// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2008-2014 Gael Guennebaud <gael.guennebaud@inria.fr>
//
// 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/.
// SPDX-License-Identifier: MPL-2.0

#ifndef EIGEN_SPARSEASSIGN_H
#define EIGEN_SPARSEASSIGN_H

// IWYU pragma: private
#include "./InternalHeaderCheck.h"

namespace Eigen {

template <typename Derived>
template <typename OtherDerived>
Derived &SparseMatrixBase<Derived>::operator=(const EigenBase<OtherDerived> &other) {
  internal::call_assignment_no_alias(derived(), other.derived());
  return derived();
}

template <typename Derived>
template <typename OtherDerived>
Derived &SparseMatrixBase<Derived>::operator=(const ReturnByValue<OtherDerived> &other) {
  // TODO: use the evaluator mechanism
  other.evalTo(derived());
  return derived();
}

template <typename Derived>
template <typename OtherDerived>
inline Derived &SparseMatrixBase<Derived>::operator=(const SparseMatrixBase<OtherDerived> &other) {
  // by default sparse evaluation do not alias, so we can safely bypass the generic call_assignment routine
  internal::Assignment<Derived, OtherDerived, internal::assign_op<Scalar, typename OtherDerived::Scalar>>::run(
      derived(), other.derived(), internal::assign_op<Scalar, typename OtherDerived::Scalar>());
  return derived();
}

template <typename Derived>
inline Derived &SparseMatrixBase<Derived>::operator=(const Derived &other) {
  internal::call_assignment_no_alias(derived(), other.derived());
  return derived();
}

namespace internal {

template <>
struct storage_kind_to_evaluator_kind<Sparse> {
  typedef IteratorBased Kind;
};

template <>
struct storage_kind_to_shape<Sparse> {
  typedef SparseShape Shape;
};

struct Sparse2Sparse {};
struct Sparse2Dense {};

template <>
struct AssignmentKind<SparseShape, SparseShape> {
  typedef Sparse2Sparse Kind;
};
template <>
struct AssignmentKind<SparseShape, SparseTriangularShape> {
  typedef Sparse2Sparse Kind;
};
template <>
struct AssignmentKind<DenseShape, SparseShape> {
  typedef Sparse2Dense Kind;
};
template <>
struct AssignmentKind<DenseShape, SparseTriangularShape> {
  typedef Sparse2Dense Kind;
};

template <typename DstXprType, typename SrcXprType>
void assign_sparse_to_sparse(DstXprType &dst, const SrcXprType &src) {
  typedef typename DstXprType::Scalar Scalar;
  typedef internal::evaluator<DstXprType> DstEvaluatorType;
  typedef internal::evaluator<SrcXprType> SrcEvaluatorType;

  SrcEvaluatorType srcEvaluator(src);

  constexpr bool transpose = (DstEvaluatorType::Flags & RowMajorBit) != (SrcEvaluatorType::Flags & RowMajorBit);
  const Index outerEvaluationSize = (SrcEvaluatorType::Flags & RowMajorBit) ? src.rows() : src.cols();

  Index reserveSize = 0;
  for (Index j = 0; j < outerEvaluationSize; ++j)
    for (typename SrcEvaluatorType::InnerIterator it(srcEvaluator, j); it; ++it) reserveSize++;

  if ((!transpose) && src.isRValue()) {
    // eval without temporary
    dst.resize(src.rows(), src.cols());
    dst.setZero();
    dst.reserve(reserveSize);
    for (Index j = 0; j < outerEvaluationSize; ++j) {
      dst.startVec(j);
      for (typename SrcEvaluatorType::InnerIterator it(srcEvaluator, j); it; ++it) {
        Scalar v = it.value();
        dst.insertBackByOuterInner(j, it.index()) = v;
      }
    }
    dst.finalize();
  } else {
    // eval through a temporary
    eigen_assert((((internal::traits<DstXprType>::SupportedAccessPatterns & OuterRandomAccessPattern) ==
                   OuterRandomAccessPattern) ||
                  (!((DstEvaluatorType::Flags & RowMajorBit) != (SrcEvaluatorType::Flags & RowMajorBit)))) &&
                 "the transpose operation is supposed to be handled in SparseMatrix::operator=");

    enum { Flip = (DstEvaluatorType::Flags & RowMajorBit) != (SrcEvaluatorType::Flags & RowMajorBit) };

    DstXprType temp(src.rows(), src.cols());

    temp.reserve(reserveSize);
    for (Index j = 0; j < outerEvaluationSize; ++j) {
      temp.startVec(j);
      for (typename SrcEvaluatorType::InnerIterator it(srcEvaluator, j); it; ++it) {
        Scalar v = it.value();
        temp.insertBackByOuterInner(Flip ? it.index() : j, Flip ? j : it.index()) = v;
      }
    }
    temp.finalize();

    dst = temp.markAsRValue();
  }
}

// Generic Sparse to Sparse assignment
template <typename DstXprType, typename SrcXprType, typename Functor>
struct Assignment<DstXprType, SrcXprType, Functor, Sparse2Sparse> {
  static void run(DstXprType &dst, const SrcXprType &src,
                  const internal::assign_op<typename DstXprType::Scalar, typename SrcXprType::Scalar> & /*func*/) {
    assign_sparse_to_sparse(dst.derived(), src.derived());
  }
};

// Generic Sparse to Dense assignment
template <typename DstXprType, typename SrcXprType, typename Functor, typename Weak>
struct Assignment<DstXprType, SrcXprType, Functor, Sparse2Dense, Weak> {
  static void run(DstXprType &dst, const SrcXprType &src, const Functor &func) {
    if (std::is_same<Functor, internal::assign_op<typename DstXprType::Scalar, typename SrcXprType::Scalar>>::value)
      dst.setZero();

    internal::evaluator<SrcXprType> srcEval(src);
    resize_if_allowed(dst, src, func);
    internal::evaluator<DstXprType> dstEval(dst);

    const Index outerEvaluationSize = (internal::evaluator<SrcXprType>::Flags & RowMajorBit) ? src.rows() : src.cols();
    for (Index j = 0; j < outerEvaluationSize; ++j)
      for (typename internal::evaluator<SrcXprType>::InnerIterator i(srcEval, j); i; ++i)
        func.assignCoeff(dstEval.coeffRef(i.row(), i.col()), i.value());
  }
};

// Specialization for dense ?= dense +/- sparse and dense ?= sparse +/- dense
template <typename DstXprType, typename Func1, typename Func2>
struct assignment_from_dense_op_sparse {
  template <typename SrcXprType, typename InitialFunc>
  static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void run(DstXprType &dst, const SrcXprType &src,
                                                        const InitialFunc & /*func*/) {
#ifdef EIGEN_SPARSE_ASSIGNMENT_FROM_DENSE_OP_SPARSE_PLUGIN
    EIGEN_SPARSE_ASSIGNMENT_FROM_DENSE_OP_SPARSE_PLUGIN
#endif

    call_assignment_no_alias(dst, src.lhs(), Func1());
    call_assignment_no_alias(dst, src.rhs(), Func2());
  }

  // Specialization for dense1 = sparse + dense2; -> dense1 = dense2; dense1 += sparse;
  template <typename Lhs, typename Rhs, typename Scalar>
  static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
      std::enable_if_t<std::is_same<typename internal::evaluator_traits<Rhs>::Shape, DenseShape>::value>
      run(DstXprType &dst, const CwiseBinaryOp<internal::scalar_sum_op<Scalar, Scalar>, const Lhs, const Rhs> &src,
          const internal::assign_op<typename DstXprType::Scalar, Scalar> & /*func*/) {
#ifdef EIGEN_SPARSE_ASSIGNMENT_FROM_SPARSE_ADD_DENSE_PLUGIN
    EIGEN_SPARSE_ASSIGNMENT_FROM_SPARSE_ADD_DENSE_PLUGIN
#endif

    // Apply the dense matrix first, then the sparse one.
    call_assignment_no_alias(dst, src.rhs(), Func1());
    call_assignment_no_alias(dst, src.lhs(), Func2());
  }

  // Specialization for dense1 = sparse - dense2; -> dense1 = -dense2; dense1 += sparse;
  template <typename Lhs, typename Rhs, typename Scalar>
  static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE
      std::enable_if_t<std::is_same<typename internal::evaluator_traits<Rhs>::Shape, DenseShape>::value>
      run(DstXprType &dst,
          const CwiseBinaryOp<internal::scalar_difference_op<Scalar, Scalar>, const Lhs, const Rhs> &src,
          const internal::assign_op<typename DstXprType::Scalar, Scalar> & /*func*/) {
#ifdef EIGEN_SPARSE_ASSIGNMENT_FROM_SPARSE_SUB_DENSE_PLUGIN
    EIGEN_SPARSE_ASSIGNMENT_FROM_SPARSE_SUB_DENSE_PLUGIN
#endif

    // Apply the dense matrix first, then the sparse one.
    call_assignment_no_alias(dst, -src.rhs(), Func1());
    call_assignment_no_alias(dst, src.lhs(), add_assign_op<typename DstXprType::Scalar, typename Lhs::Scalar>());
  }
};

#define EIGEN_CATCH_ASSIGN_DENSE_OP_SPARSE(ASSIGN_OP, BINOP, ASSIGN_OP2)                                        \
  template <typename DstXprType, typename Lhs, typename Rhs, typename Scalar>                                   \
  struct Assignment<                                                                                            \
      DstXprType, CwiseBinaryOp<internal::BINOP<Scalar, Scalar>, const Lhs, const Rhs>,                         \
      internal::ASSIGN_OP<typename DstXprType::Scalar, Scalar>, Sparse2Dense,                                   \
      std::enable_if_t<std::is_same<typename internal::evaluator_traits<Lhs>::Shape, DenseShape>::value ||      \
                       std::is_same<typename internal::evaluator_traits<Rhs>::Shape, DenseShape>::value>>       \
      : assignment_from_dense_op_sparse<DstXprType,                                                             \
                                        internal::ASSIGN_OP<typename DstXprType::Scalar, typename Lhs::Scalar>, \
                                        internal::ASSIGN_OP2<typename DstXprType::Scalar, typename Rhs::Scalar>> {}

EIGEN_CATCH_ASSIGN_DENSE_OP_SPARSE(assign_op, scalar_sum_op, add_assign_op);
EIGEN_CATCH_ASSIGN_DENSE_OP_SPARSE(add_assign_op, scalar_sum_op, add_assign_op);
EIGEN_CATCH_ASSIGN_DENSE_OP_SPARSE(sub_assign_op, scalar_sum_op, sub_assign_op);

EIGEN_CATCH_ASSIGN_DENSE_OP_SPARSE(assign_op, scalar_difference_op, sub_assign_op);
EIGEN_CATCH_ASSIGN_DENSE_OP_SPARSE(add_assign_op, scalar_difference_op, sub_assign_op);
EIGEN_CATCH_ASSIGN_DENSE_OP_SPARSE(sub_assign_op, scalar_difference_op, add_assign_op);

// Specialization for "dst = dec.solve(rhs)"
// NOTE we need to specialize it for Sparse2Sparse to avoid ambiguous specialization error
template <typename DstXprType, typename DecType, typename RhsType, typename Scalar>
struct Assignment<DstXprType, Solve<DecType, RhsType>, internal::assign_op<Scalar, Scalar>, Sparse2Sparse> {
  typedef Solve<DecType, RhsType> SrcXprType;
  static void run(DstXprType &dst, const SrcXprType &src, const internal::assign_op<Scalar, Scalar> &) {
    Index dstRows = src.rows();
    Index dstCols = src.cols();
    if ((dst.rows() != dstRows) || (dst.cols() != dstCols)) dst.resize(dstRows, dstCols);

    src.dec()._solve_impl(src.rhs(), dst);
  }
};

struct Diagonal2Sparse {};

template <>
struct AssignmentKind<SparseShape, DiagonalShape> {
  typedef Diagonal2Sparse Kind;
};

template <typename DstXprType, typename SrcXprType, typename Functor>
struct Assignment<DstXprType, SrcXprType, Functor, Diagonal2Sparse> {
  typedef typename DstXprType::StorageIndex StorageIndex;
  typedef typename DstXprType::Scalar Scalar;

  template <int Options, typename AssignFunc>
  static void run(SparseMatrix<Scalar, Options, StorageIndex> &dst, const SrcXprType &src, const AssignFunc &func) {
    dst.assignDiagonal(src.diagonal(), func);
  }

  template <typename DstDerived>
  static void run(SparseMatrixBase<DstDerived> &dst, const SrcXprType &src,
                  const internal::assign_op<typename DstXprType::Scalar, typename SrcXprType::Scalar> & /*func*/) {
    dst.derived().diagonal() = src.diagonal();
  }

  template <typename DstDerived>
  static void run(SparseMatrixBase<DstDerived> &dst, const SrcXprType &src,
                  const internal::add_assign_op<typename DstXprType::Scalar, typename SrcXprType::Scalar> & /*func*/) {
    dst.derived().diagonal() += src.diagonal();
  }

  template <typename DstDerived>
  static void run(SparseMatrixBase<DstDerived> &dst, const SrcXprType &src,
                  const internal::sub_assign_op<typename DstXprType::Scalar, typename SrcXprType::Scalar> & /*func*/) {
    dst.derived().diagonal() -= src.diagonal();
  }
};
}  // end namespace internal

}  // end namespace Eigen

#endif  // EIGEN_SPARSEASSIGN_H