// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/metrics/unsent_log_store.h"

#include <stddef.h>
#include <limits>

#include "base/base64.h"
#include "base/hash/sha1.h"
#include "base/rand_util.h"
#include "base/values.h"
#include "components/metrics/unsent_log_store_metrics_impl.h"
#include "components/prefs/pref_registry_simple.h"
#include "components/prefs/scoped_user_pref_update.h"
#include "components/prefs/testing_pref_service.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "third_party/zlib/google/compression_utils.h"

namespace metrics {

namespace {

const char kTestPrefName[] = "TestPref";
const char kTestMetaDataPrefName[] = "TestMetaDataPref";

const size_t kLogCountLimit = 3;
const size_t kLogByteLimit = 1000;

// Compresses |log_data| and returns the result.
std::string Compress(const std::string& log_data) {
  std::string compressed_log_data;
  EXPECT_TRUE(compression::GzipCompress(log_data, &compressed_log_data));
  return compressed_log_data;
}

// Generates and returns log data such that its size after compression is at
// least |min_compressed_size|.
std::string GenerateLogWithMinCompressedSize(size_t min_compressed_size) {
  // Since the size check is done against a compressed log, generate enough
  // data that compresses to larger than |log_size|.
  std::string rand_bytes = base::RandBytesAsString(min_compressed_size);
  while (Compress(rand_bytes).size() < min_compressed_size)
    rand_bytes.append(base::RandBytesAsString(min_compressed_size));
  std::string base64_data_for_logging;
  base::Base64Encode(rand_bytes, &base64_data_for_logging);
  SCOPED_TRACE(testing::Message()
               << "Using random data " << base64_data_for_logging);
  return rand_bytes;
}

class UnsentLogStoreTest : public testing::Test {
 public:
  UnsentLogStoreTest() {
    prefs_.registry()->RegisterListPref(kTestPrefName);
    prefs_.registry()->RegisterDictionaryPref(kTestMetaDataPrefName);
  }

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

 protected:
  TestingPrefServiceSimple prefs_;
};

class TestUnsentLogStoreMetrics : public UnsentLogStoreMetrics {
 public:
  TestUnsentLogStoreMetrics() = default;

  void RecordLastUnsentLogMetadataMetrics(int unsent_samples_count,
                                          int sent_samples_count,
                                          int persisted_size_in_kb) override {
    unsent_samples_count_ = unsent_samples_count;
    sent_samples_count_ = sent_samples_count;
    persisted_size_in_kb_ = persisted_size_in_kb;
  }

  int unsent_samples_count() const { return unsent_samples_count_; }
  int sent_samples_count() const { return sent_samples_count_; }
  int persisted_size_in_kb() const { return persisted_size_in_kb_; }

 private:
  int unsent_samples_count_ = 0;
  int sent_samples_count_ = 0;
  int persisted_size_in_kb_ = 0;
};

class TestUnsentLogStore : public UnsentLogStore {
 public:
  TestUnsentLogStore(PrefService* service, size_t min_log_bytes)
      : UnsentLogStore(std::make_unique<UnsentLogStoreMetricsImpl>(),
                       service,
                       kTestPrefName,
                       /*metadata_pref_name=*/nullptr,
                       UnsentLogStore::UnsentLogStoreLimits{
                           .min_log_count = kLogCountLimit,
                           .min_queue_size_bytes = min_log_bytes,
                       },
                       /*signing_key=*/std::string(),
                       /*logs_event_manager=*/nullptr) {}
  TestUnsentLogStore(PrefService* service,
                     size_t min_log_bytes,
                     const std::string& signing_key)
      : UnsentLogStore(std::make_unique<UnsentLogStoreMetricsImpl>(),
                       service,
                       kTestPrefName,
                       /*metadata_pref_name=*/nullptr,
                       UnsentLogStore::UnsentLogStoreLimits{
                           .min_log_count = kLogCountLimit,
                           .min_queue_size_bytes = min_log_bytes,
                       },
                       signing_key,
                       /*logs_event_manager=*/nullptr) {}
  TestUnsentLogStore(std::unique_ptr<UnsentLogStoreMetrics> metrics,
                     PrefService* service,
                     size_t max_log_size)
      : UnsentLogStore(std::move(metrics),
                       service,
                       kTestPrefName,
                       kTestMetaDataPrefName,
                       UnsentLogStore::UnsentLogStoreLimits{
                           .min_log_count = kLogCountLimit,
                           .min_queue_size_bytes = 1,
                           .max_log_size_bytes = max_log_size,
                       },
                       /*signing_key=*/std::string(),
                       /*logs_event_manager=*/nullptr) {}

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

  // Stages and removes the next log, while testing it's value.
  void ExpectNextLog(const std::string& expected_log) {
    StageNextLog();
    EXPECT_EQ(staged_log(), Compress(expected_log));
    DiscardStagedLog();
  }
};

}  // namespace

// Store and retrieve empty list_value.
TEST_F(UnsentLogStoreTest, EmptyLogList) {
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);

  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);
  EXPECT_EQ(0U, prefs_.GetList(kTestPrefName).size());

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(0U, result_unsent_log_store.size());
}

// Store and retrieve a single log value.
TEST_F(UnsentLogStoreTest, SingleElementLogList) {
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);

  LogMetadata log_metadata;
  unsent_log_store.StoreLog("Hello world!", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(1U, result_unsent_log_store.size());

  // Verify that the result log matches the initial log.
  unsent_log_store.StageNextLog();
  result_unsent_log_store.StageNextLog();
  EXPECT_EQ(unsent_log_store.staged_log(),
            result_unsent_log_store.staged_log());
  EXPECT_EQ(unsent_log_store.staged_log_hash(),
            result_unsent_log_store.staged_log_hash());
  EXPECT_EQ(unsent_log_store.staged_log_signature(),
            result_unsent_log_store.staged_log_signature());
  EXPECT_EQ(unsent_log_store.staged_log_timestamp(),
            result_unsent_log_store.staged_log_timestamp());
}

// Store a set of logs over the length limit, but smaller than the min number of
// bytes. This should leave the logs unchanged.
TEST_F(UnsentLogStoreTest, LongButTinyLogList) {
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  LogMetadata log_metadata;

  size_t log_count = kLogCountLimit * 5;
  for (size_t i = 0; i < log_count; ++i)
    unsent_log_store.StoreLog("x", log_metadata,
                              MetricsLogsEventManager::CreateReason::kUnknown);

  EXPECT_EQ(log_count, unsent_log_store.size());
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);
  EXPECT_EQ(log_count, unsent_log_store.size());

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(unsent_log_store.size(), result_unsent_log_store.size());

  result_unsent_log_store.ExpectNextLog("x");
}

// Store a set of logs over the length limit, but that doesn't reach the minimum
// number of bytes until after passing the length limit.
TEST_F(UnsentLogStoreTest, LongButSmallLogList) {
  size_t log_count = kLogCountLimit * 5;
  size_t log_size = 50;
  LogMetadata log_metadata;

  std::string first_kept = "First to keep";
  first_kept.resize(log_size, ' ');

  std::string blank_log = std::string(log_size, ' ');

  std::string last_kept = "Last to keep";
  last_kept.resize(log_size, ' ');

  // Set the byte limit enough to keep everything but the first two logs.
  const size_t min_log_bytes = Compress(first_kept).length() +
                               Compress(last_kept).length() +
                               (log_count - 4) * Compress(blank_log).length();
  TestUnsentLogStore unsent_log_store(&prefs_, min_log_bytes);

  unsent_log_store.StoreLog("one", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StoreLog("two", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StoreLog(first_kept, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  for (size_t i = unsent_log_store.size(); i < log_count - 1; ++i) {
    unsent_log_store.StoreLog(blank_log, log_metadata,
                              MetricsLogsEventManager::CreateReason::kUnknown);
  }
  unsent_log_store.StoreLog(last_kept, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);

  size_t original_size = unsent_log_store.size();
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);
  // New size has been reduced.
  EXPECT_EQ(original_size - 2, unsent_log_store.size());

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  // Prefs should be the same size.
  EXPECT_EQ(unsent_log_store.size(), result_unsent_log_store.size());

  result_unsent_log_store.ExpectNextLog(last_kept);
  while (result_unsent_log_store.size() > 1) {
    result_unsent_log_store.ExpectNextLog(blank_log);
  }
  result_unsent_log_store.ExpectNextLog(first_kept);
}

// Store a set of logs within the length limit, but well over the minimum
// number of bytes. This should leave the logs unchanged.
TEST_F(UnsentLogStoreTest, ShortButLargeLogList) {
  // Make the total byte count about twice the minimum.
  size_t log_count = kLogCountLimit;
  size_t log_size = (kLogByteLimit / log_count) * 2;
  std::string log_data = GenerateLogWithMinCompressedSize(log_size);

  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  LogMetadata log_metadata;
  for (size_t i = 0; i < log_count; ++i) {
    unsent_log_store.StoreLog(log_data, log_metadata,
                              MetricsLogsEventManager::CreateReason::kUnknown);
  }
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  // Both have expected number of logs (original amount).
  EXPECT_EQ(kLogCountLimit, unsent_log_store.size());
  EXPECT_EQ(kLogCountLimit, result_unsent_log_store.size());
}

// Store a set of logs over the length limit, and over the minimum number of
// bytes. This will trim the set of logs.
TEST_F(UnsentLogStoreTest, LongAndLargeLogList) {
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);

  // Include twice the max number of logs.
  size_t log_count = kLogCountLimit * 2;
  // Make the total byte count about four times the minimum.
  size_t log_size = (kLogByteLimit / log_count) * 4;

  std::string target_log = "First to keep";
  target_log += GenerateLogWithMinCompressedSize(log_size);

  std::string log_data = GenerateLogWithMinCompressedSize(log_size);
  LogMetadata log_metadata;
  for (size_t i = 0; i < log_count; ++i) {
    if (i == log_count - kLogCountLimit)
      unsent_log_store.StoreLog(
          target_log, log_metadata,
          MetricsLogsEventManager::CreateReason::kUnknown);
    else
      unsent_log_store.StoreLog(
          log_data, log_metadata,
          MetricsLogsEventManager::CreateReason::kUnknown);
  }

  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  // Both original log and persisted are reduced to limit.
  EXPECT_EQ(kLogCountLimit, unsent_log_store.size());
  EXPECT_EQ(kLogCountLimit, result_unsent_log_store.size());

  while (result_unsent_log_store.size() > 1) {
    result_unsent_log_store.ExpectNextLog(log_data);
  }
  result_unsent_log_store.ExpectNextLog(target_log);
}

// Store a set of logs over the length limit, and over the minimum number of
// bytes. The first log will be a staged log that should be trimmed away. This
// should make the log store not have a staged log anymore.
TEST_F(UnsentLogStoreTest, TrimStagedLog) {
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);

  // Make each log byte count the limit.
  size_t log_size = kLogByteLimit;

  // Create a target log that will be the staged log that we want to trim away.
  std::string target_log = "First that should be trimmed";
  target_log += GenerateLogWithMinCompressedSize(log_size);
  LogMetadata log_metadata;
  unsent_log_store.StoreLog(target_log, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StageNextLog();
  EXPECT_TRUE(unsent_log_store.has_staged_log());

  // Add |kLogCountLimit| additional logs.
  std::string log_data = GenerateLogWithMinCompressedSize(log_size);
  for (size_t i = 0; i < kLogCountLimit; ++i) {
    unsent_log_store.StoreLog(log_data, log_metadata,
                              MetricsLogsEventManager::CreateReason::kUnknown);
  }

  EXPECT_EQ(kLogCountLimit + 1, unsent_log_store.size());
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  // Verify that the first log (the staged one) was trimmed away, and that the
  // log store does not consider to have any staged log anymore. The other logs
  // are not trimmed because the most recent logs are prioritized and we trim
  // until we have |kLogCountLimit| logs.
  EXPECT_EQ(kLogCountLimit, unsent_log_store.size());
  EXPECT_FALSE(unsent_log_store.has_staged_log());
  // Verify that all of the logs in the log store are not the |target_log|.
  while (unsent_log_store.size() > 0) {
    unsent_log_store.ExpectNextLog(log_data);
  }
}

// Verifies that when calling TrimAndPersistUnsentLogs() with
// |overwrite_in_memory_store| set to false, the in memory log store is
// unaffected.
TEST_F(UnsentLogStoreTest,
       TrimAndPersistUnsentLogs_DoNotOverwriteInMemoryStore) {
  TestUnsentLogStore unsent_log_store(
      std::make_unique<UnsentLogStoreMetricsImpl>(), &prefs_, kLogByteLimit);

  LogMetadata log_metadata;
  std::string log_data = GenerateLogWithMinCompressedSize(kLogByteLimit + 1);
  unsent_log_store.StoreLog(log_data, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.TrimAndPersistUnsentLogs(
      /*overwrite_in_memory_store=*/false);

  // Verify that the log store still contains the log.
  EXPECT_EQ(1U, unsent_log_store.size());
  unsent_log_store.ExpectNextLog(log_data);

  // Verify that the log was trimmed when persisted to memory.
  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(0U, result_unsent_log_store.size());
}

// Verifies that TrimAndPersistUnsentLogs() maintains the log order.
TEST_F(UnsentLogStoreTest, TrimAndPersistUnsentLogs_MaintainsLogOrder) {
  TestUnsentLogStore unsent_log_store(
      std::make_unique<UnsentLogStoreMetricsImpl>(), &prefs_, kLogByteLimit);

  LogMetadata log_metadata;
  unsent_log_store.StoreLog("1", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StoreLog(GenerateLogWithMinCompressedSize(kLogByteLimit + 1),
                            log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StoreLog("2", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  // Verify that only the second log was trimmed (since it was over the max log
  // size), and that the log order was maintained. I.e., "2" should be the most
  // recent log, followed by "1".
  EXPECT_EQ(2U, unsent_log_store.size());
  unsent_log_store.ExpectNextLog("2");
  unsent_log_store.ExpectNextLog("1");

  // Similarly, verify that the order was also maintained in persistent memory.
  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(2U, result_unsent_log_store.size());
  result_unsent_log_store.ExpectNextLog("2");
  result_unsent_log_store.ExpectNextLog("1");
}

// Verifies that calling TrimAndPersistUnsentLogs() clears the pref list before
// writing the trimmed logs list.
TEST_F(UnsentLogStoreTest, TrimAndPersistUnsentLogs_OverwritesPrefs) {
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);

  LogMetadata log_metadata;
  unsent_log_store.StoreLog("Hello world!", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  // Call TrimAndPersistUnsentLogs(). The log should not be trimmed.
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(1U, result_unsent_log_store.size());

  // Verify that the result log matches the initial log.
  result_unsent_log_store.ExpectNextLog("Hello world!");

  // Call TrimAndPersistUnsentLogs() and load the persisted logs once again.
  // There should still only be one log.
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  TestUnsentLogStore result_unsent_log_store2(&prefs_, kLogByteLimit);
  result_unsent_log_store2.LoadPersistedUnsentLogs();
  EXPECT_EQ(1U, result_unsent_log_store2.size());

  // Verify that the result log matches the initial log.
  result_unsent_log_store2.ExpectNextLog("Hello world!");
}

// Check that the store/stage/discard functions work as expected.
TEST_F(UnsentLogStoreTest, Staging) {
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  LogMetadata log_metadata;
  std::string tmp;

  EXPECT_FALSE(unsent_log_store.has_staged_log());
  unsent_log_store.StoreLog("one", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  EXPECT_FALSE(unsent_log_store.has_staged_log());
  unsent_log_store.StoreLog("two", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StageNextLog();
  EXPECT_TRUE(unsent_log_store.has_staged_log());
  EXPECT_EQ(unsent_log_store.staged_log(), Compress("two"));
  unsent_log_store.StoreLog("three", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  EXPECT_EQ(unsent_log_store.staged_log(), Compress("two"));
  EXPECT_EQ(unsent_log_store.size(), 3U);
  unsent_log_store.DiscardStagedLog();
  EXPECT_FALSE(unsent_log_store.has_staged_log());
  EXPECT_EQ(unsent_log_store.size(), 2U);
  unsent_log_store.StageNextLog();
  EXPECT_EQ(unsent_log_store.staged_log(), Compress("three"));
  unsent_log_store.DiscardStagedLog();
  unsent_log_store.StageNextLog();
  EXPECT_EQ(unsent_log_store.staged_log(), Compress("one"));
  unsent_log_store.DiscardStagedLog();
  EXPECT_FALSE(unsent_log_store.has_staged_log());
  EXPECT_EQ(unsent_log_store.size(), 0U);
}

TEST_F(UnsentLogStoreTest, DiscardOrder) {
  // Ensure that the correct log is discarded if new logs are pushed while
  // a log is staged.
  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  LogMetadata log_metadata;

  unsent_log_store.StoreLog("one", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StageNextLog();
  unsent_log_store.StoreLog("two", log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.DiscardStagedLog();
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  TestUnsentLogStore result_unsent_log_store(&prefs_, kLogByteLimit);
  result_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(1U, result_unsent_log_store.size());
  result_unsent_log_store.ExpectNextLog("two");
}

TEST_F(UnsentLogStoreTest, Hashes) {
  const char kFooText[] = "foo";
  const std::string foo_hash = base::SHA1HashString(kFooText);
  LogMetadata log_metadata;

  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  unsent_log_store.StoreLog(kFooText, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StageNextLog();

  EXPECT_EQ(Compress(kFooText), unsent_log_store.staged_log());
  EXPECT_EQ(foo_hash, unsent_log_store.staged_log_hash());
}

TEST_F(UnsentLogStoreTest, Signatures) {
  const char kFooText[] = "foo";
  LogMetadata log_metadata;

  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  unsent_log_store.StoreLog(kFooText, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StageNextLog();

  EXPECT_EQ(Compress(kFooText), unsent_log_store.staged_log());

  // The expected signature as a base 64 encoded string. The value was obtained
  // by running the test with an empty expected_signature_base64 and taking the
  // actual value from the test failure message. Can be verifying by the
  // following python code:
  // import hmac, hashlib, base64
  // key = ''
  // print(base64.b64encode(
  //   hmac.new(key, msg='foo', digestmod=hashlib.sha256).digest()).decode())
  std::string expected_signature_base64 =
      "DA2Y9+PZ1F5y6Id7wbEEMn77nAexjy/+ztdtgTB/H/8=";

  std::string actual_signature_base64;
  base::Base64Encode(unsent_log_store.staged_log_signature(),
                     &actual_signature_base64);
  EXPECT_EQ(expected_signature_base64, actual_signature_base64);

  // Test a different key results in a different signature.
  std::string key = "secret key, don't tell anyone";
  TestUnsentLogStore unsent_log_store_different_key(&prefs_, kLogByteLimit,
                                                    key);

  unsent_log_store_different_key.StoreLog(
      kFooText, log_metadata, MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store_different_key.StageNextLog();

  EXPECT_EQ(Compress(kFooText), unsent_log_store_different_key.staged_log());

  // Base 64 encoded signature obtained in similar fashion to previous
  // signature. To use previous python code change:
  // key = "secret key, don't tell anyone"
  expected_signature_base64 = "DV7z8wdDrjLkQrCzrXR3UjWsR3/YVM97tIhMnhUvfXM=";
  base::Base64Encode(unsent_log_store_different_key.staged_log_signature(),
                     &actual_signature_base64);

  EXPECT_EQ(expected_signature_base64, actual_signature_base64);
}

TEST_F(UnsentLogStoreTest, StoreLogWithUserId) {
  const char foo_text[] = "foo";
  const uint64_t user_id = 12345L;

  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  LogMetadata log_metadata(absl::nullopt, user_id);
  unsent_log_store.StoreLog(foo_text, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StageNextLog();

  EXPECT_EQ(Compress(foo_text), unsent_log_store.staged_log());
  EXPECT_EQ(unsent_log_store.staged_log_user_id().value(), user_id);

  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  // Reads persisted logs from new log store.
  TestUnsentLogStore read_unsent_log_store(&prefs_, kLogByteLimit);
  read_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(1U, read_unsent_log_store.size());

  // Ensure that the user_id was parsed correctly.
  read_unsent_log_store.StageNextLog();
  EXPECT_EQ(user_id, read_unsent_log_store.staged_log_user_id().value());
}

TEST_F(UnsentLogStoreTest, StoreLogWithLargeUserId) {
  const char foo_text[] = "foo";
  const uint64_t large_user_id = std::numeric_limits<uint64_t>::max();

  TestUnsentLogStore unsent_log_store(&prefs_, kLogByteLimit);
  LogMetadata log_metadata(absl::nullopt, large_user_id);
  unsent_log_store.StoreLog(foo_text, log_metadata,
                            MetricsLogsEventManager::CreateReason::kUnknown);
  unsent_log_store.StageNextLog();

  EXPECT_EQ(Compress(foo_text), unsent_log_store.staged_log());
  EXPECT_EQ(unsent_log_store.staged_log_user_id().value(), large_user_id);

  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  // Reads persisted logs from new log store.
  TestUnsentLogStore read_unsent_log_store(&prefs_, kLogByteLimit);
  read_unsent_log_store.LoadPersistedUnsentLogs();
  EXPECT_EQ(1U, read_unsent_log_store.size());

  // Ensure that the user_id was parsed correctly.
  read_unsent_log_store.StageNextLog();
  EXPECT_EQ(large_user_id, read_unsent_log_store.staged_log_user_id().value());
}

TEST_F(UnsentLogStoreTest, UnsentLogMetadataMetrics) {
  std::unique_ptr<TestUnsentLogStoreMetrics> metrics =
      std::make_unique<TestUnsentLogStoreMetrics>();
  TestUnsentLogStoreMetrics* m = metrics.get();
  TestUnsentLogStore unsent_log_store(std::move(metrics), &prefs_,
                                      kLogByteLimit * 10);

  // Prepare 4 logs.
  const char kFooText[] = "foo";
  const base::HistogramBase::Count kFooSampleCount = 3;

  // The |foobar_log| whose compressed size is over 1kb will be staged first, so
  // the persisted_size_in_kb shall be reduced by 1kb afterwards.
  std::string foobar_log = GenerateLogWithMinCompressedSize(1024);
  const base::HistogramBase::Count kFooBarSampleCount = 5;

  // The |oversize_log| shall not be persisted.
  std::string oversize_log =
      GenerateLogWithMinCompressedSize(kLogByteLimit * 10 + 1);
  const base::HistogramBase::Count kOversizeLogSampleCount = 50;

  // The log without the SampleCount will not be counted to metrics.
  const char kNoSampleLog[] = "no sample log";

  LogMetadata log_metadata_with_oversize_sample(kOversizeLogSampleCount,
                                                absl::nullopt);
  unsent_log_store.StoreLog(oversize_log, log_metadata_with_oversize_sample,
                            MetricsLogsEventManager::CreateReason::kUnknown);

  LogMetadata log_metadata_with_no_sample;
  unsent_log_store.StoreLog(kNoSampleLog, log_metadata_with_no_sample,
                            MetricsLogsEventManager::CreateReason::kUnknown);

  LogMetadata log_metadata_foo_sample(kFooSampleCount, absl::nullopt);
  unsent_log_store.StoreLog(kFooText, log_metadata_foo_sample,
                            MetricsLogsEventManager::CreateReason::kUnknown);

  // The foobar_log will be staged first.
  LogMetadata log_metadata_foo_bar_sample(kFooBarSampleCount, absl::nullopt);
  unsent_log_store.StoreLog(foobar_log, log_metadata_foo_bar_sample,
                            MetricsLogsEventManager::CreateReason::kUnknown);

  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);

  unsent_log_store.RecordMetaDataMetrics();
  // The |oversize_log| was ignored, the kNoSampleLog won't be counted to
  // metrics,
  EXPECT_EQ(kFooSampleCount + kFooBarSampleCount, m->unsent_samples_count());
  EXPECT_EQ(0, m->sent_samples_count());
  EXPECT_EQ(2, m->persisted_size_in_kb());

  // Pretend to send log.
  unsent_log_store.StageNextLog();
  unsent_log_store.MarkStagedLogAsSent();
  unsent_log_store.DiscardStagedLog();
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);
  unsent_log_store.RecordMetaDataMetrics();

  // The |foobar_log| shall be sent.
  EXPECT_EQ(kFooSampleCount, m->unsent_samples_count());
  EXPECT_EQ(kFooBarSampleCount, m->sent_samples_count());
  EXPECT_EQ(1, m->persisted_size_in_kb());

  // Pretend |kFooText| upload failure.
  unsent_log_store.StageNextLog();
  unsent_log_store.DiscardStagedLog();
  unsent_log_store.TrimAndPersistUnsentLogs(/*overwrite_in_memory_store=*/true);
  unsent_log_store.RecordMetaDataMetrics();

  // Verify the failed upload wasn't added to the sent samples count.
  EXPECT_EQ(0, m->unsent_samples_count());
  EXPECT_EQ(kFooBarSampleCount, m->sent_samples_count());
  EXPECT_EQ(1, m->persisted_size_in_kb());
}

}  // namespace metrics