// SPDX-License-Identifier: Apache-2.0
//
// 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 fn_dot
//! @{

template <typename T1, typename T2>
arma_warn_unused arma_inline typename enable_if2<
    is_arma_type<T1>::value && is_arma_type<T2>::value &&
        is_same_type<typename T1::elem_type, typename T2::elem_type>::yes,
    typename T1::elem_type>::result
dot(const T1& A, const T2& B) {
  arma_extra_debug_sigprint();

  return op_dot::apply(A, B);
}

template <typename T1, typename T2>
arma_warn_unused inline typename enable_if2<
    is_arma_type<T1>::value && is_arma_type<T2>::value &&
        is_same_type<typename T1::elem_type, typename T2::elem_type>::no,
    typename promote_type<typename T1::elem_type, typename T2::elem_type>::result>::result
dot(const T1& A, const T2& B) {
  arma_extra_debug_sigprint();

  return op_dot_mixed::apply(A, B);
}

template <typename T1, typename T2>
arma_warn_unused inline typename enable_if2<
    is_arma_type<T1>::value && is_arma_type<T2>::value &&
        is_same_type<typename T1::elem_type, typename T2::elem_type>::value,
    typename T1::elem_type>::result
norm_dot(const T1& A, const T2& B) {
  arma_extra_debug_sigprint();

  return op_norm_dot::apply(A, B);
}

//
// cdot

template <typename T1, typename T2>
arma_warn_unused arma_inline typename enable_if2<
    is_arma_type<T1>::value && is_arma_type<T2>::value &&
        is_same_type<typename T1::elem_type, typename T2::elem_type>::value &&
        is_cx<typename T1::elem_type>::no,
    typename T1::elem_type>::result
cdot(const T1& A, const T2& B) {
  arma_extra_debug_sigprint();

  return op_dot::apply(A, B);
}

template <typename T1, typename T2>
arma_warn_unused arma_inline typename enable_if2<
    is_arma_type<T1>::value && is_arma_type<T2>::value &&
        is_same_type<typename T1::elem_type, typename T2::elem_type>::value &&
        is_cx<typename T1::elem_type>::yes,
    typename T1::elem_type>::result
cdot(const T1& A, const T2& B) {
  arma_extra_debug_sigprint();

  return op_cdot::apply(A, B);
}

// convert dot(htrans(x), y) to cdot(x,y)

template <typename T1, typename T2>
arma_warn_unused arma_inline typename enable_if2<
    is_arma_type<T2>::value &&
        is_same_type<typename T1::elem_type, typename T2::elem_type>::value &&
        is_cx<typename T1::elem_type>::yes,
    typename T1::elem_type>::result
dot(const Op<T1, op_htrans>& A, const T2& B) {
  arma_extra_debug_sigprint();

  return cdot(A.m, B);
}

//
// for sparse matrices
//

namespace priv {

template <typename T1, typename T2>
arma_hot inline typename T1::elem_type dot_helper(const SpProxy<T1>& pa,
                                                  const SpProxy<T2>& pb) {
  typedef typename T1::elem_type eT;

  // Iterate over both objects and see when they are the same
  eT result = eT(0);

  typename SpProxy<T1>::const_iterator_type a_it = pa.begin();
  typename SpProxy<T1>::const_iterator_type a_end = pa.end();

  typename SpProxy<T2>::const_iterator_type b_it = pb.begin();
  typename SpProxy<T2>::const_iterator_type b_end = pb.end();

  while ((a_it != a_end) && (b_it != b_end)) {
    if (a_it == b_it) {
      result += (*a_it) * (*b_it);

      ++a_it;
      ++b_it;
    } else if ((a_it.col() < b_it.col()) ||
               ((a_it.col() == b_it.col()) && (a_it.row() < b_it.row()))) {
      // a_it is "behind"
      ++a_it;
    } else {
      // b_it is "behind"
      ++b_it;
    }
  }

  return result;
}

}  // namespace priv

//! dot product of two sparse objects
template <typename T1, typename T2>
arma_warn_unused arma_hot inline typename enable_if2<
    (is_arma_sparse_type<T1>::value) && (is_arma_sparse_type<T2>::value) &&
        (is_same_type<typename T1::elem_type, typename T2::elem_type>::value),
    typename T1::elem_type>::result
dot(const T1& x, const T2& y) {
  arma_extra_debug_sigprint();

  const SpProxy<T1> pa(x);
  const SpProxy<T2> pb(y);

  arma_debug_assert_same_size(pa.get_n_rows(), pa.get_n_cols(), pb.get_n_rows(),
                              pb.get_n_cols(), "dot()");

  typedef typename T1::elem_type eT;

  typedef typename SpProxy<T1>::stored_type pa_Q_type;
  typedef typename SpProxy<T2>::stored_type pb_Q_type;

  if (((SpProxy<T1>::use_iterator == false) && (SpProxy<T2>::use_iterator == false)) &&
      ((is_SpMat<pa_Q_type>::value == true) && (is_SpMat<pb_Q_type>::value == true))) {
    const unwrap_spmat<pa_Q_type> tmp_a(pa.Q);
    const unwrap_spmat<pb_Q_type> tmp_b(pb.Q);

    const SpMat<eT>& A = tmp_a.M;
    const SpMat<eT>& B = tmp_b.M;

    if (&A == &B) {
      // We can do it directly!
      return op_dot::direct_dot_arma(A.n_nonzero, A.values, A.values);
    } else {
      return priv::dot_helper(pa, pb);
    }
  } else {
    return priv::dot_helper(pa, pb);
  }
}

//! dot product of one dense and one sparse object
template <typename T1, typename T2>
arma_warn_unused arma_hot inline typename enable_if2<
    (is_arma_type<T1>::value) && (is_arma_sparse_type<T2>::value) &&
        (is_same_type<typename T1::elem_type, typename T2::elem_type>::value),
    typename T1::elem_type>::result
dot(const T1& x, const T2& y) {
  arma_extra_debug_sigprint();

  const Proxy<T1> pa(x);
  const SpProxy<T2> pb(y);

  arma_debug_assert_same_size(pa.get_n_rows(), pa.get_n_cols(), pb.get_n_rows(),
                              pb.get_n_cols(), "dot()");

  typedef typename T1::elem_type eT;

  eT result = eT(0);

  typename SpProxy<T2>::const_iterator_type it = pb.begin();
  typename SpProxy<T2>::const_iterator_type it_end = pb.end();

  // use_at == false won't save us operations
  while (it != it_end) {
    result += (*it) * pa.at(it.row(), it.col());
    ++it;
  }

  return result;
}

//! dot product of one sparse and one dense object
template <typename T1, typename T2>
arma_warn_unused arma_hot inline typename enable_if2<
    (is_arma_sparse_type<T1>::value) && (is_arma_type<T2>::value) &&
        (is_same_type<typename T1::elem_type, typename T2::elem_type>::value),
    typename T1::elem_type>::result
dot(const T1& x, const T2& y) {
  arma_extra_debug_sigprint();

  // this is commutative
  return dot(y, x);
}

//! @}
