// 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 gmm_diag
//! @{


namespace gmm_priv
{

template<typename eT>
class gmm_diag
  {
  public:
  
  const Mat<eT> means;
  const Mat<eT> dcovs;
  const Row<eT> hefts;
  
  //
  //
  
  inline ~gmm_diag();
  inline  gmm_diag();
  
  inline            gmm_diag(const gmm_diag& x);
  inline gmm_diag& operator=(const gmm_diag& x);
  
  inline explicit            gmm_diag(const gmm_full<eT>& x);
  inline          gmm_diag& operator=(const gmm_full<eT>& x);
  
  inline      gmm_diag(const uword in_n_dims, const uword in_n_gaus);
  inline void    reset(const uword in_n_dims, const uword in_n_gaus);
  inline void    reset();
  
  template<typename T1, typename T2, typename T3>
  inline void set_params(const Base<eT,T1>& in_means, const Base<eT,T2>& in_dcovs, const Base<eT,T3>& in_hefts);
  
  template<typename T1> inline void set_means(const Base<eT,T1>& in_means);
  template<typename T1> inline void set_dcovs(const Base<eT,T1>& in_dcovs);
  template<typename T1> inline void set_hefts(const Base<eT,T1>& in_hefts);
  
  inline uword n_dims() const;
  inline uword n_gaus() const;
  
  inline bool load(const std::string name);
  inline bool save(const std::string name) const;
  
  inline Col<eT> generate()              const;
  inline Mat<eT> generate(const uword N) const;
  
  template<typename T1> inline eT      log_p(const T1& expr, const gmm_empty_arg& junk1 = gmm_empty_arg(), typename enable_if<((is_arma_type<T1>::value) && (resolves_to_colvector<T1>::value == true ))>::result* junk2 = nullptr) const;
  template<typename T1> inline eT      log_p(const T1& expr, const uword gaus_id,                          typename enable_if<((is_arma_type<T1>::value) && (resolves_to_colvector<T1>::value == true ))>::result* junk2 = nullptr) const;
  
  template<typename T1> inline Row<eT> log_p(const T1& expr, const gmm_empty_arg& junk1 = gmm_empty_arg(), typename enable_if<((is_arma_type<T1>::value) && (resolves_to_colvector<T1>::value == false))>::result* junk2 = nullptr) const;
  template<typename T1> inline Row<eT> log_p(const T1& expr, const uword gaus_id,                          typename enable_if<((is_arma_type<T1>::value) && (resolves_to_colvector<T1>::value == false))>::result* junk2 = nullptr) const;
  
  template<typename T1> inline eT  sum_log_p(const Base<eT,T1>& expr)                      const;
  template<typename T1> inline eT  sum_log_p(const Base<eT,T1>& expr, const uword gaus_id) const;
  
  template<typename T1> inline eT  avg_log_p(const Base<eT,T1>& expr)                      const;
  template<typename T1> inline eT  avg_log_p(const Base<eT,T1>& expr, const uword gaus_id) const;
  
  template<typename T1> inline uword   assign(const T1& expr, const gmm_dist_mode& dist, typename enable_if<((is_arma_type<T1>::value) && (resolves_to_colvector<T1>::value == true ))>::result* junk = nullptr) const;
  template<typename T1> inline urowvec assign(const T1& expr, const gmm_dist_mode& dist, typename enable_if<((is_arma_type<T1>::value) && (resolves_to_colvector<T1>::value == false))>::result* junk = nullptr) const;
  
  template<typename T1> inline urowvec  raw_hist(const Base<eT,T1>& expr, const gmm_dist_mode& dist_mode) const;
  template<typename T1> inline Row<eT> norm_hist(const Base<eT,T1>& expr, const gmm_dist_mode& dist_mode) const;
  
  template<typename T1>
  inline
  bool
  learn
    (
    const Base<eT,T1>&    data,
    const uword           n_gaus,
    const gmm_dist_mode&  dist_mode,
    const gmm_seed_mode&  seed_mode,
    const uword           km_iter,
    const uword           em_iter,
    const eT              var_floor,
    const bool            print_mode
    );
  
  
  template<typename T1>
  inline
  bool
  kmeans_wrapper
    (
           Mat<eT>&       user_means,
    const Base<eT,T1>&    data,
    const uword           n_gaus,
    const gmm_seed_mode&  seed_mode,
    const uword           km_iter,
    const bool            print_mode
    );
  
  
  //
  
  protected:
  
  Mat<eT> inv_dcovs;
  Row<eT> log_det_etc;
  Row<eT> log_hefts;
  Col<eT> mah_aux;
  
  //
  
  inline void init(const gmm_diag&     x);
  inline void init(const gmm_full<eT>& x);
  
  inline void init(const uword in_n_dim, const uword in_n_gaus);
  
  inline void init_constants();
  
  inline umat internal_gen_boundaries(const uword N) const;
  
  inline eT internal_scalar_log_p(const eT* x                     ) const;
  inline eT internal_scalar_log_p(const eT* x, const uword gaus_id) const;
  
  inline Row<eT> internal_vec_log_p(const Mat<eT>& X                     ) const;
  inline Row<eT> internal_vec_log_p(const Mat<eT>& X, const uword gaus_id) const;
  
  inline eT internal_sum_log_p(const Mat<eT>& X                     ) const;
  inline eT internal_sum_log_p(const Mat<eT>& X, const uword gaus_id) const;
  
  inline eT internal_avg_log_p(const Mat<eT>& X                     ) const;
  inline eT internal_avg_log_p(const Mat<eT>& X, const uword gaus_id) const;
  
  inline uword internal_scalar_assign(const Mat<eT>& X, const gmm_dist_mode& dist_mode) const;
  
  inline void internal_vec_assign(urowvec& out, const Mat<eT>& X, const gmm_dist_mode& dist_mode) const;
  
  inline void internal_raw_hist(urowvec& hist, const Mat<eT>& X, const gmm_dist_mode& dist_mode) const;
  
  //
  
  template<uword dist_id> inline void generate_initial_means(const Mat<eT>& X, const gmm_seed_mode& seed);
  
  template<uword dist_id> inline void generate_initial_params(const Mat<eT>& X, const eT var_floor);
  
  template<uword dist_id> inline bool km_iterate(const Mat<eT>& X, const uword max_iter, const bool verbose, const char* signature);
  
  //
  
  inline bool em_iterate(const Mat<eT>& X, const uword max_iter, const eT var_floor, const bool verbose);
  
  inline void em_update_params(const Mat<eT>& X, const umat& boundaries, field< Mat<eT> >& t_acc_means, field< Mat<eT> >& t_acc_dcovs, field< Col<eT> >& t_acc_norm_lhoods, field< Col<eT> >& t_gaus_log_lhoods, Col<eT>& t_progress_log_lhoods);
  
  inline void em_generate_acc(const Mat<eT>& X, const uword start_index, const uword end_index, Mat<eT>& acc_means, Mat<eT>& acc_dcovs, Col<eT>& acc_norm_lhoods, Col<eT>& gaus_log_lhoods, eT& progress_log_lhood) const;
  
  inline void em_fix_params(const eT var_floor);
  };

}


typedef gmm_priv::gmm_diag<double>  gmm_diag;
typedef gmm_priv::gmm_diag<float>  fgmm_diag;


//! @}