/*
 *  Copyright (c) 2012 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 "modules/rtp_rtcp/source/rtp_sender.h"

#include <memory>
#include <vector>

#include "api/rtc_event_log/rtc_event.h"
#include "api/transport/field_trial_based_config.h"
#include "api/video/video_codec_constants.h"
#include "api/video/video_timing.h"
#include "logging/rtc_event_log/mock/mock_rtc_event_log.h"
#include "modules/rtp_rtcp/include/rtp_cvo.h"
#include "modules/rtp_rtcp/include/rtp_header_extension_map.h"
#include "modules/rtp_rtcp/include/rtp_packet_sender.h"
#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
#include "modules/rtp_rtcp/source/rtcp_packet/transport_feedback.h"
#include "modules/rtp_rtcp/source/rtp_format_video_generic.h"
#include "modules/rtp_rtcp/source/rtp_generic_frame_descriptor.h"
#include "modules/rtp_rtcp/source/rtp_generic_frame_descriptor_extension.h"
#include "modules/rtp_rtcp/source/rtp_header_extensions.h"
#include "modules/rtp_rtcp/source/rtp_packet_received.h"
#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "modules/rtp_rtcp/source/rtp_sender_egress.h"
#include "modules/rtp_rtcp/source/rtp_sender_video.h"
#include "modules/rtp_rtcp/source/rtp_utility.h"
#include "modules/rtp_rtcp/source/video_fec_generator.h"
#include "rtc_base/arraysize.h"
#include "rtc_base/logging.h"
#include "rtc_base/rate_limiter.h"
#include "rtc_base/strings/string_builder.h"
#include "rtc_base/task_utils/to_queued_task.h"
#include "test/field_trial.h"
#include "test/gmock.h"
#include "test/gtest.h"
#include "test/mock_transport.h"
#include "test/rtp_header_parser.h"
#include "test/time_controller/simulated_time_controller.h"

namespace webrtc {

namespace {
enum : int {  // The first valid value is 1.
  kAbsoluteSendTimeExtensionId = 1,
  kAudioLevelExtensionId,
  kGenericDescriptorId,
  kMidExtensionId,
  kRepairedRidExtensionId,
  kRidExtensionId,
  kTransmissionTimeOffsetExtensionId,
  kTransportSequenceNumberExtensionId,
  kVideoRotationExtensionId,
  kVideoTimingExtensionId,
};

const int kPayload = 100;
const int kRtxPayload = 98;
const uint32_t kTimestamp = 10;
const uint16_t kSeqNum = 33;
const uint32_t kSsrc = 725242;
const uint32_t kRtxSsrc = 12345;
const uint32_t kFlexFecSsrc = 45678;
const uint64_t kStartTime = 123456789;
const size_t kMaxPaddingSize = 224u;
const uint8_t kPayloadData[] = {47, 11, 32, 93, 89};
const int64_t kDefaultExpectedRetransmissionTimeMs = 125;
const size_t kMaxPaddingLength = 224;      // Value taken from rtp_sender.cc.
const uint32_t kTimestampTicksPerMs = 90;  // 90kHz clock.

using ::testing::_;
using ::testing::AllOf;
using ::testing::AtLeast;
using ::testing::Contains;
using ::testing::Each;
using ::testing::ElementsAreArray;
using ::testing::Eq;
using ::testing::Field;
using ::testing::Gt;
using ::testing::IsEmpty;
using ::testing::NiceMock;
using ::testing::Not;
using ::testing::Pointee;
using ::testing::Property;
using ::testing::Return;
using ::testing::SizeIs;
using ::testing::StrictMock;

class LoopbackTransportTest : public webrtc::Transport {
 public:
  LoopbackTransportTest() : total_bytes_sent_(0) {
    receivers_extensions_.Register<TransmissionOffset>(
        kTransmissionTimeOffsetExtensionId);
    receivers_extensions_.Register<AbsoluteSendTime>(
        kAbsoluteSendTimeExtensionId);
    receivers_extensions_.Register<TransportSequenceNumber>(
        kTransportSequenceNumberExtensionId);
    receivers_extensions_.Register<VideoOrientation>(kVideoRotationExtensionId);
    receivers_extensions_.Register<AudioLevel>(kAudioLevelExtensionId);
    receivers_extensions_.Register<VideoTimingExtension>(
        kVideoTimingExtensionId);
    receivers_extensions_.Register<RtpMid>(kMidExtensionId);
    receivers_extensions_.Register<RtpGenericFrameDescriptorExtension00>(
        kGenericDescriptorId);
    receivers_extensions_.Register<RtpStreamId>(kRidExtensionId);
    receivers_extensions_.Register<RepairedRtpStreamId>(
        kRepairedRidExtensionId);
  }

  bool SendRtp(const uint8_t* data,
               size_t len,
               const PacketOptions& options) override {
    last_options_ = options;
    total_bytes_sent_ += len;
    sent_packets_.push_back(RtpPacketReceived(&receivers_extensions_));
    EXPECT_TRUE(sent_packets_.back().Parse(data, len));
    return true;
  }
  bool SendRtcp(const uint8_t* data, size_t len) override { return false; }
  const RtpPacketReceived& last_sent_packet() { return sent_packets_.back(); }
  int packets_sent() { return sent_packets_.size(); }

  size_t total_bytes_sent_;
  PacketOptions last_options_;
  std::vector<RtpPacketReceived> sent_packets_;

 private:
  RtpHeaderExtensionMap receivers_extensions_;
};

MATCHER_P(SameRtcEventTypeAs, value, "") {
  return value == arg->GetType();
}

struct TestConfig {
  explicit TestConfig(bool with_overhead) : with_overhead(with_overhead) {}
  bool with_overhead = false;
};

class MockRtpPacketPacer : public RtpPacketSender {
 public:
  MockRtpPacketPacer() {}
  virtual ~MockRtpPacketPacer() {}

  MOCK_METHOD(void,
              EnqueuePackets,
              (std::vector<std::unique_ptr<RtpPacketToSend>>),
              (override));
};

class MockSendSideDelayObserver : public SendSideDelayObserver {
 public:
  MOCK_METHOD(void,
              SendSideDelayUpdated,
              (int, int, uint64_t, uint32_t),
              (override));
};

class MockSendPacketObserver : public SendPacketObserver {
 public:
  MOCK_METHOD(void, OnSendPacket, (uint16_t, int64_t, uint32_t), (override));
};

class MockTransportFeedbackObserver : public TransportFeedbackObserver {
 public:
  MOCK_METHOD(void, OnAddPacket, (const RtpPacketSendInfo&), (override));
  MOCK_METHOD(void,
              OnTransportFeedback,
              (const rtcp::TransportFeedback&),
              (override));
};

class StreamDataTestCallback : public StreamDataCountersCallback {
 public:
  StreamDataTestCallback()
      : StreamDataCountersCallback(), ssrc_(0), counters_() {}
  ~StreamDataTestCallback() override = default;

  void DataCountersUpdated(const StreamDataCounters& counters,
                           uint32_t ssrc) override {
    ssrc_ = ssrc;
    counters_ = counters;
  }

  uint32_t ssrc_;
  StreamDataCounters counters_;

  void MatchPacketCounter(const RtpPacketCounter& expected,
                          const RtpPacketCounter& actual) {
    EXPECT_EQ(expected.payload_bytes, actual.payload_bytes);
    EXPECT_EQ(expected.header_bytes, actual.header_bytes);
    EXPECT_EQ(expected.padding_bytes, actual.padding_bytes);
    EXPECT_EQ(expected.packets, actual.packets);
  }

  void Matches(uint32_t ssrc, const StreamDataCounters& counters) {
    EXPECT_EQ(ssrc, ssrc_);
    MatchPacketCounter(counters.transmitted, counters_.transmitted);
    MatchPacketCounter(counters.retransmitted, counters_.retransmitted);
    EXPECT_EQ(counters.fec.packets, counters_.fec.packets);
  }
};

class TaskQueuePacketSender : public RtpPacketSender {
 public:
  TaskQueuePacketSender(TimeController* time_controller,
                        std::unique_ptr<RtpPacketSender> packet_sender)
      : time_controller_(time_controller),
        packet_sender_(std::move(packet_sender)),
        queue_(time_controller_->CreateTaskQueueFactory()->CreateTaskQueue(
            "PacerQueue",
            TaskQueueFactory::Priority::NORMAL)) {}

  void EnqueuePackets(
      std::vector<std::unique_ptr<RtpPacketToSend>> packets) override {
    queue_->PostTask(ToQueuedTask([sender = packet_sender_.get(),
                                   packets_ = std::move(packets)]() mutable {
      sender->EnqueuePackets(std::move(packets_));
    }));
    // Trigger task we just enqueued to be executed by updating the simulated
    // time controller.
    time_controller_->AdvanceTime(TimeDelta::Zero());
  }

  TaskQueueBase* task_queue() const { return queue_.get(); }

  TimeController* const time_controller_;
  std::unique_ptr<RtpPacketSender> packet_sender_;
  std::unique_ptr<TaskQueueBase, TaskQueueDeleter> queue_;
};

// Mimics ModuleRtpRtcp::RtpSenderContext.
// TODO(sprang): Split up unit tests and test these components individually
// wherever possible.
struct RtpSenderContext : public SequenceNumberAssigner {
  RtpSenderContext(const RtpRtcpInterface::Configuration& config,
                   TimeController* time_controller)
      : time_controller_(time_controller),
        packet_history_(config.clock, config.enable_rtx_padding_prioritization),
        packet_sender_(config, &packet_history_),
        pacer_(time_controller,
               std::make_unique<RtpSenderEgress::NonPacedPacketSender>(
                   &packet_sender_,
                   this)),
        packet_generator_(config,
                          &packet_history_,
                          config.paced_sender ? config.paced_sender : &pacer_) {
  }
  void AssignSequenceNumber(RtpPacketToSend* packet) override {
    packet_generator_.AssignSequenceNumber(packet);
  }
  // Inject packet straight into RtpSenderEgress without passing through the
  // pacer, but while still running on the pacer task queue.
  void InjectPacket(std::unique_ptr<RtpPacketToSend> packet,
                    const PacedPacketInfo& packet_info) {
    pacer_.task_queue()->PostTask(
        ToQueuedTask([sender_ = &packet_sender_, packet_ = std::move(packet),
                      packet_info]() mutable {
          sender_->SendPacket(packet_.get(), packet_info);
        }));
    time_controller_->AdvanceTime(TimeDelta::Zero());
  }
  TimeController* time_controller_;
  RtpPacketHistory packet_history_;
  RtpSenderEgress packet_sender_;
  TaskQueuePacketSender pacer_;
  RTPSender packet_generator_;
};

class FieldTrialConfig : public WebRtcKeyValueConfig {
 public:
  FieldTrialConfig()
      : overhead_enabled_(false),
        max_padding_factor_(1200) {}
  ~FieldTrialConfig() override {}

  void SetOverHeadEnabled(bool enabled) { overhead_enabled_ = enabled; }
  void SetMaxPaddingFactor(double factor) { max_padding_factor_ = factor; }

  std::string Lookup(absl::string_view key) const override {
    if (key == "WebRTC-LimitPaddingSize") {
      char string_buf[32];
      rtc::SimpleStringBuilder ssb(string_buf);
      ssb << "factor:" << max_padding_factor_;
      return ssb.str();
    } else if (key == "WebRTC-SendSideBwe-WithOverhead") {
      return overhead_enabled_ ? "Enabled" : "Disabled";
    }
    return "";
  }

 private:
  bool overhead_enabled_;
  double max_padding_factor_;
};

}  // namespace

class RtpSenderTest : public ::testing::TestWithParam<TestConfig> {
 protected:
  RtpSenderTest()
      : time_controller_(Timestamp::Millis(kStartTime)),
        clock_(time_controller_.GetClock()),
        retransmission_rate_limiter_(clock_, 1000),
        flexfec_sender_(0,
                        kFlexFecSsrc,
                        kSsrc,
                        "",
                        std::vector<RtpExtension>(),
                        std::vector<RtpExtensionSize>(),
                        nullptr,
                        clock_),
        kMarkerBit(true) {
    field_trials_.SetOverHeadEnabled(GetParam().with_overhead);
  }

  void SetUp() override { SetUpRtpSender(true, false, false); }

  RTPSender* rtp_sender() {
    RTC_DCHECK(rtp_sender_context_);
    return &rtp_sender_context_->packet_generator_;
  }

  RtpSenderEgress* rtp_egress() {
    RTC_DCHECK(rtp_sender_context_);
    return &rtp_sender_context_->packet_sender_;
  }

  void SetUpRtpSender(bool pacer,
                      bool populate_network2,
                      bool always_send_mid_and_rid) {
    SetUpRtpSender(pacer, populate_network2, always_send_mid_and_rid,
                   &flexfec_sender_);
  }

  void SetUpRtpSender(bool pacer,
                      bool populate_network2,
                      bool always_send_mid_and_rid,
                      VideoFecGenerator* fec_generator) {
    RtpRtcpInterface::Configuration config;
    config.clock = clock_;
    config.outgoing_transport = &transport_;
    config.local_media_ssrc = kSsrc;
    config.rtx_send_ssrc = kRtxSsrc;
    config.fec_generator = fec_generator;
    config.event_log = &mock_rtc_event_log_;
    config.send_packet_observer = &send_packet_observer_;
    config.retransmission_rate_limiter = &retransmission_rate_limiter_;
    config.paced_sender = pacer ? &mock_paced_sender_ : nullptr;
    config.populate_network2_timestamp = populate_network2;
    config.rtp_stats_callback = &rtp_stats_callback_;
    config.always_send_mid_and_rid = always_send_mid_and_rid;
    config.field_trials = &field_trials_;

    rtp_sender_context_ =
        std::make_unique<RtpSenderContext>(config, &time_controller_);
    rtp_sender()->SetSequenceNumber(kSeqNum);
    rtp_sender()->SetTimestampOffset(0);
  }

  GlobalSimulatedTimeController time_controller_;
  Clock* const clock_;
  NiceMock<MockRtcEventLog> mock_rtc_event_log_;
  MockRtpPacketPacer mock_paced_sender_;
  StrictMock<MockSendPacketObserver> send_packet_observer_;
  StrictMock<MockTransportFeedbackObserver> feedback_observer_;
  RateLimiter retransmission_rate_limiter_;
  FlexfecSender flexfec_sender_;

  std::unique_ptr<RtpSenderContext> rtp_sender_context_;

  LoopbackTransportTest transport_;
  const bool kMarkerBit;
  FieldTrialConfig field_trials_;
  StreamDataTestCallback rtp_stats_callback_;

  std::unique_ptr<RtpPacketToSend> BuildRtpPacket(int payload_type,
                                                  bool marker_bit,
                                                  uint32_t timestamp,
                                                  int64_t capture_time_ms) {
    auto packet = rtp_sender()->AllocatePacket();
    packet->SetPayloadType(payload_type);
    packet->set_packet_type(RtpPacketMediaType::kVideo);
    packet->SetMarker(marker_bit);
    packet->SetTimestamp(timestamp);
    packet->set_capture_time_ms(capture_time_ms);
    EXPECT_TRUE(rtp_sender()->AssignSequenceNumber(packet.get()));
    return packet;
  }

  std::unique_ptr<RtpPacketToSend> SendPacket(int64_t capture_time_ms,
                                              int payload_length) {
    uint32_t timestamp = capture_time_ms * 90;
    auto packet =
        BuildRtpPacket(kPayload, kMarkerBit, timestamp, capture_time_ms);
    packet->AllocatePayload(payload_length);
    packet->set_allow_retransmission(true);

    // Packet should be stored in a send bucket.
    EXPECT_TRUE(rtp_sender()->SendToNetwork(
        std::make_unique<RtpPacketToSend>(*packet)));
    return packet;
  }

  std::unique_ptr<RtpPacketToSend> SendGenericPacket() {
    const int64_t kCaptureTimeMs = clock_->TimeInMilliseconds();
    // Use maximum allowed size to catch corner cases when packet is dropped
    // because of lack of capacity for the media packet, or for an rtx packet
    // containing the media packet.
    return SendPacket(kCaptureTimeMs,
                      /*payload_length=*/rtp_sender()->MaxRtpPacketSize() -
                          rtp_sender()->ExpectedPerPacketOverhead());
  }

  size_t GenerateAndSendPadding(size_t target_size_bytes) {
    size_t generated_bytes = 0;
    for (auto& packet :
         rtp_sender()->GeneratePadding(target_size_bytes, true)) {
      generated_bytes += packet->payload_size() + packet->padding_size();
      rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
    }
    return generated_bytes;
  }

  // The following are helpers for configuring the RTPSender. They must be
  // called before sending any packets.

  // Enable the retransmission stream with sizable packet storage.
  void EnableRtx() {
    // RTX needs to be able to read the source packets from the packet store.
    // Pick a number of packets to store big enough for any unit test.
    constexpr uint16_t kNumberOfPacketsToStore = 100;
    rtp_sender_context_->packet_history_.SetStorePacketsStatus(
        RtpPacketHistory::StorageMode::kStoreAndCull, kNumberOfPacketsToStore);
    rtp_sender()->SetRtxPayloadType(kRtxPayload, kPayload);
    rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  }

  // Enable sending of the MID header extension for both the primary SSRC and
  // the RTX SSRC.
  void EnableMidSending(const std::string& mid) {
    rtp_sender()->RegisterRtpHeaderExtension(RtpMid::kUri, kMidExtensionId);
    rtp_sender()->SetMid(mid);
  }

  // Enable sending of the RSID header extension for the primary SSRC and the
  // RRSID header extension for the RTX SSRC.
  void EnableRidSending(const std::string& rid) {
    rtp_sender()->RegisterRtpHeaderExtension(RtpStreamId::kUri,
                                             kRidExtensionId);
    rtp_sender()->RegisterRtpHeaderExtension(RepairedRtpStreamId::kUri,
                                             kRepairedRidExtensionId);
    rtp_sender()->SetRid(rid);
  }
};

// TODO(pbos): Move tests over from WithoutPacer to RtpSenderTest as this is our
// default code path.
class RtpSenderTestWithoutPacer : public RtpSenderTest {
 public:
  void SetUp() override { SetUpRtpSender(false, false, false); }
};

TEST_P(RtpSenderTestWithoutPacer, AllocatePacketSetCsrc) {
  // Configure rtp_sender with csrc.
  std::vector<uint32_t> csrcs;
  csrcs.push_back(0x23456789);
  rtp_sender()->SetCsrcs(csrcs);

  auto packet = rtp_sender()->AllocatePacket();

  ASSERT_TRUE(packet);
  EXPECT_EQ(rtp_sender()->SSRC(), packet->Ssrc());
  EXPECT_EQ(csrcs, packet->Csrcs());
}

TEST_P(RtpSenderTestWithoutPacer, AllocatePacketReserveExtensions) {
  // Configure rtp_sender with extensions.
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransmissionOffset::kUri, kTransmissionTimeOffsetExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      AbsoluteSendTime::kUri, kAbsoluteSendTimeExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(AudioLevel::kUri,
                                                       kAudioLevelExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      VideoOrientation::kUri, kVideoRotationExtensionId));

  auto packet = rtp_sender()->AllocatePacket();

  ASSERT_TRUE(packet);
  // Preallocate BWE extensions RtpSender set itself.
  EXPECT_TRUE(packet->HasExtension<TransmissionOffset>());
  EXPECT_TRUE(packet->HasExtension<AbsoluteSendTime>());
  EXPECT_TRUE(packet->HasExtension<TransportSequenceNumber>());
  // Do not allocate media specific extensions.
  EXPECT_FALSE(packet->HasExtension<AudioLevel>());
  EXPECT_FALSE(packet->HasExtension<VideoOrientation>());
}

TEST_P(RtpSenderTest, PaddingAlwaysAllowedOnAudio) {
  MockTransport transport;
  RtpRtcpInterface::Configuration config;
  config.audio = true;
  config.clock = clock_;
  config.outgoing_transport = &transport;
  config.paced_sender = &mock_paced_sender_;
  config.local_media_ssrc = kSsrc;
  config.event_log = &mock_rtc_event_log_;
  config.retransmission_rate_limiter = &retransmission_rate_limiter_;
  rtp_sender_context_ =
      std::make_unique<RtpSenderContext>(config, &time_controller_);

  rtp_sender()->SetTimestampOffset(0);

  std::unique_ptr<RtpPacketToSend> audio_packet =
      rtp_sender()->AllocatePacket();
  // Padding on audio stream allowed regardless of marker in the last packet.
  audio_packet->SetMarker(false);
  audio_packet->SetPayloadType(kPayload);
  rtp_sender()->AssignSequenceNumber(audio_packet.get());

  const size_t kPaddingSize = 59;
  EXPECT_CALL(transport, SendRtp(_, kPaddingSize + kRtpHeaderSize, _))
      .WillOnce(Return(true));
  EXPECT_EQ(kPaddingSize, GenerateAndSendPadding(kPaddingSize));

  // Requested padding size is too small, will send a larger one.
  const size_t kMinPaddingSize = 50;
  EXPECT_CALL(transport, SendRtp(_, kMinPaddingSize + kRtpHeaderSize, _))
      .WillOnce(Return(true));
  EXPECT_EQ(kMinPaddingSize, GenerateAndSendPadding(kMinPaddingSize - 5));
}

TEST_P(RtpSenderTest, SendToNetworkForwardsPacketsToPacer) {
  auto packet = BuildRtpPacket(kPayload, kMarkerBit, kTimestamp, 0);
  int64_t now_ms = clock_->TimeInMilliseconds();

  EXPECT_CALL(
      mock_paced_sender_,
      EnqueuePackets(Contains(AllOf(
          Pointee(Property(&RtpPacketToSend::Ssrc, kSsrc)),
          Pointee(Property(&RtpPacketToSend::SequenceNumber, kSeqNum)),
          Pointee(Property(&RtpPacketToSend::capture_time_ms, now_ms))))));
  EXPECT_TRUE(
      rtp_sender()->SendToNetwork(std::make_unique<RtpPacketToSend>(*packet)));
}

TEST_P(RtpSenderTest, ReSendPacketForwardsPacketsToPacer) {
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 10);
  int64_t now_ms = clock_->TimeInMilliseconds();
  auto packet = BuildRtpPacket(kPayload, kMarkerBit, kTimestamp, now_ms);
  uint16_t seq_no = packet->SequenceNumber();
  packet->set_allow_retransmission(true);
  rtp_sender_context_->packet_history_.PutRtpPacket(std::move(packet), now_ms);

  EXPECT_CALL(mock_paced_sender_,
              EnqueuePackets(Contains(AllOf(
                  Pointee(Property(&RtpPacketToSend::Ssrc, kSsrc)),
                  Pointee(Property(&RtpPacketToSend::SequenceNumber, kSeqNum)),
                  Pointee(Property(&RtpPacketToSend::capture_time_ms, now_ms)),
                  Pointee(Property(&RtpPacketToSend::packet_type,
                                   RtpPacketMediaType::kRetransmission))))));
  EXPECT_TRUE(rtp_sender()->ReSendPacket(seq_no));
}

// This test sends 1 regular video packet, then 4 padding packets, and then
// 1 more regular packet.
TEST_P(RtpSenderTest, SendPadding) {
  constexpr int kNumPaddingPackets = 4;
  EXPECT_CALL(mock_paced_sender_, EnqueuePackets);
  std::unique_ptr<RtpPacketToSend> media_packet =
      SendPacket(/*capture_time_ms=*/clock_->TimeInMilliseconds(),
                 /*payload_size=*/100);

  // Wait 50 ms before generating each padding packet.
  for (int i = 0; i < kNumPaddingPackets; ++i) {
    time_controller_.AdvanceTime(TimeDelta::Millis(50));
    const size_t kPaddingTargetBytes = 100;  // Request 100 bytes of padding.

    // Padding should be sent on the media ssrc, with a continous sequence
    // number range. Size will be forced to full pack size and the timestamp
    // shall be that of the last media packet.
    EXPECT_CALL(mock_paced_sender_,
                EnqueuePackets(Contains(AllOf(
                    Pointee(Property(&RtpPacketToSend::Ssrc, kSsrc)),
                    Pointee(Property(&RtpPacketToSend::SequenceNumber,
                                     media_packet->SequenceNumber() + i + 1)),
                    Pointee(Property(&RtpPacketToSend::padding_size,
                                     kMaxPaddingLength)),
                    Pointee(Property(&RtpPacketToSend::Timestamp,
                                     media_packet->Timestamp()))))));
    std::vector<std::unique_ptr<RtpPacketToSend>> padding_packets =
        rtp_sender()->GeneratePadding(kPaddingTargetBytes,
                                      /*media_has_been_sent=*/true);
    ASSERT_THAT(padding_packets, SizeIs(1));
    rtp_sender()->SendToNetwork(std::move(padding_packets[0]));
  }

  // Send a regular video packet again.
  EXPECT_CALL(mock_paced_sender_,
              EnqueuePackets(Contains(AllOf(
                  Pointee(Property(
                      &RtpPacketToSend::SequenceNumber,
                      media_packet->SequenceNumber() + kNumPaddingPackets + 1)),
                  Pointee(Property(&RtpPacketToSend::Timestamp,
                                   Gt(media_packet->Timestamp())))))));

  std::unique_ptr<RtpPacketToSend> next_media_packet =
      SendPacket(/*capture_time_ms=*/clock_->TimeInMilliseconds(),
                 /*payload_size=*/100);
}

TEST_P(RtpSenderTest, NoPaddingAsFirstPacketWithoutBweExtensions) {
  EXPECT_THAT(rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                            /*media_has_been_sent=*/false),
              IsEmpty());

  // Don't send padding before media even with RTX.
  EnableRtx();
  EXPECT_THAT(rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                            /*media_has_been_sent=*/false),
              IsEmpty());
}

TEST_P(RtpSenderTest, AllowPaddingAsFirstPacketOnRtxWithTransportCc) {
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));

  // Padding can't be sent as first packet on media SSRC since we don't know
  // what payload type to assign.
  EXPECT_THAT(rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                            /*media_has_been_sent=*/false),
              IsEmpty());

  // With transportcc padding can be sent as first packet on the RTX SSRC.
  EnableRtx();
  EXPECT_THAT(rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                            /*media_has_been_sent=*/false),
              Not(IsEmpty()));
}

TEST_P(RtpSenderTest, AllowPaddingAsFirstPacketOnRtxWithAbsSendTime) {
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      AbsoluteSendTime::kUri, kAbsoluteSendTimeExtensionId));

  // Padding can't be sent as first packet on media SSRC since we don't know
  // what payload type to assign.
  EXPECT_THAT(rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                            /*media_has_been_sent=*/false),
              IsEmpty());

  // With abs send time, padding can be sent as first packet on the RTX SSRC.
  EnableRtx();
  EXPECT_THAT(rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                            /*media_has_been_sent=*/false),
              Not(IsEmpty()));
}

TEST_P(RtpSenderTest, UpdatesTimestampsOnPlainRtxPadding) {
  EnableRtx();
  // Timestamps as set based on capture time in RtpSenderTest.
  const int64_t start_time = clock_->TimeInMilliseconds();
  const uint32_t start_timestamp = start_time * kTimestampTicksPerMs;

  // Start by sending one media packet.
  EXPECT_CALL(
      mock_paced_sender_,
      EnqueuePackets(Contains(AllOf(
          Pointee(Property(&RtpPacketToSend::padding_size, 0u)),
          Pointee(Property(&RtpPacketToSend::Timestamp, start_timestamp)),
          Pointee(Property(&RtpPacketToSend::capture_time_ms, start_time))))));
  std::unique_ptr<RtpPacketToSend> media_packet =
      SendPacket(start_time, /*payload_size=*/600);

  // Advance time before sending padding.
  const TimeDelta kTimeDiff = TimeDelta::Millis(17);
  time_controller_.AdvanceTime(kTimeDiff);

  // Timestamps on padding should be offset from the sent media.
  EXPECT_THAT(
      rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                    /*media_has_been_sent=*/true),
      Each(AllOf(
          Pointee(Property(&RtpPacketToSend::padding_size, kMaxPaddingLength)),
          Pointee(Property(
              &RtpPacketToSend::Timestamp,
              start_timestamp + (kTimestampTicksPerMs * kTimeDiff.ms()))),
          Pointee(Property(&RtpPacketToSend::capture_time_ms,
                           start_time + kTimeDiff.ms())))));
}

TEST_P(RtpSenderTest, KeepsTimestampsOnPayloadPadding) {
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));
  EnableRtx();
  // Timestamps as set based on capture time in RtpSenderTest.
  const int64_t start_time = clock_->TimeInMilliseconds();
  const uint32_t start_timestamp = start_time * kTimestampTicksPerMs;
  const size_t kPayloadSize = 600;
  const size_t kRtxHeaderSize = 2;

  // Start by sending one media packet and putting in the packet history.
  EXPECT_CALL(
      mock_paced_sender_,
      EnqueuePackets(Contains(AllOf(
          Pointee(Property(&RtpPacketToSend::padding_size, 0u)),
          Pointee(Property(&RtpPacketToSend::Timestamp, start_timestamp)),
          Pointee(Property(&RtpPacketToSend::capture_time_ms, start_time))))));
  std::unique_ptr<RtpPacketToSend> media_packet =
      SendPacket(start_time, kPayloadSize);
  rtp_sender_context_->packet_history_.PutRtpPacket(std::move(media_packet),
                                                    start_time);

  // Advance time before sending padding.
  const TimeDelta kTimeDiff = TimeDelta::Millis(17);
  time_controller_.AdvanceTime(kTimeDiff);

  // Timestamps on payload padding should be set to original.
  EXPECT_THAT(
      rtp_sender()->GeneratePadding(/*target_size_bytes=*/100,
                                    /*media_has_been_sent=*/true),
      Each(AllOf(
          Pointee(Property(&RtpPacketToSend::padding_size, 0u)),
          Pointee(Property(&RtpPacketToSend::payload_size,
                           kPayloadSize + kRtxHeaderSize)),
          Pointee(Property(&RtpPacketToSend::Timestamp, start_timestamp)),
          Pointee(Property(&RtpPacketToSend::capture_time_ms, start_time)))));
}

// Test that the MID header extension is included on sent packets when
// configured.
TEST_P(RtpSenderTestWithoutPacer, MidIncludedOnSentPackets) {
  const char kMid[] = "mid";

  EnableMidSending(kMid);

  // Send a couple packets.
  SendGenericPacket();
  SendGenericPacket();

  // Expect both packets to have the MID set.
  ASSERT_EQ(2u, transport_.sent_packets_.size());
  for (const RtpPacketReceived& packet : transport_.sent_packets_) {
    std::string mid;
    ASSERT_TRUE(packet.GetExtension<RtpMid>(&mid));
    EXPECT_EQ(kMid, mid);
  }
}

TEST_P(RtpSenderTestWithoutPacer, RidIncludedOnSentPackets) {
  const char kRid[] = "f";

  EnableRidSending(kRid);

  SendGenericPacket();

  ASSERT_EQ(1u, transport_.sent_packets_.size());
  const RtpPacketReceived& packet = transport_.sent_packets_[0];
  std::string rid;
  ASSERT_TRUE(packet.GetExtension<RtpStreamId>(&rid));
  EXPECT_EQ(kRid, rid);
}

TEST_P(RtpSenderTestWithoutPacer, RidIncludedOnRtxSentPackets) {
  const char kRid[] = "f";
  const char kNoRid[] = "";

  EnableRtx();
  EnableRidSending(kRid);

  SendGenericPacket();
  ASSERT_EQ(1u, transport_.sent_packets_.size());
  const RtpPacketReceived& packet = transport_.sent_packets_[0];
  std::string rid;
  ASSERT_TRUE(packet.GetExtension<RtpStreamId>(&rid));
  EXPECT_EQ(kRid, rid);
  rid = kNoRid;
  EXPECT_FALSE(packet.HasExtension<RepairedRtpStreamId>());

  uint16_t packet_id = packet.SequenceNumber();
  rtp_sender()->ReSendPacket(packet_id);
  ASSERT_EQ(2u, transport_.sent_packets_.size());
  const RtpPacketReceived& rtx_packet = transport_.sent_packets_[1];
  ASSERT_TRUE(rtx_packet.GetExtension<RepairedRtpStreamId>(&rid));
  EXPECT_EQ(kRid, rid);
  EXPECT_FALSE(rtx_packet.HasExtension<RtpStreamId>());
}

TEST_P(RtpSenderTestWithoutPacer, MidAndRidNotIncludedOnSentPacketsAfterAck) {
  const char kMid[] = "mid";
  const char kRid[] = "f";

  EnableMidSending(kMid);
  EnableRidSending(kRid);

  // This first packet should include both MID and RID.
  auto first_built_packet = SendGenericPacket();

  rtp_sender()->OnReceivedAckOnSsrc(first_built_packet->SequenceNumber());

  // The second packet should include neither since an ack was received.
  SendGenericPacket();

  ASSERT_EQ(2u, transport_.sent_packets_.size());

  const RtpPacketReceived& first_packet = transport_.sent_packets_[0];
  std::string mid, rid;
  ASSERT_TRUE(first_packet.GetExtension<RtpMid>(&mid));
  EXPECT_EQ(kMid, mid);
  ASSERT_TRUE(first_packet.GetExtension<RtpStreamId>(&rid));
  EXPECT_EQ(kRid, rid);

  const RtpPacketReceived& second_packet = transport_.sent_packets_[1];
  EXPECT_FALSE(second_packet.HasExtension<RtpMid>());
  EXPECT_FALSE(second_packet.HasExtension<RtpStreamId>());
}

TEST_P(RtpSenderTestWithoutPacer,
       MidAndRidAlwaysIncludedOnSentPacketsWhenConfigured) {
  SetUpRtpSender(false, false, /*always_send_mid_and_rid=*/true);
  const char kMid[] = "mid";
  const char kRid[] = "f";
  EnableMidSending(kMid);
  EnableRidSending(kRid);

  // Send two media packets: one before and one after the ack.
  auto first_packet = SendGenericPacket();
  rtp_sender()->OnReceivedAckOnSsrc(first_packet->SequenceNumber());
  SendGenericPacket();

  // Due to the configuration, both sent packets should contain MID and RID.
  ASSERT_EQ(2u, transport_.sent_packets_.size());
  for (const RtpPacketReceived& packet : transport_.sent_packets_) {
    EXPECT_EQ(packet.GetExtension<RtpMid>(), kMid);
    EXPECT_EQ(packet.GetExtension<RtpStreamId>(), kRid);
  }
}

// Test that the first RTX packet includes both MID and RRID even if the packet
// being retransmitted did not have MID or RID. The MID and RID are needed on
// the first packets for a given SSRC, and RTX packets are sent on a separate
// SSRC.
TEST_P(RtpSenderTestWithoutPacer, MidAndRidIncludedOnFirstRtxPacket) {
  const char kMid[] = "mid";
  const char kRid[] = "f";

  EnableRtx();
  EnableMidSending(kMid);
  EnableRidSending(kRid);

  // This first packet will include both MID and RID.
  auto first_built_packet = SendGenericPacket();
  rtp_sender()->OnReceivedAckOnSsrc(first_built_packet->SequenceNumber());

  // The second packet will include neither since an ack was received.
  auto second_built_packet = SendGenericPacket();

  // The first RTX packet should include MID and RRID.
  ASSERT_LT(0,
            rtp_sender()->ReSendPacket(second_built_packet->SequenceNumber()));

  ASSERT_EQ(3u, transport_.sent_packets_.size());

  const RtpPacketReceived& rtx_packet = transport_.sent_packets_[2];
  std::string mid, rrid;
  ASSERT_TRUE(rtx_packet.GetExtension<RtpMid>(&mid));
  EXPECT_EQ(kMid, mid);
  ASSERT_TRUE(rtx_packet.GetExtension<RepairedRtpStreamId>(&rrid));
  EXPECT_EQ(kRid, rrid);
}

// Test that the RTX packets sent after receving an ACK on the RTX SSRC does
// not include either MID or RRID even if the packet being retransmitted did
// had a MID or RID.
TEST_P(RtpSenderTestWithoutPacer, MidAndRidNotIncludedOnRtxPacketsAfterAck) {
  const char kMid[] = "mid";
  const char kRid[] = "f";

  EnableRtx();
  EnableMidSending(kMid);
  EnableRidSending(kRid);

  // This first packet will include both MID and RID.
  auto first_built_packet = SendGenericPacket();
  rtp_sender()->OnReceivedAckOnSsrc(first_built_packet->SequenceNumber());

  // The second packet will include neither since an ack was received.
  auto second_built_packet = SendGenericPacket();

  // The first RTX packet will include MID and RRID.
  ASSERT_LT(0,
            rtp_sender()->ReSendPacket(second_built_packet->SequenceNumber()));

  ASSERT_EQ(3u, transport_.sent_packets_.size());
  const RtpPacketReceived& first_rtx_packet = transport_.sent_packets_[2];

  rtp_sender()->OnReceivedAckOnRtxSsrc(first_rtx_packet.SequenceNumber());

  // The second and third RTX packets should not include MID nor RRID.
  ASSERT_LT(0,
            rtp_sender()->ReSendPacket(first_built_packet->SequenceNumber()));
  ASSERT_LT(0,
            rtp_sender()->ReSendPacket(second_built_packet->SequenceNumber()));

  ASSERT_EQ(5u, transport_.sent_packets_.size());

  const RtpPacketReceived& second_rtx_packet = transport_.sent_packets_[3];
  EXPECT_FALSE(second_rtx_packet.HasExtension<RtpMid>());
  EXPECT_FALSE(second_rtx_packet.HasExtension<RepairedRtpStreamId>());

  const RtpPacketReceived& third_rtx_packet = transport_.sent_packets_[4];
  EXPECT_FALSE(third_rtx_packet.HasExtension<RtpMid>());
  EXPECT_FALSE(third_rtx_packet.HasExtension<RepairedRtpStreamId>());
}

TEST_P(RtpSenderTestWithoutPacer,
       MidAndRidAlwaysIncludedOnRtxPacketsWhenConfigured) {
  SetUpRtpSender(false, false, /*always_send_mid_and_rid=*/true);
  const char kMid[] = "mid";
  const char kRid[] = "f";
  EnableRtx();
  EnableMidSending(kMid);
  EnableRidSending(kRid);

  // Send two media packets: one before and one after the ack.
  auto media_packet1 = SendGenericPacket();
  rtp_sender()->OnReceivedAckOnSsrc(media_packet1->SequenceNumber());
  auto media_packet2 = SendGenericPacket();

  // Send three RTX packets with different combinations of orders w.r.t. the
  // media and RTX acks.
  ASSERT_LT(0, rtp_sender()->ReSendPacket(media_packet2->SequenceNumber()));
  ASSERT_EQ(3u, transport_.sent_packets_.size());
  rtp_sender()->OnReceivedAckOnRtxSsrc(
      transport_.sent_packets_[2].SequenceNumber());
  ASSERT_LT(0, rtp_sender()->ReSendPacket(media_packet1->SequenceNumber()));
  ASSERT_LT(0, rtp_sender()->ReSendPacket(media_packet2->SequenceNumber()));

  // Due to the configuration, all sent packets should contain MID
  // and either RID (media) or RRID (RTX).
  ASSERT_EQ(5u, transport_.sent_packets_.size());
  for (const auto& packet : transport_.sent_packets_) {
    EXPECT_EQ(packet.GetExtension<RtpMid>(), kMid);
  }
  for (size_t i = 0; i < 2; ++i) {
    const RtpPacketReceived& packet = transport_.sent_packets_[i];
    EXPECT_EQ(packet.GetExtension<RtpStreamId>(), kRid);
  }
  for (size_t i = 2; i < transport_.sent_packets_.size(); ++i) {
    const RtpPacketReceived& packet = transport_.sent_packets_[i];
    EXPECT_EQ(packet.GetExtension<RepairedRtpStreamId>(), kRid);
  }
}

// Test that if the RtpState indicates an ACK has been received on that SSRC
// then neither the MID nor RID header extensions will be sent.
TEST_P(RtpSenderTestWithoutPacer,
       MidAndRidNotIncludedOnSentPacketsAfterRtpStateRestored) {
  const char kMid[] = "mid";
  const char kRid[] = "f";

  EnableMidSending(kMid);
  EnableRidSending(kRid);

  RtpState state = rtp_sender()->GetRtpState();
  EXPECT_FALSE(state.ssrc_has_acked);
  state.ssrc_has_acked = true;
  rtp_sender()->SetRtpState(state);

  SendGenericPacket();

  ASSERT_EQ(1u, transport_.sent_packets_.size());
  const RtpPacketReceived& packet = transport_.sent_packets_[0];
  EXPECT_FALSE(packet.HasExtension<RtpMid>());
  EXPECT_FALSE(packet.HasExtension<RtpStreamId>());
}

// Test that if the RTX RtpState indicates an ACK has been received on that
// RTX SSRC then neither the MID nor RRID header extensions will be sent on
// RTX packets.
TEST_P(RtpSenderTestWithoutPacer,
       MidAndRridNotIncludedOnRtxPacketsAfterRtpStateRestored) {
  const char kMid[] = "mid";
  const char kRid[] = "f";

  EnableRtx();
  EnableMidSending(kMid);
  EnableRidSending(kRid);

  RtpState rtx_state = rtp_sender()->GetRtxRtpState();
  EXPECT_FALSE(rtx_state.ssrc_has_acked);
  rtx_state.ssrc_has_acked = true;
  rtp_sender()->SetRtxRtpState(rtx_state);

  auto built_packet = SendGenericPacket();
  ASSERT_LT(0, rtp_sender()->ReSendPacket(built_packet->SequenceNumber()));

  ASSERT_EQ(2u, transport_.sent_packets_.size());
  const RtpPacketReceived& rtx_packet = transport_.sent_packets_[1];
  EXPECT_FALSE(rtx_packet.HasExtension<RtpMid>());
  EXPECT_FALSE(rtx_packet.HasExtension<RepairedRtpStreamId>());
}

TEST_P(RtpSenderTestWithoutPacer, StreamDataCountersCallbacks) {
  const uint8_t kPayloadType = 127;
  const VideoCodecType kCodecType = VideoCodecType::kVideoCodecGeneric;
  FieldTrialBasedConfig field_trials;
  RTPSenderVideo::Config video_config;
  video_config.clock = clock_;
  video_config.rtp_sender = rtp_sender();
  video_config.field_trials = &field_trials;
  RTPSenderVideo rtp_sender_video(video_config);
  uint8_t payload[] = {47, 11, 32, 93, 89};
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 1);
  uint32_t ssrc = rtp_sender()->SSRC();

  // Send a frame.
  RTPVideoHeader video_header;
  video_header.frame_type = VideoFrameType::kVideoFrameKey;
  ASSERT_TRUE(rtp_sender_video.SendVideo(kPayloadType, kCodecType, 1234, 4321,
                                         payload, video_header,
                                         kDefaultExpectedRetransmissionTimeMs));
  StreamDataCounters expected;
  expected.transmitted.payload_bytes = 6;
  expected.transmitted.header_bytes = 12;
  expected.transmitted.padding_bytes = 0;
  expected.transmitted.packets = 1;
  expected.retransmitted.payload_bytes = 0;
  expected.retransmitted.header_bytes = 0;
  expected.retransmitted.padding_bytes = 0;
  expected.retransmitted.packets = 0;
  expected.fec.packets = 0;
  rtp_stats_callback_.Matches(ssrc, expected);

  // Retransmit a frame.
  uint16_t seqno = rtp_sender()->SequenceNumber() - 1;
  rtp_sender()->ReSendPacket(seqno);
  expected.transmitted.payload_bytes = 12;
  expected.transmitted.header_bytes = 24;
  expected.transmitted.packets = 2;
  expected.retransmitted.payload_bytes = 6;
  expected.retransmitted.header_bytes = 12;
  expected.retransmitted.padding_bytes = 0;
  expected.retransmitted.packets = 1;
  rtp_stats_callback_.Matches(ssrc, expected);

  // Send padding.
  GenerateAndSendPadding(kMaxPaddingSize);
  expected.transmitted.payload_bytes = 12;
  expected.transmitted.header_bytes = 36;
  expected.transmitted.padding_bytes = kMaxPaddingSize;
  expected.transmitted.packets = 3;
  rtp_stats_callback_.Matches(ssrc, expected);
}

TEST_P(RtpSenderTestWithoutPacer, StreamDataCountersCallbacksUlpfec) {
  const uint8_t kRedPayloadType = 96;
  const uint8_t kUlpfecPayloadType = 97;
  const uint8_t kPayloadType = 127;
  const VideoCodecType kCodecType = VideoCodecType::kVideoCodecGeneric;

  UlpfecGenerator ulpfec_generator(kRedPayloadType, kUlpfecPayloadType, clock_);
  SetUpRtpSender(false, false, false, &ulpfec_generator);
  RTPSenderVideo::Config video_config;
  video_config.clock = clock_;
  video_config.rtp_sender = rtp_sender();
  video_config.field_trials = &field_trials_;
  video_config.red_payload_type = kRedPayloadType;
  video_config.fec_type = ulpfec_generator.GetFecType();
  video_config.fec_overhead_bytes = ulpfec_generator.MaxPacketOverhead();
  RTPSenderVideo rtp_sender_video(video_config);
  uint8_t payload[] = {47, 11, 32, 93, 89};
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 1);
  uint32_t ssrc = rtp_sender()->SSRC();

  RTPVideoHeader video_header;
  StreamDataCounters expected;

  // Send ULPFEC.
  FecProtectionParams fec_params;
  fec_params.fec_mask_type = kFecMaskRandom;
  fec_params.fec_rate = 1;
  fec_params.max_fec_frames = 1;
  rtp_egress()->SetFecProtectionParameters(fec_params, fec_params);
  video_header.frame_type = VideoFrameType::kVideoFrameDelta;
  ASSERT_TRUE(rtp_sender_video.SendVideo(kPayloadType, kCodecType, 1234, 4321,
                                         payload, video_header,
                                         kDefaultExpectedRetransmissionTimeMs));
  expected.transmitted.payload_bytes = 28;
  expected.transmitted.header_bytes = 24;
  expected.transmitted.packets = 2;
  expected.fec.packets = 1;
  rtp_stats_callback_.Matches(ssrc, expected);
}

TEST_P(RtpSenderTestWithoutPacer, BytesReportedCorrectly) {
  const uint8_t kPayloadType = 127;
  const size_t kPayloadSize = 1400;
  rtp_sender()->SetRtxPayloadType(kPayloadType - 1, kPayloadType);
  rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);

  SendPacket(clock_->TimeInMilliseconds(), kPayloadSize);
  // Will send 2 full-size padding packets.
  GenerateAndSendPadding(1);
  GenerateAndSendPadding(1);

  StreamDataCounters rtp_stats;
  StreamDataCounters rtx_stats;
  rtp_egress()->GetDataCounters(&rtp_stats, &rtx_stats);

  // Payload
  EXPECT_GT(rtp_stats.first_packet_time_ms, -1);
  EXPECT_EQ(rtp_stats.transmitted.payload_bytes, kPayloadSize);
  EXPECT_EQ(rtp_stats.transmitted.header_bytes, 12u);
  EXPECT_EQ(rtp_stats.transmitted.padding_bytes, 0u);
  EXPECT_EQ(rtx_stats.transmitted.payload_bytes, 0u);
  EXPECT_EQ(rtx_stats.transmitted.header_bytes, 24u);
  EXPECT_EQ(rtx_stats.transmitted.padding_bytes, 2 * kMaxPaddingSize);

  EXPECT_EQ(rtp_stats.transmitted.TotalBytes(),
            rtp_stats.transmitted.payload_bytes +
                rtp_stats.transmitted.header_bytes +
                rtp_stats.transmitted.padding_bytes);
  EXPECT_EQ(rtx_stats.transmitted.TotalBytes(),
            rtx_stats.transmitted.payload_bytes +
                rtx_stats.transmitted.header_bytes +
                rtx_stats.transmitted.padding_bytes);

  EXPECT_EQ(
      transport_.total_bytes_sent_,
      rtp_stats.transmitted.TotalBytes() + rtx_stats.transmitted.TotalBytes());
}

TEST_P(RtpSenderTestWithoutPacer, RespectsNackBitrateLimit) {
  const int32_t kPacketSize = 1400;
  const int32_t kNumPackets = 30;

  retransmission_rate_limiter_.SetMaxRate(kPacketSize * kNumPackets * 8);

  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, kNumPackets);
  const uint16_t kStartSequenceNumber = rtp_sender()->SequenceNumber();
  std::vector<uint16_t> sequence_numbers;
  for (int32_t i = 0; i < kNumPackets; ++i) {
    sequence_numbers.push_back(kStartSequenceNumber + i);
    time_controller_.AdvanceTime(TimeDelta::Millis(1));
    SendPacket(clock_->TimeInMilliseconds(), kPacketSize);
  }
  EXPECT_EQ(kNumPackets, transport_.packets_sent());

  time_controller_.AdvanceTime(TimeDelta::Millis(1000 - kNumPackets));

  // Resending should work - brings the bandwidth up to the limit.
  // NACK bitrate is capped to the same bitrate as the encoder, since the max
  // protection overhead is 50% (see MediaOptimization::SetTargetRates).
  rtp_sender()->OnReceivedNack(sequence_numbers, 0);
  EXPECT_EQ(kNumPackets * 2, transport_.packets_sent());

  // Must be at least 5ms in between retransmission attempts.
  time_controller_.AdvanceTime(TimeDelta::Millis(5));

  // Resending should not work, bandwidth exceeded.
  rtp_sender()->OnReceivedNack(sequence_numbers, 0);
  EXPECT_EQ(kNumPackets * 2, transport_.packets_sent());
}

TEST_P(RtpSenderTest, UpdatingCsrcsUpdatedOverhead) {
  RtpRtcpInterface::Configuration config;
  config.clock = clock_;
  config.outgoing_transport = &transport_;
  config.local_media_ssrc = kSsrc;
  config.retransmission_rate_limiter = &retransmission_rate_limiter_;
  rtp_sender_context_ =
      std::make_unique<RtpSenderContext>(config, &time_controller_);

  // Base RTP overhead is 12B.
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 12u);

  // Adding two csrcs adds 2*4 bytes to the header.
  rtp_sender()->SetCsrcs({1, 2});
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 20u);
}

TEST_P(RtpSenderTest, OnOverheadChanged) {
  RtpRtcpInterface::Configuration config;
  config.clock = clock_;
  config.outgoing_transport = &transport_;
  config.local_media_ssrc = kSsrc;
  config.retransmission_rate_limiter = &retransmission_rate_limiter_;
  rtp_sender_context_ =
      std::make_unique<RtpSenderContext>(config, &time_controller_);

  // Base RTP overhead is 12B.
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 12u);

  rtp_sender()->RegisterRtpHeaderExtension(TransmissionOffset::kUri,
                                           kTransmissionTimeOffsetExtensionId);

  // TransmissionTimeOffset extension has a size of 3B, but with the addition
  // of header index and rounding to 4 byte boundary we end up with 20B total.
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 20u);
}

TEST_P(RtpSenderTest, CountMidOnlyUntilAcked) {
  RtpRtcpInterface::Configuration config;
  config.clock = clock_;
  config.outgoing_transport = &transport_;
  config.local_media_ssrc = kSsrc;
  config.retransmission_rate_limiter = &retransmission_rate_limiter_;
  rtp_sender_context_ =
      std::make_unique<RtpSenderContext>(config, &time_controller_);

  // Base RTP overhead is 12B.
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 12u);

  rtp_sender()->RegisterRtpHeaderExtension(RtpMid::kUri, kMidExtensionId);
  rtp_sender()->RegisterRtpHeaderExtension(RtpStreamId::kUri, kRidExtensionId);

  // Counted only if set.
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 12u);
  rtp_sender()->SetMid("foo");
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 36u);
  rtp_sender()->SetRid("bar");
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 52u);

  // Ack received, mid/rid no longer sent.
  rtp_sender()->OnReceivedAckOnSsrc(0);
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 12u);
}

TEST_P(RtpSenderTest, DontCountVolatileExtensionsIntoOverhead) {
  RtpRtcpInterface::Configuration config;
  config.clock = clock_;
  config.outgoing_transport = &transport_;
  config.local_media_ssrc = kSsrc;
  config.retransmission_rate_limiter = &retransmission_rate_limiter_;
  rtp_sender_context_ =
      std::make_unique<RtpSenderContext>(config, &time_controller_);

  // Base RTP overhead is 12B.
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 12u);

  rtp_sender()->RegisterRtpHeaderExtension(InbandComfortNoiseExtension::kUri,
                                           1);
  rtp_sender()->RegisterRtpHeaderExtension(AbsoluteCaptureTimeExtension::kUri,
                                           2);
  rtp_sender()->RegisterRtpHeaderExtension(VideoOrientation::kUri, 3);
  rtp_sender()->RegisterRtpHeaderExtension(PlayoutDelayLimits::kUri, 4);
  rtp_sender()->RegisterRtpHeaderExtension(VideoContentTypeExtension::kUri, 5);
  rtp_sender()->RegisterRtpHeaderExtension(VideoTimingExtension::kUri, 6);
  rtp_sender()->RegisterRtpHeaderExtension(RepairedRtpStreamId::kUri, 7);
  rtp_sender()->RegisterRtpHeaderExtension(ColorSpaceExtension::kUri, 8);

  // Still only 12B counted since can't count on above being sent.
  EXPECT_EQ(rtp_sender()->ExpectedPerPacketOverhead(), 12u);
}

TEST_P(RtpSenderTest, SendPacketMatchesVideo) {
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_packet_type(RtpPacketMediaType::kVideo);

  // Verify sent with correct SSRC.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kSsrc);
  packet->set_packet_type(RtpPacketMediaType::kVideo);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 1);
}

TEST_P(RtpSenderTest, SendPacketMatchesAudio) {
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_packet_type(RtpPacketMediaType::kAudio);

  // Verify sent with correct SSRC.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kSsrc);
  packet->set_packet_type(RtpPacketMediaType::kAudio);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 1);
}

TEST_P(RtpSenderTest, SendPacketMatchesRetransmissions) {
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_packet_type(RtpPacketMediaType::kRetransmission);

  // Verify sent with correct SSRC (non-RTX).
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kSsrc);
  packet->set_packet_type(RtpPacketMediaType::kRetransmission);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 1);

  // RTX retransmission.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kRtxSsrc);
  packet->set_packet_type(RtpPacketMediaType::kRetransmission);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 2);
}

TEST_P(RtpSenderTest, SendPacketMatchesPadding) {
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_packet_type(RtpPacketMediaType::kPadding);

  // Verify sent with correct SSRC (non-RTX).
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kSsrc);
  packet->set_packet_type(RtpPacketMediaType::kPadding);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 1);

  // RTX padding.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kRtxSsrc);
  packet->set_packet_type(RtpPacketMediaType::kPadding);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 2);
}

TEST_P(RtpSenderTest, SendPacketMatchesFlexfec) {
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_packet_type(RtpPacketMediaType::kForwardErrorCorrection);

  // Verify sent with correct SSRC.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kFlexFecSsrc);
  packet->set_packet_type(RtpPacketMediaType::kForwardErrorCorrection);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 1);
}

TEST_P(RtpSenderTest, SendPacketMatchesUlpfec) {
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_packet_type(RtpPacketMediaType::kForwardErrorCorrection);

  // Verify sent with correct SSRC.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetSsrc(kSsrc);
  packet->set_packet_type(RtpPacketMediaType::kForwardErrorCorrection);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_EQ(transport_.packets_sent(), 1);
}

TEST_P(RtpSenderTest, SendPacketHandlesRetransmissionHistory) {
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 10);

  // Ignore calls to EnqueuePackets() for this test.
  EXPECT_CALL(mock_paced_sender_, EnqueuePackets).WillRepeatedly(Return());

  // Build a media packet and send it.
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  const uint16_t media_sequence_number = packet->SequenceNumber();
  packet->set_packet_type(RtpPacketMediaType::kVideo);
  packet->set_allow_retransmission(true);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  // Simulate retransmission request.
  time_controller_.AdvanceTime(TimeDelta::Millis(30));
  EXPECT_GT(rtp_sender()->ReSendPacket(media_sequence_number), 0);

  // Packet already pending, retransmission not allowed.
  time_controller_.AdvanceTime(TimeDelta::Millis(30));
  EXPECT_EQ(rtp_sender()->ReSendPacket(media_sequence_number), 0);

  // Packet exiting pacer, mark as not longer pending.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  EXPECT_NE(packet->SequenceNumber(), media_sequence_number);
  packet->set_packet_type(RtpPacketMediaType::kRetransmission);
  packet->SetSsrc(kRtxSsrc);
  packet->set_retransmitted_sequence_number(media_sequence_number);
  packet->set_allow_retransmission(false);
  uint16_t seq_no = packet->SequenceNumber();
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  // Retransmissions allowed again.
  time_controller_.AdvanceTime(TimeDelta::Millis(30));
  EXPECT_GT(rtp_sender()->ReSendPacket(media_sequence_number), 0);

  // Retransmission of RTX packet should not be allowed.
  EXPECT_EQ(rtp_sender()->ReSendPacket(seq_no), 0);
}

TEST_P(RtpSenderTest, SendPacketUpdatesExtensions) {
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransmissionOffset::kUri, kTransmissionTimeOffsetExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      AbsoluteSendTime::kUri, kAbsoluteSendTimeExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      VideoTimingExtension::kUri, kVideoTimingExtensionId));

  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_packetization_finish_time_ms(clock_->TimeInMilliseconds());

  const int32_t kDiffMs = 10;
  time_controller_.AdvanceTime(TimeDelta::Millis(kDiffMs));

  packet->set_packet_type(RtpPacketMediaType::kVideo);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  const RtpPacketReceived& received_packet = transport_.last_sent_packet();

  EXPECT_EQ(received_packet.GetExtension<TransmissionOffset>(), kDiffMs * 90);

  EXPECT_EQ(received_packet.GetExtension<AbsoluteSendTime>(),
            AbsoluteSendTime::MsTo24Bits(clock_->TimeInMilliseconds()));

  VideoSendTiming timing;
  EXPECT_TRUE(received_packet.GetExtension<VideoTimingExtension>(&timing));
  EXPECT_EQ(timing.pacer_exit_delta_ms, kDiffMs);
}

TEST_P(RtpSenderTest, SendPacketSetsPacketOptions) {
  const uint16_t kPacketId = 42;
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetExtension<TransportSequenceNumber>(kPacketId);

  packet->set_packet_type(RtpPacketMediaType::kVideo);
  EXPECT_CALL(send_packet_observer_, OnSendPacket);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  EXPECT_EQ(transport_.last_options_.packet_id, kPacketId);
  EXPECT_TRUE(transport_.last_options_.included_in_allocation);
  EXPECT_TRUE(transport_.last_options_.included_in_feedback);
  EXPECT_FALSE(transport_.last_options_.is_retransmit);

  // Send another packet as retransmission, verify options are populated.
  packet = BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->SetExtension<TransportSequenceNumber>(kPacketId + 1);
  packet->set_packet_type(RtpPacketMediaType::kRetransmission);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
  EXPECT_TRUE(transport_.last_options_.is_retransmit);
}

TEST_P(RtpSenderTest, SendPacketUpdatesStats) {
  const size_t kPayloadSize = 1000;

  StrictMock<MockSendSideDelayObserver> send_side_delay_observer;

  RtpRtcpInterface::Configuration config;
  config.clock = clock_;
  config.outgoing_transport = &transport_;
  config.local_media_ssrc = kSsrc;
  config.rtx_send_ssrc = kRtxSsrc;
  config.fec_generator = &flexfec_sender_;
  config.send_side_delay_observer = &send_side_delay_observer;
  config.event_log = &mock_rtc_event_log_;
  config.send_packet_observer = &send_packet_observer_;
  rtp_sender_context_ =
      std::make_unique<RtpSenderContext>(config, &time_controller_);
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));

  const int64_t capture_time_ms = clock_->TimeInMilliseconds();

  std::unique_ptr<RtpPacketToSend> video_packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  video_packet->set_packet_type(RtpPacketMediaType::kVideo);
  video_packet->SetPayloadSize(kPayloadSize);
  video_packet->SetExtension<TransportSequenceNumber>(1);

  std::unique_ptr<RtpPacketToSend> rtx_packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  rtx_packet->SetSsrc(kRtxSsrc);
  rtx_packet->set_packet_type(RtpPacketMediaType::kRetransmission);
  rtx_packet->SetPayloadSize(kPayloadSize);
  rtx_packet->SetExtension<TransportSequenceNumber>(2);

  std::unique_ptr<RtpPacketToSend> fec_packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  fec_packet->SetSsrc(kFlexFecSsrc);
  fec_packet->set_packet_type(RtpPacketMediaType::kForwardErrorCorrection);
  fec_packet->SetPayloadSize(kPayloadSize);
  fec_packet->SetExtension<TransportSequenceNumber>(3);

  const int64_t kDiffMs = 25;
  time_controller_.AdvanceTime(TimeDelta::Millis(kDiffMs));

  EXPECT_CALL(send_side_delay_observer,
              SendSideDelayUpdated(kDiffMs, kDiffMs, kDiffMs, kSsrc));
  EXPECT_CALL(
      send_side_delay_observer,
      SendSideDelayUpdated(kDiffMs, kDiffMs, 2 * kDiffMs, kFlexFecSsrc));

  EXPECT_CALL(send_packet_observer_, OnSendPacket(1, capture_time_ms, kSsrc));

  rtp_sender_context_->InjectPacket(std::move(video_packet), PacedPacketInfo());

  // Send packet observer not called for padding/retransmissions.
  EXPECT_CALL(send_packet_observer_, OnSendPacket(2, _, _)).Times(0);
  rtp_sender_context_->InjectPacket(std::move(rtx_packet), PacedPacketInfo());

  EXPECT_CALL(send_packet_observer_,
              OnSendPacket(3, capture_time_ms, kFlexFecSsrc));
  rtp_sender_context_->InjectPacket(std::move(fec_packet), PacedPacketInfo());

  StreamDataCounters rtp_stats;
  StreamDataCounters rtx_stats;
  rtp_egress()->GetDataCounters(&rtp_stats, &rtx_stats);
  EXPECT_EQ(rtp_stats.transmitted.packets, 2u);
  EXPECT_EQ(rtp_stats.fec.packets, 1u);
  EXPECT_EQ(rtx_stats.retransmitted.packets, 1u);
}

TEST_P(RtpSenderTest, GeneratedPaddingHasBweExtensions) {
  // Min requested size in order to use RTX payload.
  const size_t kMinPaddingSize = 50;

  rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  rtp_sender()->SetRtxPayloadType(kRtxPayload, kPayload);
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 1);

  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransmissionOffset::kUri, kTransmissionTimeOffsetExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      AbsoluteSendTime::kUri, kAbsoluteSendTimeExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));

  // Send a payload packet first, to enable padding and populate the packet
  // history.
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_allow_retransmission(true);
  packet->SetPayloadSize(kMinPaddingSize);
  packet->set_packet_type(RtpPacketMediaType::kVideo);
  EXPECT_CALL(send_packet_observer_, OnSendPacket).Times(1);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  // Generate a plain padding packet, check that extensions are registered.
  std::vector<std::unique_ptr<RtpPacketToSend>> generated_packets =
      rtp_sender()->GeneratePadding(/*target_size_bytes=*/1, true);
  ASSERT_THAT(generated_packets, SizeIs(1));
  auto& plain_padding = generated_packets.front();
  EXPECT_GT(plain_padding->padding_size(), 0u);
  EXPECT_TRUE(plain_padding->HasExtension<TransportSequenceNumber>());
  EXPECT_TRUE(plain_padding->HasExtension<AbsoluteSendTime>());
  EXPECT_TRUE(plain_padding->HasExtension<TransmissionOffset>());

  // Verify all header extensions have been written.
  rtp_sender_context_->InjectPacket(std::move(plain_padding),
                                    PacedPacketInfo());
  const auto& sent_plain_padding = transport_.last_sent_packet();
  EXPECT_TRUE(sent_plain_padding.HasExtension<TransportSequenceNumber>());
  EXPECT_TRUE(sent_plain_padding.HasExtension<AbsoluteSendTime>());
  EXPECT_TRUE(sent_plain_padding.HasExtension<TransmissionOffset>());
  webrtc::RTPHeader rtp_header;
  sent_plain_padding.GetHeader(&rtp_header);
  EXPECT_TRUE(rtp_header.extension.hasAbsoluteSendTime);
  EXPECT_TRUE(rtp_header.extension.hasTransmissionTimeOffset);
  EXPECT_TRUE(rtp_header.extension.hasTransportSequenceNumber);

  // Generate a payload padding packets, check that extensions are registered.
  generated_packets = rtp_sender()->GeneratePadding(kMinPaddingSize, true);
  ASSERT_EQ(generated_packets.size(), 1u);
  auto& payload_padding = generated_packets.front();
  EXPECT_EQ(payload_padding->padding_size(), 0u);
  EXPECT_TRUE(payload_padding->HasExtension<TransportSequenceNumber>());
  EXPECT_TRUE(payload_padding->HasExtension<AbsoluteSendTime>());
  EXPECT_TRUE(payload_padding->HasExtension<TransmissionOffset>());

  // Verify all header extensions have been written.
  rtp_sender_context_->InjectPacket(std::move(payload_padding),
                                    PacedPacketInfo());
  const auto& sent_payload_padding = transport_.last_sent_packet();
  EXPECT_TRUE(sent_payload_padding.HasExtension<TransportSequenceNumber>());
  EXPECT_TRUE(sent_payload_padding.HasExtension<AbsoluteSendTime>());
  EXPECT_TRUE(sent_payload_padding.HasExtension<TransmissionOffset>());
  sent_payload_padding.GetHeader(&rtp_header);
  EXPECT_TRUE(rtp_header.extension.hasAbsoluteSendTime);
  EXPECT_TRUE(rtp_header.extension.hasTransmissionTimeOffset);
  EXPECT_TRUE(rtp_header.extension.hasTransportSequenceNumber);
}

TEST_P(RtpSenderTest, GeneratePaddingResendsOldPacketsWithRtx) {
  // Min requested size in order to use RTX payload.
  const size_t kMinPaddingSize = 50;

  rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  rtp_sender()->SetRtxPayloadType(kRtxPayload, kPayload);
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 1);

  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));

  const size_t kPayloadPacketSize = kMinPaddingSize;
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_allow_retransmission(true);
  packet->SetPayloadSize(kPayloadPacketSize);
  packet->set_packet_type(RtpPacketMediaType::kVideo);

  // Send a dummy video packet so it ends up in the packet history.
  EXPECT_CALL(send_packet_observer_, OnSendPacket).Times(1);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  // Generated padding has large enough budget that the video packet should be
  // retransmitted as padding.
  std::vector<std::unique_ptr<RtpPacketToSend>> generated_packets =
      rtp_sender()->GeneratePadding(kMinPaddingSize, true);
  ASSERT_EQ(generated_packets.size(), 1u);
  auto& padding_packet = generated_packets.front();
  EXPECT_EQ(padding_packet->packet_type(), RtpPacketMediaType::kPadding);
  EXPECT_EQ(padding_packet->Ssrc(), kRtxSsrc);
  EXPECT_EQ(padding_packet->payload_size(),
            kPayloadPacketSize + kRtxHeaderSize);

  // Not enough budged for payload padding, use plain padding instead.
  const size_t kPaddingBytesRequested = kMinPaddingSize - 1;

  size_t padding_bytes_generated = 0;
  generated_packets =
      rtp_sender()->GeneratePadding(kPaddingBytesRequested, true);
  EXPECT_EQ(generated_packets.size(), 1u);
  for (auto& packet : generated_packets) {
    EXPECT_EQ(packet->packet_type(), RtpPacketMediaType::kPadding);
    EXPECT_EQ(packet->Ssrc(), kRtxSsrc);
    EXPECT_EQ(packet->payload_size(), 0u);
    EXPECT_GT(packet->padding_size(), 0u);
    padding_bytes_generated += packet->padding_size();
  }

  EXPECT_EQ(padding_bytes_generated, kMaxPaddingSize);
}

TEST_P(RtpSenderTest, LimitsPayloadPaddingSize) {
  // Limit RTX payload padding to 2x target size.
  const double kFactor = 2.0;
  field_trials_.SetMaxPaddingFactor(kFactor);
  SetUpRtpSender(true, false, false);
  rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  rtp_sender()->SetRtxPayloadType(kRtxPayload, kPayload);
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 1);

  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));

  // Send a dummy video packet so it ends up in the packet history.
  const size_t kPayloadPacketSize = 1234u;
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_allow_retransmission(true);
  packet->SetPayloadSize(kPayloadPacketSize);
  packet->set_packet_type(RtpPacketMediaType::kVideo);
  EXPECT_CALL(send_packet_observer_, OnSendPacket).Times(1);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  // Smallest target size that will result in the sent packet being returned as
  // padding.
  const size_t kMinTargerSizeForPayload =
      (kPayloadPacketSize + kRtxHeaderSize) / kFactor;

  // Generated padding has large enough budget that the video packet should be
  // retransmitted as padding.
  EXPECT_THAT(
      rtp_sender()->GeneratePadding(kMinTargerSizeForPayload, true),
      AllOf(Not(IsEmpty()),
            Each(Pointee(Property(&RtpPacketToSend::padding_size, Eq(0u))))));

  // If payload padding is > 2x requested size, plain padding is returned
  // instead.
  EXPECT_THAT(
      rtp_sender()->GeneratePadding(kMinTargerSizeForPayload - 1, true),
      AllOf(Not(IsEmpty()),
            Each(Pointee(Property(&RtpPacketToSend::padding_size, Gt(0u))))));
}

TEST_P(RtpSenderTest, GeneratePaddingCreatesPurePaddingWithoutRtx) {
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 1);
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransmissionOffset::kUri, kTransmissionTimeOffsetExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      AbsoluteSendTime::kUri, kAbsoluteSendTimeExtensionId));
  ASSERT_TRUE(rtp_sender()->RegisterRtpHeaderExtension(
      TransportSequenceNumber::kUri, kTransportSequenceNumberExtensionId));

  const size_t kPayloadPacketSize = 1234;
  // Send a dummy video packet so it ends up in the packet history. Since we
  // are not using RTX, it should never be used as padding.
  std::unique_ptr<RtpPacketToSend> packet =
      BuildRtpPacket(kPayload, true, 0, clock_->TimeInMilliseconds());
  packet->set_allow_retransmission(true);
  packet->SetPayloadSize(kPayloadPacketSize);
  packet->set_packet_type(RtpPacketMediaType::kVideo);
  EXPECT_CALL(send_packet_observer_, OnSendPacket).Times(1);
  rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());

  // Payload padding not available without RTX, only generate plain padding on
  // the media SSRC.
  // Number of padding packets is the requested padding size divided by max
  // padding packet size, rounded up. Pure padding packets are always of the
  // maximum size.
  const size_t kPaddingBytesRequested = kPayloadPacketSize + kRtxHeaderSize;
  const size_t kExpectedNumPaddingPackets =
      (kPaddingBytesRequested + kMaxPaddingSize - 1) / kMaxPaddingSize;
  size_t padding_bytes_generated = 0;
  std::vector<std::unique_ptr<RtpPacketToSend>> padding_packets =
      rtp_sender()->GeneratePadding(kPaddingBytesRequested, true);
  EXPECT_EQ(padding_packets.size(), kExpectedNumPaddingPackets);
  for (auto& packet : padding_packets) {
    EXPECT_EQ(packet->packet_type(), RtpPacketMediaType::kPadding);
    EXPECT_EQ(packet->Ssrc(), kSsrc);
    EXPECT_EQ(packet->payload_size(), 0u);
    EXPECT_GT(packet->padding_size(), 0u);
    padding_bytes_generated += packet->padding_size();
    EXPECT_TRUE(packet->HasExtension<TransportSequenceNumber>());
    EXPECT_TRUE(packet->HasExtension<AbsoluteSendTime>());
    EXPECT_TRUE(packet->HasExtension<TransmissionOffset>());

    // Verify all header extensions are received.
    rtp_sender_context_->InjectPacket(std::move(packet), PacedPacketInfo());
    webrtc::RTPHeader rtp_header;
    transport_.last_sent_packet().GetHeader(&rtp_header);
    EXPECT_TRUE(rtp_header.extension.hasAbsoluteSendTime);
    EXPECT_TRUE(rtp_header.extension.hasTransmissionTimeOffset);
    EXPECT_TRUE(rtp_header.extension.hasTransportSequenceNumber);
  }

  EXPECT_EQ(padding_bytes_generated,
            kExpectedNumPaddingPackets * kMaxPaddingSize);
}

TEST_P(RtpSenderTest, SupportsPadding) {
  bool kSendingMediaStats[] = {true, false};
  bool kEnableRedundantPayloads[] = {true, false};
  absl::string_view kBweExtensionUris[] = {
      TransportSequenceNumber::kUri, TransportSequenceNumberV2::kUri,
      AbsoluteSendTime::kUri, TransmissionOffset::kUri};
  const int kExtensionsId = 7;

  for (bool sending_media : kSendingMediaStats) {
    rtp_sender()->SetSendingMediaStatus(sending_media);
    for (bool redundant_payloads : kEnableRedundantPayloads) {
      int rtx_mode = kRtxRetransmitted;
      if (redundant_payloads) {
        rtx_mode |= kRtxRedundantPayloads;
      }
      rtp_sender()->SetRtxStatus(rtx_mode);

      for (auto extension_uri : kBweExtensionUris) {
        EXPECT_FALSE(rtp_sender()->SupportsPadding());
        rtp_sender()->RegisterRtpHeaderExtension(extension_uri, kExtensionsId);
        if (!sending_media) {
          EXPECT_FALSE(rtp_sender()->SupportsPadding());
        } else {
          EXPECT_TRUE(rtp_sender()->SupportsPadding());
          if (redundant_payloads) {
            EXPECT_TRUE(rtp_sender()->SupportsRtxPayloadPadding());
          } else {
            EXPECT_FALSE(rtp_sender()->SupportsRtxPayloadPadding());
          }
        }
        rtp_sender()->DeregisterRtpHeaderExtension(extension_uri);
        EXPECT_FALSE(rtp_sender()->SupportsPadding());
      }
    }
  }
}

TEST_P(RtpSenderTest, SetsCaptureTimeAndPopulatesTransmissionOffset) {
  rtp_sender()->RegisterRtpHeaderExtension(TransmissionOffset::kUri,
                                           kTransmissionTimeOffsetExtensionId);

  rtp_sender()->SetSendingMediaStatus(true);
  rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  rtp_sender()->SetRtxPayloadType(kRtxPayload, kPayload);
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 10);

  const int64_t kMissingCaptureTimeMs = 0;
  const int64_t kOffsetMs = 10;

  auto packet =
      BuildRtpPacket(kPayload, kMarkerBit, clock_->TimeInMilliseconds(),
                     kMissingCaptureTimeMs);
  packet->set_packet_type(RtpPacketMediaType::kVideo);
  packet->ReserveExtension<TransmissionOffset>();
  packet->AllocatePayload(sizeof(kPayloadData));

  std::unique_ptr<RtpPacketToSend> packet_to_pace;
  EXPECT_CALL(mock_paced_sender_, EnqueuePackets)
      .WillOnce([&](std::vector<std::unique_ptr<RtpPacketToSend>> packets) {
        EXPECT_EQ(packets.size(), 1u);
        EXPECT_GT(packets[0]->capture_time_ms(), 0);
        packet_to_pace = std::move(packets[0]);
      });

  packet->set_allow_retransmission(true);
  EXPECT_TRUE(rtp_sender()->SendToNetwork(std::move(packet)));

  time_controller_.AdvanceTime(TimeDelta::Millis(kOffsetMs));

  rtp_sender_context_->InjectPacket(std::move(packet_to_pace),
                                    PacedPacketInfo());

  EXPECT_EQ(1, transport_.packets_sent());
  absl::optional<int32_t> transmission_time_extension =
      transport_.sent_packets_.back().GetExtension<TransmissionOffset>();
  ASSERT_TRUE(transmission_time_extension.has_value());
  EXPECT_EQ(*transmission_time_extension, kOffsetMs * kTimestampTicksPerMs);

  // Retransmit packet. The RTX packet should get the same capture time as the
  // original packet, so offset is delta from original packet to now.
  time_controller_.AdvanceTime(TimeDelta::Millis(kOffsetMs));

  std::unique_ptr<RtpPacketToSend> rtx_packet_to_pace;
  EXPECT_CALL(mock_paced_sender_, EnqueuePackets)
      .WillOnce([&](std::vector<std::unique_ptr<RtpPacketToSend>> packets) {
        EXPECT_GT(packets[0]->capture_time_ms(), 0);
        rtx_packet_to_pace = std::move(packets[0]);
      });

  EXPECT_GT(rtp_sender()->ReSendPacket(kSeqNum), 0);
  rtp_sender_context_->InjectPacket(std::move(rtx_packet_to_pace),
                                    PacedPacketInfo());

  EXPECT_EQ(2, transport_.packets_sent());
  transmission_time_extension =
      transport_.sent_packets_.back().GetExtension<TransmissionOffset>();
  ASSERT_TRUE(transmission_time_extension.has_value());
  EXPECT_EQ(*transmission_time_extension, 2 * kOffsetMs * kTimestampTicksPerMs);
}

TEST_P(RtpSenderTestWithoutPacer, ClearHistoryOnSequenceNumberCange) {
  const int64_t kRtt = 10;

  rtp_sender()->SetSendingMediaStatus(true);
  rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  rtp_sender()->SetRtxPayloadType(kRtxPayload, kPayload);
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 10);
  rtp_sender_context_->packet_history_.SetRtt(kRtt);

  // Send a packet and record its sequence numbers.
  SendGenericPacket();
  ASSERT_EQ(1u, transport_.sent_packets_.size());
  const uint16_t packet_seqence_number =
      transport_.sent_packets_.back().SequenceNumber();

  // Advance time and make sure it can be retransmitted, even if we try to set
  // the ssrc the what it already is.
  rtp_sender()->SetSequenceNumber(rtp_sender()->SequenceNumber());
  time_controller_.AdvanceTime(TimeDelta::Millis(kRtt));
  EXPECT_GT(rtp_sender()->ReSendPacket(packet_seqence_number), 0);

  // Change the sequence number, then move the time and try to retransmit again.
  // The old packet should now be gone.
  rtp_sender()->SetSequenceNumber(rtp_sender()->SequenceNumber() - 1);
  time_controller_.AdvanceTime(TimeDelta::Millis(kRtt));
  EXPECT_EQ(rtp_sender()->ReSendPacket(packet_seqence_number), 0);
}

TEST_P(RtpSenderTest, IgnoresNackAfterDisablingMedia) {
  const int64_t kRtt = 10;

  rtp_sender()->SetSendingMediaStatus(true);
  rtp_sender()->SetRtxStatus(kRtxRetransmitted | kRtxRedundantPayloads);
  rtp_sender()->SetRtxPayloadType(kRtxPayload, kPayload);
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 10);
  rtp_sender_context_->packet_history_.SetRtt(kRtt);

  // Send a packet so it is in the packet history.
    std::unique_ptr<RtpPacketToSend> packet_to_pace;
    EXPECT_CALL(mock_paced_sender_, EnqueuePackets)
        .WillOnce([&](std::vector<std::unique_ptr<RtpPacketToSend>> packets) {
          packet_to_pace = std::move(packets[0]);
        });

    SendGenericPacket();
    rtp_sender_context_->InjectPacket(std::move(packet_to_pace),
                                      PacedPacketInfo());

    ASSERT_EQ(1u, transport_.sent_packets_.size());

    // Disable media sending and try to retransmit the packet, it should fail.
    rtp_sender()->SetSendingMediaStatus(false);
    time_controller_.AdvanceTime(TimeDelta::Millis(kRtt));
    EXPECT_LT(rtp_sender()->ReSendPacket(kSeqNum), 0);
}

TEST_P(RtpSenderTest, DoesntFecProtectRetransmissions) {
  // Set up retranmission without RTX, so that a plain copy of the old packet is
  // re-sent instead.
  const int64_t kRtt = 10;
  rtp_sender()->SetSendingMediaStatus(true);
  rtp_sender()->SetRtxStatus(kRtxOff);
  rtp_sender_context_->packet_history_.SetStorePacketsStatus(
      RtpPacketHistory::StorageMode::kStoreAndCull, 10);
  rtp_sender_context_->packet_history_.SetRtt(kRtt);

  // Send a packet so it is in the packet history, make sure to mark it for
  // FEC protection.
  std::unique_ptr<RtpPacketToSend> packet_to_pace;
  EXPECT_CALL(mock_paced_sender_, EnqueuePackets)
      .WillOnce([&](std::vector<std::unique_ptr<RtpPacketToSend>> packets) {
        packet_to_pace = std::move(packets[0]);
      });

  SendGenericPacket();
  packet_to_pace->set_fec_protect_packet(true);
  rtp_sender_context_->InjectPacket(std::move(packet_to_pace),
                                    PacedPacketInfo());

  ASSERT_EQ(1u, transport_.sent_packets_.size());

  // Re-send packet, the retransmitted packet should not have the FEC protection
  // flag set.
  EXPECT_CALL(mock_paced_sender_,
              EnqueuePackets(Each(Pointee(
                  Property(&RtpPacketToSend::fec_protect_packet, false)))));

  time_controller_.AdvanceTime(TimeDelta::Millis(kRtt));
  EXPECT_GT(rtp_sender()->ReSendPacket(kSeqNum), 0);
}

TEST_P(RtpSenderTest, MarksPacketsWithKeyframeStatus) {
  FieldTrialBasedConfig field_trials;
  RTPSenderVideo::Config video_config;
  video_config.clock = clock_;
  video_config.rtp_sender = rtp_sender();
  video_config.field_trials = &field_trials;
  RTPSenderVideo rtp_sender_video(video_config);

  const uint8_t kPayloadType = 127;
  const absl::optional<VideoCodecType> kCodecType =
      VideoCodecType::kVideoCodecGeneric;

  const uint32_t kCaptureTimeMsToRtpTimestamp = 90;  // 90 kHz clock

  {
    EXPECT_CALL(mock_paced_sender_,
                EnqueuePackets(Each(
                    Pointee(Property(&RtpPacketToSend::is_key_frame, true)))))
        .Times(AtLeast(1));
    RTPVideoHeader video_header;
    video_header.frame_type = VideoFrameType::kVideoFrameKey;
    int64_t capture_time_ms = clock_->TimeInMilliseconds();
    EXPECT_TRUE(rtp_sender_video.SendVideo(
        kPayloadType, kCodecType,
        capture_time_ms * kCaptureTimeMsToRtpTimestamp, capture_time_ms,
        kPayloadData, video_header, kDefaultExpectedRetransmissionTimeMs));

    time_controller_.AdvanceTime(TimeDelta::Millis(33));
  }

  {
    EXPECT_CALL(mock_paced_sender_,
                EnqueuePackets(Each(
                    Pointee(Property(&RtpPacketToSend::is_key_frame, false)))))
        .Times(AtLeast(1));
    RTPVideoHeader video_header;
    video_header.frame_type = VideoFrameType::kVideoFrameDelta;
    int64_t capture_time_ms = clock_->TimeInMilliseconds();
    EXPECT_TRUE(rtp_sender_video.SendVideo(
        kPayloadType, kCodecType,
        capture_time_ms * kCaptureTimeMsToRtpTimestamp, capture_time_ms,
        kPayloadData, video_header, kDefaultExpectedRetransmissionTimeMs));

    time_controller_.AdvanceTime(TimeDelta::Millis(33));
  }
}

INSTANTIATE_TEST_SUITE_P(WithAndWithoutOverhead,
                         RtpSenderTest,
                         ::testing::Values(TestConfig{false},
                                           TestConfig{true}));

INSTANTIATE_TEST_SUITE_P(WithAndWithoutOverhead,
                         RtpSenderTestWithoutPacer,
                         ::testing::Values(TestConfig{false},
                                           TestConfig{true}));

}  // namespace webrtc