// Copyright 2014 The Chromium 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 "components/metrics/compression_utils.h"

#include <string>

#include "base/basictypes.h"
#include "base/logging.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace metrics {

namespace {

// The data to be compressed by gzip. This is the hex representation of "hello
// world".
const uint8 kData[] =
    {0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x77, 0x6f,
     0x72, 0x6c, 0x64};

// This is the string representation of gzip compressed string above. It was
// obtained by running echo -n "hello world" | gzip -c | hexdump -e '8 1 ",
// 0x%x"' followed by 0'ing out the OS byte (10th byte) in the header. This is
// so that the test passes on all platforms (that run various OS'es).
const uint8 kCompressedData[] =
    {0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
     0x00, 0xcb, 0x48, 0xcd, 0xc9, 0xc9, 0x57, 0x28, 0xcf,
     0x2f, 0xca, 0x49, 0x01, 0x00, 0x85, 0x11, 0x4a, 0x0d,
     0x0b, 0x00, 0x00, 0x00};

}  // namespace

TEST(CompressionUtilsTest, GzipCompression) {
  std::string data(reinterpret_cast<const char*>(kData), arraysize(kData));
  std::string compressed_data;
  EXPECT_TRUE(GzipCompress(data, &compressed_data));
  std::string golden_compressed_data(
      reinterpret_cast<const char*>(kCompressedData),
      arraysize(kCompressedData));
  EXPECT_EQ(golden_compressed_data, compressed_data);
}

TEST(CompressionUtilsTest, GzipUncompression) {
  std::string compressed_data(reinterpret_cast<const char*>(kCompressedData),
                              arraysize(kCompressedData));

  std::string uncompressed_data;
  EXPECT_TRUE(GzipUncompress(compressed_data, &uncompressed_data));

  std::string golden_data(reinterpret_cast<const char*>(kData),
                          arraysize(kData));
  EXPECT_EQ(golden_data, uncompressed_data);
}

// Checks that compressing/decompressing input > 256 bytes works as expected.
TEST(CompressionUtilsTest, LargeInput) {
  const size_t kSize = 32 * 1024;

  // Generate a data string of |kSize| for testing.
  std::string data;
  data.resize(kSize);
  for (size_t i = 0; i < kSize; ++i)
    data[i] = static_cast<char>(i & 0xFF);

  std::string compressed_data;
  EXPECT_TRUE(GzipCompress(data, &compressed_data));

  std::string uncompressed_data;
  EXPECT_TRUE(GzipUncompress(compressed_data, &uncompressed_data));

  EXPECT_EQ(data, uncompressed_data);
}

TEST(CompressionUtilsTest, InPlace) {
  const std::string original_data(reinterpret_cast<const char*>(kData),
                                  arraysize(kData));
  const std::string golden_compressed_data(
      reinterpret_cast<const char*>(kCompressedData),
      arraysize(kCompressedData));

  std::string data(original_data);
  EXPECT_TRUE(GzipCompress(data, &data));
  EXPECT_EQ(golden_compressed_data, data);
  EXPECT_TRUE(GzipUncompress(data, &data));
  EXPECT_EQ(original_data, data);
}

}  // namespace metrics