/*
 *  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 <utility>

#include "webrtc/test/gtest.h"
#include "webrtc/modules/audio_coding/audio_network_adaptor/frame_length_controller.h"

namespace webrtc {

namespace {

constexpr float kFlIncreasingPacketLossFraction = 0.04f;
constexpr float kFlDecreasingPacketLossFraction = 0.05f;
constexpr int kFl20msTo60msBandwidthBps = 22000;
constexpr int kFl60msTo20msBandwidthBps = 88000;
constexpr int kMinReceiverFrameLengthMs = 10;
constexpr int kMaxReceiverFrameLengthMs = 120;
constexpr int kMediumBandwidthBps =
    (kFl60msTo20msBandwidthBps + kFl20msTo60msBandwidthBps) / 2;
constexpr float kMediumPacketLossFraction =
    (kFlDecreasingPacketLossFraction + kFlIncreasingPacketLossFraction) / 2;

void SetReceiverFrameLengthRange(FrameLengthController* controller,
                                 int min_frame_length_ms,
                                 int max_frame_length_ms) {
  Controller::Constraints constraints;
  using FrameLengthRange = Controller::Constraints::FrameLengthRange;
  constraints.receiver_frame_length_range = rtc::Optional<FrameLengthRange>(
      FrameLengthRange(min_frame_length_ms, max_frame_length_ms));
  controller->SetConstraints(constraints);
}

std::unique_ptr<FrameLengthController> CreateController(
    int initial_frame_length_ms) {
  std::unique_ptr<FrameLengthController> controller(
      new FrameLengthController(FrameLengthController::Config(
          {20, 60}, initial_frame_length_ms, kFlIncreasingPacketLossFraction,
          kFlDecreasingPacketLossFraction, kFl20msTo60msBandwidthBps,
          kFl60msTo20msBandwidthBps)));
  SetReceiverFrameLengthRange(controller.get(), kMinReceiverFrameLengthMs,
                              kMaxReceiverFrameLengthMs);
  return controller;
}

void CheckDecision(FrameLengthController* controller,
                   const rtc::Optional<int>& uplink_bandwidth_bps,
                   const rtc::Optional<float>& uplink_packet_loss_fraction,
                   const rtc::Optional<bool>& enable_fec,
                   int expected_frame_length_ms) {
  Controller::NetworkMetrics metrics;
  metrics.uplink_bandwidth_bps = uplink_bandwidth_bps;
  metrics.uplink_packet_loss_fraction = uplink_packet_loss_fraction;
  AudioNetworkAdaptor::EncoderRuntimeConfig config;
  config.enable_fec = enable_fec;
  controller->MakeDecision(metrics, &config);
  EXPECT_EQ(rtc::Optional<int>(expected_frame_length_ms),
            config.frame_length_ms);
}

}  // namespace

TEST(FrameLengthControllerTest,
     OutputInitValueWhenReceiverFrameLengthRangeUnset) {
  constexpr int kInitialFrameLenghtMs = 60;
  std::unique_ptr<FrameLengthController> controller(
      new FrameLengthController(FrameLengthController::Config(
          {20, 60}, kInitialFrameLenghtMs, kFlIncreasingPacketLossFraction,
          kFlDecreasingPacketLossFraction, kFl20msTo60msBandwidthBps,
          kFl60msTo20msBandwidthBps)));
  // Use a high uplink bandwidth that would cause frame length to decrease if
  // receiver frame length is set.
  CheckDecision(controller.get(), rtc::Optional<int>(kFl60msTo20msBandwidthBps),
                rtc::Optional<float>(), rtc::Optional<bool>(),
                kInitialFrameLenghtMs);
}

TEST(FrameLengthControllerTest, DecreaseTo20MsOnHighUplinkBandwidth) {
  auto controller = CreateController(60);
  CheckDecision(controller.get(), rtc::Optional<int>(kFl60msTo20msBandwidthBps),
                rtc::Optional<float>(), rtc::Optional<bool>(), 20);
}

TEST(FrameLengthControllerTest, DecreaseTo20MsOnHighUplinkPacketLossFraction) {
  auto controller = CreateController(60);
  CheckDecision(controller.get(), rtc::Optional<int>(),
                rtc::Optional<float>(kFlDecreasingPacketLossFraction),
                rtc::Optional<bool>(), 20);
}

TEST(FrameLengthControllerTest, DecreaseTo20MsWhenFecIsOn) {
  auto controller = CreateController(60);
  CheckDecision(controller.get(), rtc::Optional<int>(), rtc::Optional<float>(),
                rtc::Optional<bool>(true), 20);
}

TEST(FrameLengthControllerTest,
     Maintain60MsIf20MsNotInReceiverFrameLengthRange) {
  auto controller = CreateController(60);
  SetReceiverFrameLengthRange(controller.get(), 21, 60);
  // Set FEC on that would cause frame length to decrease if receiver frame
  // length range included 20ms.
  CheckDecision(controller.get(), rtc::Optional<int>(), rtc::Optional<float>(),
                rtc::Optional<bool>(true), 60);
}

TEST(FrameLengthControllerTest, Maintain60MsOnMultipleConditions) {
  // Maintain 60ms frame length if
  // 1. |uplink_bandwidth_bps| is at medium level,
  // 2. |uplink_packet_loss_fraction| is at medium,
  // 3. FEC is not decided ON.
  auto controller = CreateController(60);
  CheckDecision(controller.get(), rtc::Optional<int>(kMediumBandwidthBps),
                rtc::Optional<float>(kMediumPacketLossFraction),
                rtc::Optional<bool>(), 60);
}

TEST(FrameLengthControllerTest, IncreaseTo60MsOnMultipleConditions) {
  // Increase to 60ms frame length if
  // 1. |uplink_bandwidth_bps| is known to be smaller than a threshold AND
  // 2. |uplink_packet_loss_fraction| is known to be smaller than a threshold
  //    AND
  // 3. FEC is not decided or OFF.
  auto controller = CreateController(20);
  CheckDecision(controller.get(), rtc::Optional<int>(kFl20msTo60msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 60);
}

TEST(FrameLengthControllerTest,
     Maintain20MsIf60MsNotInReceiverFrameLengthRange) {
  auto controller = CreateController(20);
  SetReceiverFrameLengthRange(controller.get(), 10, 59);
  // Use a low uplink bandwidth and a low uplink packet loss fraction that would
  // cause frame length to increase if receiver frame length included 60ms.
  CheckDecision(controller.get(), rtc::Optional<int>(kFl20msTo60msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 20);
}

TEST(FrameLengthControllerTest, Maintain20MsOnMediumUplinkBandwidth) {
  auto controller = CreateController(20);
  CheckDecision(controller.get(), rtc::Optional<int>(kMediumBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 20);
}

TEST(FrameLengthControllerTest, Maintain20MsOnMediumUplinkPacketLossFraction) {
  auto controller = CreateController(20);
  // Use a low uplink bandwidth that would cause frame length to increase if
  // uplink packet loss fraction was low.
  CheckDecision(controller.get(), rtc::Optional<int>(kFl20msTo60msBandwidthBps),
                rtc::Optional<float>(kMediumPacketLossFraction),
                rtc::Optional<bool>(), 20);
}

TEST(FrameLengthControllerTest, Maintain20MsWhenFecIsOn) {
  auto controller = CreateController(20);
  // Use a low uplink bandwidth and a low uplink packet loss fraction that would
  // cause frame length to increase if FEC was not ON.
  CheckDecision(controller.get(), rtc::Optional<int>(kFl20msTo60msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(true), 20);
}

TEST(FrameLengthControllerTest,
     MaintainFrameLengthOnSetReceiverFrameLengthRange) {
  auto controller = CreateController(60);
  CheckDecision(controller.get(), rtc::Optional<int>(), rtc::Optional<float>(),
                rtc::Optional<bool>(true), 20);
  SetReceiverFrameLengthRange(controller.get(), 10, 60);
  CheckDecision(controller.get(), rtc::Optional<int>(), rtc::Optional<float>(),
                rtc::Optional<bool>(), 20);
}

namespace {
constexpr int kFl60msTo120msBandwidthBps = 18000;
constexpr int kFl120msTo60msBandwidthBps = 72000;
}

class FrameLengthControllerForTest {
 public:
  // This class is to test multiple frame lengths. FrameLengthController is
  // implemented to support this, but is not enabled for the default constructor
  // for the time being. We use this class to test it.
  explicit FrameLengthControllerForTest(int initial_frame_length_ms)
      : frame_length_controller_(
            FrameLengthController::Config({20, 60, 120},
                                          initial_frame_length_ms,
                                          kFlIncreasingPacketLossFraction,
                                          kFlDecreasingPacketLossFraction,
                                          kFl20msTo60msBandwidthBps,
                                          kFl60msTo20msBandwidthBps)) {
    frame_length_controller_.frame_length_change_criteria_.insert(
        std::make_pair(FrameLengthController::FrameLengthChange(60, 120),
                       kFl60msTo120msBandwidthBps));
    frame_length_controller_.frame_length_change_criteria_.insert(
        std::make_pair(FrameLengthController::FrameLengthChange(120, 60),
                       kFl120msTo60msBandwidthBps));
    frame_length_controller_.SetReceiverFrameLengthRange(20, 120);
  }
  FrameLengthController* get() { return &frame_length_controller_; }

 private:
  FrameLengthController frame_length_controller_;
};

TEST(FrameLengthControllerTest, From120MsTo20MsOnHighUplinkBandwidth) {
  FrameLengthControllerForTest controller(120);
  // It takes two steps for frame length to go from 120ms to 20ms.
  CheckDecision(controller.get(), rtc::Optional<int>(kFl60msTo20msBandwidthBps),
                rtc::Optional<float>(), rtc::Optional<bool>(), 60);
  CheckDecision(controller.get(), rtc::Optional<int>(kFl60msTo20msBandwidthBps),
                rtc::Optional<float>(), rtc::Optional<bool>(), 20);
}

TEST(FrameLengthControllerTest, From120MsTo20MsOnHighUplinkPacketLossFraction) {
  FrameLengthControllerForTest controller(120);
  // It takes two steps for frame length to go from 120ms to 20ms.
  CheckDecision(controller.get(), rtc::Optional<int>(),
                rtc::Optional<float>(kFlDecreasingPacketLossFraction),
                rtc::Optional<bool>(), 60);
  CheckDecision(controller.get(), rtc::Optional<int>(),
                rtc::Optional<float>(kFlDecreasingPacketLossFraction),
                rtc::Optional<bool>(), 20);
}

TEST(FrameLengthControllerTest, From120MsTo20MsWhenFecIsOn) {
  FrameLengthControllerForTest controller(120);
  // It takes two steps for frame length to go from 120ms to 20ms.
  CheckDecision(controller.get(), rtc::Optional<int>(), rtc::Optional<float>(),
                rtc::Optional<bool>(true), 60);
  CheckDecision(controller.get(), rtc::Optional<int>(), rtc::Optional<float>(),
                rtc::Optional<bool>(true), 20);
}

TEST(FrameLengthControllerTest, From20MsTo120MsOnMultipleConditions) {
  // Increase to 120ms frame length if
  // 1. |uplink_bandwidth_bps| is known to be smaller than a threshold AND
  // 2. |uplink_packet_loss_fraction| is known to be smaller than a threshold
  //    AND
  // 3. FEC is not decided or OFF.
  FrameLengthControllerForTest controller(20);
  // It takes two steps for frame length to go from 20ms to 120ms.
  CheckDecision(controller.get(),
                rtc::Optional<int>(kFl60msTo120msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 60);
  CheckDecision(controller.get(),
                rtc::Optional<int>(kFl60msTo120msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 120);
}

TEST(FrameLengthControllerTest, Stall60MsIf120MsNotInReceiverFrameLengthRange) {
  FrameLengthControllerForTest controller(20);
  SetReceiverFrameLengthRange(controller.get(), 20, 119);
  CheckDecision(controller.get(),
                rtc::Optional<int>(kFl60msTo120msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 60);
  CheckDecision(controller.get(),
                rtc::Optional<int>(kFl60msTo120msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 60);
}

TEST(FrameLengthControllerTest, CheckBehaviorOnChangingNetworkMetrics) {
  FrameLengthControllerForTest controller(20);
  CheckDecision(controller.get(), rtc::Optional<int>(kMediumBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 20);
  CheckDecision(controller.get(), rtc::Optional<int>(kFl20msTo60msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 60);
  CheckDecision(controller.get(),
                rtc::Optional<int>(kFl60msTo120msBandwidthBps),
                rtc::Optional<float>(kMediumPacketLossFraction),
                rtc::Optional<bool>(), 60);
  CheckDecision(controller.get(),
                rtc::Optional<int>(kFl60msTo120msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 120);
  CheckDecision(controller.get(),
                rtc::Optional<int>(kFl120msTo60msBandwidthBps),
                rtc::Optional<float>(kFlIncreasingPacketLossFraction),
                rtc::Optional<bool>(), 60);
  CheckDecision(controller.get(), rtc::Optional<int>(kMediumPacketLossFraction),
                rtc::Optional<float>(kFlDecreasingPacketLossFraction),
                rtc::Optional<bool>(), 20);
}

}  // namespace webrtc