// 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 glue_times
//! @{

//! \brief
//! Template metaprogram depth_lhs
//! calculates the number of Glue<Tx,Ty, glue_type> instances on the left hand side
//! argument of Glue<Tx,Ty, glue_type> ie. it recursively expands each Tx, until the type
//! of Tx is not "Glue<..,.., glue_type>"  (i.e the "glue_type" changes)

template <typename glue_type, typename T1>
struct depth_lhs {
  static constexpr uword num = 0;
};

template <typename glue_type, typename T1, typename T2>
struct depth_lhs<glue_type, Glue<T1, T2, glue_type> > {
  static constexpr uword num = 1 + depth_lhs<glue_type, T1>::num;
};

template <bool do_inv_detect>
struct glue_times_redirect2_helper {
  template <typename T1, typename T2>
  arma_hot inline static void apply(Mat<typename T1::elem_type>& out,
                                    const Glue<T1, T2, glue_times>& X);
};

template <>
struct glue_times_redirect2_helper<true> {
  template <typename T1, typename T2>
  arma_hot inline static void apply(Mat<typename T1::elem_type>& out,
                                    const Glue<T1, T2, glue_times>& X);
};

template <bool do_inv_detect>
struct glue_times_redirect3_helper {
  template <typename T1, typename T2, typename T3>
  arma_hot inline static void apply(
      Mat<typename T1::elem_type>& out,
      const Glue<Glue<T1, T2, glue_times>, T3, glue_times>& X);
};

template <>
struct glue_times_redirect3_helper<true> {
  template <typename T1, typename T2, typename T3>
  arma_hot inline static void apply(
      Mat<typename T1::elem_type>& out,
      const Glue<Glue<T1, T2, glue_times>, T3, glue_times>& X);
};

template <uword N>
struct glue_times_redirect {
  template <typename T1, typename T2>
  arma_hot inline static void apply(Mat<typename T1::elem_type>& out,
                                    const Glue<T1, T2, glue_times>& X);
};

template <>
struct glue_times_redirect<2> {
  template <typename T1, typename T2>
  arma_hot inline static void apply(Mat<typename T1::elem_type>& out,
                                    const Glue<T1, T2, glue_times>& X);
};

template <>
struct glue_times_redirect<3> {
  template <typename T1, typename T2, typename T3>
  arma_hot inline static void apply(
      Mat<typename T1::elem_type>& out,
      const Glue<Glue<T1, T2, glue_times>, T3, glue_times>& X);
};

template <>
struct glue_times_redirect<4> {
  template <typename T1, typename T2, typename T3, typename T4>
  arma_hot inline static void apply(
      Mat<typename T1::elem_type>& out,
      const Glue<Glue<Glue<T1, T2, glue_times>, T3, glue_times>, T4, glue_times>& X);
};

//! Class which implements the immediate multiplication of two or more matrices
class glue_times {
 public:
  template <typename T1, typename T2>
  struct traits {
    static constexpr bool is_row = T1::is_row;
    static constexpr bool is_col = T2::is_col;
    static constexpr bool is_xvec = false;
  };

  template <typename T1, typename T2>
  arma_hot inline static void apply(Mat<typename T1::elem_type>& out,
                                    const Glue<T1, T2, glue_times>& X);

  template <typename T1>
  arma_hot inline static void apply_inplace(Mat<typename T1::elem_type>& out,
                                            const T1& X);

  template <typename T1, typename T2>
  arma_hot inline static void apply_inplace_plus(Mat<typename T1::elem_type>& out,
                                                 const Glue<T1, T2, glue_times>& X,
                                                 const sword sign);

  //

  template <typename eT, const bool do_trans_A, const bool do_trans_B, typename TA,
            typename TB>
  arma_inline static uword mul_storage_cost(const TA& A, const TB& B);

  template <typename eT, const bool do_trans_A, const bool do_trans_B,
            const bool do_scalar_times, typename TA, typename TB>
  arma_hot inline static void apply(Mat<eT>& out, const TA& A, const TB& B, const eT val);

  template <typename eT, const bool do_trans_A, const bool do_trans_B,
            const bool do_trans_C, const bool do_scalar_times, typename TA, typename TB,
            typename TC>
  arma_hot inline static void apply(Mat<eT>& out, const TA& A, const TB& B, const TC& C,
                                    const eT val);

  template <typename eT, const bool do_trans_A, const bool do_trans_B,
            const bool do_trans_C, const bool do_trans_D, const bool do_scalar_times,
            typename TA, typename TB, typename TC, typename TD>
  arma_hot inline static void apply(Mat<eT>& out, const TA& A, const TB& B, const TC& C,
                                    const TD& D, const eT val);
};

class glue_times_diag {
 public:
  template <typename T1, typename T2>
  struct traits {
    static constexpr bool is_row = T1::is_row;
    static constexpr bool is_col = T2::is_col;
    static constexpr bool is_xvec = false;
  };

  template <typename T1, typename T2>
  arma_hot inline static void apply(Mat<typename T1::elem_type>& out,
                                    const Glue<T1, T2, glue_times_diag>& X);
};

//! @}
