// Copyright 2020 The Pigweed Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

#include <array>

#include "gtest/gtest.h"
#include "pw_polyfill/language_feature_macros.h"
#include "pw_polyfill/standard.h"
#include "pw_polyfill/standard_library/bit.h"
#include "pw_polyfill/standard_library/cstddef.h"
#include "pw_polyfill/standard_library/iterator.h"
#include "pw_polyfill/standard_library/type_traits.h"
#include "pw_polyfill/standard_library/utility.h"

namespace pw {
namespace polyfill {
namespace {

PW_INLINE_VARIABLE constexpr int foo = 42;

static_assert(foo == 42, "Error!");

static_assert(PW_CXX_STANDARD_IS_SUPPORTED(98), "C++98 must be supported");
static_assert(PW_CXX_STANDARD_IS_SUPPORTED(11), "C++11 must be supported");

#if __cplusplus >= 201402L
static_assert(PW_CXX_STANDARD_IS_SUPPORTED(14), "C++14 must be not supported");
#else
static_assert(!PW_CXX_STANDARD_IS_SUPPORTED(14), "C++14 must be supported");
#endif  // __cplusplus >= 201402L

#if __cplusplus >= 201703L
static_assert(PW_CXX_STANDARD_IS_SUPPORTED(17), "C++17 must be not supported");
#else
static_assert(!PW_CXX_STANDARD_IS_SUPPORTED(17), "C++17 must be supported");
#endif  // __cplusplus >= 201703L

TEST(Array, ToArray_StringLiteral) {
  std::array<char, sizeof("literally!")> array = std::to_array("literally!");
  EXPECT_TRUE(std::strcmp(array.data(), "literally!") == 0);
}

TEST(Array, ToArray_Inline) {
  constexpr std::array<int, 3> kArray = std::to_array({1, 2, 3});
  static_assert(kArray.size() == 3);
  EXPECT_TRUE(kArray[0] == 1);
}

TEST(Array, ToArray_Array) {
  char c_array[] = "array!";
  std::array<char, sizeof("array!")> array = std::to_array(c_array);
  EXPECT_TRUE(std::strcmp(array.data(), "array!") == 0);
}

struct MoveOnly {
  MoveOnly(char ch) : value(ch) {}

  MoveOnly(const MoveOnly&) = delete;
  MoveOnly& operator=(const MoveOnly&) = delete;

  MoveOnly(MoveOnly&&) = default;
  MoveOnly& operator=(MoveOnly&&) = default;

  char value;
};

TEST(Array, ToArray_MoveOnly) {
  MoveOnly c_array[]{MoveOnly('a'), MoveOnly('b')};
  std::array<MoveOnly, 2> array = std::to_array(std::move(c_array));
  EXPECT_TRUE(array[0].value == 'a');
  EXPECT_TRUE(array[1].value == 'b');
}

TEST(Bit, Endian) {
  if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) {
    EXPECT_TRUE(std::endian::native == std::endian::big);
  } else if (__BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__) {
    EXPECT_TRUE(std::endian::native == std::endian::little);
  } else {
    FAIL();
  }
}

TEST(Cstddef, Byte_Operators) {
  std::byte value = std::byte(0);
  EXPECT_TRUE((value | std::byte(0x12)) == std::byte(0x12));
  EXPECT_TRUE((value & std::byte(0x12)) == std::byte(0));
  EXPECT_TRUE((value ^ std::byte(0x12)) == std::byte(0x12));
  EXPECT_TRUE(~std::byte(0) == std::byte(-1));
  EXPECT_TRUE((std::byte(1) << 3) == std::byte(0x8));
  EXPECT_TRUE((std::byte(0x8) >> 3) == std::byte(1));
}

TEST(Cstddef, Byte_AssignmentOperators) {
  std::byte value = std::byte(0);
  EXPECT_TRUE((value |= std::byte(0x12)) == std::byte(0x12));
  EXPECT_TRUE((value &= std::byte(0x0F)) == std::byte(0x02));
  EXPECT_TRUE((value ^= std::byte(0xFF)) == std::byte(0xFD));
  EXPECT_TRUE((value <<= 4) == std::byte(0xD0));
  EXPECT_TRUE((value >>= 5) == std::byte(0x6));
}

// Check that consteval is at least equivalent to constexpr.
PW_CONSTEVAL int ConstevalFunction() { return 123; }
static_assert(ConstevalFunction() == 123);

int c_array[5423] = {};
std::array<int, 32> array;

TEST(Iterator, Size) {
  EXPECT_TRUE(std::size(c_array) == sizeof(c_array) / sizeof(*c_array));
  EXPECT_TRUE(std::size(array) == array.size());
}

TEST(Iterator, Data) {
  EXPECT_TRUE(std::data(c_array) == c_array);
  EXPECT_TRUE(std::data(array) == array.data());
}

PW_CONSTINIT bool mutable_value = true;

TEST(Constinit, ValueIsMutable) {
  ASSERT_TRUE(mutable_value);
  mutable_value = false;
  ASSERT_FALSE(mutable_value);
  mutable_value = true;
}

TEST(TypeTraits, Aliases) {
  static_assert(
      std::is_same<std::aligned_storage_t<40, 40>,
                   typename std::aligned_storage<40, 40>::type>::value,
      "Alias must be defined");

  static_assert(std::is_same<std::common_type_t<int, bool>,
                             typename std::common_type<int, bool>::type>::value,
                "Alias must be defined");

  static_assert(
      std::is_same<std::conditional_t<false, int, char>,
                   typename std::conditional<false, int, char>::type>::value,
      "Alias must be defined");

  static_assert(
      std::is_same<std::decay_t<int>, typename std::decay<int>::type>::value,
      "Alias must be defined");

  static_assert(std::is_same<std::enable_if_t<true, int>,
                             typename std::enable_if<true, int>::type>::value,
                "Alias must be defined");

  static_assert(std::is_same<std::make_signed_t<int>,
                             typename std::make_signed<int>::type>::value,
                "Alias must be defined");

  static_assert(std::is_same<std::make_unsigned_t<int>,
                             typename std::make_unsigned<int>::type>::value,
                "Alias must be defined");

  static_assert(std::is_same<std::remove_cv_t<int>,
                             typename std::remove_cv<int>::type>::value,
                "Alias must be defined");

  static_assert(std::is_same<std::remove_pointer_t<int>,
                             typename std::remove_pointer<int>::type>::value,
                "Alias must be defined");

  static_assert(std::is_same<std::remove_reference_t<int>,
                             typename std::remove_reference<int>::type>::value,
                "Alias must be defined");
}

TEST(Utility, IntegerSequence) {
  static_assert(std::integer_sequence<int>::size() == 0);
  static_assert(std::integer_sequence<int, 9, 8, 7>::size() == 3);
  static_assert(std::make_index_sequence<1>::size() == 1);
  static_assert(std::make_index_sequence<123>::size() == 123);
}

TEST(Utility, LogicalTraits) {
  static_assert(std::conjunction<std::true_type, std::true_type>::value);
  static_assert(!std::conjunction<std::true_type, std::false_type>::value);
  static_assert(!std::conjunction<std::false_type, std::false_type>::value);

  static_assert(std::disjunction<std::true_type, std::true_type>::value);
  static_assert(std::disjunction<std::true_type, std::false_type>::value);
  static_assert(!std::disjunction<std::false_type, std::false_type>::value);

  static_assert(!std::negation<std::true_type>::value);
  static_assert(std::negation<std::false_type>::value);
}

}  // namespace
}  // namespace polyfill
}  // namespace pw