//===----------------------------------------------------------------------===//
//
// Part of libcu++, the C++ Standard Library for your entire system,
// under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// SPDX-FileCopyrightText: Copyright (c) 2023 NVIDIA CORPORATION & AFFILIATES.
//
//===----------------------------------------------------------------------===//

#ifndef _CUDA_STD_RATIO
#define _CUDA_STD_RATIO

#include <cuda/std/detail/__config>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header

#include <cuda/std/__type_traits/integral_constant.h>
#include <cuda/std/climits>
#include <cuda/std/cstdint>

#include <cuda/std/__cccl/prologue.h>

_LIBCUDACXX_BEGIN_NAMESPACE_STD

// __static_gcd

template <intmax_t _Xp, intmax_t _Yp>
struct __static_gcd
{
  static const intmax_t value = __static_gcd<_Yp, _Xp % _Yp>::value;
};

template <intmax_t _Xp>
struct __static_gcd<_Xp, 0>
{
  static const intmax_t value = _Xp;
};

template <>
struct __static_gcd<0, 0>
{
  static const intmax_t value = 1;
};

// __static_lcm

template <intmax_t _Xp, intmax_t _Yp>
struct __static_lcm
{
  static const intmax_t value = _Xp / __static_gcd<_Xp, _Yp>::value * _Yp;
};

template <intmax_t _Xp>
struct __static_abs
{
  static const intmax_t value = _Xp < 0 ? -_Xp : _Xp;
};

template <intmax_t _Xp>
struct __static_sign
{
  static const intmax_t value = _Xp == 0 ? 0 : (_Xp < 0 ? -1 : 1);
};

template <intmax_t _Xp, intmax_t _Yp, intmax_t = __static_sign<_Yp>::value>
class __ll_add;

template <intmax_t _Xp, intmax_t _Yp>
class __ll_add<_Xp, _Yp, 1>
{
  static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
  static const intmax_t max = -min;

  static_assert(_Xp <= max - _Yp, "overflow in __ll_add");

public:
  static const intmax_t value = _Xp + _Yp;
};

template <intmax_t _Xp, intmax_t _Yp>
class __ll_add<_Xp, _Yp, 0>
{
public:
  static const intmax_t value = _Xp;
};

template <intmax_t _Xp, intmax_t _Yp>
class __ll_add<_Xp, _Yp, -1>
{
  static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
  static const intmax_t max = -min;

  static_assert(min - _Yp <= _Xp, "overflow in __ll_add");

public:
  static const intmax_t value = _Xp + _Yp;
};

template <intmax_t _Xp, intmax_t _Yp, intmax_t = __static_sign<_Yp>::value>
class __ll_sub;

template <intmax_t _Xp, intmax_t _Yp>
class __ll_sub<_Xp, _Yp, 1>
{
  static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
  static const intmax_t max = -min;

  static_assert(min + _Yp <= _Xp, "overflow in __ll_sub");

public:
  static const intmax_t value = _Xp - _Yp;
};

template <intmax_t _Xp, intmax_t _Yp>
class __ll_sub<_Xp, _Yp, 0>
{
public:
  static const intmax_t value = _Xp;
};

template <intmax_t _Xp, intmax_t _Yp>
class __ll_sub<_Xp, _Yp, -1>
{
  static const intmax_t min = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1)) + 1;
  static const intmax_t max = -min;

  static_assert(_Xp <= max + _Yp, "overflow in __ll_sub");

public:
  static const intmax_t value = _Xp - _Yp;
};

template <intmax_t _Xp, intmax_t _Yp>
class __ll_mul
{
  static const intmax_t nan   = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1));
  static const intmax_t min   = nan + 1;
  static const intmax_t max   = -min;
  static const intmax_t __a_x = __static_abs<_Xp>::value;
  static const intmax_t __a_y = __static_abs<_Yp>::value;

  static_assert(_Xp != nan && _Yp != nan && __a_x <= max / __a_y, "overflow in __ll_mul");

public:
  static const intmax_t value = _Xp * _Yp;
};

template <intmax_t _Yp>
class __ll_mul<0, _Yp>
{
public:
  static const intmax_t value = 0;
};

template <intmax_t _Xp>
class __ll_mul<_Xp, 0>
{
public:
  static const intmax_t value = 0;
};

template <>
class __ll_mul<0, 0>
{
public:
  static const intmax_t value = 0;
};

// Not actually used but left here in case needed in future maintenance
template <intmax_t _Xp, intmax_t _Yp>
class __ll_div
{
  static const intmax_t nan = (1LL << (sizeof(intmax_t) * CHAR_BIT - 1));
  static const intmax_t min = nan + 1;
  static const intmax_t max = -min;

  static_assert(_Xp != nan && _Yp != nan && _Yp != 0, "overflow in __ll_div");

public:
  static const intmax_t value = _Xp / _Yp;
};

template <intmax_t _Num, intmax_t _Den = 1>
class _CCCL_TYPE_VISIBILITY_DEFAULT ratio
{
  static_assert(__static_abs<_Num>::value >= 0, "ratio numerator is out of range");
  static_assert(_Den != 0, "ratio divide by 0");
  static_assert(__static_abs<_Den>::value > 0, "ratio denominator is out of range");
  static constexpr intmax_t __na  = __static_abs<_Num>::value;
  static constexpr intmax_t __da  = __static_abs<_Den>::value;
  static constexpr intmax_t __s   = __static_sign<_Num>::value * __static_sign<_Den>::value;
  static constexpr intmax_t __gcd = __static_gcd<__na, __da>::value;

public:
  static constexpr intmax_t num = __s * __na / __gcd;
  static constexpr intmax_t den = __da / __gcd;

  using type = ratio<num, den>;
};

template <intmax_t _Num, intmax_t _Den>
constexpr intmax_t ratio<_Num, _Den>::num;

template <intmax_t _Num, intmax_t _Den>
constexpr intmax_t ratio<_Num, _Den>::den;

template <class _Tp>
struct __is_ratio : false_type
{};
template <intmax_t _Num, intmax_t _Den>
struct __is_ratio<ratio<_Num, _Den>> : true_type
{};

using atto  = ratio<1LL, 1000000000000000000LL>;
using femto = ratio<1LL, 1000000000000000LL>;
using pico  = ratio<1LL, 1000000000000LL>;
using nano  = ratio<1LL, 1000000000LL>;
using micro = ratio<1LL, 1000000LL>;
using milli = ratio<1LL, 1000LL>;
using centi = ratio<1LL, 100LL>;
using deci  = ratio<1LL, 10LL>;
using deca  = ratio<10LL, 1LL>;
using hecto = ratio<100LL, 1LL>;
using kilo  = ratio<1000LL, 1LL>;
using mega  = ratio<1000000LL, 1LL>;
using giga  = ratio<1000000000LL, 1LL>;
using tera  = ratio<1000000000000LL, 1LL>;
using peta  = ratio<1000000000000000LL, 1LL>;
using exa   = ratio<1000000000000000000LL, 1LL>;

template <class _R1, class _R2>
struct __ratio_multiply
{
  // private:
  static const intmax_t __gcd_n1_d2 = __static_gcd<_R1::num, _R2::den>::value;
  static const intmax_t __gcd_d1_n2 = __static_gcd<_R1::den, _R2::num>::value;

public:
  using type = typename ratio<__ll_mul<_R1::num / __gcd_n1_d2, _R2::num / __gcd_d1_n2>::value,
                              __ll_mul<_R2::den / __gcd_n1_d2, _R1::den / __gcd_d1_n2>::value>::type;
};

template <class _R1, class _R2>
using ratio_multiply = typename __ratio_multiply<_R1, _R2>::type;

template <class _R1, class _R2>
struct __ratio_divide
{
  // private:
  static const intmax_t __gcd_n1_n2 = __static_gcd<_R1::num, _R2::num>::value;
  static const intmax_t __gcd_d1_d2 = __static_gcd<_R1::den, _R2::den>::value;

public:
  using type = typename ratio<__ll_mul<_R1::num / __gcd_n1_n2, _R2::den / __gcd_d1_d2>::value,
                              __ll_mul<_R2::num / __gcd_n1_n2, _R1::den / __gcd_d1_d2>::value>::type;
};

template <class _R1, class _R2>
using ratio_divide = typename __ratio_divide<_R1, _R2>::type;

template <class _R1, class _R2>
struct __ratio_add
{
  // private:
  static const intmax_t __gcd_n1_n2 = __static_gcd<_R1::num, _R2::num>::value;
  static const intmax_t __gcd_d1_d2 = __static_gcd<_R1::den, _R2::den>::value;

public:
  using type =
    typename ratio_multiply<ratio<__gcd_n1_n2, _R1::den / __gcd_d1_d2>,
                            ratio<__ll_add<__ll_mul<_R1::num / __gcd_n1_n2, _R2::den / __gcd_d1_d2>::value,
                                           __ll_mul<_R2::num / __gcd_n1_n2, _R1::den / __gcd_d1_d2>::value>::value,
                                  _R2::den>>::type;
};

template <class _R1, class _R2>
using ratio_add = typename __ratio_add<_R1, _R2>::type;

template <class _R1, class _R2>
struct __ratio_subtract
{
  // private:
  static const intmax_t __gcd_n1_n2 = __static_gcd<_R1::num, _R2::num>::value;
  static const intmax_t __gcd_d1_d2 = __static_gcd<_R1::den, _R2::den>::value;

public:
  using type =
    typename ratio_multiply<ratio<__gcd_n1_n2, _R1::den / __gcd_d1_d2>,
                            ratio<__ll_sub<__ll_mul<_R1::num / __gcd_n1_n2, _R2::den / __gcd_d1_d2>::value,
                                           __ll_mul<_R2::num / __gcd_n1_n2, _R1::den / __gcd_d1_d2>::value>::value,
                                  _R2::den>>::type;
};

template <class _R1, class _R2>
using ratio_subtract = typename __ratio_subtract<_R1, _R2>::type;

// ratio_equal

template <class _R1, class _R2>
struct _CCCL_TYPE_VISIBILITY_DEFAULT ratio_equal : public bool_constant<(_R1::num == _R2::num && _R1::den == _R2::den)>
{};

template <class _R1, class _R2>
struct _CCCL_TYPE_VISIBILITY_DEFAULT ratio_not_equal : public bool_constant<(!ratio_equal<_R1, _R2>::value)>
{};

// ratio_less

template <class _R1,
          class _R2,
          bool _Odd    = false,
          intmax_t _Q1 = _R1::num / _R1::den,
          intmax_t _M1 = _R1::num % _R1::den,
          intmax_t _Q2 = _R2::num / _R2::den,
          intmax_t _M2 = _R2::num % _R2::den>
struct __ratio_less1
{
  static const bool value = _Odd ? _Q2 < _Q1 : _Q1 < _Q2;
};

template <class _R1, class _R2, bool _Odd, intmax_t _Qp>
struct __ratio_less1<_R1, _R2, _Odd, _Qp, 0, _Qp, 0>
{
  static const bool value = false;
};

template <class _R1, class _R2, bool _Odd, intmax_t _Qp, intmax_t _M2>
struct __ratio_less1<_R1, _R2, _Odd, _Qp, 0, _Qp, _M2>
{
  static const bool value = !_Odd;
};

template <class _R1, class _R2, bool _Odd, intmax_t _Qp, intmax_t _M1>
struct __ratio_less1<_R1, _R2, _Odd, _Qp, _M1, _Qp, 0>
{
  static const bool value = _Odd;
};

template <class _R1, class _R2, bool _Odd, intmax_t _Qp, intmax_t _M1, intmax_t _M2>
struct __ratio_less1<_R1, _R2, _Odd, _Qp, _M1, _Qp, _M2>
{
  static const bool value = __ratio_less1<ratio<_R1::den, _M1>, ratio<_R2::den, _M2>, !_Odd>::value;
};

template <class _R1,
          class _R2,
          intmax_t _S1 = __static_sign<_R1::num>::value,
          intmax_t _S2 = __static_sign<_R2::num>::value>
struct __ratio_less
{
  static const bool value = _S1 < _S2;
};

template <class _R1, class _R2>
struct __ratio_less<_R1, _R2, 1LL, 1LL>
{
  static const bool value = __ratio_less1<_R1, _R2>::value;
};

template <class _R1, class _R2>
struct __ratio_less<_R1, _R2, -1LL, -1LL>
{
  static const bool value = __ratio_less1<ratio<-_R2::num, _R2::den>, ratio<-_R1::num, _R1::den>>::value;
};

template <class _R1, class _R2>
struct _CCCL_TYPE_VISIBILITY_DEFAULT ratio_less : public bool_constant<(__ratio_less<_R1, _R2>::value)>
{};

template <class _R1, class _R2>
struct _CCCL_TYPE_VISIBILITY_DEFAULT ratio_less_equal : public bool_constant<(!ratio_less<_R2, _R1>::value)>
{};

template <class _R1, class _R2>
struct _CCCL_TYPE_VISIBILITY_DEFAULT ratio_greater : public bool_constant<(ratio_less<_R2, _R1>::value)>
{};

template <class _R1, class _R2>
struct _CCCL_TYPE_VISIBILITY_DEFAULT ratio_greater_equal : public bool_constant<(!ratio_less<_R1, _R2>::value)>
{};

template <class _R1, class _R2>
struct __ratio_gcd
{
  using type = ratio<__static_gcd<_R1::num, _R2::num>::value, __static_lcm<_R1::den, _R2::den>::value>;
};

template <class _R1, class _R2>
inline constexpr bool ratio_equal_v = ratio_equal<_R1, _R2>::value;

template <class _R1, class _R2>
inline constexpr bool ratio_not_equal_v = ratio_not_equal<_R1, _R2>::value;

template <class _R1, class _R2>
inline constexpr bool ratio_less_v = ratio_less<_R1, _R2>::value;

template <class _R1, class _R2>
inline constexpr bool ratio_less_equal_v = ratio_less_equal<_R1, _R2>::value;

template <class _R1, class _R2>
inline constexpr bool ratio_greater_v = ratio_greater<_R1, _R2>::value;

template <class _R1, class _R2>
inline constexpr bool ratio_greater_equal_v = ratio_greater_equal<_R1, _R2>::value;

_LIBCUDACXX_END_NAMESPACE_STD

#include <cuda/std/__cccl/epilogue.h>

#endif // _CUDA_STD_RATIO