/*
 * Copyright 2014 Christian Mollekopf <mollekopf@kolabsys.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) version 3 or any later version
 * accepted by the membership of KDE e.V. (or its successor approved
 * by the membership of KDE e.V.), which shall act as a proxy
 * defined in Section 14 of version 3 of the license.
 *
 * 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, see <https://www.gnu.org/licenses/>.
 *
 */

#include "scheduler.h"

#include "akonadi_indexer_agent_debug.h"
#include "collectionindexingjob.h"
#include <AkonadiCore/CollectionFetchJob>
#include <AkonadiCore/CollectionFetchScope>
#include <AkonadiAgentBase/AgentBase>
#include <AkonadiCore/ServerManager>
#include <AkonadiCore/IndexPolicyAttribute>
#include <KLocalizedString>
#include <KConfigGroup>
#include <QTimer>

JobFactory::~JobFactory()
{
}

CollectionIndexingJob *JobFactory::createCollectionIndexingJob(Index &index, const Akonadi::Collection &col,
        const QList<Akonadi::Item::Id> &pending,
        bool fullSync,
        QObject *parent)
{
    CollectionIndexingJob *job = new CollectionIndexingJob(index, col, pending, parent);
    job->setFullSync(fullSync);
    return job;
}

Scheduler::Scheduler(Index &index, const KSharedConfigPtr &config,
                     const QSharedPointer<JobFactory> &jobFactory, QObject *parent)
    :   QObject(parent),
        m_config(config),
        m_index(index),
        m_currentJob(nullptr),
        m_jobFactory(jobFactory),
        m_busyTimeout(5000)
{
    if (!m_jobFactory) {
        m_jobFactory = QSharedPointer<JobFactory>(new JobFactory);
    }
    m_processTimer.setSingleShot(true);
    m_processTimer.setInterval(100);
    connect(&m_processTimer, &QTimer::timeout, this, &Scheduler::processNext);

    KConfigGroup cfg = m_config->group("General");
    m_dirtyCollections = cfg.readEntry("dirtyCollections", QList<Akonadi::Collection::Id>()).toSet();
    if (m_dirtyCollections.isEmpty()) {
        KConfig baloorc(Akonadi::ServerManager::addNamespace(QStringLiteral("baloorc")));
        KConfigGroup baloorcGroup = baloorc.group("Akonadi");

        //Schedule collections we know have missing items from last time
        m_dirtyCollections = baloorcGroup.readEntry("dirtyCollections", QList<Akonadi::Collection::Id>()).toSet();
    }

    qCDebug(AKONADI_INDEXER_AGENT_LOG) << "Dirty collections " << m_dirtyCollections;
    for (Akonadi::Collection::Id col : qAsConst(m_dirtyCollections)) {
        scheduleCollection(Akonadi::Collection(col), true);
    }

    bool initialIndexingDone = cfg.readEntry("initialIndexingDone", false);
    if (!initialIndexingDone) {
        KConfig baloorc(Akonadi::ServerManager::addNamespace(QStringLiteral("baloorc")));
        KConfigGroup baloorcGroup = baloorc.group("Akonadi");
        initialIndexingDone = baloorcGroup.readEntry("initialIndexingDone", false);
        cfg.writeEntry("initialIndexingDone", initialIndexingDone);
        baloorcGroup.deleteEntry("initialIndexingDone"); // make sure that editing akonadi_indexing_agentrc by hand works in the future
    }
    //Trigger a full sync initially
    if (!initialIndexingDone) {
        qCDebug(AKONADI_INDEXER_AGENT_LOG) << "initial indexing";
        QMetaObject::invokeMethod(this, &Scheduler::scheduleCompleteSync, Qt::QueuedConnection);
    }
    cfg.writeEntry("initialIndexingDone", true);
    cfg.sync();
}

Scheduler::~Scheduler()
{
    collectDirtyCollections();
}

void Scheduler::setBusyTimeout(int timeout)
{
    m_busyTimeout = timeout;
}

int Scheduler::numberOfCollectionQueued() const
{
    return m_collectionQueue.count();
}

void Scheduler::collectDirtyCollections()
{
    KConfigGroup cfg = m_config->group("General");
    //Store collections where we did not manage to index all, we'll need to do a full sync for them the next time
    QHash<Akonadi::Collection::Id, QQueue<Akonadi::Item::Id>>::ConstIterator it = m_queues.constBegin();
    QHash<Akonadi::Collection::Id, QQueue<Akonadi::Item::Id>>::ConstIterator end = m_queues.constEnd();
    for (; it != end; ++it) {
        if (!it.value().isEmpty()) {
            m_dirtyCollections.insert(it.key());
        }
    }
    qCDebug(AKONADI_INDEXER_AGENT_LOG) << m_dirtyCollections;
    cfg.writeEntry("dirtyCollections", m_dirtyCollections.toList());
    cfg.sync();
}

void Scheduler::scheduleCollection(const Akonadi::Collection &col, bool fullSync)
{
    if (!m_collectionQueue.contains(col.id())) {
        m_collectionQueue.enqueue(col.id());
    }
    if (fullSync) {
        m_dirtyCollections.insert(col.id());
    }
    processNext();
}

void Scheduler::addItem(const Akonadi::Item &item)
{
    Q_ASSERT(item.parentCollection().isValid());
    m_lastModifiedTimestamps.insert(item.parentCollection().id(), QDateTime::currentMSecsSinceEpoch());
    m_queues[item.parentCollection().id()].append(item.id());
    //Move to the back
    m_collectionQueue.removeOne(item.parentCollection().id());
    m_collectionQueue.enqueue(item.parentCollection().id());
    if (!m_processTimer.isActive()) {
        m_processTimer.start();
    }
}

void Scheduler::scheduleCompleteSync()
{
    qCDebug(AKONADI_INDEXER_AGENT_LOG);
    {
        Akonadi::CollectionFetchJob *job = new Akonadi::CollectionFetchJob(Akonadi::Collection::root(),
                Akonadi::CollectionFetchJob::Recursive);
        job->fetchScope().setAncestorRetrieval(Akonadi::CollectionFetchScope::All);
        job->fetchScope().setListFilter(Akonadi::CollectionFetchScope::Index);
        job->fetchScope().fetchAttribute<Akonadi::IndexPolicyAttribute>();
        connect(job, &KJob::finished, this, &Scheduler::slotRootCollectionsFetched);
        job->start();
    }

    //We want to index all collections, even if we don't index their content
    {
        Akonadi::CollectionFetchJob *job = new Akonadi::CollectionFetchJob(Akonadi::Collection::root(),
                Akonadi::CollectionFetchJob::Recursive);
        job->fetchScope().setAncestorRetrieval(Akonadi::CollectionFetchScope::All);
        job->fetchScope().setListFilter(Akonadi::CollectionFetchScope::NoFilter);
        job->fetchScope().setListFilter(Akonadi::CollectionFetchScope::Index);
        connect(job, &KJob::finished, this, &Scheduler::slotCollectionsToIndexFetched);
        job->start();
    }
}

void Scheduler::slotRootCollectionsFetched(KJob *kjob)
{
    Akonadi::CollectionFetchJob *cjob = static_cast<Akonadi::CollectionFetchJob *>(kjob);
    const Akonadi::Collection::List lstCols = cjob->collections();
    for (const Akonadi::Collection &c : lstCols) {
        //For skipping search collections
        if (c.isVirtual()) {
            continue;
        }
        if (c == Akonadi::Collection::root()) {
            continue;
        }
        if (c.hasAttribute<Akonadi::IndexPolicyAttribute>() &&
                !c.attribute<Akonadi::IndexPolicyAttribute>()->indexingEnabled()) {
            continue;
        }
        scheduleCollection(c, true);
    }

    // If we did not schedule any collection
    if (m_collectionQueue.isEmpty()) {
        qCDebug(AKONADI_INDEXER_AGENT_LOG) << "No collections scheduled";
        Q_EMIT status(Akonadi::AgentBase::Idle, i18n("Ready"));
    }
}

void Scheduler::slotCollectionsToIndexFetched(KJob *kjob)
{
    Akonadi::CollectionFetchJob *cjob = static_cast<Akonadi::CollectionFetchJob *>(kjob);
    const Akonadi::Collection::List lstCols = cjob->collections();
    for (const Akonadi::Collection &c : lstCols) {
        //For skipping search collections
        if (c.isVirtual()) {
            continue;
        }
        if (c == Akonadi::Collection::root()) {
            continue;
        }
        if (c.hasAttribute<Akonadi::IndexPolicyAttribute>() &&
                !c.attribute<Akonadi::IndexPolicyAttribute>()->indexingEnabled()) {
            continue;
        }
        m_index.index(c);
    }
}

void Scheduler::abort()
{
    if (m_currentJob) {
        m_currentJob->kill(KJob::Quietly);
    }
    m_currentJob = nullptr;
    collectDirtyCollections();
    m_collectionQueue.clear();
    Q_EMIT status(Akonadi::AgentBase::Idle, i18n("Ready"));
}

void Scheduler::processNext()
{
    m_processTimer.stop();
    if (m_currentJob) {
        return;
    }
    if (m_collectionQueue.isEmpty()) {
        qCDebug(AKONADI_INDEXER_AGENT_LOG) << "Processing done";
        Q_EMIT status(Akonadi::AgentBase::Idle, i18n("Ready"));
        return;
    }

    //An item was queued within the last 5 seconds, we're probably in the middle of a sync
    const bool collectionIsChanging = (QDateTime::currentMSecsSinceEpoch() - m_lastModifiedTimestamps.value(m_collectionQueue.head())) < m_busyTimeout;
    if (collectionIsChanging) {
        //We're in the middle of something, wait with indexing
        m_processTimer.start();
        return;
    }

    const Akonadi::Collection col(m_collectionQueue.takeFirst());
    qCDebug(AKONADI_INDEXER_AGENT_LOG) << "Processing collection: " << col.id();
    QQueue<Akonadi::Item::Id> &itemQueue = m_queues[col.id()];
    const bool fullSync = m_dirtyCollections.contains(col.id());
    CollectionIndexingJob *job = m_jobFactory->createCollectionIndexingJob(m_index, col, itemQueue, fullSync, this);
    itemQueue.clear();
    job->setProperty("collection", col.id());
    connect(job, &KJob::result, this, &Scheduler::slotIndexingFinished);
    connect(job, &CollectionIndexingJob::status, this, &Scheduler::status);
    connect(job, SIGNAL(percent(int)), this, SIGNAL(percent(int)));
    m_currentJob = job;
    job->start();
}

void Scheduler::slotIndexingFinished(KJob *job)
{
    if (job->error()) {
        qCWarning(AKONADI_INDEXER_AGENT_LOG) << "Indexing failed: " << job->errorString();
    } else {
        const Akonadi::Collection::Id collectionId = job->property("collection").value<Akonadi::Collection::Id>();
        m_dirtyCollections.remove(collectionId);
        Q_EMIT status(Akonadi::AgentBase::Idle, i18n("Collection \"%1\" indexed", collectionId));
        Q_EMIT collectionIndexingFinished(collectionId);
    }
    m_currentJob = nullptr;
    m_processTimer.start();
}
