/*
 *  Copyright (c) 2010 Dmitry Kazakov <dimula73@gmail.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.
 *
 *  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.
 */

#include "kis_update_scheduler.h"

#include "kis_image_config.h"
#include "kis_merge_walker.h"
#include "kis_full_refresh_walker.h"

#include "kis_updater_context.h"
#include "kis_simple_update_queue.h"
#include "kis_strokes_queue.h"

#include "kis_queues_progress_updater.h"

#include <QReadWriteLock>
#include "kis_lazy_wait_condition.h"

//#define DEBUG_BALANCING

#ifdef DEBUG_BALANCING
#define DEBUG_BALANCING_METRICS(decidedFirst, excl)                     \
    qDebug() << "Balance decision:" << decidedFirst                     \
    << "(" << excl << ")"                                               \
    << "updates:" << m_d->updatesQueue->sizeMetric()                    \
    << "strokes:" << m_d->strokesQueue->sizeMetric()
#else
#define DEBUG_BALANCING_METRICS(decidedFirst, excl)
#endif


struct KisUpdateScheduler::Private {
    Private() : updatesQueue(0), strokesQueue(0),
                updaterContext(0), processingBlocked(false),
                balancingRatio(1.0),
                projectionUpdateListener(0),
                progressUpdater(0) {}

    KisSimpleUpdateQueue *updatesQueue;
    KisStrokesQueue *strokesQueue;
    KisUpdaterContext *updaterContext;
    bool processingBlocked;
    qreal balancingRatio; // updates-queue-size/strokes-queue-size
    KisProjectionUpdateListener *projectionUpdateListener;
    KisQueuesProgressUpdater *progressUpdater;

    QAtomicInt updatesLockCounter;
    QReadWriteLock updatesStartLock;
    KisLazyWaitCondition updatesFinishedCondition;
};

KisUpdateScheduler::KisUpdateScheduler(KisProjectionUpdateListener *projectionUpdateListener)
    : m_d(new Private)
{
    updateSettings();
    m_d->projectionUpdateListener = projectionUpdateListener;

    // The queue will update settings in a constructor itself
    m_d->updatesQueue = new KisSimpleUpdateQueue();
    m_d->strokesQueue = new KisStrokesQueue();
    m_d->updaterContext = new KisUpdaterContext();

    connectSignals();
}

KisUpdateScheduler::KisUpdateScheduler()
    : m_d(new Private)
{
}

KisUpdateScheduler::~KisUpdateScheduler()
{
    delete m_d->updaterContext;
    delete m_d->updatesQueue;
    delete m_d->strokesQueue;
    delete m_d->progressUpdater;
}

void KisUpdateScheduler::connectSignals()
{
    connect(m_d->updaterContext, SIGNAL(sigContinueUpdate(const QRect&)),
            SLOT(continueUpdate(const QRect&)),
            Qt::DirectConnection);

    connect(m_d->updaterContext, SIGNAL(sigDoSomeUsefulWork()),
            SLOT(doSomeUsefulWork()), Qt::DirectConnection);

    connect(m_d->updaterContext, SIGNAL(sigSpareThreadAppeared()),
            SLOT(spareThreadAppeared()), Qt::DirectConnection);
}

void KisUpdateScheduler::setProgressProxy(KoProgressProxy *progressProxy)
{
    delete m_d->progressUpdater;
    m_d->progressUpdater = new KisQueuesProgressUpdater(progressProxy);
}

void KisUpdateScheduler::progressUpdate()
{
    if(m_d->progressUpdater) {
        QString jobName = m_d->strokesQueue->currentStrokeName();
        if(jobName.isEmpty()) {
            jobName = "Update";
        }

        int sizeMetric = m_d->strokesQueue->sizeMetric() + m_d->updatesQueue->sizeMetric();
        m_d->progressUpdater->updateProgress(sizeMetric, jobName);
    }
}

void KisUpdateScheduler::progressNotifyJobDone()
{
    if(m_d->progressUpdater) {
        m_d->progressUpdater->notifyJobDone(1);
    }
}

void KisUpdateScheduler::updateProjection(KisNodeSP node, const QRect& rc, const QRect &cropRect)
{
    m_d->updatesQueue->addUpdateJob(node, rc, cropRect);
    processQueues();
}

void KisUpdateScheduler::fullRefreshAsync(KisNodeSP root, const QRect& rc, const QRect &cropRect)
{
    m_d->updatesQueue->addFullRefreshJob(root, rc, cropRect);
    processQueues();
}

void KisUpdateScheduler::fullRefresh(KisNodeSP root, const QRect& rc, const QRect &cropRect)
{
    KisBaseRectsWalkerSP walker = new KisFullRefreshWalker(cropRect);
    walker->collectRects(root, rc);

    bool needLock = true;

    if(m_d->processingBlocked) {
        warnImage << "WARNING: Calling synchronous fullRefresh under a scheduler lock held";
        warnImage << "We will not assert for now, but please port caller's to strokes";
        warnImage << "to avoid this warning";
        needLock = false;
    }

    if(needLock) lock();
    m_d->updaterContext->lock();

    Q_ASSERT(m_d->updaterContext->isJobAllowed(walker));
    m_d->updaterContext->addMergeJob(walker);
    m_d->updaterContext->waitForDone();

    m_d->updaterContext->unlock();
    if(needLock) unlock();
}

void KisUpdateScheduler::addSpontaneousJob(KisSpontaneousJob *spontaneousJob)
{
    m_d->updatesQueue->addSpontaneousJob(spontaneousJob);
    processQueues();
}

KisStrokeId KisUpdateScheduler::startStroke(KisStrokeStrategy *strokeStrategy)
{
    KisStrokeId id  = m_d->strokesQueue->startStroke(strokeStrategy);
    processQueues();
    return id;
}

void KisUpdateScheduler::addJob(KisStrokeId id, KisStrokeJobData *data)
{
    m_d->strokesQueue->addJob(id, data);
    processQueues();
}

void KisUpdateScheduler::endStroke(KisStrokeId id)
{
    m_d->strokesQueue->endStroke(id);
    processQueues();
}

bool KisUpdateScheduler::cancelStroke(KisStrokeId id)
{
    bool result = m_d->strokesQueue->cancelStroke(id);
    processQueues();
    return result;
}

bool KisUpdateScheduler::wrapAroundModeSupported() const
{
    return m_d->strokesQueue->wrapAroundModeSupported();
}

void KisUpdateScheduler::updateSettings()
{
    if(m_d->updatesQueue) {
        m_d->updatesQueue->updateSettings();
    }

    KisImageConfig config;
    m_d->balancingRatio = config.schedulerBalancingRatio();
}

void KisUpdateScheduler::lock()
{
    m_d->processingBlocked = true;
    m_d->updaterContext->waitForDone();
}

void KisUpdateScheduler::unlock()
{
    m_d->processingBlocked = false;
    processQueues();
}

void KisUpdateScheduler::waitForDone()
{
    do {
        processQueues();
        m_d->updaterContext->waitForDone();
    } while(!m_d->updatesQueue->isEmpty() || !m_d->strokesQueue->isEmpty());
}

bool KisUpdateScheduler::tryBarrierLock()
{
    if(!m_d->updatesQueue->isEmpty() || !m_d->strokesQueue->isEmpty())
        return false;

    m_d->processingBlocked = true;
    m_d->updaterContext->waitForDone();
    if(!m_d->updatesQueue->isEmpty() || !m_d->strokesQueue->isEmpty()) {
        m_d->processingBlocked = false;
        return false;
    }

    return true;
}

void KisUpdateScheduler::barrierLock()
{
    do {
        m_d->processingBlocked = false;
        processQueues();
        m_d->processingBlocked = true;
        m_d->updaterContext->waitForDone();
    } while(!m_d->updatesQueue->isEmpty() || !m_d->strokesQueue->isEmpty());
}

void KisUpdateScheduler::processQueues()
{
    wakeUpWaitingThreads();

    if(m_d->processingBlocked) return;

    if(m_d->strokesQueue->needsExclusiveAccess()) {
        DEBUG_BALANCING_METRICS("STROKES", "X");
        m_d->strokesQueue->processQueue(*m_d->updaterContext,
                                        !m_d->updatesQueue->isEmpty());

        if(!m_d->strokesQueue->needsExclusiveAccess()) {
            tryProcessUpdatesQueue();
        }
    }
    else if(m_d->balancingRatio * m_d->strokesQueue->sizeMetric() > m_d->updatesQueue->sizeMetric()) {
        DEBUG_BALANCING_METRICS("STROKES", "N");
        m_d->strokesQueue->processQueue(*m_d->updaterContext,
                                        !m_d->updatesQueue->isEmpty());
        tryProcessUpdatesQueue();
    }
    else {
        DEBUG_BALANCING_METRICS("UPDATES", "N");
        tryProcessUpdatesQueue();
        m_d->strokesQueue->processQueue(*m_d->updaterContext,
                                        !m_d->updatesQueue->isEmpty());

    }

    progressUpdate();
}

void KisUpdateScheduler::blockUpdates()
{
    m_d->updatesFinishedCondition.initWaiting();

    m_d->updatesLockCounter.ref();
    while(haveUpdatesRunning()) {
        m_d->updatesFinishedCondition.wait();
    }

    m_d->updatesFinishedCondition.endWaiting();
}

void KisUpdateScheduler::unblockUpdates()
{
    m_d->updatesLockCounter.deref();
    processQueues();
}

void KisUpdateScheduler::wakeUpWaitingThreads()
{
    if(m_d->updatesLockCounter && !haveUpdatesRunning()) {
        m_d->updatesFinishedCondition.wakeAll();
    }
}

void KisUpdateScheduler::tryProcessUpdatesQueue()
{
    QReadLocker locker(&m_d->updatesStartLock);
    if(m_d->updatesLockCounter) return;

    m_d->updatesQueue->processQueue(*m_d->updaterContext);
}

bool KisUpdateScheduler::haveUpdatesRunning()
{
    QWriteLocker locker(&m_d->updatesStartLock);

    qint32 numMergeJobs, numStrokeJobs;
    m_d->updaterContext->getJobsSnapshot(numMergeJobs, numStrokeJobs);

    return numMergeJobs;
}

void KisUpdateScheduler::continueUpdate(const QRect &rect)
{
    Q_ASSERT(m_d->projectionUpdateListener);
    m_d->projectionUpdateListener->notifyProjectionUpdated(rect);
}

void KisUpdateScheduler::doSomeUsefulWork()
{
    m_d->updatesQueue->optimize();
}

void KisUpdateScheduler::spareThreadAppeared()
{
    progressNotifyJobDone();
    processQueues();
}

KisTestableUpdateScheduler::KisTestableUpdateScheduler(KisProjectionUpdateListener *projectionUpdateListener,
                                                       qint32 threadCount)
{
    updateSettings();
    m_d->projectionUpdateListener = projectionUpdateListener;

    // The queue will update settings in a constructor itself
    m_d->updatesQueue = new KisTestableSimpleUpdateQueue();
    m_d->strokesQueue = new KisStrokesQueue();
    m_d->updaterContext = new KisTestableUpdaterContext(threadCount);

    connectSignals();
}

KisTestableUpdaterContext* KisTestableUpdateScheduler::updaterContext()
{
    return dynamic_cast<KisTestableUpdaterContext*>(m_d->updaterContext);
}

KisTestableSimpleUpdateQueue* KisTestableUpdateScheduler::updateQueue()
{
    return dynamic_cast<KisTestableSimpleUpdateQueue*>(m_d->updatesQueue);
}
