#pragma once

#include <tuple>
#include <type_traits>

#include <dune/common/ftraits.hh>
#include <dune/functions/common/indexaccess.hh>

#include <amdis/common/Concepts.hpp>
#include <amdis/common/ForEach.hpp>
#include <amdis/common/Index.hpp>
#include <amdis/common/Range.hpp>
#include <amdis/common/StaticSize.hpp>
#include <amdis/common/TypeTraits.hpp>

namespace AMDiS
{
  // forward declaration
  template <class... FV>
  class MultiTypeVector;
}

namespace Dune
{
  template <class... FV>
  struct FieldTraits<AMDiS::MultiTypeVector<FV...>>
  {
    using field_type = std::common_type_t<typename Dune::FieldTraits<FV>::field_type...>;
    using real_type = std::common_type_t<typename Dune::FieldTraits<FV>::real_type...>;
  };
}


namespace AMDiS
{
  template <class... FV>
  class MultiTypeVector
      : public std::tuple<FV...>
  {
    using Self = MultiTypeVector;
    using Super = std::tuple<FV...>;

  public:
    using field_type = typename Dune::FieldTraits<Self>::field_type;
    using real_type = typename Dune::FieldTraits<Self>::real_type;
    using size_type = std::size_t;

    static constexpr int dimension = std::tuple_size<Super>::value;

    template <class... FV_,
      REQUIRES( Concepts::Similar<Types<FV...>, Types<FV_...>> )>
    MultiTypeVector(FV_&&... fv)
      : Super(FWD(fv)...)
    {}

    /// Default construction of tuple of FieldVectors
    MultiTypeVector() = default;

    /// Construct tuple by initializing all tuple elements with a constant value
    explicit MultiTypeVector(real_type value)
    {
      *this = value;
    }

    /// Assignment of real number to all tuple elements
    MultiTypeVector& operator=(real_type value)
    {
      Tools::for_each(as_tuple(), [value](auto& fv) { fv = value; });
      return *this;
    }

    // Compound assignment operator +=
    MultiTypeVector& operator+=(MultiTypeVector const& that)
    {
      Tools::for_range<0,dimension>([&that,this](auto const i) { (*this)[i] += that[i]; });
      return *this;
    }

    // Compound assignment operator -=
    MultiTypeVector& operator-=(MultiTypeVector const& that)
    {
      Tools::for_range<0,dimension>([&that,this](auto const i) { (*this)[i] -= that[i]; });
      return *this;
    }

    // Scaling of all tuple elements by a constant value
    MultiTypeVector& operator*=(real_type value)
    {
      Tools::for_each(as_tuple(), [value](auto& fv) { fv *= value; });
      return *this;
    }

    // Scaling of all tuple elements by the inverse of a constant value
    MultiTypeVector& operator/=(real_type value)
    {
      Tools::for_each(as_tuple(), [value](auto& fv) { fv /= value; });
      return *this;
    }

    /// Const access to the tuple elements
    template <std::size_t I>
    decltype(auto) operator[](index_t<I> const) const
    {
      return std::get<I>(as_tuple());
    }

    /// Mutable access to the tuple elements
    template <std::size_t I>
    decltype(auto) operator[](index_t<I> const)
    {
      return std::get<I>(as_tuple());
    }

    /// Const access to the vector using multi-indices
    template <class Index,
      REQUIRES( Concepts::MultiIndex<Index> )>
    decltype(auto) operator[](Index const& index) const
    {
      return Dune::Functions::hybridMultiIndexAccess<field_type const&>(*this, index);
    }

    /// Mutable access to the vector using multi-indices
    template <class Index,
      REQUIRES( Concepts::MultiIndex<Index> )>
    decltype(auto) operator[](Index const& index)
    {
      return Dune::Functions::hybridMultiIndexAccess<field_type&>(*this, index);
    }

    /// Return number of elements of the tuple
    static constexpr std::size_t size()
    {
      return dimension;
    }

  private:
    std::tuple<FV...>&       as_tuple()       { return *this; }
    std::tuple<FV...> const& as_tuple() const { return *this; }
  };

} // end namespace AMDiS