN_STRONG_INLINE const EIGEN_SPARSE_CWISE_BINOP_RETURN_TYPE(internal::scalar_quotient_op)
// SparseCwise<ExpressionType>::operator/(const MatrixBase<OtherDerived> &other) const
// {
//   return EIGEN_SPARSE_CWISE_BINOP_RETURN_TYPE(internal::scalar_quotient_op)(_expression(), other.derived());
// }

// template<typename ExpressionType>
// template<typename OtherDerived>
// inline ExpressionType& SparseCwise<ExpressionType>::operator*=(const SparseMatrixBase<OtherDerived> &other)
// {
//   return m_matrix.const_cast_derived() = _expression() * other.derived();
// }


#endif // EIGEN_SPARSE_CWISE_BINARY_OP_H