/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the QtNetwork module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#ifndef QHOSTINFO_P_H
#define QHOSTINFO_P_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of the QHostInfo class.  This header file may change from
// version to version without notice, or even be removed.
//
// We mean it.
//

#include "QtCore/qcoreapplication.h"
#include "private/qcoreapplication_p.h"
#include "QtNetwork/qhostinfo.h"
#include "QtCore/qmutex.h"
#include "QtCore/qwaitcondition.h"
#include "QtCore/qobject.h"
#include "QtCore/qpointer.h"
#include "QtCore/qthread.h"
#include "QtCore/qthreadpool.h"
#include "QtCore/qrunnable.h"
#include "QtCore/qlist.h"
#include "QtCore/qqueue.h"
#include <QElapsedTimer>
#include <QCache>

#include <QNetworkSession>
#include <QSharedPointer>


QT_BEGIN_NAMESPACE


class QHostInfoResult : public QObject
{
    Q_OBJECT
public Q_SLOTS:
    inline void emitResultsReady(const QHostInfo &info)
    {
        emit resultsReady(info);
    }

Q_SIGNALS:
    void resultsReady(const QHostInfo &info);
};

// needs to be QObject because fromName calls tr()
class QHostInfoAgent : public QObject
{
    Q_OBJECT
public:
    static QHostInfo fromName(const QString &hostName);
#ifndef QT_NO_BEARERMANAGEMENT
    static QHostInfo fromName(const QString &hostName, QSharedPointer<QNetworkSession> networkSession);
#endif
};

class QHostInfoPrivate
{
public:
    inline QHostInfoPrivate()
        : err(QHostInfo::NoError),
          errorStr(QLatin1String(QT_TRANSLATE_NOOP("QHostInfo", "Unknown error"))),
          lookupId(0)
    {
    }
#ifndef QT_NO_BEARERMANAGEMENT
    //not a public API yet
    static QHostInfo fromName(const QString &hostName, QSharedPointer<QNetworkSession> networkSession);
#endif

    QHostInfo::HostInfoError err;
    QString errorStr;
    QList<QHostAddress> addrs;
    QString hostName;
    int lookupId;
};

// These functions are outside of the QHostInfo class and strictly internal.
// Do NOT use them outside of QAbstractSocket.
QHostInfo Q_NETWORK_EXPORT qt_qhostinfo_lookup(const QString &name, QObject *receiver, const char *member, bool *valid, int *id);
void Q_AUTOTEST_EXPORT qt_qhostinfo_clear_cache();
void Q_AUTOTEST_EXPORT qt_qhostinfo_enable_cache(bool e);

class QHostInfoCache
{
public:
    QHostInfoCache();
    const int max_age; // seconds

    QHostInfo get(const QString &name, bool *valid);
    void put(const QString &name, const QHostInfo &info);
    void clear();

    bool isEnabled();
    void setEnabled(bool e);
private:
    bool enabled;
    struct QHostInfoCacheElement {
        QHostInfo info;
        QElapsedTimer age;
    };
    QCache<QString,QHostInfoCacheElement> cache;
    QMutex mutex;
};

// the following classes are used for the (normal) case: We use multiple threads to lookup DNS

class QHostInfoRunnable : public QRunnable
{
public:
    QHostInfoRunnable (QString hn, int i);
    void run() Q_DECL_OVERRIDE;

    QString toBeLookedUp;
    int id;
    QHostInfoResult resultEmitter;
};


class QAbstractHostInfoLookupManager : public QObject
{
    Q_OBJECT

public:
    ~QAbstractHostInfoLookupManager() {}
    virtual void clear() = 0;

    QHostInfoCache cache;

protected:
     QAbstractHostInfoLookupManager() {}
     static QAbstractHostInfoLookupManager* globalInstance();

};

class QHostInfoLookupManager : public QAbstractHostInfoLookupManager
{
    Q_OBJECT
public:
    QHostInfoLookupManager();
    ~QHostInfoLookupManager();

    void clear() Q_DECL_OVERRIDE;
    void work();

    // called from QHostInfo
    void scheduleLookup(QHostInfoRunnable *r);
    void abortLookup(int id);

    // called from QHostInfoRunnable
    void lookupFinished(QHostInfoRunnable *r);
    bool wasAborted(int id);

    friend class QHostInfoRunnable;
protected:
    QList<QHostInfoRunnable*> currentLookups; // in progress
    QList<QHostInfoRunnable*> postponedLookups; // postponed because in progress for same host
    QQueue<QHostInfoRunnable*> scheduledLookups; // not yet started
    QList<QHostInfoRunnable*> finishedLookups; // recently finished
    QList<int> abortedLookups; // ids of aborted lookups

    QThreadPool threadPool;

    QMutex mutex;

    bool wasDeleted;

private slots:
    void waitForThreadPoolDone() { threadPool.waitForDone(); }
};

QT_END_NAMESPACE

#endif // QHOSTINFO_P_H