/*
 * Strawberry Music Player
 * This file was part of Clementine.
 * Copyright 2012, David Sansome <me@davidsansome.com>
 * Copyright 2014, John Maguire <john.maguire@gmail.com>
 * Copyright 2014, Krzysztof Sobiecki <sobkas@gmail.com>
 * Copyright 2019-2021, Jonas Kvinge <jonas@jkvinge.net>
 *
 * Strawberry is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Strawberry is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Strawberry.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <QCoreApplication>
#include <QSet>
#include <QList>
#include <QMap>
#include <QString>
#include <QUrl>
#include <QHostInfo>
#include <QNetworkReply>
#include <QNetworkCookieJar>
#include <QSettings>
#include <QTimer>

#include "core/application.h"
#include "core/logging.h"
#include "core/networkaccessmanager.h"
#include "core/timeconstants.h"
#include "core/utilities.h"
#include "podcastbackend.h"
#include "podcasturlloader.h"
#include "gpoddersync.h"

const char *GPodderSync::kSettingsGroup = "Podcasts";
const int GPodderSync::kFlushUpdateQueueDelay = 30 * kMsecPerSec;   // 30 seconds
const int GPodderSync::kGetUpdatesInterval = 30 * 60 * kMsecPerSec; // 30 minutes
const int GPodderSync::kRequestTimeout = 30 * kMsecPerSec;          // 30 seconds

GPodderSync::GPodderSync(Application *app, QObject *parent)
    : QObject(parent),
      app_(app),
      network_(new NetworkAccessManager(this)),
      backend_(app_->podcast_backend()),
      loader_(new PodcastUrlLoader(this)),
      get_updates_timer_(new QTimer(this)),
      flush_queue_timer_(new QTimer(this)),
      flushing_queue_(false) {

  ReloadSettings();
  LoadQueue();

  QObject::connect(app_, &Application::SettingsChanged, this, &GPodderSync::ReloadSettings);
  QObject::connect(backend_, &PodcastBackend::SubscriptionAdded, this, &GPodderSync::SubscriptionAdded);
  QObject::connect(backend_, &PodcastBackend::SubscriptionRemoved, this, &GPodderSync::SubscriptionRemoved);

  get_updates_timer_->setInterval(kGetUpdatesInterval);
  connect(get_updates_timer_, &QTimer::timeout, this, &GPodderSync::GetUpdatesNow);

  flush_queue_timer_->setInterval(kFlushUpdateQueueDelay);
  flush_queue_timer_->setSingleShot(true);
  QObject::connect(flush_queue_timer_, &QTimer::timeout, this, &GPodderSync::FlushUpdateQueue);

  if (is_logged_in()) {
    GetUpdatesNow();
    flush_queue_timer_->start();
    get_updates_timer_->start();
  }
}

GPodderSync::~GPodderSync() {}

QString GPodderSync::DeviceId() {

  return QString("%1-%2").arg(qApp->applicationName(), QHostInfo::localHostName()).toLower();

}

QString GPodderSync::DefaultDeviceName() {
  return tr("%1 on %2").arg(qApp->applicationName(), QHostInfo::localHostName());
}

bool GPodderSync::is_logged_in() const {
  return !username_.isEmpty() && !password_.isEmpty() && api_;
}

void GPodderSync::ReloadSettings() {

  QSettings s;
  s.beginGroup(kSettingsGroup);

  username_ = s.value("gpodder_username").toString();
  password_ = s.value("gpodder_password").toString();
  last_successful_get_ = s.value("gpodder_last_get").toDateTime();

  s.endGroup();

  if (!username_.isEmpty() && !password_.isEmpty()) {
    api_.reset(new mygpo::ApiRequest(username_, password_, network_));
  }

}

void GPodderSync::Login(const QString &username, const QString &password, const QString &device_name) {

  api_.reset(new mygpo::ApiRequest(username, password, network_));

  QNetworkReply *reply = api_->renameDevice(username, DeviceId(), device_name, mygpo::Device::DESKTOP);
  QObject::connect(reply, &QNetworkReply::finished, this, [this, reply, username, password]() { LoginFinished(reply, username, password); });

}

void GPodderSync::LoginFinished(QNetworkReply *reply, const QString &username, const QString &password) {

  reply->deleteLater();

  if (reply->error() == QNetworkReply::NoError) {
    username_ = username;
    password_ = password;

    QSettings s;
    s.beginGroup(kSettingsGroup);
    s.setValue("gpodder_username", username);
    s.setValue("gpodder_password", password);
    s.endGroup();

    DoInitialSync();
    emit LoginSuccess();
  }
  else {
    api_.reset();
    emit LoginFailure(reply->errorString());
  }

}

void GPodderSync::Logout() {

  QSettings s;
  s.beginGroup(kSettingsGroup);
  s.remove("gpodder_username");
  s.remove("gpodder_password");
  s.remove("gpodder_last_get");
  s.endGroup();

  api_.reset();

  // Remove session cookies. QNetworkAccessManager takes ownership of the new object and frees the previous.
  network_->setCookieJar(new QNetworkCookieJar());

}

void GPodderSync::GetUpdatesNow() {

  if (!is_logged_in()) return;

  qlonglong timestamp = 0;
  if (last_successful_get_.isValid()) {
    timestamp = last_successful_get_.toSecsSinceEpoch();
  }

  mygpo::DeviceUpdatesPtr reply(api_->deviceUpdates(username_, DeviceId(), timestamp));
  QObject::connect(reply.data(), &mygpo::DeviceUpdates::finished, this, [this, reply]() { DeviceUpdatesFinished(reply); });
  QObject::connect(reply.data(), &mygpo::DeviceUpdates::parseError, this, &GPodderSync::DeviceUpdatesParseError);
  QObject::connect(reply.data(), &mygpo::DeviceUpdates::requestError, this, &GPodderSync::DeviceUpdatesRequestError);

}

void GPodderSync::DeviceUpdatesParseError() {
  qLog(Warning) << "Failed to get gpodder device updates: parse error";
}

void GPodderSync::DeviceUpdatesRequestError(QNetworkReply::NetworkError error) {
  qLog(Warning) << "Failed to get gpodder device updates:" << error;
}

void GPodderSync::DeviceUpdatesFinished(mygpo::DeviceUpdatesPtr reply) {

  // Remember episode actions for each podcast, so when we add a new podcast
  // we can apply the actions immediately.
  QMap<QUrl, QList<mygpo::EpisodePtr>> episodes_by_podcast;
  for (mygpo::EpisodePtr episode : reply->updateList()) {
    episodes_by_podcast[episode->podcastUrl()].append(episode);
  }

  for (mygpo::PodcastPtr podcast : reply->addList()) {
    const QUrl url(podcast->url());

    // Are we subscribed to this podcast already?
    Podcast existing_podcast = backend_->GetSubscriptionByUrl(url);
    if (existing_podcast.is_valid()) {
      // Just apply actions to this existing podcast
      ApplyActions(episodes_by_podcast[url], existing_podcast.mutable_episodes());
      backend_->UpdateEpisodes(existing_podcast.episodes());
      continue;
    }

    // Start loading the podcast.  Remember actions and apply them after we have a list of the episodes.
    PodcastUrlLoaderReply *loader_reply = loader_->Load(url);
    QObject::connect(loader_reply, &PodcastUrlLoaderReply::Finished, this, [this, loader_reply, url, episodes_by_podcast]() { NewPodcastLoaded(loader_reply, url, episodes_by_podcast[url]); });
  }

  // Unsubscribe from podcasts that were removed.
  for (const QUrl &url : reply->removeList()) {
    backend_->Unsubscribe(backend_->GetSubscriptionByUrl(url));
  }

  last_successful_get_ = QDateTime::currentDateTime();

  QSettings s;
  s.beginGroup(kSettingsGroup);
  s.setValue("gpodder_last_get", last_successful_get_);
  s.endGroup();

}

void GPodderSync::NewPodcastLoaded(PodcastUrlLoaderReply *reply, const QUrl &url, const QList<mygpo::EpisodePtr> &actions) {

  reply->deleteLater();

  if (!reply->is_success()) {
    qLog(Warning) << "Error fetching podcast at" << url << ":" << reply->error_text();
    return;
  }

  if (reply->result_type() != PodcastUrlLoaderReply::Type_Podcast) {
    qLog(Warning) << "The URL" << url << "no longer contains a podcast";
    return;
  }

  // Apply the actions to the episodes in the podcast.
  for (Podcast podcast : reply->podcast_results()) {
    ApplyActions(actions, podcast.mutable_episodes());

    // Add the subscription
    backend_->Subscribe(&podcast);
  }
}

void GPodderSync::ApplyActions(const QList<QSharedPointer<mygpo::Episode>> &actions, PodcastEpisodeList *episodes) {

  for (PodcastEpisodeList::iterator it = episodes->begin(); it != episodes->end(); ++it) {
    // Find an action for this episode
    for (mygpo::EpisodePtr action : actions) {
      if (action->url() != it->url()) continue;

      switch (action->status()) {
        case mygpo::Episode::PLAY:
        case mygpo::Episode::DOWNLOAD:
          it->set_listened(true);
          break;

        default:
          break;
      }
      break;
    }
  }

}

void GPodderSync::SubscriptionAdded(const Podcast &podcast) {

  if (!is_logged_in()) return;

  const QUrl &url = podcast.url();

  queued_remove_subscriptions_.remove(url);
  queued_add_subscriptions_.insert(url);

  SaveQueue();
  flush_queue_timer_->start();

}

void GPodderSync::SubscriptionRemoved(const Podcast &podcast) {

  if (!is_logged_in()) return;

  const QUrl &url = podcast.url();

  queued_remove_subscriptions_.insert(url);
  queued_add_subscriptions_.remove(url);

  SaveQueue();
  flush_queue_timer_->start();

}

namespace {
template<typename T>
void WriteContainer(const T &container, QSettings *s, const char *array_name, const char *item_name) {

  s->beginWriteArray(array_name, container.count());
  int index = 0;
  for (const auto &item : container) {
    s->setArrayIndex(index++);
    s->setValue(item_name, item);
  }
  s->endArray();

}

template<typename T>
void ReadContainer(T *container, QSettings *s, const char *array_name, const char *item_name) {

  container->clear();
  const int count = s->beginReadArray(array_name);
  for (int i = 0; i < count; ++i) {
    s->setArrayIndex(i);
    *container << s->value(item_name).value<typename T::value_type>();
  }
  s->endArray();

}
}  // namespace

void GPodderSync::SaveQueue() {

  QSettings s;
  s.beginGroup(kSettingsGroup);
  WriteContainer(queued_add_subscriptions_, &s, "gpodder_queued_add_subscriptions", "url");
  WriteContainer(queued_remove_subscriptions_, &s, "gpodder_queued_remove_subscriptions", "url");
  s.endGroup();

}

void GPodderSync::LoadQueue() {

  QSettings s;
  s.beginGroup(kSettingsGroup);
  ReadContainer(&queued_add_subscriptions_, &s, "gpodder_queued_add_subscriptions", "url");
  ReadContainer(&queued_remove_subscriptions_, &s, "gpodder_queued_remove_subscriptions", "url");
  s.endGroup();

}

void GPodderSync::FlushUpdateQueue() {

  if (!is_logged_in() || flushing_queue_) return;

  QSet<QUrl> all_urls = queued_add_subscriptions_ + queued_remove_subscriptions_;
  if (all_urls.isEmpty()) return;

  flushing_queue_ = true;
  mygpo::AddRemoveResultPtr reply(api_->addRemoveSubscriptions(username_, DeviceId(), queued_add_subscriptions_.values(), queued_remove_subscriptions_.values()));

  qLog(Info) << "Sending" << all_urls.count() << "changes to gpodder.net";

  QObject::connect(reply.data(), &mygpo::AddRemoveResult::finished, this, [this, all_urls]() { AddRemoveFinished(all_urls.values()); });
  QObject::connect(reply.data(), &mygpo::AddRemoveResult::parseError, this, &GPodderSync::AddRemoveParseError);
  QObject::connect(reply.data(), &mygpo::AddRemoveResult::requestError, this, &GPodderSync::AddRemoveRequestError);
}

void GPodderSync::AddRemoveParseError() {

  flushing_queue_ = false;
  qLog(Warning) << "Failed to update gpodder subscriptions: parse error";

}

void GPodderSync::AddRemoveRequestError(QNetworkReply::NetworkError err) {

  flushing_queue_ = false;
  qLog(Warning) << "Failed to update gpodder subscriptions:" << err;

}

void GPodderSync::AddRemoveFinished(const QList<QUrl> &affected_urls) {

  flushing_queue_ = false;

  // Remove the URLs from the queue.
  for (const QUrl &url : affected_urls) {
    queued_add_subscriptions_.remove(url);
    queued_remove_subscriptions_.remove(url);
  }

  SaveQueue();

  // Did more change in the mean time?
  if (!queued_add_subscriptions_.isEmpty() ||
    !queued_remove_subscriptions_.isEmpty()) {
    flush_queue_timer_->start();
  }

}

void GPodderSync::DoInitialSync() {

  // Get updates from the server
  GetUpdatesNow();
  get_updates_timer_->start();

  // Send our complete list of subscriptions
  queued_remove_subscriptions_.clear();
  queued_add_subscriptions_.clear();
  for (const Podcast &podcast : backend_->GetAllSubscriptions()) {
    queued_add_subscriptions_.insert(podcast.url());
  }

  SaveQueue();
  FlushUpdateQueue();

}