// 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 "pw_bytes/endian.h"

#include <array>
#include <cstddef>

#include "gtest/gtest.h"

namespace pw::bytes {
namespace {

constexpr std::endian kNonNative = (std::endian::native == std::endian::little)
                                       ? std::endian::big
                                       : std::endian::little;

// ConvertOrderTo/From
//
// ConvertOrderTo and ConvertOrderFrom are implemented identically, but are
// provided as separate functions to improve readability where they are used.
//
// clang-format off

// Native endianess conversions (should do nothing)

// Convert unsigned to native endianness
static_assert(ConvertOrderTo(std::endian::native, uint8_t{0x12}) == uint8_t{0x12});
static_assert(ConvertOrderTo(std::endian::native, uint16_t{0x0011}) == uint16_t{0x0011});
static_assert(ConvertOrderTo(std::endian::native, uint32_t{0x33221100}) == uint32_t{0x33221100});
static_assert(ConvertOrderTo(std::endian::native, uint64_t{0x0011223344556677}) == uint64_t{0x0011223344556677});

// Convert signed to native endianness
static_assert(ConvertOrderTo(std::endian::native, int8_t{0x12}) == int8_t{0x12});
static_assert(ConvertOrderTo(std::endian::native, int16_t{0x0011}) == int16_t{0x0011});
static_assert(ConvertOrderTo(std::endian::native, int32_t{0x33221100}) == int32_t{0x33221100});
static_assert(ConvertOrderTo(std::endian::native, int64_t{0x0011223344556677}) == int64_t{0x0011223344556677});

// Convert unsigned from native endianness
static_assert(ConvertOrderFrom(std::endian::native, uint8_t{0x12}) == uint8_t{0x12});
static_assert(ConvertOrderFrom(std::endian::native, uint16_t{0x0011}) == uint16_t{0x0011});
static_assert(ConvertOrderFrom(std::endian::native, uint32_t{0x33221100}) == uint32_t{0x33221100});
static_assert(ConvertOrderFrom(std::endian::native, uint64_t{0x0011223344556677}) == uint64_t{0x0011223344556677});

// Convert signed from native endianness
static_assert(ConvertOrderFrom(std::endian::native, int8_t{0x12}) == int8_t{0x12});
static_assert(ConvertOrderFrom(std::endian::native, int16_t{0x0011}) == int16_t{0x0011});
static_assert(ConvertOrderFrom(std::endian::native, int32_t{0x33221100}) == int32_t{0x33221100});
static_assert(ConvertOrderFrom(std::endian::native, int64_t{0x0011223344556677}) == int64_t{0x0011223344556677});

// Non-native endianess conversions (should reverse byte order)

// Convert unsigned to non-native endianness
static_assert(ConvertOrderTo(kNonNative, uint8_t{0x12}) == uint8_t{0x12});
static_assert(ConvertOrderTo(kNonNative, uint16_t{0x0011}) == uint16_t{0x1100});
static_assert(ConvertOrderTo(kNonNative, uint32_t{0x33221100}) == uint32_t{0x00112233});
static_assert(ConvertOrderTo(kNonNative, uint64_t{0x0011223344556677}) == uint64_t{0x7766554433221100});

// Convert signed to non-native endianness
static_assert(ConvertOrderTo(kNonNative, int8_t{0x12}) == int8_t{0x12});
static_assert(ConvertOrderTo(kNonNative, int16_t{0x0011}) == int16_t{0x1100});
static_assert(ConvertOrderTo(kNonNative, int32_t{0x33221100}) == int32_t{0x00112233});
static_assert(ConvertOrderTo(kNonNative, int64_t{0x0011223344556677}) == int64_t{0x7766554433221100});

// Convert unsigned from non-native endianness
static_assert(ConvertOrderFrom(kNonNative, uint8_t{0x12}) == uint8_t{0x12});
static_assert(ConvertOrderFrom(kNonNative, uint16_t{0x0011}) == uint16_t{0x1100});
static_assert(ConvertOrderFrom(kNonNative, uint32_t{0x33221100}) == uint32_t{0x00112233});
static_assert(ConvertOrderFrom(kNonNative, uint64_t{0x0011223344556677}) == uint64_t{0x7766554433221100});

// Convert signed from non-native endianness
static_assert(ConvertOrderFrom(kNonNative, int8_t{0x12}) == int8_t{0x12});
static_assert(ConvertOrderFrom(kNonNative, int16_t{0x0011}) == int16_t{0x1100});
static_assert(ConvertOrderFrom(kNonNative, int32_t{0x33221100}) == int32_t{0x00112233});
static_assert(ConvertOrderFrom(kNonNative, int64_t{0x0011223344556677}) == int64_t{0x7766554433221100});

// clang-format on

template <typename T, typename U>
constexpr bool Equal(const T& lhs, const U& rhs) {
  if (sizeof(lhs) != sizeof(rhs) || std::size(lhs) != std::size(rhs)) {
    return false;
  }

  for (size_t i = 0; i < std::size(lhs); ++i) {
    if (lhs[i] != rhs[i]) {
      return false;
    }
  }

  return true;
}

// CopyInOrder copies a value to a std::array with the specified endianness.
//
// clang-format off

// 8-bit little
static_assert(Equal(CopyInOrder(std::endian::little, '?'),
                    Array<'?'>()));
static_assert(Equal(CopyInOrder(std::endian::little, uint8_t{0x10}),
                    Array<0x10>()));
static_assert(Equal(CopyInOrder(std::endian::little, static_cast<int8_t>(0x10)),
                    Array<0x10>()));

// 8-bit big
static_assert(Equal(CopyInOrder(std::endian::big, '?'),
                    Array<'?'>()));
static_assert(Equal(CopyInOrder(std::endian::big, static_cast<uint8_t>(0x10)),
                    Array<0x10>()));
static_assert(Equal(CopyInOrder(std::endian::big, static_cast<int8_t>(0x10)),
                    Array<0x10>()));

// 16-bit little
static_assert(Equal(CopyInOrder(std::endian::little, uint16_t{0xAB12}),
                    Array<0x12, 0xAB>()));
static_assert(Equal(CopyInOrder(std::endian::little, static_cast<int16_t>(0xAB12)),
                    Array<0x12, 0xAB>()));

// 16-bit big
static_assert(Equal(CopyInOrder(std::endian::big, uint16_t{0xAB12}),
                    Array<0xAB, 0x12>()));
static_assert(Equal(CopyInOrder(std::endian::big, static_cast<int16_t>(0xAB12)),
                    Array<0xAB, 0x12>()));

// 32-bit little
static_assert(Equal(CopyInOrder(std::endian::little, uint32_t{0xAABBCCDD}),
                    Array<0xDD, 0xCC, 0xBB, 0xAA>()));
static_assert(Equal(CopyInOrder(std::endian::little, static_cast<int32_t>(0xAABBCCDD)),
                    Array<0xDD, 0xCC, 0xBB, 0xAA>()));

// 32-bit big
static_assert(Equal(CopyInOrder(std::endian::big, uint32_t{0xAABBCCDD}),
                    Array<0xAA, 0xBB, 0xCC, 0xDD>()));
static_assert(Equal(CopyInOrder(std::endian::big, static_cast<int32_t>(0xAABBCCDD)),
                    Array<0xAA, 0xBB, 0xCC, 0xDD>()));

// 64-bit little
static_assert(Equal(CopyInOrder(std::endian::little, uint64_t{0xAABBCCDD11223344}),
                    Array<0x44, 0x33, 0x22, 0x11, 0xDD, 0xCC, 0xBB, 0xAA>()));
static_assert(Equal(CopyInOrder(std::endian::little, static_cast<int64_t>(0xAABBCCDD11223344ull)),
                    Array<0x44, 0x33, 0x22, 0x11, 0xDD, 0xCC, 0xBB, 0xAA>()));

// 64-bit big
static_assert(Equal(CopyInOrder(std::endian::big, uint64_t{0xAABBCCDD11223344}),
                    Array<0xAA, 0xBB, 0xCC, 0xDD, 0x11, 0x22, 0x33, 0x44>()));
static_assert(Equal(CopyInOrder(std::endian::big, static_cast<int64_t>(0xAABBCCDD11223344ull)),
                    Array<0xAA, 0xBB, 0xCC, 0xDD, 0x11, 0x22, 0x33, 0x44>()));

// clang-format on

constexpr const char* kNumber = "\x11\x22\x33\x44\xaa\xbb\xcc\xdd";

TEST(ReadInOrder, 8Bit_Big) {
  EXPECT_EQ(ReadInOrder<uint8_t>(std::endian::big, "\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint8_t>(std::endian::big, "\x80"), 0x80u);
  EXPECT_EQ(ReadInOrder<uint8_t>(std::endian::big, kNumber), 0x11u);

  EXPECT_EQ(ReadInOrder<int8_t>(std::endian::big, "\0"), 0);
  EXPECT_EQ(ReadInOrder<int8_t>(std::endian::big, "\x80"), -128);
  EXPECT_EQ(ReadInOrder<int8_t>(std::endian::big, kNumber), 0x11);
}

TEST(ReadInOrder, 8Bit_Little) {
  EXPECT_EQ(ReadInOrder<uint8_t>(std::endian::little, "\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint8_t>(std::endian::little, "\x80"), 0x80u);
  EXPECT_EQ(ReadInOrder<uint8_t>(std::endian::little, kNumber), 0x11u);

  EXPECT_EQ(ReadInOrder<int8_t>(std::endian::little, "\0"), 0);
  EXPECT_EQ(ReadInOrder<int8_t>(std::endian::little, "\x80"), -128);
  EXPECT_EQ(ReadInOrder<int8_t>(std::endian::little, kNumber), 0x11);
}

TEST(ReadInOrder, 16Bit_Big) {
  EXPECT_EQ(ReadInOrder<uint16_t>(std::endian::big, "\0\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint16_t>(std::endian::big, "\x80\0"), 0x8000u);
  EXPECT_EQ(ReadInOrder<uint16_t>(std::endian::big, kNumber), 0x1122u);

  EXPECT_EQ(ReadInOrder<int16_t>(std::endian::big, "\0\0"), 0);
  EXPECT_EQ(ReadInOrder<int16_t>(std::endian::big, "\x80\0"), -32768);
  EXPECT_EQ(ReadInOrder<int16_t>(std::endian::big, kNumber), 0x1122);
}

TEST(ReadInOrder, 16Bit_Little) {
  EXPECT_EQ(ReadInOrder<uint16_t>(std::endian::little, "\0\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint16_t>(std::endian::little, "\x80\0"), 0x80u);
  EXPECT_EQ(ReadInOrder<uint16_t>(std::endian::little, kNumber), 0x2211u);

  EXPECT_EQ(ReadInOrder<int16_t>(std::endian::little, "\0\0"), 0);
  EXPECT_EQ(ReadInOrder<int16_t>(std::endian::little, "\x80\0"), 0x80);
  EXPECT_EQ(ReadInOrder<int16_t>(std::endian::little, kNumber), 0x2211);
}

TEST(ReadInOrder, 32Bit_Big) {
  EXPECT_EQ(ReadInOrder<uint32_t>(std::endian::big, "\0\0\0\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint32_t>(std::endian::big, "\x80\0\0\0"), 0x80000000u);
  EXPECT_EQ(ReadInOrder<uint32_t>(std::endian::big, kNumber), 0x11223344u);

  EXPECT_EQ(ReadInOrder<int32_t>(std::endian::big, "\0\0\0\0"), 0);
  EXPECT_EQ(ReadInOrder<int32_t>(std::endian::big, "\x80\0\0\0"), -2147483648);
  EXPECT_EQ(ReadInOrder<int32_t>(std::endian::big, kNumber), 0x11223344);
}

TEST(ReadInOrder, 32Bit_Little) {
  EXPECT_EQ(ReadInOrder<uint32_t>(std::endian::little, "\0\0\0\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint32_t>(std::endian::little, "\x80\0\0\0"), 0x80u);
  EXPECT_EQ(ReadInOrder<uint32_t>(std::endian::little, kNumber), 0x44332211u);

  EXPECT_EQ(ReadInOrder<int32_t>(std::endian::little, "\0\0\0\0"), 0);
  EXPECT_EQ(ReadInOrder<int32_t>(std::endian::little, "\x80\0\0\0"), 0x80);
  EXPECT_EQ(ReadInOrder<int32_t>(std::endian::little, kNumber), 0x44332211);
}

TEST(ReadInOrder, 64Bit_Big) {
  EXPECT_EQ(ReadInOrder<uint64_t>(std::endian::big, "\0\0\0\0\0\0\0\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint64_t>(std::endian::big, "\x80\0\0\0\0\0\0\0"),
            0x80000000'00000000llu);
  EXPECT_EQ(ReadInOrder<uint64_t>(std::endian::big, kNumber),
            0x11223344AABBCCDDu);

  EXPECT_EQ(ReadInOrder<int64_t>(std::endian::big, "\0\0\0\0\0\0\0\0"), 0);
  EXPECT_EQ(ReadInOrder<int64_t>(std::endian::big, "\x80\0\0\0\0\0\0\0"),
            static_cast<int64_t>(1llu << 63));
  EXPECT_EQ(ReadInOrder<int64_t>(std::endian::big, kNumber),
            0x11223344AABBCCDD);
}

TEST(ReadInOrder, 64Bit_Little) {
  EXPECT_EQ(ReadInOrder<uint64_t>(std::endian::little, "\0\0\0\0\0\0\0\0"), 0u);
  EXPECT_EQ(ReadInOrder<uint64_t>(std::endian::little, "\x80\0\0\0\0\0\0\0"),
            0x80u);
  EXPECT_EQ(ReadInOrder<uint64_t>(std::endian::little, kNumber),
            0xDDCCBBAA44332211u);

  EXPECT_EQ(ReadInOrder<int64_t>(std::endian::little, "\0\0\0\0\0\0\0\0"), 0);
  EXPECT_EQ(ReadInOrder<int64_t>(std::endian::little, "\x80\0\0\0\0\0\0\0"),
            0x80);
  EXPECT_EQ(ReadInOrder<int64_t>(std::endian::little, kNumber),
            static_cast<int64_t>(0xDDCCBBAA44332211));
}

TEST(ReadInOrder, StdArray) {
  std::array<std::byte, 4> buffer = Array<1, 2, 3, 4>();
  EXPECT_EQ(0x04030201, ReadInOrder<int32_t>(std::endian::little, buffer));
  EXPECT_EQ(0x01020304, ReadInOrder<int32_t>(std::endian::big, buffer));
}

TEST(ReadInOrder, CArray) {
  char buffer[5] = {1, 2, 3, 4, 99};
  EXPECT_EQ(0x04030201, ReadInOrder<int32_t>(std::endian::little, buffer));
  EXPECT_EQ(0x01020304, ReadInOrder<int32_t>(std::endian::big, buffer));
}

TEST(ReadInOrder, BoundsChecking_Ok) {
  constexpr auto buffer = Array<1, 2, 3, 4>();
  uint16_t value = 0;
  EXPECT_TRUE(ReadInOrder(std::endian::little, buffer, value));
  EXPECT_EQ(0x0201, value);
}

TEST(ReadInOrder, BoundsChecking_TooSmall) {
  constexpr auto buffer = Array<1, 2, 3>();
  int32_t value = 0;
  EXPECT_FALSE(ReadInOrder(std::endian::little, buffer, value));
  EXPECT_EQ(0, value);
}

}  // namespace
}  // namespace pw::bytes