// Copyright 2019 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/developer/debug/zxdb/common/data_extractor.h"

#include <limits>

#include <gtest/gtest.h>

namespace zxdb {

TEST(DataExtractor, Numbers) {
  // clang-format off
  std::vector<uint8_t> buffer{
      0x10,
      0x20, 0x21,
      0x30, 0x31, 0x32, 0x33,
      0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47 };
  // clang-format on

  // Signed integers (little-endian).
  DataExtractor ext(buffer);
  EXPECT_FALSE(ext.done());
  EXPECT_EQ(std::optional<int8_t>(0x10), ext.Read<int8_t>());
  EXPECT_EQ(std::optional<int16_t>(0x2120), ext.Read<int16_t>());
  EXPECT_EQ(std::optional<int32_t>(0x33323130), ext.Read<int32_t>());
  EXPECT_EQ(std::optional<int64_t>(0x4746454443424140), ext.Read<int64_t>());
  EXPECT_EQ(std::optional<int8_t>(), ext.Read<int8_t>());  // Read past end fails.
  EXPECT_TRUE(ext.done());

  // Unsigned integers (little-endian).
  ext = DataExtractor(buffer);
  EXPECT_EQ(std::optional<uint8_t>(0x10), ext.Read<uint8_t>());
  EXPECT_EQ(std::optional<uint16_t>(0x2120), ext.Read<uint16_t>());
  EXPECT_EQ(std::optional<uint32_t>(0x33323130), ext.Read<uint32_t>());
  EXPECT_EQ(std::optional<uint64_t>(0x4746454443424140), ext.Read<uint64_t>());

  // Reading past the end sould leave the position unchanged (buffer is 15 bytes long).
  ext = DataExtractor(buffer);
  ext.Read<uint64_t>();
  EXPECT_EQ(8u, ext.cur());
  EXPECT_FALSE(ext.Read<uint64_t>());  // Read fails.
  EXPECT_EQ(8u, ext.cur());            // Position is unchanged.
}

TEST(DataExtractor, Manual) {
  std::vector<uint8_t> buffer{0x01, 0x02, 0x03, 0x04};

  DataExtractor ext(buffer);
  EXPECT_EQ(0u, ext.cur());
  EXPECT_TRUE(ext.CanRead(1));
  EXPECT_TRUE(ext.CanRead(4));
  EXPECT_FALSE(ext.CanRead(5));

  EXPECT_EQ(0u, ext.cur());
  ext.Advance(2);
  EXPECT_EQ(2u, ext.cur());
  ext.Advance(0);
  EXPECT_EQ(2u, ext.cur());
  EXPECT_TRUE(ext.CanRead(2));
  EXPECT_FALSE(ext.CanRead(3));

  // Advances one-past-the end. Should stop at the end.
  ext.Advance(3);
  EXPECT_EQ(4u, ext.cur());
  EXPECT_TRUE(ext.CanRead(0));
  EXPECT_FALSE(ext.CanRead(1));

  // Test overflow of size variables. In this case size + read_size overflows.
  size_t big_read = std::numeric_limits<size_t>::max() - 1;
  ext = DataExtractor(buffer);
  EXPECT_FALSE(ext.CanRead(big_read));

  // Here cur + read_size overflows.
  ext.Advance(2);
  EXPECT_FALSE(ext.CanRead(big_read));
}

}  // namespace zxdb