/*
 * Copyright (C) by Markus Goetz <markus@woboq.com>
 *
 * 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.
 */

#include "owncloudpropagator.h"
#include "propagatedownload.h"
#include "propagateupload.h"
#include "propagatorjobs.h"
#include "common/utility.h"

#ifdef Q_OS_WIN
#include <windef.h>
#include <winbase.h>
#endif

#include <QLoggingCategory>
#include <QTimer>
#include <QObject>

namespace OCC {

Q_LOGGING_CATEGORY(lcBandwidthManager, "nextcloud.sync.bandwidthmanager", QtInfoMsg)

// Because of the many layers of buffering inside Qt (and probably the OS and the network)
// we cannot lower this value much more. If we do, the estimated bw will be very high
// because the buffers fill fast while the actual network algorithms are not relevant yet.
static qint64 relativeLimitMeasuringTimerIntervalMsec = 1000 * 2;
// See also WritingState in http://code.woboq.org/qt5/qtbase/src/network/access/qhttpprotocolhandler.cpp.html#_ZN20QHttpProtocolHandler11sendRequestEv

// FIXME At some point:
//  * Register device only after the QNR received its metaDataChanged() signal
//  * Incorporate Qt buffer fill state (it's a negative absolute delta).
//  * Incorporate SSL overhead (percentage)
//  * For relative limiting, do less measuring and more delaying+giving quota
//  * For relative limiting, smoothen measurements

BandwidthManager::BandwidthManager(OwncloudPropagator *p)
    : QObject()
    , _propagator(p)
    , _relativeLimitCurrentMeasuredDevice(nullptr)
    , _relativeUploadLimitProgressAtMeasuringRestart(0)
    , _currentUploadLimit(0)
    , _relativeLimitCurrentMeasuredJob(nullptr)
    , _currentDownloadLimit(0)
{
    _currentUploadLimit = _propagator->_uploadLimit.fetchAndAddAcquire(0);
    _currentDownloadLimit = _propagator->_downloadLimit.fetchAndAddAcquire(0);

    QObject::connect(&_switchingTimer, &QTimer::timeout, this, &BandwidthManager::switchingTimerExpired);
    _switchingTimer.setInterval(10 * 1000);
    _switchingTimer.start();
    QMetaObject::invokeMethod(this, "switchingTimerExpired", Qt::QueuedConnection);

    // absolute uploads/downloads
    QObject::connect(&_absoluteLimitTimer, &QTimer::timeout, this, &BandwidthManager::absoluteLimitTimerExpired);
    _absoluteLimitTimer.setInterval(1000);
    _absoluteLimitTimer.start();

    // Relative uploads
    QObject::connect(&_relativeUploadMeasuringTimer, &QTimer::timeout,
        this, &BandwidthManager::relativeUploadMeasuringTimerExpired);
    _relativeUploadMeasuringTimer.setInterval(relativeLimitMeasuringTimerIntervalMsec);
    _relativeUploadMeasuringTimer.start();
    _relativeUploadMeasuringTimer.setSingleShot(true); // will be restarted from the delay timer
    QObject::connect(&_relativeUploadDelayTimer, &QTimer::timeout,
        this, &BandwidthManager::relativeUploadDelayTimerExpired);
    _relativeUploadDelayTimer.setSingleShot(true); // will be restarted from the measuring timer

    // Relative downloads
    QObject::connect(&_relativeDownloadMeasuringTimer, &QTimer::timeout,
        this, &BandwidthManager::relativeDownloadMeasuringTimerExpired);
    _relativeDownloadMeasuringTimer.setInterval(relativeLimitMeasuringTimerIntervalMsec);
    _relativeDownloadMeasuringTimer.start();
    _relativeDownloadMeasuringTimer.setSingleShot(true); // will be restarted from the delay timer
    QObject::connect(&_relativeDownloadDelayTimer, &QTimer::timeout,
        this, &BandwidthManager::relativeDownloadDelayTimerExpired);
    _relativeDownloadDelayTimer.setSingleShot(true); // will be restarted from the measuring timer
}

BandwidthManager::~BandwidthManager() = default;

void BandwidthManager::registerUploadDevice(UploadDevice *p)
{
    _absoluteUploadDeviceList.append(p);
    _relativeUploadDeviceList.append(p);
    QObject::connect(p, &QObject::destroyed, this, &BandwidthManager::unregisterUploadDevice);

    if (usingAbsoluteUploadLimit()) {
        p->setBandwidthLimited(true);
        p->setChoked(false);
    } else if (usingRelativeUploadLimit()) {
        p->setBandwidthLimited(true);
        p->setChoked(true);
    } else {
        p->setBandwidthLimited(false);
        p->setChoked(false);
    }
}

void BandwidthManager::unregisterUploadDevice(QObject *o)
{
    auto p = reinterpret_cast<UploadDevice *>(o); // note, we might already be in the ~QObject
    _absoluteUploadDeviceList.removeAll(p);
    _relativeUploadDeviceList.removeAll(p);
    if (p == _relativeLimitCurrentMeasuredDevice) {
        _relativeLimitCurrentMeasuredDevice = nullptr;
        _relativeUploadLimitProgressAtMeasuringRestart = 0;
    }
}

void BandwidthManager::registerDownloadJob(GETFileJob *j)
{
    _downloadJobList.append(j);
    QObject::connect(j, &QObject::destroyed, this, &BandwidthManager::unregisterDownloadJob);

    if (usingAbsoluteDownloadLimit()) {
        j->setBandwidthLimited(true);
        j->setChoked(false);
    } else if (usingRelativeDownloadLimit()) {
        j->setBandwidthLimited(true);
        j->setChoked(true);
    } else {
        j->setBandwidthLimited(false);
        j->setChoked(false);
    }
}

void BandwidthManager::unregisterDownloadJob(QObject *o)
{
    auto *j = reinterpret_cast<GETFileJob *>(o); // note, we might already be in the ~QObject
    _downloadJobList.removeAll(j);
    if (_relativeLimitCurrentMeasuredJob == j) {
        _relativeLimitCurrentMeasuredJob = nullptr;
        _relativeDownloadLimitProgressAtMeasuringRestart = 0;
    }
}

void BandwidthManager::relativeUploadMeasuringTimerExpired()
{
    if (!usingRelativeUploadLimit() || _relativeUploadDeviceList.count() == 0) {
        // Not in this limiting mode, just wait 1 sec to continue the cycle
        _relativeUploadDelayTimer.setInterval(1000);
        _relativeUploadDelayTimer.start();
        return;
    }
    if (!_relativeLimitCurrentMeasuredDevice) {
        qCDebug(lcBandwidthManager) << "No device set, just waiting 1 sec";
        _relativeUploadDelayTimer.setInterval(1000);
        _relativeUploadDelayTimer.start();
        return;
    }

    qCDebug(lcBandwidthManager) << _relativeUploadDeviceList.count() << "Starting Delay";

    qint64 relativeLimitProgressMeasured = (_relativeLimitCurrentMeasuredDevice->_readWithProgress
                                               + _relativeLimitCurrentMeasuredDevice->_read)
        / 2;
    qint64 relativeLimitProgressDifference = relativeLimitProgressMeasured - _relativeUploadLimitProgressAtMeasuringRestart;
    qCDebug(lcBandwidthManager) << _relativeUploadLimitProgressAtMeasuringRestart
                                << relativeLimitProgressMeasured << relativeLimitProgressDifference;

    qint64 speedkBPerSec = (relativeLimitProgressDifference / relativeLimitMeasuringTimerIntervalMsec * 1000.0) / 1024.0;
    qCDebug(lcBandwidthManager) << relativeLimitProgressDifference / 1024 << "kB =>" << speedkBPerSec << "kB/sec on full speed ("
                                << _relativeLimitCurrentMeasuredDevice->_readWithProgress << _relativeLimitCurrentMeasuredDevice->_read
                                << qAbs(_relativeLimitCurrentMeasuredDevice->_readWithProgress
                                       - _relativeLimitCurrentMeasuredDevice->_read)
                                << ")";

    qint64 uploadLimitPercent = -_currentUploadLimit;
    // don't use too extreme values
    uploadLimitPercent = qMin(uploadLimitPercent, qint64(90));
    uploadLimitPercent = qMax(qint64(10), uploadLimitPercent);
    qint64 wholeTimeMsec = (100.0 / uploadLimitPercent) * relativeLimitMeasuringTimerIntervalMsec;
    qint64 waitTimeMsec = wholeTimeMsec - relativeLimitMeasuringTimerIntervalMsec;
    qint64 realWaitTimeMsec = waitTimeMsec + wholeTimeMsec;
    qCDebug(lcBandwidthManager) << waitTimeMsec << " - " << realWaitTimeMsec << " msec for " << uploadLimitPercent << "%";

    // We want to wait twice as long since we want to give all
    // devices the same quota we used now since we don't want
    // any upload to timeout
    _relativeUploadDelayTimer.setInterval(realWaitTimeMsec);
    _relativeUploadDelayTimer.start();

    int deviceCount = _relativeUploadDeviceList.count();
    qint64 quotaPerDevice = relativeLimitProgressDifference * (uploadLimitPercent / 100.0) / deviceCount + 1.0;
    Q_FOREACH (UploadDevice *ud, _relativeUploadDeviceList) {
        ud->setBandwidthLimited(true);
        ud->setChoked(false);
        ud->giveBandwidthQuota(quotaPerDevice);
        qCDebug(lcBandwidthManager) << "Gave" << quotaPerDevice / 1024.0 << "kB to" << ud;
    }
    _relativeLimitCurrentMeasuredDevice = nullptr;
}

void BandwidthManager::relativeUploadDelayTimerExpired()
{
    // Switch to measuring state
    _relativeUploadMeasuringTimer.start(); // always start to continue the cycle

    if (!usingRelativeUploadLimit()) {
        return; // oh, not actually needed
    }

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

    qCDebug(lcBandwidthManager) << _relativeUploadDeviceList.count() << "Starting measuring";

    // Take first device and then append it again (= we round robin all devices)
    _relativeLimitCurrentMeasuredDevice = _relativeUploadDeviceList.takeFirst();
    _relativeUploadDeviceList.append(_relativeLimitCurrentMeasuredDevice);

    _relativeUploadLimitProgressAtMeasuringRestart = (_relativeLimitCurrentMeasuredDevice->_readWithProgress
                                                         + _relativeLimitCurrentMeasuredDevice->_read)
        / 2;
    _relativeLimitCurrentMeasuredDevice->setBandwidthLimited(false);
    _relativeLimitCurrentMeasuredDevice->setChoked(false);

    // choke all other UploadDevices
    Q_FOREACH (UploadDevice *ud, _relativeUploadDeviceList) {
        if (ud != _relativeLimitCurrentMeasuredDevice) {
            ud->setBandwidthLimited(true);
            ud->setChoked(true);
        }
    }

    // now we're in measuring state
}

// for downloads:
void BandwidthManager::relativeDownloadMeasuringTimerExpired()
{
    if (!usingRelativeDownloadLimit() || _downloadJobList.count() == 0) {
        // Not in this limiting mode, just wait 1 sec to continue the cycle
        _relativeDownloadDelayTimer.setInterval(1000);
        _relativeDownloadDelayTimer.start();
        return;
    }
    if (!_relativeLimitCurrentMeasuredJob) {
        qCDebug(lcBandwidthManager) << "No job set, just waiting 1 sec";
        _relativeDownloadDelayTimer.setInterval(1000);
        _relativeDownloadDelayTimer.start();
        return;
    }

    qCDebug(lcBandwidthManager) << _downloadJobList.count() << "Starting Delay";

    qint64 relativeLimitProgressMeasured = _relativeLimitCurrentMeasuredJob->currentDownloadPosition();
    qint64 relativeLimitProgressDifference = relativeLimitProgressMeasured - _relativeDownloadLimitProgressAtMeasuringRestart;
    qCDebug(lcBandwidthManager) << _relativeDownloadLimitProgressAtMeasuringRestart
                                << relativeLimitProgressMeasured << relativeLimitProgressDifference;

    qint64 speedkBPerSec = (relativeLimitProgressDifference / relativeLimitMeasuringTimerIntervalMsec * 1000.0) / 1024.0;
    qCDebug(lcBandwidthManager) << relativeLimitProgressDifference / 1024 << "kB =>" << speedkBPerSec << "kB/sec on full speed ("
                                << _relativeLimitCurrentMeasuredJob->currentDownloadPosition();

    qint64 downloadLimitPercent = -_currentDownloadLimit;
    // don't use too extreme values
    downloadLimitPercent = qMin(downloadLimitPercent, qint64(90));
    downloadLimitPercent = qMax(qint64(10), downloadLimitPercent);
    qint64 wholeTimeMsec = (100.0 / downloadLimitPercent) * relativeLimitMeasuringTimerIntervalMsec;
    qint64 waitTimeMsec = wholeTimeMsec - relativeLimitMeasuringTimerIntervalMsec;
    qint64 realWaitTimeMsec = waitTimeMsec + wholeTimeMsec;
    qCDebug(lcBandwidthManager) << waitTimeMsec << " - " << realWaitTimeMsec << " msec for " << downloadLimitPercent << "%";

    // We want to wait twice as long since we want to give all
    // devices the same quota we used now since we don't want
    // any download to timeout
    _relativeDownloadDelayTimer.setInterval(realWaitTimeMsec);
    _relativeDownloadDelayTimer.start();

    int jobCount = _downloadJobList.count();
    qint64 quota = relativeLimitProgressDifference * (downloadLimitPercent / 100.0);
    if (quota > 20 * 1024) {
        qCInfo(lcBandwidthManager) << "ADJUSTING QUOTA FROM " << quota << " TO " << quota - 20 * 1024;
        quota -= 20 * 1024;
    }
    qint64 quotaPerJob = quota / jobCount + 1.0;
    Q_FOREACH (GETFileJob *gfj, _downloadJobList) {
        gfj->setBandwidthLimited(true);
        gfj->setChoked(false);
        gfj->giveBandwidthQuota(quotaPerJob);
        qCDebug(lcBandwidthManager) << "Gave" << quotaPerJob / 1024.0 << "kB to" << gfj;
    }
    _relativeLimitCurrentMeasuredDevice = nullptr;
}

void BandwidthManager::relativeDownloadDelayTimerExpired()
{
    // Switch to measuring state
    _relativeDownloadMeasuringTimer.start(); // always start to continue the cycle

    if (!usingRelativeDownloadLimit()) {
        return; // oh, not actually needed
    }

    if (_downloadJobList.isEmpty()) {
        qCDebug(lcBandwidthManager) << _downloadJobList.count() << "No jobs?";
        return;
    }

    qCDebug(lcBandwidthManager) << _downloadJobList.count() << "Starting measuring";

    // Take first device and then append it again (= we round robin all devices)
    _relativeLimitCurrentMeasuredJob = _downloadJobList.takeFirst();
    _downloadJobList.append(_relativeLimitCurrentMeasuredJob);

    _relativeDownloadLimitProgressAtMeasuringRestart = _relativeLimitCurrentMeasuredJob->currentDownloadPosition();
    _relativeLimitCurrentMeasuredJob->setBandwidthLimited(false);
    _relativeLimitCurrentMeasuredJob->setChoked(false);

    // choke all other download jobs
    Q_FOREACH (GETFileJob *gfj, _downloadJobList) {
        if (gfj != _relativeLimitCurrentMeasuredJob) {
            gfj->setBandwidthLimited(true);
            gfj->setChoked(true);
        }
    }

    // now we're in measuring state
}

// end downloads

void BandwidthManager::switchingTimerExpired()
{
    qint64 newUploadLimit = _propagator->_uploadLimit.fetchAndAddAcquire(0);
    if (newUploadLimit != _currentUploadLimit) {
        qCInfo(lcBandwidthManager) << "Upload Bandwidth limit changed" << _currentUploadLimit << newUploadLimit;
        _currentUploadLimit = newUploadLimit;
        Q_FOREACH (UploadDevice *ud, _relativeUploadDeviceList) {
            if (newUploadLimit == 0) {
                ud->setBandwidthLimited(false);
                ud->setChoked(false);
            } else if (newUploadLimit > 0) {
                ud->setBandwidthLimited(true);
                ud->setChoked(false);
            } else if (newUploadLimit < 0) {
                ud->setBandwidthLimited(true);
                ud->setChoked(true);
            }
        }
    }
    qint64 newDownloadLimit = _propagator->_downloadLimit.fetchAndAddAcquire(0);
    if (newDownloadLimit != _currentDownloadLimit) {
        qCInfo(lcBandwidthManager) << "Download Bandwidth limit changed" << _currentDownloadLimit << newDownloadLimit;
        _currentDownloadLimit = newDownloadLimit;
        Q_FOREACH (GETFileJob *j, _downloadJobList) {
            if (usingAbsoluteDownloadLimit()) {
                j->setBandwidthLimited(true);
                j->setChoked(false);
            } else if (usingRelativeDownloadLimit()) {
                j->setBandwidthLimited(true);
                j->setChoked(true);
            } else {
                j->setBandwidthLimited(false);
                j->setChoked(false);
            }
        }
    }
}

void BandwidthManager::absoluteLimitTimerExpired()
{
    if (usingAbsoluteUploadLimit() && _absoluteUploadDeviceList.count() > 0) {
        qint64 quotaPerDevice = _currentUploadLimit / qMax(1, _absoluteUploadDeviceList.count());
        qCDebug(lcBandwidthManager) << quotaPerDevice << _absoluteUploadDeviceList.count() << _currentUploadLimit;
        Q_FOREACH (UploadDevice *device, _absoluteUploadDeviceList) {
            device->giveBandwidthQuota(quotaPerDevice);
            qCDebug(lcBandwidthManager) << "Gave " << quotaPerDevice / 1024.0 << " kB to" << device;
        }
    }
    if (usingAbsoluteDownloadLimit() && _downloadJobList.count() > 0) {
        qint64 quotaPerJob = _currentDownloadLimit / qMax(1, _downloadJobList.count());
        qCDebug(lcBandwidthManager) << quotaPerJob << _downloadJobList.count() << _currentDownloadLimit;
        Q_FOREACH (GETFileJob *j, _downloadJobList) {
            j->giveBandwidthQuota(quotaPerJob);
            qCDebug(lcBandwidthManager) << "Gave " << quotaPerJob / 1024.0 << " kB to" << j;
        }
    }
}
}