/*
 * Bittorrent Client using Qt and libtorrent.
 * Copyright (C) 2006  Christophe Dumez <chris@qbittorrent.org>
 *
 * This program 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 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * In addition, as a special exception, the copyright holders give permission to
 * link this program with the OpenSSL project's "OpenSSL" library (or with
 * modified versions of it that use the same license as the "OpenSSL" library),
 * and distribute the linked executables. You must obey the GNU General Public
 * License in all respects for all of the code used other than "OpenSSL".  If you
 * modify file(s), you may extend this exception to your version of the file(s),
 * but you are not obligated to do so. If you do not wish to do so, delete this
 * exception statement from your version.
 */

#pragma once

#include <QCache>
#include <QHostAddress>
#include <QObject>

class QHostInfo;
class QString;

namespace Net
{
    class ReverseResolution final : public QObject
    {
        Q_OBJECT
        Q_DISABLE_COPY_MOVE(ReverseResolution)

    public:
        static void initInstance();
        static void freeInstance();
        static ReverseResolution *instance();

        QString resolve(const QHostAddress &ip);

    signals:
        void ipResolved(const QHostAddress &ip, const QString &hostname);

    private slots:
        void hostResolved(const QHostInfo &host);

    private:
        ReverseResolution();
        ~ReverseResolution() override;

        static ReverseResolution *m_instance;

        QHash<int, QHostAddress> m_lookups;  // <LookupID, IP>
        QCache<QHostAddress, QString> m_cache;  // <IP, HostName>
    };
}
