/*******************************************************************************
 *
 * TRIQS: a Toolbox for Research in Interacting Quantum Systems
 *
 * Copyright (C) 2011-2014 by 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/>.
 *
 ******************************************************************************/
#pragma once
#include "./domain.hpp"
#include "./mem_layout.hpp"
#include <vector>
#include <boost/iterator/iterator_facade.hpp>

namespace triqs { namespace arrays {

 struct _traversal_c {};
 struct _traversal_fortran {};
 struct _traversal_dynamical {};
 template <int... Is> struct _traversal_custom {};

 template <typename T> struct _get_traversal_order_t {
  using type = T;
 };
 template <> struct _get_traversal_order_t<void> {
  using type = _traversal_c;
 };

 constexpr ull_t _get_traversal_order_permutation(int R, _traversal_c) { return permutations::identity(R); }
 constexpr ull_t _get_traversal_order_permutation(int R, _traversal_fortran) { return permutations::ridentity(R); }
 template <int... Is> constexpr ull_t _get_traversal_order_permutation(int R,_traversal_custom<Is...>) {
  static_assert(sizeof...(Is) == R, " Rank mismatch");
  return permutations::permutation(Is...);
 }

 namespace indexmaps { namespace cuboid {

 /** Standard hyper_rectangular arrays, implementing the IndexMap concept.
 */
 template <int Rank, typename TraversalOrder=void> class map {
   public :
   static const int rank = Rank;
   using lengths_type=mini_vector<size_t,rank> ;
   using strides_type=mini_vector<std::ptrdiff_t, rank> ;
   using domain_type = domain_t<Rank>;
   using traversal_order_in_template = TraversalOrder;
   using has_traversal_order_tag = void;
   domain_type const& domain() const { return mydomain; }

   // semi-regular type
   map (): start_shift_(0), memory_order_() {}
   map (map const & C) = default;
   map (map && C) = default;
   map & operator = (map const & m) = default;
   map & operator = (map && m)  = default;

   // basic construction
   map(memory_layout<Rank> const & ml):mydomain(), start_shift_(0), memory_order_(ml) {}
   map(domain_type const & C): mydomain(C), start_shift_(0), memory_order_() {compute_stride_compact();}
   map(domain_type const & C, memory_layout<Rank> ml): mydomain(C), start_shift_(0), memory_order_(std::move(ml)) {compute_stride_compact();}

   /// Construction from the length, the stride, start_shift
   map(lengths_type Lengths, strides_type strides, std::ptrdiff_t start_shift ):
    mydomain(std::move(Lengths)), strides_(std::move(strides)), start_shift_(start_shift),
    memory_order_ (memory_layout_from_strides(strides_)) {}

   /// Construction from the length, the stride, start_shift, ml
   map(lengths_type Lengths, strides_type strides, std::ptrdiff_t start_shift, memory_layout<Rank> const & ml ):
    mydomain(std::move(Lengths)), strides_(std::move(strides)), start_shift_(start_shift), memory_order_ (ml) {}

   /// Construction from another map with the same order
   template <typename To2>
   map(map<Rank, To2> const& C)
      : mydomain(C.domain()), strides_(C.strides()), start_shift_(C.start_shift()), memory_order_(C.get_memory_layout()) {}

   template <typename To2> map& operator=(map<Rank, To2> const& m) {
    *this = map{m};
   }

   // transposition
   friend map transpose(map const& m, mini_vector<int, Rank> const & perm) {
    lengths_type l;
    strides_type s;
    for (int u = 0; u < Rank; ++u) {
     l[perm[u]] = m.domain().lengths()[u];
     s[perm[u]] = m.strides_[u];
    }
    return map{l, s, m.start_shift_, transpose(m.memory_order_, perm)};
   }

   /// Returns the shift in position of the element key.
   template <typename KeyType> size_t operator[](KeyType const& key) const {
#ifdef TRIQS_ARRAYS_ENFORCE_BOUNDCHECK
     this->domain().assert_key_in_domain(key);
#endif
     return start_shift_ + dot_product(key, this->strides());
    }

   friend std::ostream & operator << (std::ostream & out, const map & P) {
    return out <<"  ordering = {"<<P.get_memory_layout()<<"}"<<std::endl
     <<"  Lengths  :  "<<P.lengths() << std::endl
     <<"  Stride  : "<<P.strides_ << std::endl;
   }

   /// TODO: replace by a tuple call....
   template<typename ... Args> size_t operator()(Args const & ... args) const {
#ifdef TRIQS_ARRAYS_ENFORCE_BOUNDCHECK
     this->domain().assert_key_in_domain_v(args...);
#endif
    return start_shift_ + _call_impl<0>(args...);
   }
   private :
   template<int N, typename Arg0, typename ... Args>
    size_t _call_impl( Arg0 const & arg0, Args const & ... args) const { return arg0* strides_[N] + _call_impl<N+1>(args...); }
   template<int N> size_t _call_impl() const { return 0;}
   public:

   ///
   bool is_contiguous() const {
    int slowest_index = memory_order_[0];
    return (strides()[slowest_index] * this->lengths()[slowest_index] == mydomain.number_of_elements());
   }

   size_t start_shift() const { return start_shift_;}
   lengths_type const & lengths() const { return mydomain.lengths();}
   strides_type const & strides() const { return this->strides_;}

   memory_layout<Rank> const & get_memory_layout() const { return memory_order_;}
   bool memory_layout_is_c() const { return get_memory_layout().is_c();}
   bool memory_layout_is_fortran() const { return get_memory_layout().is_fortran();}

   private :
   domain_type mydomain;
   strides_type strides_;
   std::ptrdiff_t start_shift_;
   memory_layout<Rank> memory_order_;

   //  BOOST Serialization
   friend class boost::serialization::access;
   template<class Archive> void serialize(Archive & ar, const unsigned int version) {
    ar & TRIQS_MAKE_NVP("domain",mydomain);
    ar & TRIQS_MAKE_NVP("strides",strides_);
    ar & TRIQS_MAKE_NVP("start_shift",start_shift_);
   }
   // for construction
   // TODO : use tupletools
   void compute_stride_compact() {
    size_t str = 1;
    csc_impl(memory_order_, str, std::integral_constant<int,rank>());
    assert(this->domain().number_of_elements()==str);
   }
   // call for indices fastest (rank -1) to slowest (0)
   template <int v> void csc_impl(memory_layout<Rank> const& ml, size_t& str, std::integral_constant<int, v>) {
    // size_t u = mem_layout::memory_rank_to_index(order, rank-v);
    int u = ml[v - 1];
    this->strides_[u] = str;
    str *= this->lengths()[u];
    csc_impl(ml, str, std::integral_constant<int, v - 1>());
   }
   void csc_impl(memory_layout<Rank> const&, size_t&, std::integral_constant<int, 0>) {}

   // iterator helper impl.
   static constexpr int __iter_get_p(int p, map const * im, _traversal_c) { return p;}
   static constexpr int __iter_get_p(int p, map const* im, _traversal_fortran) { return Rank - p - 1; }
   static int __iter_get_p(int p, map const* im, _traversal_dynamical) { return im->get_memory_layout()[p]; }
   template <int... Is> static constexpr int __iter_get_p(int p, map const* im, _traversal_custom<Is...>) {
    return permutations::apply(_get_traversal_order_permutation(Rank, _traversal_custom<Is...>{}),
                               p);
   }

   public:

   /**
    * Iterator on a cuboid_map, modeling the IndexMapIterator concept.
    * Iteration order is the order in which to iterate on the indices.
    * It is given by a permutation, with the same convention as IndexOrder.
    */
   class iterator : public boost::iterator_facade< iterator, const std::ptrdiff_t, boost::forward_traversal_tag > {
    public:
     using indexmap_type=map ;
     using indices_type=typename domain_type::index_value_type ;
     using return_type=const std::ptrdiff_t ;
     iterator (): im(NULL), pos(0),atend(true) {}
     iterator (const map & P, bool atEnd=false, ull_t iteration_order=0):
      im(&P), pos(im->start_shift()),atend(atEnd) {}
     indices_type const & indices() const { return indices_tuple; }
     operator bool() const { return !atend;}
    private:
     friend class boost::iterator_core_access;
     void increment(){ inc_ind_impl (std::integral_constant<int,Rank>()); }
     template<int v> inline void inc_ind_impl(std::integral_constant<int,v>) {
      int p = __iter_get_p(v - 1, im, typename _get_traversal_order_t<TraversalOrder>::type{});
#ifdef TRIQS_ARRAYS_ENFORCE_BOUNDCHECK
      if (atend) TRIQS_RUNTIME_ERROR << "Iterator in cuboid cannot be pushed after end !";
#endif
      if (indices_tuple[p] < im->lengths()[p]-1) { ++(indices_tuple[p]); pos += im->strides()[p]; return; }
      indices_tuple[p] = 0;
      pos -= (im->lengths()[p]-1) * im->strides()[p];
      inc_ind_impl (std::integral_constant<int,v-1>());
     }
     inline void inc_ind_impl(std::integral_constant<int,0>) { atend = true;}
     bool equal(iterator const & other) const {return ((other.im==im)&&(other.atend==atend)&&(other.pos==pos));}
     return_type & dereference() const { assert (!atend); return pos; }
     map const * im;
     indices_type indices_tuple;
     std::ptrdiff_t pos;
     bool atend;
   };

  }; //------------- end class ---------------------
 
}//namespace cuboid

template <int R1, int R2, typename To1, typename To2>
bool compatible_for_assignment(const cuboid::map<R1, To1>& X1, const cuboid::map<R2, To2>& X2) {
 return X1.lengths() == X2.lengths();
}

template <int R1, int R2, typename To1, typename To2>
bool raw_copy_possible(const cuboid::map<R1, To1>& X1, const cuboid::map<R2, To2>& X2) {
  return ( (X1.get_memory_layout() == X2.get_memory_layout())
    && X1.is_contiguous() && X2.is_contiguous()
    && (X1.domain().number_of_elements()==X2.domain().number_of_elements()));
 }
}}}//namespace triqs::arrays::indexmaps