// Copyright (c) 2012 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 "media/base/fake_audio_worker.h"
#include "base/bind.h"
#include "base/macros.h"
#include "base/message_loop/message_loop.h"
#include "base/run_loop.h"
#include "base/single_thread_task_runner.h"
#include "base/time/time.h"
#include "media/base/audio_parameters.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace media {

static const int kTestCallbacks = 5;

class FakeAudioWorkerTest : public testing::Test {
 public:
  FakeAudioWorkerTest()
      : params_(AudioParameters::AUDIO_FAKE,
                CHANNEL_LAYOUT_STEREO,
                44100,
                128),
        fake_worker_(message_loop_.task_runner(), params_),
        seen_callbacks_(0) {
    time_between_callbacks_ = base::TimeDelta::FromMicroseconds(
        params_.frames_per_buffer() * base::Time::kMicrosecondsPerSecond /
        static_cast<float>(params_.sample_rate()));
  }

  ~FakeAudioWorkerTest() override = default;

  void CalledByFakeWorker() { seen_callbacks_++; }

  void RunOnAudioThread() {
    ASSERT_TRUE(message_loop_.task_runner()->BelongsToCurrentThread());
    fake_worker_.Start(base::Bind(&FakeAudioWorkerTest::CalledByFakeWorker,
                                  base::Unretained(this)));
  }

  void RunOnceOnAudioThread() {
    ASSERT_TRUE(message_loop_.task_runner()->BelongsToCurrentThread());
    RunOnAudioThread();
    // Start() should immediately post a task to run the callback, so we
    // should end up with only a single callback being run.
    message_loop_.task_runner()->PostTask(
        FROM_HERE,
        base::Bind(&FakeAudioWorkerTest::EndTest, base::Unretained(this), 1));
  }

  void StopStartOnAudioThread() {
    ASSERT_TRUE(message_loop_.task_runner()->BelongsToCurrentThread());
    fake_worker_.Stop();
    RunOnAudioThread();
  }

  void TimeCallbacksOnAudioThread(int callbacks) {
    ASSERT_TRUE(message_loop_.task_runner()->BelongsToCurrentThread());

    if (seen_callbacks_ == 0) {
      RunOnAudioThread();
      start_time_ = base::TimeTicks::Now();
    }

    // Keep going until we've seen the requested number of callbacks.
    if (seen_callbacks_ < callbacks) {
      message_loop_.task_runner()->PostDelayedTask(
          FROM_HERE,
          base::Bind(&FakeAudioWorkerTest::TimeCallbacksOnAudioThread,
                     base::Unretained(this), callbacks),
          time_between_callbacks_ / 2);
    } else {
      end_time_ = base::TimeTicks::Now();
      EndTest(callbacks);
    }
  }

  void EndTest(int callbacks) {
    ASSERT_TRUE(message_loop_.task_runner()->BelongsToCurrentThread());
    fake_worker_.Stop();
    EXPECT_LE(callbacks, seen_callbacks_);
    run_loop_.QuitWhenIdle();
  }

 protected:
  base::MessageLoop message_loop_;
  base::RunLoop run_loop_;
  AudioParameters params_;
  FakeAudioWorker fake_worker_;
  base::TimeTicks start_time_;
  base::TimeTicks end_time_;
  base::TimeDelta time_between_callbacks_;
  int seen_callbacks_;

 private:
  DISALLOW_COPY_AND_ASSIGN(FakeAudioWorkerTest);
};

// Ensure the worker runs on the audio thread and fires callbacks.
TEST_F(FakeAudioWorkerTest, FakeBasicCallback) {
  message_loop_.task_runner()->PostTask(
      FROM_HERE, base::BindOnce(&FakeAudioWorkerTest::RunOnceOnAudioThread,
                                base::Unretained(this)));
  run_loop_.Run();
}

// Ensure the time between callbacks is sane.
TEST_F(FakeAudioWorkerTest, TimeBetweenCallbacks) {
  message_loop_.task_runner()->PostTask(
      FROM_HERE,
      base::BindOnce(&FakeAudioWorkerTest::TimeCallbacksOnAudioThread,
                     base::Unretained(this), kTestCallbacks));
  run_loop_.Run();

  // There are only (kTestCallbacks - 1) intervals between kTestCallbacks.
  base::TimeDelta actual_time_between_callbacks =
      (end_time_ - start_time_) / (seen_callbacks_ - 1);

  // Ensure callback time is no faster than the expected time between callbacks.
  EXPECT_GE(actual_time_between_callbacks, time_between_callbacks_);

  // Softly check if the callback time is no slower than twice the expected time
  // between callbacks.  Since this test runs on the bots we can't be too strict
  // with the bounds.
  if (actual_time_between_callbacks > 2 * time_between_callbacks_)
    LOG(ERROR) << "Time between fake audio callbacks is too large!";
}

// Ensure Start()/Stop() on the worker doesn't generate too many callbacks. See
// http://crbug.com/159049.
TEST_F(FakeAudioWorkerTest, StartStopClearsCallbacks) {
  message_loop_.task_runner()->PostTask(
      FROM_HERE,
      base::BindOnce(&FakeAudioWorkerTest::TimeCallbacksOnAudioThread,
                     base::Unretained(this), kTestCallbacks));

  // Issue a Stop() / Start() in between expected callbacks to maximize the
  // chance of catching the worker doing the wrong thing.
  message_loop_.task_runner()->PostDelayedTask(
      FROM_HERE,
      base::Bind(&FakeAudioWorkerTest::StopStartOnAudioThread,
                 base::Unretained(this)),
      time_between_callbacks_ / 2);

  // EndTest() will ensure the proper number of callbacks have occurred.
  run_loop_.Run();
}

}  // namespace media