// This file is part of RSS Guard.
//
// Copyright (C) 2011-2014 by Martin Rotter <rotter.martinos@gmail.com>
//
// RSS Guard 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.
//
// RSS Guard 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 RSS Guard. If not, see <http://www.gnu.org/licenses/>.

#ifndef SYSTEMFACTORY_H
#define SYSTEMFACTORY_H

#include <QObject>
#include <QPointer>
#include <QMutex>
#include <QMetaType>
#include <QHash>
#include <QPair>
#include <QNetworkReply>


class UpdateUrl {
  public:
    QString m_fileUrl;
    QString m_platform;
    QString m_os;
};

class UpdateInfo {
  public:
    enum UpdateType {
      // Corresponding enum to "maintenace" from UPDATES file.
      Maintenance,
      // Corresponding enum to "evolution" from UPDATES file.
      Evolution
    };

    QString m_availableVersion;
    QString m_changes;
    UpdateType m_type;
    QHash<QString, UpdateUrl> m_urls;
};

Q_DECLARE_METATYPE(UpdateInfo)

class SystemFactory : public QObject {
    Q_OBJECT

  private:
    // Constructors and destructors.
    explicit SystemFactory(QObject *parent = 0);

    // Performs parsing of downloaded file with list of updates.
    UpdateInfo parseUpdatesFile(const QByteArray &updates_file);

  public:
    // Constructors and destructors.
    virtual ~SystemFactory();

    // Specifies possible states of auto-start functionality.
    enum AutoStartStatus {
      Enabled,
      Disabled,
      Unavailable
    };

    // Returns current status of auto-start function.
    SystemFactory::AutoStartStatus getAutoStartStatus();

    // Sets new status for auto-start function.
    // Function returns false if setting of
    // new status failed.
    bool setAutoStartStatus(const SystemFactory::AutoStartStatus &new_status);

#if defined(Q_OS_LINUX)
    // Returns standard location where auto-start .desktop files
    // should be placed.
    QString getAutostartDesktopFileLocation();
#endif

    // Tries to download list with new updates.
    QPair<UpdateInfo, QNetworkReply::NetworkError> checkForUpdates();

    // Access to application-wide close lock.
    inline QMutex *applicationCloseLock() const {
      return m_applicationCloseLock;
    }

    // Singleton getter.
    static SystemFactory *instance();

  private:
    // This read-write lock is used by application on its close.
    // Application locks this lock for WRITING.
    // This means that if application locks that lock, then
    // no other transaction-critical action can acquire lock
    // for reading and won't be executed, so no critical action
    // will be running when application quits
    //
    // EACH critical action locks this lock for READING.
    // Several actions can lock this lock for reading.
    // But of user decides to close the application (in other words,
    // tries to lock the lock for writing), then no other
    // action will be allowed to lock for reading.
    QMutex *m_applicationCloseLock;

    static QPointer<SystemFactory> s_instance;
};

#endif // SYSTEMFACTORY_H