// For license of this file, see <object-root-folder>/LICENSE.md.

#include "services/gmail/network/gmailnetworkfactory.h"

#include "definitions/definitions.h"
#include "gui/dialogs/formmain.h"
#include "gui/tabwidget.h"
#include "miscellaneous/application.h"
#include "miscellaneous/databasequeries.h"
#include "network-web/networkfactory.h"
#include "network-web/oauth2service.h"
#include "network-web/silentnetworkaccessmanager.h"
#include "network-web/webfactory.h"
#include "services/abstract/category.h"
#include "services/gmail/definitions.h"
#include "services/gmail/gmailfeed.h"
#include "services/gmail/gmailserviceroot.h"

#include <QHttpMultiPart>
#include <QJsonArray>
#include <QJsonDocument>
#include <QJsonObject>
#include <QRegularExpression>
#include <QUrl>

GmailNetworkFactory::GmailNetworkFactory(QObject* parent) : QObject(parent),
  m_service(nullptr), m_username(QString()), m_batchSize(GMAIL_DEFAULT_BATCH_SIZE),
  m_oauth2(new OAuth2Service(GMAIL_OAUTH_AUTH_URL, GMAIL_OAUTH_TOKEN_URL,
                             QString(), QString(), GMAIL_OAUTH_SCOPE)) {
  initializeOauth();
}

void GmailNetworkFactory::setService(GmailServiceRoot* service) {
  m_service = service;
}

OAuth2Service* GmailNetworkFactory::oauth() const {
  return m_oauth2;
}

QString GmailNetworkFactory::userName() const {
  return m_username;
}

int GmailNetworkFactory::batchSize() const {
  return m_batchSize;
}

void GmailNetworkFactory::setBatchSize(int batch_size) {
  m_batchSize = batch_size;
}

void GmailNetworkFactory::initializeOauth() {
  connect(m_oauth2, &OAuth2Service::tokensRetrieveError, this, &GmailNetworkFactory::onTokensError);
  connect(m_oauth2, &OAuth2Service::authFailed, this, &GmailNetworkFactory::onAuthFailed);
  connect(m_oauth2, &OAuth2Service::tokensReceived, [this](QString access_token, QString refresh_token, int expires_in) {
    Q_UNUSED(expires_in)

    if (m_service != nullptr && !access_token.isEmpty() && !refresh_token.isEmpty()) {
      QSqlDatabase database = qApp->database()->connection(metaObject()->className(), DatabaseFactory::FromSettings);
      DatabaseQueries::storeNewInoreaderTokens(database, refresh_token, m_service->accountId());

      qApp->showGuiMessage(tr("Logged in successfully"),
                           tr("Your login to Gmail was authorized."),
                           QSystemTrayIcon::MessageIcon::Information);
    }
  });
}

void GmailNetworkFactory::setUsername(const QString& username) {
  m_username = username;
}

/*
   RootItem* GmailNetworkFactory::feedsCategories() {
   Downloader downloader;
   QEventLoop loop;
   QString bearer = m_oauth2->bearer().toLocal8Bit();

   if (bearer.isEmpty()) {
    return nullptr;
   }

   downloader.appendRawHeader(QString(HTTP_HEADERS_AUTHORIZATION).toLocal8Bit(), bearer.toLocal8Bit());

   // We need to quit event loop when the download finishes.
   connect(&downloader, &Downloader::completed, &loop, &QEventLoop::quit);

   // TODO: dodělat
   downloader.manipulateData(GMAIL_API_LABELS_LIST, QNetworkAccessManager::Operation::GetOperation);
   loop.exec();

   if (downloader.lastOutputError() != QNetworkReply::NetworkError::NoError) {
    return nullptr;
   }

   QString category_data = downloader.lastOutputData();

   return decodeFeedCategoriesData(category_data);
   }*/

QList<Message> GmailNetworkFactory::messages(const QString& stream_id, Feed::Status& error) {
  Downloader downloader;
  QEventLoop loop;
  QString bearer = m_oauth2->bearer().toLocal8Bit();
  QString next_page_token;

  QList<Message> messages;

  if (bearer.isEmpty()) {
    error = Feed::Status::AuthError;
    return QList<Message>();
  }

  downloader.appendRawHeader(QString(HTTP_HEADERS_AUTHORIZATION).toLocal8Bit(), bearer.toLocal8Bit());

  // We need to quit event loop when the download finishes.
  connect(&downloader, &Downloader::completed, &loop, &QEventLoop::quit);
  QString target_url;

  do {
    target_url = GMAIL_API_MSGS_LIST;
    target_url += QString("?labelIds=%1").arg(stream_id);

    if (batchSize() > 0) {
      target_url += QString("&maxResults=%1").arg(batchSize());
    }

    if (!next_page_token.isEmpty()) {
      target_url += QString("&pageToken=%1").arg(next_page_token);
    }

    downloader.manipulateData(target_url, QNetworkAccessManager::Operation::GetOperation);
    loop.exec();

    if (downloader.lastOutputError() == QNetworkReply::NetworkError::NoError) {
      // We parse this chunk.
      QString messages_data = downloader.lastOutputData();

      QList<Message> more_messages = decodeLiteMessages(messages_data, stream_id, next_page_token);

      // Now, we via batch HTTP request obtain full data for each message.
      bool obtained = obtainAndDecodeFullMessages(more_messages);

      if (obtained) {
        messages.append(more_messages);

        // New batch of messages was obtained, check if we have enough.
        if (batchSize() > 0 && batchSize() <= messages.size()) {
          // We have enough messages.
          break;
        }
      }
      else {

        error = Feed::Status::NetworkError;
        return messages;
      }
    }
    else {
      error = Feed::Status::NetworkError;
      return messages;
    }
  } while (!next_page_token.isEmpty());

  error = Feed::Status::Normal;
  return messages;
}

void GmailNetworkFactory::markMessagesRead(RootItem::ReadStatus status, const QStringList& custom_ids, bool async) {
  QString target_url;// TODO: dodělat
  // = INOREADER_API_EDIT_TAG;
  // TODO: dodělat
  //

  /*
     if (status == RootItem::ReadStatus::Read) {
     target_url += QString("?a=user/-/") + INOREADER_STATE_READ + "&";
     }
     else {
     target_url += QString("?r=user/-/") + INOREADER_STATE_READ + "&";
     }*/
  QString bearer = m_oauth2->bearer().toLocal8Bit();

  if (bearer.isEmpty()) {
    return;
  }

  QList<QPair<QByteArray, QByteArray>> headers;
  headers.append(QPair<QByteArray, QByteArray>(QString(HTTP_HEADERS_AUTHORIZATION).toLocal8Bit(),
                                               m_oauth2->bearer().toLocal8Bit()));

  QStringList trimmed_ids;
  QRegularExpression regex_short_id(QSL("[0-9a-zA-Z]+$"));

  foreach (const QString& id, custom_ids) {
    QString simplified_id = regex_short_id.match(id).captured();

    trimmed_ids.append(QString("i=") + simplified_id);
  }

  QStringList working_subset;
  int timeout = qApp->settings()->value(GROUP(Feeds), SETTING(Feeds::UpdateTimeout)).toInt();

  working_subset.reserve(trimmed_ids.size() > 200 ? 200 : trimmed_ids.size());

  // Now, we perform messages update in batches (max 200 messages per batch).
  while (!trimmed_ids.isEmpty()) {
    // We take 200 IDs.
    for (int i = 0; i < 200 && !trimmed_ids.isEmpty(); i++) {
      working_subset.append(trimmed_ids.takeFirst());
    }

    QString batch_final_url = target_url + working_subset.join(QL1C('&'));

    // We send this batch.
    if (async) {

      NetworkFactory::performAsyncNetworkOperation(batch_final_url,
                                                   timeout,
                                                   QByteArray(),
                                                   QNetworkAccessManager::Operation::GetOperation,
                                                   headers);
    }
    else {
      QByteArray output;

      NetworkFactory::performNetworkOperation(batch_final_url,
                                              timeout,
                                              QByteArray(),
                                              output,
                                              QNetworkAccessManager::Operation::GetOperation,
                                              headers);
    }

    // Cleanup for next batch.
    working_subset.clear();
  }
}

void GmailNetworkFactory::markMessagesStarred(RootItem::Importance importance, const QStringList& custom_ids, bool async) {
  QString target_url; // TODO: dodělat
  //= INOREADER_API_EDIT_TAG;

/*
   if (importance == RootItem::Importance::Important) {
    target_url += QString("?a=user/-/") + INOREADER_STATE_IMPORTANT + "&";
   }
   else {
    target_url += QString("?r=user/-/") + INOREADER_STATE_IMPORTANT + "&";
   }*/
  QString bearer = m_oauth2->bearer().toLocal8Bit();

  if (bearer.isEmpty()) {
    return;
  }

  QList<QPair<QByteArray, QByteArray>> headers;
  headers.append(QPair<QByteArray, QByteArray>(QString(HTTP_HEADERS_AUTHORIZATION).toLocal8Bit(),
                                               m_oauth2->bearer().toLocal8Bit()));

  QStringList trimmed_ids;
  QRegularExpression regex_short_id(QSL("[0-9a-zA-Z]+$"));

  foreach (const QString& id, custom_ids) {
    QString simplified_id = regex_short_id.match(id).captured();

    trimmed_ids.append(QString("i=") + simplified_id);
  }

  QStringList working_subset;
  int timeout = qApp->settings()->value(GROUP(Feeds), SETTING(Feeds::UpdateTimeout)).toInt();

  working_subset.reserve(trimmed_ids.size() > 200 ? 200 : trimmed_ids.size());

  // Now, we perform messages update in batches (max 200 messages per batch).
  while (!trimmed_ids.isEmpty()) {
    // We take 200 IDs.
    for (int i = 0; i < 200 && !trimmed_ids.isEmpty(); i++) {
      working_subset.append(trimmed_ids.takeFirst());
    }

    QString batch_final_url = target_url + working_subset.join(QL1C('&'));

    // We send this batch.
    if (async) {

      NetworkFactory::performAsyncNetworkOperation(batch_final_url,
                                                   timeout,
                                                   QByteArray(),
                                                   QNetworkAccessManager::Operation::GetOperation,
                                                   headers);
    }
    else {
      QByteArray output;

      NetworkFactory::performNetworkOperation(batch_final_url,
                                              timeout,
                                              QByteArray(),
                                              output,
                                              QNetworkAccessManager::Operation::GetOperation,
                                              headers);
    }

    // Cleanup for next batch.
    working_subset.clear();
  }
}

void GmailNetworkFactory::onTokensError(const QString& error, const QString& error_description) {
  Q_UNUSED(error)

  qApp->showGuiMessage(tr("Inoreader: authentication error"),
                       tr("Click this to login again. Error is: '%1'").arg(error_description),
                       QSystemTrayIcon::Critical,
                       nullptr, false,
                       [this]() {
    m_oauth2->login();
  });
}

void GmailNetworkFactory::onAuthFailed() {
  qApp->showGuiMessage(tr("Inoreader: authorization denied"),
                       tr("Click this to login again."),
                       QSystemTrayIcon::Critical,
                       nullptr, false,
                       [this]() {
    m_oauth2->login();
  });
}

bool GmailNetworkFactory::obtainAndDecodeFullMessages(QList<Message>& lite_messages) {
  QHttpMultiPart* multi = new QHttpMultiPart();

  multi->setContentType(QHttpMultiPart::ContentType::MixedType);

  QHash<QString, Message> msgs;

  foreach (const Message& msg, lite_messages) {
    QHttpPart part;

    part.setRawHeader(HTTP_HEADERS_CONTENT_TYPE, GMAIL_CONTENT_TYPE_HTTP);
    QString full_msg_endpoint = QString("GET /gmail/v1/users/me/messages/%1\r\n").arg(msg.m_customId);

    part.setBody(full_msg_endpoint.toUtf8());
    multi->append(part);
    msgs.insert(msg.m_customId, msg);
  }

  QString bearer = m_oauth2->bearer();

  if (bearer.isEmpty()) {
    return false;
  }

  QList<QPair<QByteArray, QByteArray>> headers;
  QList<HttpResponse> output;
  int timeout = qApp->settings()->value(GROUP(Feeds), SETTING(Feeds::UpdateTimeout)).toInt();

  headers.append(QPair<QByteArray, QByteArray>(QString(HTTP_HEADERS_AUTHORIZATION).toLocal8Bit(),
                                               bearer.toLocal8Bit()));

  if (NetworkFactory::performNetworkOperation(GMAIL_API_BATCH,
                                              timeout,
                                              multi,
                                              output,
                                              QNetworkAccessManager::Operation::PostOperation,
                                              headers).first == QNetworkReply::NetworkError::NoError) {
    // We parse each part of HTTP response (it contains HTTP headers and payload with msg full data).
    foreach (const HttpResponse& part, output) {}
  }
  else {
    return false;
  }
}

QList<Message> GmailNetworkFactory::decodeLiteMessages(const QString& messages_json_data, const QString& stream_id,
                                                       QString& next_page_token) {
  QList<Message> messages;
  QJsonObject top_object = QJsonDocument::fromJson(messages_json_data.toUtf8()).object();
  QJsonArray json_msgs = top_object["messages"].toArray();

  next_page_token = top_object["nextPageToken"].toString();
  messages.reserve(json_msgs.count());

  foreach (const QJsonValue& obj, json_msgs) {
    auto message_obj = obj.toObject();
    Message message;

    message.m_customId = message_obj["id"].toString();
    message.m_feedId = stream_id;

    messages.append(message);
  }

  return messages;
}

/*
   RootItem* GmailNetworkFactory::decodeFeedCategoriesData(const QString& categories) {
   RootItem* parent = new RootItem();
   QJsonArray json = QJsonDocument::fromJson(categories.toUtf8()).object()["labels"].toArray();

   QMap<QString, RootItem*> cats;
   cats.insert(QString(), parent);

   foreach (const QJsonValue& obj, json) {
    auto label = obj.toObject();
    QString label_id = label["id"].toString();
    QString label_name = label["name"].toString();
    QString label_type = label["type"].toString();

    if (label_name.contains(QL1C('/'))) {
      // We have nested labels.
    }
    else {
      GmailFeed* feed = new GmailFeed();

      feed->setTitle(label_name);
      feed->setCustomId(label_id);

      parent->appendChild(feed);
    }


    if (label_id.contains(QSL("/label/"))) {
      // We have label (not "state").
      Category* category = new Category();

      category->setDescription(label["htmlUrl"].toString());
      category->setTitle(label_id.mid(label_id.lastIndexOf(QL1C('/')) + 1));
      category->setCustomId(label_id);

      cats.insert(category->customId(), category);

      // All categories in ownCloud are top-level.
      parent->appendChild(category);
    }
   }

   json = QJsonDocument::fromJson(feeds.toUtf8()).object()["subscriptions"].toArray();

   foreach (const QJsonValue& obj, json) {
    auto subscription = obj.toObject();
    QString id = subscription["id"].toString();
    QString title = subscription["title"].toString();
    QString url = subscription["htmlUrl"].toString();
    QString parent_label;
    QJsonArray categories = subscription["categories"].toArray();

    foreach (const QJsonValue& cat, categories) {
      QString potential_id = cat.toObject()["id"].toString();

      if (potential_id.contains(QSL("/label/"))) {
        parent_label = potential_id;
        break;
      }
    }

    // We have label (not "state").
    GmailFeed* feed = new GmailFeed();

    feed->setDescription(url);
    feed->setUrl(url);
    feed->setTitle(title);
    feed->setCustomId(id);

    if (cats.contains(parent_label)) {
      cats[parent_label]->appendChild(feed);
    }
   }

   return parent;
   }
 */