// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, 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
//
//===----------------------------------------------------------------------===//
#ifndef SUPPORT_POISONED_HASH_HELPER_H
#define SUPPORT_POISONED_HASH_HELPER_H

#include <cuda/std/cassert>

#include <type_traits>

#include "test_macros.h"
#include "test_workarounds.h"

template <class... Args>
struct TypeList;

// Test that the specified Hash meets the requirements of an enabled hash
template <class Hash, class Key, class InputKey = Key>
void test_hash_enabled(InputKey const& key = InputKey{});

template <class T, class InputKey = T>
void test_hash_enabled_for_type(InputKey const& key = InputKey{})
{
  return test_hash_enabled<std::hash<T>, T, InputKey>(key);
}

// Test that the specified Hash meets the requirements of a disabled hash.
template <class Hash, class Key>
void test_hash_disabled();

template <class T>
void test_hash_disabled_for_type()
{
  return test_hash_disabled<std::hash<T>, T>();
}

namespace PoisonedHashDetail
{
enum Enum
{
};
enum EnumClass : bool
{
};
struct Class
{};
} // namespace PoisonedHashDetail

// Each header that declares the template hash provides enabled
// specializations of hash for nullptr t and all cv-unqualified
// arithmetic, enumeration, and pointer types.
using LibraryHashTypes = TypeList<
  decltype(nullptr),
  bool,
  char,
  signed char,
  unsigned char,
  wchar_t,
#ifndef _LIBCUDACXX_HAS_NO_UNICODE_CHARS
  char16_t,
  char32_t,
#endif
  short,
  unsigned short,
  int,
  unsigned int,
  long,
  unsigned long,
  long long,
  unsigned long long,
#if _CCCL_HAS_INT128()
  __int128_t,
  __uint128_t,
#endif // _CCCL_HAS_INT128()
  float,
  double,
  long double,
  // Enum types
  PoisonedHashDetail::Enum,
  PoisonedHashDetail::EnumClass,
  // pointer types
  void*,
  void const*,
  PoisonedHashDetail::Class*>;

// Test that each of the library hash specializations for  arithmetic types,
// enum types, and pointer types are available and enabled.
template <class Types = LibraryHashTypes>
void test_library_hash_specializations_available(Types = Types{});

namespace PoisonedHashDetail
{

template <class T, class = typename T::foo_bar_baz>
constexpr bool instantiate(int)
{
  return true;
}
template <class>
constexpr bool instantiate(long)
{
  return true;
}
template <class T>
constexpr bool instantiate()
{
  return instantiate<T>(0);
}

template <class To>
struct ConvertibleToSimple
{
  operator To() const
  {
    return To{};
  }
};

template <class To>
struct ConvertibleTo
{
  To to{};
  operator To&() &
  {
    return to;
  }
  operator To const&() const&
  {
    return to;
  }
  operator To&&() &&
  {
    return std::move(to);
  }
  operator To const&&() const&&
  {
    return std::move(to);
  }
};

template <class HashExpr, class Res = typename std::result_of<HashExpr>::type>
constexpr bool can_hash(int)
{
  return std::is_same<Res, size_t>::value;
}
template <class>
constexpr bool can_hash(long)
{
  return false;
}
template <class T>
constexpr bool can_hash()
{
  return can_hash<T>(0);
}

} // namespace PoisonedHashDetail

template <class Hash, class Key, class InputKey>
void test_hash_enabled(InputKey const& key)
{
  using namespace PoisonedHashDetail;

  static_assert(std::is_destructible<Hash>::value, "");
  // Enabled hash requirements
  static_assert(std::is_default_constructible<Hash>::value, "");
  static_assert(std::is_copy_constructible<Hash>::value, "");
  static_assert(std::is_move_constructible<Hash>::value, "");
  static_assert(std::is_copy_assignable<Hash>::value, "");
  static_assert(std::is_move_assignable<Hash>::value, "");

  static_assert(std::is_swappable<Hash>::value, "");

  // Hashable requirements
  static_assert(can_hash<Hash(Key&)>(), "");
  static_assert(can_hash<Hash(Key const&)>(), "");
  static_assert(can_hash<Hash(Key&&)>(), "");
  static_assert(can_hash<Hash const&(Key&)>(), "");
  static_assert(can_hash<Hash const&(Key const&)>(), "");
  static_assert(can_hash<Hash const&(Key&&)>(), "");

  static_assert(can_hash<Hash(ConvertibleToSimple<Key>&)>(), "");
  static_assert(can_hash<Hash(ConvertibleToSimple<Key> const&)>(), "");
  static_assert(can_hash<Hash(ConvertibleToSimple<Key>&&)>(), "");

  static_assert(can_hash<Hash(ConvertibleTo<Key>&)>(), "");
  static_assert(can_hash<Hash(ConvertibleTo<Key> const&)>(), "");
  static_assert(can_hash<Hash(ConvertibleTo<Key>&&)>(), "");
  static_assert(can_hash<Hash(ConvertibleTo<Key> const&&)>(), "");

  const Hash h{};
  assert(h(key) == h(key));
}

template <class Hash, class Key>
void test_hash_disabled()
{
  using namespace PoisonedHashDetail;

  // Disabled hash requirements
  static_assert(!std::is_default_constructible<Hash>::value, "");
  static_assert(!std::is_copy_constructible<Hash>::value, "");
  static_assert(!std::is_move_constructible<Hash>::value, "");
  static_assert(!std::is_copy_assignable<Hash>::value, "");
  static_assert(!std::is_move_assignable<Hash>::value, "");

  static_assert(
    !std::is_function<typename std::remove_pointer<typename std::remove_reference<Hash>::type>::type>::value, "");

  // Hashable requirements
  static_assert(!can_hash<Hash(Key&)>(), "");
  static_assert(!can_hash<Hash(Key const&)>(), "");
  static_assert(!can_hash<Hash(Key&&)>(), "");
  static_assert(!can_hash<Hash const&(Key&)>(), "");
  static_assert(!can_hash<Hash const&(Key const&)>(), "");
  static_assert(!can_hash<Hash const&(Key&&)>(), "");

  static_assert(!can_hash<Hash(ConvertibleToSimple<Key>&)>(), "");
  static_assert(!can_hash<Hash(ConvertibleToSimple<Key> const&)>(), "");
  static_assert(!can_hash<Hash(ConvertibleToSimple<Key>&&)>(), "");

  static_assert(!can_hash<Hash(ConvertibleTo<Key>&)>(), "");
  static_assert(!can_hash<Hash(ConvertibleTo<Key> const&)>(), "");
  static_assert(!can_hash<Hash(ConvertibleTo<Key>&&)>(), "");
  static_assert(!can_hash<Hash(ConvertibleTo<Key> const&&)>(), "");
}

template <class First, class... Rest>
struct TypeList<First, Rest...>
{
  template <template <class> class Trait, bool Expect = true>
  static constexpr bool assertTrait()
  {
    static_assert(Trait<First>::value == Expect, "");
    return TypeList<Rest...>::template assertTrait<Trait, Expect>();
  }

  template <class Trait>
  static void applyTrait()
  {
    Trait::template apply<First>();
    TypeList<Rest...>::template applyTrait<Trait>();
  }
};

template <>
struct TypeList<>
{
  template <template <class> class Trait, bool Expect = true>
  static constexpr bool assertTrait()
  {
    return true;
  }
  template <class Trait>
  static void applyTrait()
  {}
};

struct TestLibraryTrait
{
  template <class Type>
  static void apply()
  {
    test_hash_enabled<std::hash<Type>, Type>();
  }
};

template <class Types>
void test_library_hash_specializations_available(Types)
{
  Types::template applyTrait<TestLibraryTrait>();
}

#endif // SUPPORT_POISONED_HASH_HELPER_H
