/*
 *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */

#include "webrtc/modules/remote_bitrate_estimator/test/bwe_test_framework.h"

#include <numeric>

#include "webrtc/test/gtest.h"
#include "webrtc/base/constructormagic.h"
#include "webrtc/modules/remote_bitrate_estimator/test/packet.h"
#include "webrtc/modules/remote_bitrate_estimator/test/packet_sender.h"
#include "webrtc/test/testsupport/fileutils.h"

namespace webrtc {
namespace testing {
namespace bwe {

static bool IsSequenceNumberSorted(const Packets& packets) {
  PacketsConstIt last_it = packets.begin();
  for (PacketsConstIt it = last_it; it != packets.end(); ++it) {
    const MediaPacket* packet = static_cast<const MediaPacket*>(*it);
    const MediaPacket* last_packet = static_cast<const MediaPacket*>(*last_it);
    if (IsNewerSequenceNumber(last_packet->header().sequenceNumber,
                              packet->header().sequenceNumber)) {
      return false;
    }
    last_it = it;
  }
  return true;
}

TEST(BweTestFramework_PacketTest, IsTimeSorted) {
  Packets packets;
  // Insert some packets in order...
  EXPECT_TRUE(IsTimeSorted(packets));

  packets.push_back(new MediaPacket(100, 0));
  EXPECT_TRUE(IsTimeSorted(packets));

  packets.push_back(new MediaPacket(110, 0));
  EXPECT_TRUE(IsTimeSorted(packets));

  // ...and one out-of-order...
  packets.push_back(new MediaPacket(100, 0));
  EXPECT_FALSE(IsTimeSorted(packets));

  // ...remove the out-of-order packet, insert another in-order packet.
  delete packets.back();
  packets.pop_back();
  packets.push_back(new MediaPacket(120, 0));
  EXPECT_TRUE(IsTimeSorted(packets));

  for (auto* packet : packets)
    delete packet;
}

TEST(BweTestFramework_PacketTest, IsSequenceNumberSorted) {
  Packets packets;
  // Insert some packets in order...
  EXPECT_TRUE(IsSequenceNumberSorted(packets));

  packets.push_back(new MediaPacket(0, 100));
  EXPECT_TRUE(IsSequenceNumberSorted(packets));

  packets.push_back(new MediaPacket(0, 110));
  EXPECT_TRUE(IsSequenceNumberSorted(packets));

  // ...and one out-of-order...
  packets.push_back(new MediaPacket(0, 100));
  EXPECT_FALSE(IsSequenceNumberSorted(packets));

  // ...remove the out-of-order packet, insert another in-order packet.
  delete packets.back();
  packets.pop_back();
  packets.push_back(new MediaPacket(0, 120));
  EXPECT_TRUE(IsSequenceNumberSorted(packets));

  for (auto* packet : packets)
    delete packet;
}

TEST(BweTestFramework_StatsTest, Mean) {
  Stats<int32_t> stats;
  EXPECT_EQ(0, stats.GetMean());

  stats.Push(1);
  stats.Push(3);
  EXPECT_EQ(2, stats.GetMean());

  // Integer division rounds (1+3-3)/3 to 0.
  stats.Push(-3);
  EXPECT_EQ(0, stats.GetMean());
}

TEST(BweTestFramework_StatsTest, Variance) {
  Stats<int32_t> stats;
  EXPECT_EQ(0, stats.GetVariance());

  // Mean is 2 ; ((1-2)*(1-2)+(3-2)*(3-2))/2 = (1+1)/2 = 1
  stats.Push(1);
  stats.Push(3);
  EXPECT_EQ(1, stats.GetVariance());

  // Integer division rounds 26/3 to 8
  // Mean is 0 ; (1*1+3*3+(-4)*(-4))/3 = (1+9+16)/3 = 8
  stats.Push(-4);
  EXPECT_EQ(8, stats.GetVariance());
}

TEST(BweTestFramework_StatsTest, StdDev) {
  Stats<int32_t> stats;
  EXPECT_EQ(0, stats.GetStdDev());

  // Variance is 1 ; sqrt(1) = 1
  stats.Push(1);
  stats.Push(3);
  EXPECT_EQ(1, stats.GetStdDev());

  // Variance is 8 ; sqrt(8) = 2 with integers.
  stats.Push(-4);
  EXPECT_EQ(2, stats.GetStdDev());
}

TEST(BweTestFramework_StatsTest, MinMax) {
  Stats<int32_t> stats;
  EXPECT_EQ(0, stats.GetMin());
  EXPECT_EQ(0, stats.GetMax());

  stats.Push(1);
  EXPECT_EQ(1, stats.GetMin());
  EXPECT_EQ(1, stats.GetMax());

  stats.Push(3);
  EXPECT_EQ(1, stats.GetMin());
  EXPECT_EQ(3, stats.GetMax());

  stats.Push(-4);
  EXPECT_EQ(-4, stats.GetMin());
  EXPECT_EQ(3, stats.GetMax());
}

class BweTestFramework_RateCounterFilterTest : public ::testing::Test {
 public:
  BweTestFramework_RateCounterFilterTest()
      : filter_(NULL, 0, "", ""), now_ms_(0) {}
  virtual ~BweTestFramework_RateCounterFilterTest() {}

 protected:
  void TestRateCounter(int64_t run_for_ms, uint32_t payload_bits,
                       uint32_t expected_pps, uint32_t expected_bps) {
    Packets packets;
    RTPHeader header;
    // "Send" a packet every 10 ms.
    for (int64_t i = 0; i < run_for_ms; i += 10, now_ms_ += 10) {
      packets.push_back(
          new MediaPacket(0, now_ms_ * 1000, payload_bits / 8, header));
    }
    filter_.RunFor(run_for_ms, &packets);
    ASSERT_TRUE(IsTimeSorted(packets));
    EXPECT_EQ(expected_pps, filter_.packets_per_second());
    EXPECT_EQ(expected_bps, filter_.bits_per_second());

    for (auto* packet : packets)
      delete packet;
  }

 private:
  RateCounterFilter filter_;
  int64_t now_ms_;

  RTC_DISALLOW_COPY_AND_ASSIGN(BweTestFramework_RateCounterFilterTest);
};

TEST_F(BweTestFramework_RateCounterFilterTest, Short) {
  // 100ms, 100 bytes per packet, should result in 10 pps and 8 kbps. We're
  // generating one packet every 10 ms ; 10 * 800 = 8k
  TestRateCounter(100, 800, 10, 8000);
}

TEST_F(BweTestFramework_RateCounterFilterTest, Medium) {
  // 100ms, like above.
  TestRateCounter(100, 800, 10, 8000);
  // 1000ms, 100 bpp, should result in 100 pps and 80 kbps. We're still
  // generating packets every 10 ms.
  TestRateCounter(900, 800, 100, 80000);
}

TEST_F(BweTestFramework_RateCounterFilterTest, Long) {
  // 100ms, 1000ms, like above.
  TestRateCounter(100, 800, 10, 8000);
  TestRateCounter(900, 800, 100, 80000);
  // 2000ms, should only see rate of last second, so 100 pps, and 40 kbps now.
  TestRateCounter(1000, 400, 100, 40000);
  // 2500ms, half a second with zero payload size. We should get same pps as
  // before, but kbps should drop to half of previous rate.
  TestRateCounter(500, 0, 100, 20000);
  // Another half second with zero payload size. Now the kbps rate should drop
  // to zero.
  TestRateCounter(500, 0, 100, 0);
  // Increate payload size again. 200 * 100 * 0.5 = 10 kbps.
  TestRateCounter(500, 200, 100, 10000);
}

static void TestLossFilter(float loss_percent, bool zero_tolerance) {
  LossFilter filter(NULL, 0);
  filter.SetLoss(loss_percent);
  Packets::size_type sent_packets = 0;
  Packets::size_type remaining_packets = 0;

  // No input should yield no output
  {
    Packets packets;
    sent_packets += packets.size();
    filter.RunFor(0, &packets);
    ASSERT_TRUE(IsTimeSorted(packets));
    ASSERT_TRUE(IsSequenceNumberSorted(packets));
    remaining_packets += packets.size();
    EXPECT_EQ(0u, sent_packets);
    EXPECT_EQ(0u, remaining_packets);
    for (auto* packet : packets)
      delete packet;
  }

  // Generate and process 10000 packets in different batch sizes (some empty)
  for (int i = 0; i < 2225; ++i) {
    Packets packets;
    for (int j = 0; j < i % 10; ++j)
      packets.push_back(new MediaPacket(i, i));
    sent_packets += packets.size();
    filter.RunFor(0, &packets);
    ASSERT_TRUE(IsTimeSorted(packets));
    ASSERT_TRUE(IsSequenceNumberSorted(packets));
    remaining_packets += packets.size();
    for (auto* packet : packets)
      delete packet;
  }

  float loss_fraction = 0.01f * (100.0f - loss_percent);
  Packets::size_type expected_packets = loss_fraction * sent_packets;
  if (zero_tolerance) {
    EXPECT_EQ(expected_packets, remaining_packets);
  } else {
    // Require within 1% of expected
    EXPECT_NEAR(expected_packets, remaining_packets, 100);
  }
}

TEST(BweTestFramework_LossFilterTest, Loss0) {
  // With 0% loss, the result should be exact (no loss).
  TestLossFilter(0.0f, true);
}

TEST(BweTestFramework_LossFilterTest, Loss10) {
  TestLossFilter(10.0f, false);
}

TEST(BweTestFramework_LossFilterTest, Loss50) {
  TestLossFilter(50.0f, false);
}

TEST(BweTestFramework_LossFilterTest, Loss100) {
  // With 100% loss, the result should be exact (no packets out).
  TestLossFilter(100.0f, true);
}

class BweTestFramework_DelayFilterTest : public ::testing::Test {
 public:
  BweTestFramework_DelayFilterTest()
      : filter_(NULL, 0), now_ms_(0), sequence_number_(0) {}
  virtual ~BweTestFramework_DelayFilterTest() {
    for (auto* packet : accumulated_packets_)
      delete packet;
  }

 protected:
  void TestDelayFilter(int64_t run_for_ms, uint32_t in_packets,
                       uint32_t out_packets) {
    Packets packets;
    for (uint32_t i = 0; i < in_packets; ++i) {
      packets.push_back(new MediaPacket(
          now_ms_ * 1000 + (sequence_number_ >> 4), sequence_number_));
      sequence_number_++;
    }
    filter_.RunFor(run_for_ms, &packets);
    ASSERT_TRUE(IsTimeSorted(packets));
    ASSERT_TRUE(IsSequenceNumberSorted(packets));
    for (PacketsConstIt it = packets.begin(); it != packets.end(); ++it) {
      EXPECT_LE(now_ms_ * 1000, (*it)->send_time_us());
    }
    EXPECT_EQ(out_packets, packets.size());
    accumulated_packets_.splice(accumulated_packets_.end(), packets);
    now_ms_ += run_for_ms;
  }

  void TestDelayFilter(int64_t delay_ms) {
    filter_.SetOneWayDelayMs(delay_ms);
    TestDelayFilter(1, 0, 0);    // No input should yield no output

    // Single packet
    TestDelayFilter(0, 1, 1);
    TestDelayFilter(delay_ms, 0, 0);

    for (int i = 0; i < delay_ms; ++i) {
      filter_.SetOneWayDelayMs(i);
      TestDelayFilter(1, 10, 10);
    }
    TestDelayFilter(0, 0, 0);
    TestDelayFilter(delay_ms, 0, 0);

    // Wait a little longer - should still see no output
    TestDelayFilter(delay_ms, 0, 0);

    for (int i = 1; i < delay_ms + 1; ++i) {
      filter_.SetOneWayDelayMs(i);
      TestDelayFilter(1, 5, 5);
    }
    TestDelayFilter(0, 0, 0);
    filter_.SetOneWayDelayMs(2 * delay_ms);
    TestDelayFilter(1, 0, 0);
    TestDelayFilter(delay_ms, 13, 13);
    TestDelayFilter(delay_ms, 0, 0);

    // Wait a little longer - should still see no output
    TestDelayFilter(delay_ms, 0, 0);

    for (int i = 0; i < 2 * delay_ms; ++i) {
      filter_.SetOneWayDelayMs(2 * delay_ms - i - 1);
      TestDelayFilter(1, 5, 5);
    }
    TestDelayFilter(0, 0, 0);
    filter_.SetOneWayDelayMs(0);
    TestDelayFilter(0, 7, 7);

    ASSERT_TRUE(IsTimeSorted(accumulated_packets_));
    ASSERT_TRUE(IsSequenceNumberSorted(accumulated_packets_));
  }

  DelayFilter filter_;
  Packets accumulated_packets_;

 private:
  int64_t now_ms_;
  uint16_t sequence_number_;

  RTC_DISALLOW_COPY_AND_ASSIGN(BweTestFramework_DelayFilterTest);
};

TEST_F(BweTestFramework_DelayFilterTest, Delay0) {
  TestDelayFilter(1, 0, 0);    // No input should yield no output
  TestDelayFilter(1, 10, 10);  // Expect no delay (delay time is zero)
  TestDelayFilter(1, 0, 0);    // Check no packets are still in buffer
  filter_.SetOneWayDelayMs(0);
  TestDelayFilter(1, 5, 5);    // Expect no delay (delay time is zero)
  TestDelayFilter(1, 0, 0);    // Check no packets are still in buffer
}

TEST_F(BweTestFramework_DelayFilterTest, Delay1) {
  TestDelayFilter(1);
}

TEST_F(BweTestFramework_DelayFilterTest, Delay2) {
  TestDelayFilter(2);
}

TEST_F(BweTestFramework_DelayFilterTest, Delay20) {
  TestDelayFilter(20);
}

TEST_F(BweTestFramework_DelayFilterTest, Delay100) {
  TestDelayFilter(100);
}

TEST_F(BweTestFramework_DelayFilterTest, JumpToZeroDelay) {
  DelayFilter delay(NULL, 0);
  Packets acc;
  Packets packets;

  // Delay a bunch of packets, accumulate them to the 'acc' list.
  delay.SetOneWayDelayMs(100.0f);
  for (uint32_t i = 0; i < 10; ++i) {
    packets.push_back(new MediaPacket(i * 100, i));
  }
  delay.RunFor(1000, &packets);
  acc.splice(acc.end(), packets);
  ASSERT_TRUE(IsTimeSorted(acc));
  ASSERT_TRUE(IsSequenceNumberSorted(acc));

  // Drop delay to zero, send a few more packets through the delay, append them
  // to the 'acc' list and verify that it is all sorted.
  delay.SetOneWayDelayMs(0.0f);
  for (uint32_t i = 10; i < 50; ++i) {
    packets.push_back(new MediaPacket(i * 100, i));
  }
  delay.RunFor(1000, &packets);
  acc.splice(acc.end(), packets);
  ASSERT_TRUE(IsTimeSorted(acc));
  ASSERT_TRUE(IsSequenceNumberSorted(acc));

  for (auto* packet : acc)
    delete packet;
}

TEST_F(BweTestFramework_DelayFilterTest, IncreasingDelay) {
  // Gradually increase delay.
  for (int i = 1; i < 50; i += 4) {
    TestDelayFilter(i);
  }
  // Reach a steady state.
  filter_.SetOneWayDelayMs(100);
  TestDelayFilter(1, 20, 20);
  TestDelayFilter(2, 0, 0);
  TestDelayFilter(99, 20, 20);
  // Drop delay back down to zero.
  filter_.SetOneWayDelayMs(0);
  TestDelayFilter(1, 100, 100);
  TestDelayFilter(23010, 0, 0);
  ASSERT_TRUE(IsTimeSorted(accumulated_packets_));
  ASSERT_TRUE(IsSequenceNumberSorted(accumulated_packets_));
}

static void TestJitterFilter(int64_t max_jitter_ms) {
  JitterFilter filter(NULL, 0);
  filter.SetMaxJitter(max_jitter_ms);

  int64_t now_ms = 0;
  uint16_t sequence_number = 0;

  // Generate packets, add jitter to them, accumulate the altered packets.
  Packets original;
  Packets jittered;
  for (uint32_t i = 0; i < 1000; ++i) {
    Packets packets;
    for (uint32_t j = 0; j < i % 100; ++j) {
      packets.push_back(new MediaPacket(now_ms * 1000, sequence_number));
      original.push_back(new MediaPacket(now_ms * 1000, sequence_number));
      ++sequence_number;
      now_ms += 5 * max_jitter_ms;
    }
    filter.RunFor(max_jitter_ms, &packets);
    jittered.splice(jittered.end(), packets);
  }

  // Jittered packets should still be in order.
  ASSERT_TRUE(IsTimeSorted(original));
  ASSERT_TRUE(IsTimeSorted(jittered));
  ASSERT_TRUE(IsSequenceNumberSorted(original));
  ASSERT_TRUE(IsSequenceNumberSorted(jittered));
  EXPECT_EQ(original.size(), jittered.size());

  // Make sure jittered and original packets are in same order. Collect time
  // difference (jitter) in stats, then check that mean jitter is close to zero
  // and standard deviation of jitter is what we set it to.
  Stats<double> jitter_us;
  int64_t max_jitter_obtained_us = 0;
  for (PacketsIt it1 = original.begin(), it2 = jittered.begin();
       it1 != original.end() && it2 != jittered.end(); ++it1, ++it2) {
    const MediaPacket* packet1 = static_cast<const MediaPacket*>(*it1);
    const MediaPacket* packet2 = static_cast<const MediaPacket*>(*it2);
    EXPECT_EQ(packet1->header().sequenceNumber,
              packet2->header().sequenceNumber);
    max_jitter_obtained_us =
        std::max(max_jitter_obtained_us,
                 packet2->send_time_us() - packet1->send_time_us());
    jitter_us.Push(packet2->send_time_us() - packet1->send_time_us());
  }
  EXPECT_NEAR(filter.MeanUs(), jitter_us.GetMean(),
              max_jitter_ms * 1000.0 * 0.01);
  EXPECT_NEAR(max_jitter_ms * 1000.0, max_jitter_obtained_us,
              max_jitter_ms * 1000.0 * 0.01);
  for (auto* packet : original)
    delete packet;
  for (auto* packet : jittered)
    delete packet;
}

TEST(BweTestFramework_JitterFilterTest, Jitter0) {
  TestJitterFilter(0);
}

TEST(BweTestFramework_JitterFilterTest, Jitter1) {
  TestJitterFilter(1);
}

TEST(BweTestFramework_JitterFilterTest, Jitter5) {
  TestJitterFilter(5);
}

TEST(BweTestFramework_JitterFilterTest, Jitter10) {
  TestJitterFilter(10);
}

TEST(BweTestFramework_JitterFilterTest, Jitter1031) {
  TestJitterFilter(1031);
}

static void TestReorderFilter(uint16_t reorder_percent) {
  const uint16_t kPacketCount = 10000;

  // Generate packets with 10 ms interval.
  Packets packets;
  int64_t now_ms = 0;
  uint16_t sequence_number = 1;
  for (uint16_t i = 0; i < kPacketCount; ++i, now_ms += 10) {
    packets.push_back(new MediaPacket(now_ms * 1000, sequence_number++));
  }
  ASSERT_TRUE(IsTimeSorted(packets));
  ASSERT_TRUE(IsSequenceNumberSorted(packets));

  // Reorder packets, verify that send times are still in order.
  ReorderFilter filter(NULL, 0);
  filter.SetReorder(reorder_percent);
  filter.RunFor(now_ms, &packets);
  ASSERT_TRUE(IsTimeSorted(packets));

  // We measure the amount of reordering by summing the distance by which out-
  // of-order packets have been moved in the stream.
  uint16_t distance = 0;
  uint16_t last_sequence_number = 0;
  for (auto* packet : packets) {
    const MediaPacket* media_packet = static_cast<const MediaPacket*>(packet);
    uint16_t sequence_number = media_packet->header().sequenceNumber;
    // The expected position for sequence number s is in position s-1.
    if (sequence_number < last_sequence_number) {
      distance += last_sequence_number - sequence_number;
    }
    last_sequence_number = sequence_number;
  }

  // The probability that two elements are swapped is p = reorder_percent / 100.
  double p = static_cast<double>(reorder_percent) / 100;
  // The expected number of swaps we perform is p * (PacketCount - 1),
  // and each swap increases the distance by one.
  double mean = p * (kPacketCount - 1);
  // If pair i is chosen to be swapped with probability p, the variance for that
  // pair is p * (1 - p). Since there are (kPacketCount - 1) independent pairs,
  // the variance for the number of swaps is (kPacketCount - 1) * p * (1 - p).
  double std_deviation = sqrt((kPacketCount - 1) * p * (1 - p));
  EXPECT_NEAR(mean, distance, 3 * std_deviation);

  for (auto* packet : packets)
    delete packet;
}

TEST(BweTestFramework_ReorderFilterTest, Reorder0) {
  // For 0% reordering, no packets should have been moved, so result is exact.
  TestReorderFilter(0);
}

TEST(BweTestFramework_ReorderFilterTest, Reorder10) {
  TestReorderFilter(10);
}

TEST(BweTestFramework_ReorderFilterTest, Reorder20) {
  TestReorderFilter(20);
}

TEST(BweTestFramework_ReorderFilterTest, Reorder50) {
  TestReorderFilter(50);
}

TEST(BweTestFramework_ReorderFilterTest, Reorder70) {
  TestReorderFilter(70);
}

TEST(BweTestFramework_ReorderFilterTest, Reorder100) {
  // Note that because the implementation works by optionally swapping two
  // adjacent packets, when the likelihood of a swap is 1.0, a swap will always
  // occur, so the stream will be in order except for the first packet, which
  // has been moved to the end. Therefore we expect the result to be exact here.
  TestReorderFilter(100.0);
}

class BweTestFramework_ChokeFilterTest : public ::testing::Test {
 public:
  BweTestFramework_ChokeFilterTest()
    : now_ms_(0),
      sequence_number_(0),
      output_packets_(),
      send_times_us_() {
  }
  virtual ~BweTestFramework_ChokeFilterTest() {
    for (auto* packet : output_packets_)
      delete packet;
  }

 protected:
  void TestChoke(PacketProcessor* filter,
                 int64_t run_for_ms,
                 uint32_t packets_to_generate,
                 size_t expected_kbit_transmitted) {
    // Generate a bunch of packets, apply choke, verify output is ordered.
    Packets packets;
    RTPHeader header;
    for (uint32_t i = 0; i < packets_to_generate; ++i) {
      int64_t send_time_ms = now_ms_ + (i * run_for_ms) / packets_to_generate;
      header.sequenceNumber = sequence_number_++;
      // Payload is 1000 bits.
      packets.push_back(new MediaPacket(0, send_time_ms * 1000, 125, header));
      send_times_us_.push_back(send_time_ms * 1000);
    }
    ASSERT_TRUE(IsTimeSorted(packets));
    filter->RunFor(run_for_ms, &packets);
    now_ms_ += run_for_ms;
    output_packets_.splice(output_packets_.end(), packets);
    ASSERT_TRUE(IsTimeSorted(output_packets_));
    ASSERT_TRUE(IsSequenceNumberSorted(output_packets_));

    // Sum up the transmitted bytes up until the current time.
    size_t bytes_transmitted = 0;
    while (!output_packets_.empty()) {
      const Packet* packet = output_packets_.front();
      if (packet->send_time_us() > now_ms_ * 1000) {
        break;
      }
      bytes_transmitted += packet->payload_size();
      delete output_packets_.front();
      output_packets_.pop_front();
    }
    EXPECT_EQ(expected_kbit_transmitted, (bytes_transmitted * 8 + 500) / 1000);
  }

  void CheckMaxDelay(int64_t max_delay_ms) {
    for (const auto* packet : output_packets_) {
      const MediaPacket* media_packet = static_cast<const MediaPacket*>(packet);
      int64_t delay_us = media_packet->send_time_us() -
                         send_times_us_[media_packet->header().sequenceNumber];
      EXPECT_GE(max_delay_ms * 1000, delay_us);
    }
  }

 private:
  int64_t now_ms_;
  uint16_t sequence_number_;
  Packets output_packets_;
  std::vector<int64_t> send_times_us_;

  RTC_DISALLOW_COPY_AND_ASSIGN(BweTestFramework_ChokeFilterTest);
};

TEST_F(BweTestFramework_ChokeFilterTest, NoQueue) {
  const int kCapacityKbps = 10;
  const size_t kPacketSizeBytes = 125;
  const int64_t kExpectedSendTimeUs =
      (kPacketSizeBytes * 8 * 1000 + kCapacityKbps / 2) / kCapacityKbps;
  uint16_t sequence_number = 0;
  int64_t send_time_us = 0;
  ChokeFilter filter(NULL, 0);
  filter.set_capacity_kbps(10);
  Packets packets;
  RTPHeader header;
  for (int i = 0; i < 2; ++i) {
    header.sequenceNumber = sequence_number++;
    // Payload is 1000 bits.
    packets.push_back(
        new MediaPacket(0, send_time_us, kPacketSizeBytes, header));
    // Packets are sent far enough a part plus an extra millisecond so that they
    // will never be in the choke queue at the same time.
    send_time_us += kExpectedSendTimeUs + 1000;
  }
  ASSERT_TRUE(IsTimeSorted(packets));
  filter.RunFor(2 * kExpectedSendTimeUs + 1000, &packets);
  EXPECT_EQ(kExpectedSendTimeUs, packets.front()->send_time_us());
  delete packets.front();
  packets.pop_front();
  EXPECT_EQ(2 * kExpectedSendTimeUs + 1000, packets.front()->send_time_us());
  delete packets.front();
  packets.pop_front();
}

TEST_F(BweTestFramework_ChokeFilterTest, Short) {
  // 100ms, 100 packets, 10 kbps choke -> 1 kbit of data should have propagated.
  // That is actually just a single packet, since each packet has 1000 bits of
  // payload.
  ChokeFilter filter(NULL, 0);
  filter.set_capacity_kbps(10);
  TestChoke(&filter, 100, 100, 1);
}

TEST_F(BweTestFramework_ChokeFilterTest, Medium) {
  // 100ms, 10 packets, 10 kbps choke -> 1 packet through, or 1 kbit.
  ChokeFilter filter(NULL, 0);
  filter.set_capacity_kbps(10);
  TestChoke(&filter, 100, 10, 1);
  // 200ms, no new packets -> another packet through.
  TestChoke(&filter, 100, 0, 1);
  // 1000ms, no new packets -> 8 more packets.
  TestChoke(&filter, 800, 0, 8);
  // 2000ms, no new packets -> queue is empty so no output.
  TestChoke(&filter, 1000, 0, 0);
}

TEST_F(BweTestFramework_ChokeFilterTest, Long) {
  // 100ms, 100 packets in queue, 10 kbps choke -> 1 packet through, or 1 kbit.
  ChokeFilter filter(NULL, 0);
  filter.set_capacity_kbps(10);
  TestChoke(&filter, 100, 100, 1);
  // 200ms, no input, another packet through.
  TestChoke(&filter, 100, 0, 1);
  // 1000ms, no input, 8 packets through.
  TestChoke(&filter, 800, 0, 8);
  // 10000ms, no input, raise choke to 100 kbps. Remaining 90 packets in queue
  // should be propagated, for a total of 90 kbps.
  filter.set_capacity_kbps(100);
  TestChoke(&filter, 9000, 0, 90);
  // 10100ms, 20 more packets -> 10 packets or 10 kbit through.
  TestChoke(&filter, 100, 20, 10);
  // 10300ms, 10 more packets -> 20 packets out.
  TestChoke(&filter, 200, 10, 20);
  // 11300ms, no input, queue should be empty.
  filter.set_capacity_kbps(10);
  TestChoke(&filter, 1000, 0, 0);
}

TEST_F(BweTestFramework_ChokeFilterTest, MaxDelay) {
  // 10 kbps choke, 500 ms delay cap
  ChokeFilter filter(NULL, 0);
  filter.set_capacity_kbps(10);
  filter.set_max_delay_ms(500);
  // 100ms, 100 packets in queue, 10 kbps choke -> 1 packet through, or 1 kbit.
  TestChoke(&filter, 100, 100, 1);
  CheckMaxDelay(500);
  // 500ms, no input, 4 more packets through.
  TestChoke(&filter, 400, 0, 4);
  // 10000ms, no input, remaining packets should have been dropped.
  TestChoke(&filter, 9500, 0, 0);

  // 100 ms delay cap
  filter.set_max_delay_ms(100);
  // 10100ms, 50 more packets -> 1 packets or 1 kbit through.
  TestChoke(&filter, 100, 50, 1);
  CheckMaxDelay(100);
  // 20000ms, no input, remaining packets in queue should have been dropped.
  TestChoke(&filter, 9900, 0, 0);

  // Reset delay cap (0 is no cap) and verify no packets are dropped.
  filter.set_capacity_kbps(10);
  filter.set_max_delay_ms(0);
  TestChoke(&filter, 100, 100, 1);
  TestChoke(&filter, 9900, 0, 99);
}

TEST_F(BweTestFramework_ChokeFilterTest, ShortTrace) {
  // According to the input file 6 packets should be transmitted within
  // 100 milliseconds.
  TraceBasedDeliveryFilter filter(NULL, 0);
  ASSERT_TRUE(filter.Init(test::ResourcePath("synthetic-trace", "rx")));
  TestChoke(&filter, 100, 100, 6);
}

TEST_F(BweTestFramework_ChokeFilterTest, ShortTraceTwoWraps) {
  // According to the input file 19 packets should be transmitted within
  // 280 milliseconds (at the wrapping point two packets are sent back to back).
  TraceBasedDeliveryFilter filter(NULL, 0);
  ASSERT_TRUE(filter.Init(test::ResourcePath("synthetic-trace", "rx")));
  TestChoke(&filter, 280, 100, 19);
}

TEST_F(BweTestFramework_ChokeFilterTest, ShortTraceMaxDelay) {
  TraceBasedDeliveryFilter filter(NULL, 0);
  filter.set_max_delay_ms(25);
  ASSERT_TRUE(filter.Init(test::ResourcePath("synthetic-trace", "rx")));
  // Uses all slots up to 110 ms. Several packets are being dropped.
  TestChoke(&filter, 110, 20, 9);
  CheckMaxDelay(25);
  // Simulate enough time for the next slot (at 135 ms) to be used. This makes
  // sure that a slot isn't missed between runs.
  TestChoke(&filter, 25, 1, 1);
}

void TestVideoSender(VideoSender* sender,
                     int64_t run_for_ms,
                     uint32_t expected_packets,
                     uint32_t expected_payload_size,
                     size_t expected_total_payload_size) {
  assert(sender);
  Packets packets;
  sender->RunFor(run_for_ms, &packets);
  ASSERT_TRUE(IsTimeSorted(packets));
  ASSERT_TRUE(IsSequenceNumberSorted(packets));
  EXPECT_EQ(expected_packets, packets.size());

  int64_t send_time_us = -1;
  size_t total_payload_size = 0;
  uint32_t absolute_send_time = 0;
  uint32_t absolute_send_time_wraps = 0;
  uint32_t rtp_timestamp = 0;
  uint32_t rtp_timestamp_wraps = 0;

  for (const auto* packet : packets) {
    const MediaPacket* media_packet = static_cast<const MediaPacket*>(packet);
    EXPECT_LE(send_time_us, media_packet->send_time_us());
    send_time_us = media_packet->send_time_us();
    if (sender->source()->max_payload_size_bytes() !=
        media_packet->payload_size()) {
      EXPECT_EQ(expected_payload_size, media_packet->payload_size());
    }
    total_payload_size += media_packet->payload_size();
    if (absolute_send_time >
        media_packet->header().extension.absoluteSendTime) {
      absolute_send_time_wraps++;
    }
    absolute_send_time = media_packet->header().extension.absoluteSendTime;
    if (rtp_timestamp > media_packet->header().timestamp) {
      rtp_timestamp_wraps++;
    }
    rtp_timestamp = media_packet->header().timestamp;
  }

  EXPECT_EQ(expected_total_payload_size, total_payload_size);
  EXPECT_GE(1u, absolute_send_time_wraps);
  EXPECT_GE(1u, rtp_timestamp_wraps);

  for (auto* packet : packets)
    delete packet;
}

// Random {-1, 0, +1} ms was added to frame timestamps.

TEST(BweTestFramework_VideoSenderTest, Fps1Kbps80_1s) {
  // 1 fps, 80 kbps
  VideoSource source(0, 1.0f, 80, 0x1234, 0);
  VideoSender sender(NULL, &source, kNullEstimator);
  EXPECT_EQ(80000u, source.bits_per_second());
  // We're at 1 fps, so all packets should be generated on first call, giving 10
  // packets of each 1000 bytes, total 10000 bytes.
  TestVideoSender(&sender, 1, 9, 400, 10000);
  // 998ms, should see no output here.
  TestVideoSender(&sender, 997, 0, 0, 0);
  // 1001ms, should get data for one more frame.
  TestVideoSender(&sender, 3, 9, 400, 10000);
  // 1998ms, should see no output here.
  TestVideoSender(&sender, 997, 0, 0, 0);
  // 2001ms, one more frame.
  TestVideoSender(&sender, 3, 9, 400, 10000);
  // 2998ms, should see nothing.
  TestVideoSender(&sender, 997, 0, 0, 0);
}

TEST(BweTestFramework_VideoSenderTest, Fps1Kbps80_1s_Offset) {
  // 1 fps, 80 kbps, offset 0.5 of a frame period, ==0.5s in this case.
  VideoSource source(0, 1.0f, 80, 0x1234, 500);
  VideoSender sender(NULL, &source, kNullEstimator);
  EXPECT_EQ(80000u, source.bits_per_second());
  // 498ms, no output.
  TestVideoSender(&sender, 498, 0, 0, 0);
  // 501ms, first frame (this is the offset we set), 10 packets of 1000 bytes.
  TestVideoSender(&sender, 3, 9, 400, 10000);
  // 1498ms, nothing.
  TestVideoSender(&sender, 997, 0, 0, 0);
  // 1501ms, second frame.
  TestVideoSender(&sender, 3, 9, 400, 10000);
  // 2498ms, nothing.
  TestVideoSender(&sender, 997, 0, 0, 0);
  // 2501ms, third frame.
  TestVideoSender(&sender, 3, 9, 400, 10000);
  // 3498ms, nothing.
  TestVideoSender(&sender, 997, 0, 0, 0);
}

TEST(BweTestFramework_VideoSenderTest, Fps50Kpbs80_11s) {
  // 50 fps, 80 kbps.
  VideoSource source(0, 50.0f, 80, 0x1234, 0);
  VideoSender sender(NULL, &source, kNullEstimator);
  EXPECT_EQ(80000u, source.bits_per_second());
  // 9981, should see 500 frames, 200 byte payloads, total 100000 bytes.
  TestVideoSender(&sender, 9981, 500, 200, 100000);
  // 9998ms, nothing.
  TestVideoSender(&sender, 17, 0, 0, 0);
  // 10001ms, 501st frame as a single packet.
  TestVideoSender(&sender, 3, 1, 200, 200);
  // 10981ms, 49 more frames.
  TestVideoSender(&sender, 981, 49, 200, 9800);
  // 10998ms, nothing.
  TestVideoSender(&sender, 17, 0, 0, 0);
}

TEST(BweTestFramework_VideoSenderTest, Fps20Kpbs120_1s) {
  // 20 fps, 120 kbps.
  VideoSource source(0, 20.0f, 120, 0x1234, 0);
  VideoSender sender(NULL, &source, kNullEstimator);
  EXPECT_EQ(120000u, source.bits_per_second());
  // 451ms, 10 frames with 750 byte payloads, total 7500 bytes.
  TestVideoSender(&sender, 451, 10, 750, 7500);
  // 498ms, nothing.
  TestVideoSender(&sender, 47, 0, 0, 0);
  // 501ms, one more frame.
  TestVideoSender(&sender, 3, 1, 750, 750);
  // 951ms, 9 more frames.
  TestVideoSender(&sender, 450, 9, 750, 6750);
  // 998ms, nothing.
  TestVideoSender(&sender, 47, 0, 0, 0);
}

TEST(BweTestFramework_VideoSenderTest, Fps25Kbps820_20s) {
  // 25 fps, 820 kbps.
  VideoSource source(0, 25.0f, 820, 0x1234, 0);
  VideoSender sender(NULL, &source, kNullEstimator);
  EXPECT_EQ(820000u, source.bits_per_second());
  // 9961ms, 250 frames. 820 kbps = 102500 bytes/s, so total should be 1025000.
  // Each frame is 102500/25=4100 bytes, or 5 packets (4 @1000 bytes, 1 @100),
  // so packet count should be 5*250=1250 and last packet of each frame has
  // 100 bytes of payload.
  TestVideoSender(&sender, 9961, 1000, 500, 1025000);
  // 9998ms, nothing.
  TestVideoSender(&sender, 37, 0, 0, 0);
  // 19961ms, 250 more frames.
  TestVideoSender(&sender, 9963, 1000, 500, 1025000);
  // 19998ms, nothing.
  TestVideoSender(&sender, 37, 0, 0, 0);
  // 20001ms, one more frame, as described above (25fps == 40ms/frame).
  TestVideoSender(&sender, 3, 4, 500, 4100);
  // 20038ms, nothing.
  TestVideoSender(&sender, 37, 0, 0, 0);
}

TEST(BweTestFramework_VideoSenderTest, TestAppendInOrder) {
  // 1 fps, 80 kbps, 250ms offset.
  VideoSource source1(0, 1.0f, 80, 0x1234, 250);
  VideoSender sender1(NULL, &source1, kNullEstimator);
  EXPECT_EQ(80000u, source1.bits_per_second());
  Packets packets;
  // Generate some packets, verify they are sorted.
  sender1.RunFor(999, &packets);
  ASSERT_TRUE(IsTimeSorted(packets));
  ASSERT_TRUE(IsSequenceNumberSorted(packets));
  EXPECT_EQ(9u, packets.size());
  // Generate some more packets and verify they are appended to end of list.
  sender1.RunFor(1000, &packets);
  ASSERT_TRUE(IsTimeSorted(packets));
  ASSERT_TRUE(IsSequenceNumberSorted(packets));
  EXPECT_EQ(18u, packets.size());

  // Another sender, 2 fps, 160 kbps, 150ms offset
  VideoSource source2(0, 2.0f, 160, 0x2234, 150);
  VideoSender sender2(NULL, &source2, kNullEstimator);
  EXPECT_EQ(160000u, source2.bits_per_second());
  // Generate some packets, verify that they are merged with the packets already
  // on the list.
  sender2.RunFor(999, &packets);
  ASSERT_TRUE(IsTimeSorted(packets));
  EXPECT_EQ(36u, packets.size());
  // Generate some more.
  sender2.RunFor(1000, &packets);
  ASSERT_TRUE(IsTimeSorted(packets));
  EXPECT_EQ(54u, packets.size());

  for (auto* packet : packets)
    delete packet;
}

TEST(BweTestFramework_VideoSenderTest, FeedbackIneffective) {
  VideoSource source(0, 25.0f, 820, 0x1234, 0);
  VideoSender sender(NULL, &source, kNullEstimator);

  EXPECT_EQ(820000u, source.bits_per_second());
  TestVideoSender(&sender, 9961, 1000, 500, 1025000);

  // Make sure feedback has no effect on a regular video sender.
  RembFeedback* feedback = new RembFeedback(0, 0, 0, 512000, RTCPReportBlock());
  Packets packets;
  packets.push_back(feedback);
  sender.RunFor(0, &packets);
  EXPECT_EQ(820000u, source.bits_per_second());
  TestVideoSender(&sender, 10000, 1000, 500, 1025000);
}
}  // namespace bwe
}  // namespace testing
}  // namespace webrtc