// Copyright 2018 Google LLC
//
// 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
//
//     http://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 "google/cloud/log.h"
#include "google/cloud/testing_util/scoped_environment.h"
#include <gmock/gmock.h>
#include <chrono>
#include <thread>

namespace google {
namespace cloud {
inline namespace GOOGLE_CLOUD_CPP_NS {
namespace {

using ::testing::_;
using ::testing::ExitedWithCode;
using ::testing::HasSubstr;

TEST(LogSeverityTest, Streaming) {
  std::ostringstream os;
  os << Severity::GCP_LS_TRACE;
  EXPECT_EQ("TRACE", os.str());
}

TEST(LogRecordTest, Streaming) {
  LogRecord lr;
  lr.severity = Severity::GCP_LS_INFO;
  lr.function = "Func";
  lr.filename = "filename.cc";
  lr.lineno = 123;
  lr.timestamp = std::chrono::system_clock::from_time_t(1585112316) +
                 std::chrono::microseconds(123456);
  lr.message = "message";
  auto const actual = [&] {
    std::ostringstream os;
    os << lr;
    return std::move(os).str();
  }();
  auto tid = [] {
    std::ostringstream os;
    os << std::this_thread::get_id();
    return std::move(os).str();
  }();
  EXPECT_THAT(actual, HasSubstr("2020-03-25T04:58:36.123456000Z"));
  EXPECT_THAT(actual, HasSubstr("[INFO]"));
  EXPECT_THAT(actual, HasSubstr("<" + tid + ">"));
  EXPECT_THAT(actual, HasSubstr("message"));
  EXPECT_THAT(actual, HasSubstr("(filename.cc:123)"));
}

TEST(LogSinkTest, CompileTimeEnabled) {
  EXPECT_TRUE(LogSink::CompileTimeEnabled(Severity::GCP_LS_CRITICAL));
  if (Severity::GCP_LS_LOWEST_ENABLED >= Severity::GCP_LS_TRACE) {
    EXPECT_FALSE(LogSink::CompileTimeEnabled(Severity::GCP_LS_TRACE));
  }
}

TEST(LogSinkTest, RuntimeSeverity) {
  LogSink sink;
  EXPECT_EQ(Severity::GCP_LS_LOWEST_ENABLED, sink.minimum_severity());
  sink.set_minimum_severity(Severity::GCP_LS_ERROR);
  EXPECT_EQ(Severity::GCP_LS_ERROR, sink.minimum_severity());
}

namespace {
class MockLogBackend : public LogBackend {
 public:
  MOCK_METHOD1(Process, void(LogRecord const&));
  MOCK_METHOD1(ProcessWithOwnership, void(LogRecord));
};
}  // namespace

TEST(LogSinkTest, BackendAddRemove) {
  LogSink sink;
  EXPECT_TRUE(sink.empty());
  // NOLINTNEXTLINE(google-runtime-int)
  long id = sink.AddBackend(std::make_shared<MockLogBackend>());
  EXPECT_FALSE(sink.empty());
  sink.RemoveBackend(id);
  EXPECT_TRUE(sink.empty());
}

TEST(LogSinkTest, ClearBackend) {
  LogSink sink;
  (void)sink.AddBackend(std::make_shared<MockLogBackend>());
  (void)sink.AddBackend(std::make_shared<MockLogBackend>());
  EXPECT_FALSE(sink.empty());
  sink.ClearBackends();
  EXPECT_TRUE(sink.empty());
}

TEST(LogSinkTest, LogEnabled) {
  LogSink sink;
  auto backend = std::make_shared<MockLogBackend>();
  EXPECT_CALL(*backend, ProcessWithOwnership(_))
      .WillOnce([](LogRecord const& lr) {
        EXPECT_EQ(Severity::GCP_LS_WARNING, lr.severity);
        EXPECT_EQ("test message", lr.message);
      });
  sink.AddBackend(backend);

  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_WARNING, sink) << "test message";
}

TEST(LogSinkTest, LogEnabledMultipleBackends) {
  LogSink sink;
  auto be1 = std::make_shared<MockLogBackend>();
  auto be2 = std::make_shared<MockLogBackend>();
  EXPECT_CALL(*be1, Process(_)).WillOnce([](LogRecord const& lr) {
    EXPECT_EQ(Severity::GCP_LS_WARNING, lr.severity);
    EXPECT_EQ("test message", lr.message);
  });
  sink.AddBackend(be1);
  EXPECT_CALL(*be2, Process(_)).WillOnce([](LogRecord const& lr) {
    EXPECT_EQ(Severity::GCP_LS_WARNING, lr.severity);
    EXPECT_EQ("test message", lr.message);
  });
  sink.AddBackend(be2);

  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_WARNING, sink) << "test message";
}

TEST(LogSinkTest, LogDefaultInstance) {
  auto backend = std::make_shared<MockLogBackend>();
  EXPECT_CALL(*backend, ProcessWithOwnership(_))
      .WillOnce([](LogRecord const& lr) {
        EXPECT_EQ(Severity::GCP_LS_WARNING, lr.severity);
        EXPECT_EQ("test message", lr.message);
      });
  LogSink::Instance().AddBackend(backend);

  GCP_LOG(WARNING) << "test message";
  LogSink::Instance().ClearBackends();
}

TEST(LogSinkTest, LogToClog) {
  LogSink::EnableStdClog();
  EXPECT_FALSE(LogSink::Instance().empty());
  LogSink::Instance().set_minimum_severity(Severity::GCP_LS_NOTICE);
  GCP_LOG(NOTICE) << "test message";
  LogSink::DisableStdClog();
  EXPECT_TRUE(LogSink::Instance().empty());
  EXPECT_EQ(0, LogSink::Instance().BackendCount());
  LogSink::Instance().ClearBackends();
}

TEST(LogSinkTest, ClogMultiple) {
  LogSink::EnableStdClog();
  EXPECT_FALSE(LogSink::Instance().empty());
  EXPECT_EQ(1, LogSink::Instance().BackendCount());
  LogSink::EnableStdClog();
  EXPECT_FALSE(LogSink::Instance().empty());
  EXPECT_EQ(1, LogSink::Instance().BackendCount());
  LogSink::EnableStdClog();
  EXPECT_FALSE(LogSink::Instance().empty());
  EXPECT_EQ(1, LogSink::Instance().BackendCount());
  LogSink::Instance().set_minimum_severity(Severity::GCP_LS_NOTICE);
  GCP_LOG(NOTICE) << "test message";
  LogSink::DisableStdClog();
  EXPECT_TRUE(LogSink::Instance().empty());
  EXPECT_EQ(0, LogSink::Instance().BackendCount());
}

TEST(LogSinkTest, ClogEnvironment) {
  // We set the death test style to "threadsafe", which causes the
  // ASSERT_EXIT() call to re-exec the test binary before executing the given
  // statement. This makes the death test thread-safe and it also ensures that
  // the LogSink singleton instance will be reconstructed in the child and will
  // see the environment variable. See also:
  // https://github.com/google/googletest/blob/master/googletest/docs/advanced.md#death-test-styles
  auto old_style = testing::FLAGS_gtest_death_test_style;
  testing::FLAGS_gtest_death_test_style = "threadsafe";

  testing_util::ScopedEnvironment env("GOOGLE_CLOUD_CPP_ENABLE_CLOG",
                                      "anyvalue");

  auto f = [] {
    GCP_LOG(INFO) << "testing clog";
    std::exit(42);
  };
  ASSERT_EXIT(f(), ExitedWithCode(42), HasSubstr("testing clog"));

  testing::FLAGS_gtest_death_test_style = old_style;
}

namespace {
/// A class to count calls to IOStream operator.
struct IOStreamCounter {
  int count;
};
std::ostream& operator<<(std::ostream& os, IOStreamCounter& rhs) {
  ++rhs.count;
  return os;
}
}  // namespace

TEST(LogSinkTest, LogCheckCounter) {
  LogSink sink;
  IOStreamCounter counter{0};
  // The following tests could pass if the << operator was a no-op, so for
  // extra paranoia check that this is not the case.
  auto backend = std::make_shared<MockLogBackend>();
  EXPECT_CALL(*backend, ProcessWithOwnership(_)).Times(2);
  sink.AddBackend(backend);
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_ALERT, sink) << "count is " << counter;
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_FATAL, sink) << "count is " << counter;
  EXPECT_EQ(2, counter.count);
}

TEST(LogSinkTest, LogNoSinks) {
  LogSink sink;
  IOStreamCounter counter{0};
  EXPECT_EQ(0, counter.count);
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_WARNING, sink) << "count is " << counter;
  // With no backends, we expect no calls to the iostream operators.
  EXPECT_EQ(0, counter.count);
}

TEST(LogSinkTest, LogDisabledLevels) {
  LogSink sink;
  IOStreamCounter counter{0};
  auto backend = std::make_shared<MockLogBackend>();
  EXPECT_CALL(*backend, ProcessWithOwnership(_)).Times(1);
  sink.AddBackend(backend);

  sink.set_minimum_severity(Severity::GCP_LS_INFO);
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_DEBUG, sink) << "count is " << counter;
  // With the DEBUG level disabled we expect no calls.
  EXPECT_EQ(0, counter.count);

  sink.set_minimum_severity(Severity::GCP_LS_ALERT);
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_ALERT, sink) << "count is " << counter;
  EXPECT_EQ(1, counter.count);
}

TEST(LogSinkTest, CompileTimeDisabledCannotBeEnabled) {
  LogSink sink;
  IOStreamCounter counter{0};
  auto backend = std::make_shared<MockLogBackend>();
  EXPECT_CALL(*backend, ProcessWithOwnership(_)).Times(1);
  sink.AddBackend(backend);

  // Compile-time disabled logs cannot be enabled at r
  if (Severity::GCP_LS_LOWEST_ENABLED >= Severity::GCP_LS_TRACE) {
    sink.set_minimum_severity(Severity::GCP_LS_TRACE);
    GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_TRACE, sink) << "count is " << counter;
    EXPECT_EQ(0, counter.count);
  }
  sink.set_minimum_severity(Severity::GCP_LS_CRITICAL);
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_CRITICAL, sink) << "count is " << counter;
  EXPECT_EQ(1, counter.count);
}

TEST(LogSinkTest, DisabledLogsMakeNoCalls) {
  LogSink sink;

  int counter = 0;
  auto caller = [&counter] { return ++counter; };

  EXPECT_EQ(0, counter);
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_WARNING, sink) << "count is " << caller();
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_WARNING, sink) << "count is " << caller();
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_WARNING, sink) << "count is " << caller();
  GOOGLE_CLOUD_CPP_LOG_I(GCP_LS_WARNING, sink) << "count is " << caller();
  // With no backends, we expect no calls to the expressions in the log line.
  EXPECT_EQ(0, counter);
}

}  // namespace
}  // namespace GOOGLE_CLOUD_CPP_NS
}  // namespace cloud
}  // namespace google