/*
 *  Copyright (c) 2016 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 <memory>

#include "modules/congestion_controller/probe_controller.h"
#include "modules/pacing/mock/mock_paced_sender.h"
#include "rtc_base/logging.h"
#include "system_wrappers/include/clock.h"
#include "test/gmock.h"
#include "test/gtest.h"

using testing::_;
using testing::AtLeast;
using testing::NiceMock;
using testing::Return;

namespace webrtc {
namespace test {

namespace {

constexpr int kMinBitrateBps = 100;
constexpr int kStartBitrateBps = 300;
constexpr int kMaxBitrateBps = 10000;

constexpr int kExponentialProbingTimeoutMs = 5000;

constexpr int kAlrProbeInterval = 5000;
constexpr int kAlrEndedTimeoutMs = 3000;
constexpr int kBitrateDropTimeoutMs = 5000;

}  // namespace

class ProbeControllerTest : public ::testing::Test {
 protected:
  ProbeControllerTest() : clock_(100000000L) {
    probe_controller_.reset(new ProbeController(&pacer_, &clock_));
  }
  ~ProbeControllerTest() override {}

  SimulatedClock clock_;
  NiceMock<MockPacedSender> pacer_;
  std::unique_ptr<ProbeController> probe_controller_;
};

TEST_F(ProbeControllerTest, InitiatesProbingAtStart) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(AtLeast(2));
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
}

TEST_F(ProbeControllerTest, ProbeOnlyWhenNetworkIsUp) {
  probe_controller_->OnNetworkStateChanged(kNetworkDown);
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);

  testing::Mock::VerifyAndClearExpectations(&pacer_);
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(AtLeast(2));
  probe_controller_->OnNetworkStateChanged(kNetworkUp);
}

TEST_F(ProbeControllerTest, InitiatesProbingOnMaxBitrateIncrease) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(AtLeast(2));
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  // Long enough to time out exponential probing.
  clock_.AdvanceTimeMilliseconds(kExponentialProbingTimeoutMs);
  probe_controller_->SetEstimatedBitrate(kStartBitrateBps);
  probe_controller_->Process();

  EXPECT_CALL(pacer_, CreateProbeCluster(kMaxBitrateBps + 100));
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps + 100);
}

TEST_F(ProbeControllerTest, InitiatesProbingOnMaxBitrateIncreaseAtMaxBitrate) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(AtLeast(2));
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  // Long enough to time out exponential probing.
  clock_.AdvanceTimeMilliseconds(kExponentialProbingTimeoutMs);
  probe_controller_->SetEstimatedBitrate(kStartBitrateBps);
  probe_controller_->Process();

  probe_controller_->SetEstimatedBitrate(kMaxBitrateBps);
  EXPECT_CALL(pacer_, CreateProbeCluster(kMaxBitrateBps + 100));
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps + 100);
}

TEST_F(ProbeControllerTest, TestExponentialProbing) {
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);

  // Repeated probe should only be sent when estimated bitrate climbs above
  // 0.7 * 6 * kStartBitrateBps = 1260.
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
  probe_controller_->SetEstimatedBitrate(1000);
  testing::Mock::VerifyAndClearExpectations(&pacer_);

  EXPECT_CALL(pacer_, CreateProbeCluster(2 * 1800));
  probe_controller_->SetEstimatedBitrate(1800);
}

TEST_F(ProbeControllerTest, TestExponentialProbingTimeout) {
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);

  // Advance far enough to cause a time out in waiting for probing result.
  clock_.AdvanceTimeMilliseconds(kExponentialProbingTimeoutMs);
  probe_controller_->Process();

  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
  probe_controller_->SetEstimatedBitrate(1800);
}

TEST_F(ProbeControllerTest, RequestProbeInAlr) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);
  EXPECT_CALL(pacer_, CreateProbeCluster(0.85 * 500)).Times(1);
  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(clock_.TimeInMilliseconds()));
  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
  probe_controller_->Process();
  probe_controller_->SetEstimatedBitrate(250);
  probe_controller_->RequestProbe();
}

TEST_F(ProbeControllerTest, RequestProbeWhenAlrEndedRecently) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);
  EXPECT_CALL(pacer_, CreateProbeCluster(0.85 * 500)).Times(1);
  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(rtc::nullopt));
  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
  probe_controller_->Process();
  probe_controller_->SetEstimatedBitrate(250);
  probe_controller_->SetAlrEndedTimeMs(clock_.TimeInMilliseconds());
  clock_.AdvanceTimeMilliseconds(kAlrEndedTimeoutMs - 1);
  probe_controller_->RequestProbe();
}

TEST_F(ProbeControllerTest, RequestProbeWhenAlrNotEndedRecently) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(rtc::nullopt));
  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
  probe_controller_->Process();
  probe_controller_->SetEstimatedBitrate(250);
  probe_controller_->SetAlrEndedTimeMs(clock_.TimeInMilliseconds());
  clock_.AdvanceTimeMilliseconds(kAlrEndedTimeoutMs + 1);
  probe_controller_->RequestProbe();
}

TEST_F(ProbeControllerTest, RequestProbeWhenBweDropNotRecent) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(clock_.TimeInMilliseconds()));
  clock_.AdvanceTimeMilliseconds(kAlrProbeInterval + 1);
  probe_controller_->Process();
  probe_controller_->SetEstimatedBitrate(250);
  clock_.AdvanceTimeMilliseconds(kBitrateDropTimeoutMs + 1);
  probe_controller_->RequestProbe();
}

TEST_F(ProbeControllerTest, PeriodicProbing) {
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(2);
  probe_controller_->EnablePeriodicAlrProbing(true);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);

  int64_t start_time = clock_.TimeInMilliseconds();

  // Expect the controller to send a new probe after 5s has passed.
  EXPECT_CALL(pacer_, CreateProbeCluster(1000)).Times(1);
  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(start_time));
  clock_.AdvanceTimeMilliseconds(5000);
  probe_controller_->Process();
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);

  // The following probe should be sent at 10s into ALR.
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(start_time));
  clock_.AdvanceTimeMilliseconds(4000);
  probe_controller_->Process();
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);

  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(1);
  EXPECT_CALL(pacer_, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(start_time));
  clock_.AdvanceTimeMilliseconds(1000);
  probe_controller_->Process();
  probe_controller_->SetEstimatedBitrate(500);
  testing::Mock::VerifyAndClearExpectations(&pacer_);
}

TEST_F(ProbeControllerTest, PeriodicProbingAfterReset) {
  testing::StrictMock<MockPacedSender> local_pacer;
  probe_controller_.reset(new ProbeController(&local_pacer, &clock_));
  int64_t alr_start_time = clock_.TimeInMilliseconds();
  EXPECT_CALL(local_pacer, GetApplicationLimitedRegionStartTime())
      .WillRepeatedly(Return(alr_start_time));

  EXPECT_CALL(local_pacer, CreateProbeCluster(_)).Times(2);
  probe_controller_->EnablePeriodicAlrProbing(true);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);
  probe_controller_->Reset();

  clock_.AdvanceTimeMilliseconds(10000);
  probe_controller_->Process();

  EXPECT_CALL(local_pacer, CreateProbeCluster(_)).Times(2);
  probe_controller_->SetBitrates(kMinBitrateBps, kStartBitrateBps,
                                 kMaxBitrateBps);

  // Make sure we use |kStartBitrateBps| as the estimated bitrate
  // until SetEstimatedBitrate is called with an updated estimate.
  clock_.AdvanceTimeMilliseconds(10000);
  EXPECT_CALL(local_pacer, CreateProbeCluster(kStartBitrateBps*2));
  probe_controller_->Process();
}

TEST_F(ProbeControllerTest, TestExponentialProbingOverflow) {
  const int64_t kMbpsMultiplier = 1000000;
  probe_controller_->SetBitrates(kMinBitrateBps, 10 * kMbpsMultiplier,
                                 100 * kMbpsMultiplier);

  // Verify that probe bitrate is capped at the specified max bitrate
  EXPECT_CALL(pacer_, CreateProbeCluster(100 * kMbpsMultiplier));
  probe_controller_->SetEstimatedBitrate(60 * kMbpsMultiplier);
  testing::Mock::VerifyAndClearExpectations(&pacer_);

  // Verify that repeated probes aren't sent.
  EXPECT_CALL(pacer_, CreateProbeCluster(_)).Times(0);
  probe_controller_->SetEstimatedBitrate(100 * kMbpsMultiplier);
}

}  // namespace test
}  // namespace webrtc