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 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright notice,
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 * contributors may be used to endorse or promote products derived from
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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#pragma once

#include <cstddef>
#include <utility>

#include <cute/config.hpp>

namespace cute
{

template <class T, std::size_t N>
struct array
{
  using value_type = T;
  using size_type = std::size_t;
  using difference_type = std::ptrdiff_t;
  using reference = value_type&;
  using const_reference = const value_type&;
  using pointer = value_type*;
  using const_pointer = const value_type*;
  using iterator = pointer;
  using const_iterator = const_pointer;

  CUTE_HOST_DEVICE constexpr
  reference operator[](size_type pos)
  {
    return begin()[pos];
  }

  CUTE_HOST_DEVICE constexpr
  const_reference operator[](size_type pos) const
  {
    return begin()[pos];
  }

  CUTE_HOST_DEVICE constexpr
  reference front()
  {
    return *begin();
  }

  CUTE_HOST_DEVICE constexpr
  const_reference front() const
  {
    return *begin();
  }

  CUTE_HOST_DEVICE constexpr
  reference back()
  {
    // return *rbegin();
    return operator[](N-1);
  }

  CUTE_HOST_DEVICE constexpr
  const_reference back() const
  {
    // return *rbegin();
    return operator[](N-1);
  }

  CUTE_HOST_DEVICE constexpr
  T* data()
  {
    return __elems_;
  }

  CUTE_HOST_DEVICE constexpr
  T const* data() const
  {
    return __elems_;
  }

  CUTE_HOST_DEVICE constexpr
  iterator begin()
  {
    return data();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator begin() const
  {
    return data();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cbegin()
  {
    return begin();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cbegin() const
  {
    return begin();
  }

  CUTE_HOST_DEVICE constexpr
  iterator end()
  {
    return data() + size();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator end() const
  {
    return data() + size();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cend()
  {
    return end();
  }

  CUTE_HOST_DEVICE constexpr
  const_iterator cend() const
  {
    return end();
  }

  CUTE_HOST_DEVICE constexpr
  bool empty() const
  {
    return size() == 0;
  }

  CUTE_HOST_DEVICE constexpr
  size_type size() const
  {
    return N;
  }

  CUTE_HOST_DEVICE constexpr
  size_type max_size() const
  {
    return size();
  }

  CUTE_HOST_DEVICE constexpr
  void fill(const T& value)
  {
    for (auto& e : *this) {
      e = value;
    }
  }

  CUTE_HOST_DEVICE constexpr
  void clear()
  {
    fill(T(0));
  }

  CUTE_HOST_DEVICE constexpr
  void swap(array& other)
  {
    using std::swap;
    for (size_type i = 0; i < size(); ++i) {
      swap((*this)[i], other[i]);
    }
  }

  value_type __elems_[N > 0 ? N : 1];
};


template<class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
bool operator==(array<T,N> const& lhs, array<T,N> const& rhs)
{
  for (std::size_t i = 0; i < N; ++i) {
    if (lhs[i] != rhs[i]) {
      return false;
    }
  }
  return true;
}

template <typename T, std::size_t N>
CUTE_HOST_DEVICE constexpr
void clear(array<T,N>& a)
{
  a.fill(T(0));
}

template <typename T, std::size_t N>
CUTE_HOST_DEVICE constexpr
void fill(array<T,N>& a, T const& value)
{
  a.fill(value);
}

template<class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
void swap(array<T,N>& a, array<T,N>& b)
{
  a.swap(b);
}

} // end cute


//
// Specialize tuple-related functionality for cute::array
//

#include <tuple>

namespace cute
{

template<std::size_t I, class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
T& get(array<T,N>& a)
{
  static_assert(I < N, "Index out of range");
  return a[I];
}

template<std::size_t I, class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
T const& get(array<T,N> const& a)
{
  static_assert(I < N, "Index out of range");       
  return a[I];
}

template<std::size_t I, class T, std::size_t N>
CUTE_HOST_DEVICE constexpr
T&& get(array<T,N>&& a)
{
  static_assert(I < N, "Index out of range");
  return std::move(a[I]);
}

} // end namespace cute

namespace std
{

template <class T, std::size_t N>
struct tuple_size<cute::array<T,N>>
    : std::integral_constant<std::size_t, N>
{};

template <std::size_t I, class T, std::size_t N>
struct tuple_element<I, cute::array<T,N>>
{
  using type = T;
};

} // end std