/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-*/
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "gtest/gtest.h"

#include "DriftController.h"
#include "mozilla/Maybe.h"

using namespace mozilla;

TEST(TestDriftController, Basic)
{
  // The buffer level is the only input to the controller logic.
  constexpr uint32_t buffered = 5 * 480;
  constexpr uint32_t bufferedLow = 3 * 480;
  constexpr uint32_t bufferedHigh = 7 * 480;

  DriftController c(48000, 48000, media::TimeUnit::FromSeconds(0.05));
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000U);

  // The adjustment interval is 1s.
  const auto oneSec = media::TimeUnit(48000, 48000);

  c.UpdateClock(oneSec, oneSec, buffered, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, bufferedLow, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48048u);

  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 47952u);
}

TEST(TestDriftController, BasicResampler)
{
  // The buffer level is the only input to the controller logic.
  constexpr uint32_t buffered = 5 * 240;
  constexpr uint32_t bufferedLow = 3 * 240;
  constexpr uint32_t bufferedHigh = 7 * 240;

  DriftController c(24000, 48000, media::TimeUnit::FromSeconds(0.05));

  // The adjustment interval is 1s.
  const auto oneSec = media::TimeUnit(48000, 48000);

  c.UpdateClock(oneSec, oneSec, buffered, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  // low
  c.UpdateClock(oneSec, oneSec, bufferedLow, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48048u);

  // high
  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  // high
  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 47964u);
}

TEST(TestDriftController, BufferedInput)
{
  // The buffer level is the only input to the controller logic.
  constexpr uint32_t buffered = 5 * 480;
  constexpr uint32_t bufferedLow = 3 * 480;
  constexpr uint32_t bufferedHigh = 7 * 480;

  DriftController c(48000, 48000, media::TimeUnit::FromSeconds(0.05));
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  // The adjustment interval is 1s.
  const auto oneSec = media::TimeUnit(48000, 48000);

  c.UpdateClock(oneSec, oneSec, buffered, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  // 0 buffered when updating correction
  c.UpdateClock(oneSec, oneSec, 0, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48048u);

  c.UpdateClock(oneSec, oneSec, bufferedLow, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, buffered, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 47952u);
}

TEST(TestDriftController, BufferedInputWithResampling)
{
  // The buffer level is the only input to the controller logic.
  constexpr uint32_t buffered = 5 * 240;
  constexpr uint32_t bufferedLow = 3 * 240;
  constexpr uint32_t bufferedHigh = 7 * 240;

  DriftController c(24000, 48000, media::TimeUnit::FromSeconds(0.05));
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  // The adjustment interval is 1s.
  const auto oneSec = media::TimeUnit(24000, 24000);

  c.UpdateClock(oneSec, oneSec, buffered, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  // 0 buffered when updating correction
  c.UpdateClock(oneSec, oneSec, 0, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48048u);

  c.UpdateClock(oneSec, oneSec, bufferedLow, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, buffered, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 47952u);
}

TEST(TestDriftController, SmallError)
{
  // The buffer level is the only input to the controller logic.
  constexpr uint32_t buffered = 5 * 480;
  constexpr uint32_t bufferedLow = buffered - 48;
  constexpr uint32_t bufferedHigh = buffered + 48;

  DriftController c(48000, 48000, media::TimeUnit::FromSeconds(0.05));
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  // The adjustment interval is 1s.
  const auto oneSec = media::TimeUnit(48000, 48000);

  c.UpdateClock(oneSec, oneSec, buffered, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, bufferedLow, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);

  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);
  c.UpdateClock(oneSec, oneSec, bufferedHigh, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000u);
}

TEST(TestDriftController, SmallBufferedFrames)
{
  // The buffer level is the only input to the controller logic.
  constexpr uint32_t bufferedLow = 3 * 480;

  DriftController c(48000, 48000, media::TimeUnit::FromSeconds(0.05));
  media::TimeUnit oneSec = media::TimeUnit::FromSeconds(1);
  media::TimeUnit hundredMillis = oneSec / 10;

  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000U);
  for (uint32_t i = 0; i < 9; ++i) {
    c.UpdateClock(hundredMillis, hundredMillis, bufferedLow, 0);
  }
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48000U);
  c.UpdateClock(hundredMillis, hundredMillis, bufferedLow, 0);
  EXPECT_EQ(c.GetCorrectedTargetRate(), 48048U);
}