// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "components/download/internal/background_service/navigation_monitor_impl.h"

#include "base/functional/bind.h"
#include "base/functional/callback_helpers.h"
#include "base/task/single_thread_task_runner.h"

namespace download {

NavigationMonitorImpl::NavigationMonitorImpl()
    : observer_(nullptr), current_navigation_count_(0) {}

NavigationMonitorImpl::~NavigationMonitorImpl() = default;

void NavigationMonitorImpl::Configure(
    base::TimeDelta navigation_completion_delay,
    base::TimeDelta navigation_timeout_delay) {
  navigation_completion_delay_ = navigation_completion_delay;
  navigation_timeout_delay_ = navigation_timeout_delay;
}

bool NavigationMonitorImpl::IsNavigationInProgress() const {
  return current_navigation_count_ > 0;
}

void NavigationMonitorImpl::SetObserver(NavigationMonitor::Observer* observer) {
  observer_ = observer;
  if (observer_)
    observer_->OnNavigationEvent();
}

void NavigationMonitorImpl::OnNavigationEvent(NavigationEvent event) {
  if (event == NavigationEvent::START_NAVIGATION) {
    current_navigation_count_++;
    if (observer_)
      observer_->OnNavigationEvent();

    navigation_finished_callback_.Cancel();
    ScheduleBackupTask();
  } else {
    if (current_navigation_count_ == 0) {
      // Somehow we didn't record the beginning of the navigation. No need to
      // take any action.
      backup_navigation_finished_callback_.Cancel();
      navigation_finished_callback_.Cancel();
      return;
    }

    current_navigation_count_--;
    if (current_navigation_count_ == 0)
      NotifyNavigationFinished();
  }
}

void NavigationMonitorImpl::NotifyNavigationFinished() {
  backup_navigation_finished_callback_.Cancel();
  navigation_finished_callback_.Reset(
      base::BindOnce(&NavigationMonitorImpl::OnNavigationFinished,
                     weak_ptr_factory_.GetWeakPtr()));
  base::SingleThreadTaskRunner::GetCurrentDefault()->PostDelayedTask(
      FROM_HERE, navigation_finished_callback_.callback(),
      navigation_completion_delay_);
}

void NavigationMonitorImpl::OnNavigationFinished() {
  // Reset the counter to handle timeout.
  current_navigation_count_ = 0;
  if (observer_)
    observer_->OnNavigationEvent();
}

void NavigationMonitorImpl::ScheduleBackupTask() {
  backup_navigation_finished_callback_.Reset(
      base::BindOnce(&NavigationMonitorImpl::OnNavigationFinished,
                     weak_ptr_factory_.GetWeakPtr()));
  base::SingleThreadTaskRunner::GetCurrentDefault()->PostDelayedTask(
      FROM_HERE, backup_navigation_finished_callback_.callback(),
      navigation_timeout_delay_);
}

}  // namespace download