/*
 *  Copyright 2017 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 "rtc_tools/network_tester/packet_sender.h"

#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <string>
#include <utility>

#include "absl/functional/any_invocable.h"
#include "api/environment/environment.h"
#include "api/scoped_refptr.h"
#include "api/sequence_checker.h"
#include "api/task_queue/pending_task_safety_flag.h"
#include "api/task_queue/task_queue_base.h"
#include "api/units/time_delta.h"
#include "rtc_tools/network_tester/config_reader.h"
#include "rtc_tools/network_tester/test_controller.h"
#include "system_wrappers/include/clock.h"

namespace webrtc {

namespace {

absl::AnyInvocable<void() &&> SendPacketTask(
    Clock* clock,
    PacketSender* packet_sender,
    scoped_refptr<PendingTaskSafetyFlag> task_safety_flag,
    int64_t target_time_ms) {
  return [clock, target_time_ms, packet_sender,
          task_safety_flag = std::move(task_safety_flag)]() mutable {
    if (task_safety_flag->alive() && packet_sender->IsSending()) {
      packet_sender->SendPacket();
      target_time_ms += packet_sender->GetSendIntervalMs();
      int64_t delay_ms = std::max(static_cast<int64_t>(0),
                                  target_time_ms - clock->TimeInMilliseconds());
      TaskQueueBase::Current()->PostDelayedTask(
          SendPacketTask(clock, packet_sender, std::move(task_safety_flag),
                         target_time_ms),
          TimeDelta::Millis(delay_ms));
    }
  };
}

absl::AnyInvocable<void() &&> UpdateTestSettingTask(
    PacketSender* packet_sender,
    std::unique_ptr<ConfigReader> config_reader,
    scoped_refptr<PendingTaskSafetyFlag> task_safety_flag) {
  return [packet_sender, config_reader = std::move(config_reader),
          task_safety_flag = std::move(task_safety_flag)]() mutable {
    if (!task_safety_flag->alive()) {
      return;
    }
    if (std::optional<ConfigReader::Config> config =
            config_reader->GetNextConfig()) {
      packet_sender->UpdateTestSetting(config->packet_size,
                                       config->packet_send_interval_ms);
      TaskQueueBase::Current()->PostDelayedTask(
          UpdateTestSettingTask(packet_sender, std::move(config_reader),
                                std::move(task_safety_flag)),
          TimeDelta::Millis(config->execution_time_ms));
    } else {
      packet_sender->StopSending();
    }
  };
}

}  // namespace

PacketSender::PacketSender(
    const Environment& env,
    TestController* test_controller,
    TaskQueueBase* worker_queue,
    scoped_refptr<PendingTaskSafetyFlag> task_safety_flag,
    const std::string& config_file_path)
    : env_(env),
      packet_size_(0),
      send_interval_ms_(0),
      sequence_number_(0),
      sending_(false),
      config_file_path_(config_file_path),
      test_controller_(test_controller),
      worker_queue_(worker_queue),
      task_safety_flag_(task_safety_flag) {}

PacketSender::~PacketSender() = default;

void PacketSender::StartSending() {
  worker_queue_checker_.Detach();
  worker_queue_->PostTask(SafeTask(task_safety_flag_, [this]() {
    RTC_DCHECK_RUN_ON(&worker_queue_checker_);
    sending_ = true;
  }));
  worker_queue_->PostTask(UpdateTestSettingTask(
      this, std::make_unique<ConfigReader>(config_file_path_),
      task_safety_flag_));
  worker_queue_->PostTask(SendPacketTask(&env_.clock(), this, task_safety_flag_,
                                         env_.clock().TimeInMilliseconds()));
}

void PacketSender::StopSending() {
  RTC_DCHECK_RUN_ON(&worker_queue_checker_);
  sending_ = false;
  test_controller_->OnTestDone();
}

bool PacketSender::IsSending() const {
  RTC_DCHECK_RUN_ON(&worker_queue_checker_);
  return sending_;
}

void PacketSender::SendPacket() {
  RTC_DCHECK_RUN_ON(&worker_queue_checker_);
  NetworkTesterPacket packet;
  packet.set_type(NetworkTesterPacket::TEST_DATA);
  packet.set_sequence_number(sequence_number_++);
  packet.set_send_timestamp(env_.clock().TimeInMicroseconds());
  test_controller_->SendData(packet, packet_size_);
}

int64_t PacketSender::GetSendIntervalMs() const {
  RTC_DCHECK_RUN_ON(&worker_queue_checker_);
  return send_interval_ms_;
}

void PacketSender::UpdateTestSetting(size_t packet_size,
                                     int64_t send_interval_ms) {
  RTC_DCHECK_RUN_ON(&worker_queue_checker_);
  send_interval_ms_ = send_interval_ms;
  packet_size_ = packet_size;
}

}  // namespace webrtc