/*******************************************************************************
 *
 * TRIQS: a Toolbox for Research in Interacting Quantum Systems
 *
 * Copyright (C) 2012 by M. Ferrero, O. Parcollet
 *
 * TRIQS is free software: 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 3 of the License, or (at your option) any later
 * version.
 *
 * TRIQS 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License along with
 * TRIQS. If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/
#ifndef TRIQS_GF_BLOCK_H
#define TRIQS_GF_BLOCK_H
#include "./tools.hpp"
#include "./gf.hpp"
#include "./local/tail.hpp"
#include "./meshes/discrete.hpp"

namespace triqs { namespace gfs {

 struct block_index {};

 template<typename Opt> struct gf_mesh<block_index,Opt> : discrete_mesh<discrete_domain> {
  typedef discrete_mesh<discrete_domain> B;
  gf_mesh() = default;
  gf_mesh(int s) : B(s) {}
  gf_mesh(discrete_domain const & d) : B(d) {}
  gf_mesh(std::initializer_list<std::string> const & s) : B(s){}
 };

 namespace gfs_implementation {

  /// ---------------------------  hdf5 ---------------------------------

  template<typename Target, typename Opt> struct h5_name<block_index,Target,Opt>      { static std::string invoke(){ return  "BlockGf";}};

  template <typename Target, typename Opt> struct h5_rw<block_index,Target,Opt>  {

   static void write (h5::group gr, gf_const_view<block_index,Target,Opt> g) {
    for (size_t i =0; i<g.mesh().size(); ++i) h5_write(gr,g.mesh().domain().names()[i],g._data[i]);
    //h5_write(gr,"symmetry",g._symmetry);
   }

   template<bool IsView>
   static void read (h5::group gr, gf_impl<block_index,Target,Opt,IsView,false> &g) {
    // does not work : need to read the block name and remake the mesh...
    g._mesh = gf_mesh<block_index,Opt> (gr.get_all_subgroup_names());
    g._data.resize(g._mesh.size());
    //if (g._data.size() != g._mesh.size()) TRIQS_RUNTIME_ERROR << "h5 read block gf : number of block mismatch";
    for (size_t i =0; i<g.mesh().size(); ++i) h5_read(gr,g.mesh().domain().names()[i],g._data[i]);
    //h5_read(gr,"symmetry",g._symmetry);
   }
  
 };

  /// ---------------------------  data access  ---------------------------------

  template<typename Target, typename Opt> struct data_proxy<block_index,Target,Opt> : data_proxy_vector <typename regular_type_if_exists_else_type<Target>::type>{};

  // -------------------------------   Factories  --------------------------------------------------

  template<typename Target, typename Opt>
   struct factories<block_index,Target,Opt>  { 
    typedef gf_mesh<block_index, Opt> mesh_t;
    typedef gf<block_index,Target> gf_t;
    typedef gf_view<block_index,Target> gf_view_t;
    struct target_shape_t{};

    static typename gf_t::data_t make_data(mesh_t const & m, target_shape_t) { return std::vector<Target> (m.size()); }
    static typename gf_t::singularity_t make_singularity (mesh_t const & m, target_shape_t) { return {};}
   };

 } // gfs_implementation

 // -------------------------------  aliases  --------------------------------------------------
 
 template<typename ... T> using block_gf = gf<block_index, gf<T...>>;
 template<typename ... T> using block_gf_view = gf_view<block_index, gf<T...>>;
 template<typename ... T> using block_gf_const_view = gf_const_view<block_index, gf<T...>>;

 // -------------------------------   Free Factories for regular type  --------------------------------------------------

 // from a number and a gf to be copied
 template <typename Variable, typename Target, typename Opt>
 block_gf<Variable, Target, Opt> make_block_gf(int n, gf<Variable, Target, Opt> const & g) {
  auto V = std::vector<gf<Variable, Target, Opt>>{};
  for (int i = 0; i < n; ++i) V.push_back(g);
  return {{n}, std::move(V), nothing{}, nothing{}};
 }

 // from a vector of gf (moving directly)
 template <typename Variable, typename Target, typename Opt, typename GF2>
 block_gf<Variable, Target, Opt> make_block_gf(std::vector<gf<Variable, Target, Opt>> &&V) {
  return {{int(V.size())}, std::move(V), nothing{}, nothing{}};
 }

 // from a vector of gf : generalized to have a different type of gf in the vector (e.g. views...)
 template <typename Variable, typename Target, typename Opt, typename GF2>
 block_gf<Variable, Target, Opt> make_block_gf(std::vector<GF2> const &V) {
  auto V2 = std::vector<gf<Variable, Target, Opt>>{};
  for (auto const &g : V) V2.push_back(g);
  return {{int(V.size())}, std::move(V2), nothing{}, nothing{}};
 }

 // from a init list of GF with the correct type
 template <typename Variable, typename Target, typename Opt>
 block_gf<Variable, Target, Opt> make_block_gf(std::initializer_list<gf<Variable, Target, Opt>> const &V) {
  return {{int(V.size())}, V, nothing{}, nothing{}};
 }

 // from vector<string> and a gf to be copied
 template <typename Variable, typename Target, typename Opt>
 block_gf<Variable, Target, Opt> make_block_gf(std::vector<std::string> const &block_names, gf<Variable, Target, Opt> const &g) {
  auto V = std::vector<gf<Variable, Target, Opt>>{};
  for (int i = 0; i < block_names.size(); ++i) V.push_back(g);
  return {{block_names}, std::move(V), nothing{}, nothing{}};
 }
 
 // from vector<string>, vector<gf>
 template <typename Variable, typename Target, typename Opt>
 block_gf<Variable, Target, Opt> make_block_gf(std::vector<std::string> const &block_names,
                                               std::vector<gf<Variable, Target, Opt>> V) {
  if (block_names.size() != V.size())
   TRIQS_RUNTIME_ERROR << "make_block_gf(vector<string>, vector<gf>) : the two vectors do not have the same size !";
  return {{block_names}, std::move(V), nothing{}, nothing{}};
 }

 // from vector<string>, init_list<GF>
 template <typename Variable, typename Target, typename Opt>
 block_gf<Variable, Target, Opt> make_block_gf(std::vector<std::string> const &block_names,
                                               std::initializer_list<gf<Variable, Target, Opt>> const &V) {
  if (block_names.size() != V.size()) TRIQS_RUNTIME_ERROR << "make_block_gf(vector<string>, init_list) : size mismatch !";
  return {{block_names}, V, nothing{}, nothing{}};
 }

 // -------------------------------   Free Factories for view type  --------------------------------------------------

 template<typename G0, typename ... G> 
  gf_view<block_index, typename std::remove_reference<G0>::type::view_type> make_block_gf_view(G0 && g0, G && ... g) { 
   auto V = std::vector<typename std::remove_reference<G0>::type::view_type>{std::forward<G0>(g0), std::forward<G>(g)...};
   return { {int(V.size())}, std::move(V), nothing{}, nothing{} } ;
   //return { gf_mesh<block_index, Opt> {int(V.size())}, std::move(V), nothing{}, nothing{} } ;
  }

 template<typename GF, typename GF2>
  gf_view<block_index,GF> 
  make_block_gf_view_from_vector (std::vector<GF2> V) { return { {int(V.size())}, std::move(V), nothing{}, nothing{}} ; }

 // -------------------------------   Free functions   --------------------------------------------------

 // a simple function to get the number of blocks
 template<typename T> size_t n_blocks (gf<block_index,T> const & g)      { return g.mesh().size();}
 template<typename T> size_t n_blocks (gf_view<block_index,T> const & g) { return g.mesh().size();}

 // an iterator over the block
 template<typename Target, typename Opt>
  class block_gf_iterator : 
   public boost::iterator_facade< block_gf_iterator<Target,Opt>, typename Target::view_type , boost::forward_traversal_tag, typename Target::view_type  > {
    friend class boost::iterator_core_access;
    typedef gf_view<block_index,Target,Opt> big_gf_t;
    typedef typename big_gf_t::mesh_t::const_iterator mesh_iterator_t;
    big_gf_t big_gf;
    mesh_iterator_t mesh_it;

    typename Target::view_type const & dereference() const { return big_gf[*mesh_it];}
    bool equal(block_gf_iterator const & other) const { return ((mesh_it == other.mesh_it));}
    public:
    block_gf_iterator(gf_view<block_index,Target,Opt> bgf, bool at_end = false): big_gf(std::move(bgf)), mesh_it(&big_gf.mesh(),at_end) {}
    void increment() { ++mesh_it; }
    bool at_end() const { return mesh_it.at_end();}
   };

 template<typename Target, typename Opt, bool B, bool C>
  block_gf_iterator<Target,Opt> begin(gf_impl<block_index,Target,Opt,B,C> const & bgf) { return {bgf,false};}

 template<typename Target, typename Opt, bool B, bool C>
  block_gf_iterator<Target,Opt> end(gf_impl<block_index,Target,Opt,B,C> const & bgf) { return {bgf,true};}

}}
#endif