/*
 *   SPDX-FileCopyrightText: 2012 Aleix Pol Gonzalez <aleixpol@blue-systems.com>
 *
 *   SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
 */

// Qt includes
#include <QDebug>
#include <QDir>
#include <QFileInfo>
#include <QStandardPaths>
#include <QTimer>
#include <QDirIterator>

// Attica includes
#include <Attica/Content>
#include <Attica/ProviderManager>

// KDE includes
#include <knewstuffcore_version.h>
#include <KNSCore/Engine>
#include <KNSCore/QuestionManager>
#include <KConfig>
#include <KConfigGroup>
#include <KLocalizedString>

// DiscoverCommon includes
#include "Transaction/Transaction.h"
#include "Transaction/TransactionModel.h"
#include "Category/Category.h"

// Own includes
#include "KNSBackend.h"
#include "KNSResource.h"
#include "KNSReviews.h"
#include <resources/StandardBackendUpdater.h>
#include "utils.h"

class KNSBackendFactory : public AbstractResourcesBackendFactory {
    Q_OBJECT
    Q_PLUGIN_METADATA(IID "org.kde.muon.AbstractResourcesBackendFactory")
    Q_INTERFACES(AbstractResourcesBackendFactory)
    public:
        KNSBackendFactory() {
            connect(KNSCore::QuestionManager::instance(), &KNSCore::QuestionManager::askQuestion, this, [](KNSCore::Question* q) {
                qWarning() << q->question() << q->questionType();
                q->setResponse(KNSCore::Question::InvalidResponse);
            });
        }

        QVector<AbstractResourcesBackend*> newInstance(QObject* parent, const QString &/*name*/) const override
        {
            QVector<AbstractResourcesBackend*> ret;
            const QStringList locations = KNSCore::Engine::configSearchLocations();
            QSet<QString> files;
            for (const QString &path: locations) {
                QDirIterator dirIt(path, {QStringLiteral("*.knsrc")}, QDir::Files);
                for(; dirIt.hasNext(); ) {
                    dirIt.next();

                    if (files.contains(dirIt.fileName()))
                        continue;
                    files << dirIt.fileName();

                    auto bk = new KNSBackend(parent, QStringLiteral("plasma"), dirIt.filePath());
                    if (bk->isValid())
                        ret += bk;
                    else
                        delete bk;
                }
            }
            return ret;
        }
};

Q_DECLARE_METATYPE(KNSCore::EntryInternal)

KNSBackend::KNSBackend(QObject* parent, const QString& iconName, const QString &knsrc)
    : AbstractResourcesBackend(parent)
    , m_fetching(false)
    , m_isValid(true)
    , m_reviews(new KNSReviews(this))
    , m_name(knsrc)
    , m_iconName(iconName)
    , m_updater(new StandardBackendUpdater(this))
{
    const QString fileName = QFileInfo(m_name).fileName();
    setName(fileName);
    setObjectName(knsrc);

    const KConfig conf(m_name, KConfig::SimpleConfig);
    if (!conf.hasGroup("KNewStuff3")) {
        markInvalid(QStringLiteral("Config group not found! Check your KNS3 installation."));
        return;
    }

    m_categories = QStringList{ fileName };

    const KConfigGroup group = conf.group("KNewStuff3");
    m_extends = group.readEntry("Extends", QStringList());
    m_reviews->setProviderUrl(QUrl(group.readEntry("ProvidersUrl", QString())));

    setFetching(true);

    // This ensures we have something to track when checking after the initialization timeout
    connect(this, &KNSBackend::initialized, this, [this](){ m_initialized = true; });
    // If we have not initialized in 60 seconds, consider this KNS backend invalid
    QTimer::singleShot(60000, this, [this](){
        if(!m_initialized) {
            markInvalid(i18n("Backend %1 took too long to initialize", m_displayName));
            m_responsePending = false;
            Q_EMIT searchFinished();
            Q_EMIT availableForQueries();
        }
    });

    const QVector<QPair<FilterType, QString>> filters = { {CategoryFilter, fileName } };
    const QSet<QString> backendName = { name() };
    m_displayName = group.readEntry("Name", QString());
    if (m_displayName.isEmpty()) {
        m_displayName = fileName.mid(0, fileName.indexOf(QLatin1Char('.')));
        m_displayName[0] = m_displayName[0].toUpper();
    }
    m_hasApplications = group.readEntry<bool>("X-Discover-HasApplications", false);

    const QStringList cats = group.readEntry<QStringList>("Categories", QStringList{});
    QVector<Category*> categories;
    if (cats.count() > 1) {
        m_categories += cats;
        for(const auto &cat: cats) {
            if (m_hasApplications)
                categories << new Category(cat, QStringLiteral("applications-other"), { {CategoryFilter, cat } }, backendName, {}, {}, true);
            else
                categories << new Category(cat, QStringLiteral("plasma"), { {CategoryFilter, cat } }, backendName, {}, {}, true);
        }
    }

    QVector<Category*> topCategories{categories};
    for (const auto &cat: qAsConst(categories)) {
        const QString catName = cat->name().append(QLatin1Char('/'));
        for (const auto& potentialSubCat: qAsConst(categories)) {
            if(potentialSubCat->name().startsWith(catName)) {
                cat->addSubcategory(potentialSubCat);
                topCategories.removeOne(potentialSubCat);
            }
        }
    }

    m_engine = new KNSCore::Engine(this);
    connect(m_engine, &KNSCore::Engine::signalErrorCode, this, &KNSBackend::signalErrorCode);
    connect(m_engine, &KNSCore::Engine::signalEntriesLoaded, this, &KNSBackend::receivedEntries, Qt::QueuedConnection);
    connect(m_engine, &KNSCore::Engine::signalEntryChanged, this, &KNSBackend::statusChanged, Qt::QueuedConnection);
    connect(m_engine, &KNSCore::Engine::signalEntryDetailsLoaded, this, &KNSBackend::detailsLoaded);
    connect(m_engine, &KNSCore::Engine::signalProvidersLoaded, this, &KNSBackend::fetchInstalled);
    connect(m_engine, &KNSCore::Engine::signalCategoriesMetadataLoded, this, [categories] (const QList<KNSCore::Provider::CategoryMetadata>& categoryMetadatas){
        for (const KNSCore::Provider::CategoryMetadata& category : categoryMetadatas) {
            for (Category* cat : qAsConst(categories)) {
                if (cat->orFilters().count() > 0 && cat->orFilters().constFirst().second == category.name) {
                    cat->setName(category.displayName);
                    break;
                }
            }
        }
    });
    m_engine->setPageSize(100);
    m_engine->init(m_name);

    if(m_hasApplications) {
        auto actualCategory = new Category(m_displayName, QStringLiteral("applications-other"), filters, backendName, topCategories, QUrl(), false);
        auto applicationCategory = new Category(i18n("Applications"), QStringLiteral("applications-internet"), filters, backendName, { actualCategory }, QUrl(), false);
        applicationCategory->setAndFilter({ {CategoryFilter, QLatin1String("Application")} });
        m_categories.append(applicationCategory->name());
        m_rootCategories = { applicationCategory };
        // Make sure we filter out any apps which won't run on the current system architecture
        QStringList tagFilter = m_engine->tagFilter();
        if(QSysInfo::currentCpuArchitecture() == QLatin1String("arm")) {
            tagFilter << QLatin1String("application##architecture==armhf");
        } else if(QSysInfo::currentCpuArchitecture() == QLatin1String("arm64")) {
            tagFilter << QLatin1String("application##architecture==arm64");
        } else if(QSysInfo::currentCpuArchitecture() == QLatin1String("i386")) {
            tagFilter << QLatin1String("application##architecture==x86");
        } else if(QSysInfo::currentCpuArchitecture() == QLatin1String("ia64")) {
            tagFilter << QLatin1String("application##architecture==x86-64");
        } else if(QSysInfo::currentCpuArchitecture() == QLatin1String("x86_64")) {
            tagFilter << QLatin1String("application##architecture==x86");
            tagFilter << QLatin1String("application##architecture==x86-64");
        }
        m_engine->setTagFilter(tagFilter);
    } else {
        static const QSet<QString> knsrcPlasma = {
            QStringLiteral("aurorae.knsrc"), QStringLiteral("icons.knsrc"), QStringLiteral("kfontinst.knsrc"), QStringLiteral("lookandfeel.knsrc"), QStringLiteral("plasma-themes.knsrc"), QStringLiteral("plasmoids.knsrc"),
            QStringLiteral("wallpaper.knsrc"), QStringLiteral("xcursor.knsrc"),

            QStringLiteral("cgcgtk3.knsrc"), QStringLiteral("cgcicon.knsrc"), QStringLiteral("cgctheme.knsrc"), //GTK integration
            QStringLiteral("kwinswitcher.knsrc"), QStringLiteral("kwineffect.knsrc"), QStringLiteral("kwinscripts.knsrc"), //KWin
            QStringLiteral("comic.knsrc"), QStringLiteral("colorschemes.knsrc"),
            QStringLiteral("emoticons.knsrc"), QStringLiteral("plymouth.knsrc"),
            QStringLiteral("sddmtheme.knsrc"), QStringLiteral("wallpaperplugin.knsrc"),
            QStringLiteral("ksplash.knsrc"), QStringLiteral("window-decorations.knsrc")
        };
        const auto iconName = knsrcPlasma.contains(fileName)? QStringLiteral("plasma") : QStringLiteral("applications-other");
        auto actualCategory = new Category(m_displayName, iconName, filters, backendName, categories, QUrl(), true);

        const auto topLevelName = knsrcPlasma.contains(fileName)? i18n("Plasma Addons") : i18n("Application Addons");
        auto addonsCategory = new Category(topLevelName, iconName, filters, backendName, {actualCategory}, QUrl(), true);
        m_rootCategories = { addonsCategory };
    }
}

KNSBackend::~KNSBackend()
{
    qDeleteAll(m_rootCategories);
}

void KNSBackend::markInvalid(const QString &message)
{
    m_rootCategories.clear();
    qWarning() << "invalid kns backend!" << m_name << "because:" << message;
    m_isValid = false;
    setFetching(false);
    Q_EMIT initialized();
}

void KNSBackend::fetchInstalled()
{
    auto search = new OneTimeAction([this]() {
        // First we ensure we've got data loaded on what we've got installed already
        Q_EMIT startingSearch();
        m_onePage = true;
        m_responsePending = true;
        m_engine->checkForInstalled();
        // And then we check for updates - we could do only one, if all we cared about was updates,
        // but to have both a useful initial list, /and/ information on updates, we want to get both.
        // The reason we are not doing a checkUpdates() overload for this is that the caching for this
        // information is done by KNSEngine, and we want to actually load it every time we initialize.
        auto updateChecker = new OneTimeAction([this]() {
            Q_EMIT startingSearch();
            m_onePage = true;
            m_responsePending = true;
            m_engine->checkForUpdates();
        }, this);
        connect(this, &KNSBackend::availableForQueries, updateChecker, &OneTimeAction::trigger, Qt::QueuedConnection);
    }, this);

    if (m_responsePending) {
        connect(this, &KNSBackend::availableForQueries, search, &OneTimeAction::trigger, Qt::QueuedConnection);
    } else {
        search->trigger();
    }
}

void KNSBackend::checkForUpdates()
{
    // Since we load the updates during initialization already, don't overburden
    // the machine with multiple of these, because that would just be silly.
    if (m_initialized) {
        auto updateChecker = new OneTimeAction([this]() {
            Q_EMIT startingSearch();
            m_onePage = true;
            m_responsePending = true;
            m_engine->checkForUpdates();
        }, this);

        if (m_responsePending) {
            connect(this, &KNSBackend::availableForQueries, updateChecker, &OneTimeAction::trigger, Qt::QueuedConnection);
        } else {
            updateChecker->trigger();
        }
    }
}

void KNSBackend::setFetching(bool f)
{
    if(m_fetching!=f) {
        m_fetching = f;
        emit fetchingChanged();

        if (!m_fetching) {
            Q_EMIT initialized();
        }
    }

}

bool KNSBackend::isValid() const
{
    return m_isValid;
}

KNSResource* KNSBackend::resourceForEntry(const KNSCore::EntryInternal& entry)
{
    KNSResource* r = static_cast<KNSResource*>(m_resourcesByName.value(entry.uniqueId()));
    if (!r) {
        QStringList categories{name(), m_rootCategories.first()->name()};
        const auto cats = m_engine->categoriesMetadata();
        const int catIndex = kIndexOf(cats, [&entry](const KNSCore::Provider::CategoryMetadata& cat){ return entry.category() == cat.id; });
        if (catIndex > -1) {
            categories << cats.at(catIndex).name;
        }
        if(m_hasApplications) {
            categories << QLatin1String("Application");
        }
        r = new KNSResource(entry, categories, this);
        m_resourcesByName.insert(entry.uniqueId(), r);
    } else {
        r->setEntry(entry);
    }
    return r;
}

void KNSBackend::receivedEntries(const KNSCore::EntryInternal::List& entries)
{
    m_responsePending = false;
    const auto filtered = kFilter<KNSCore::EntryInternal::List>(entries, [](const KNSCore::EntryInternal& entry){ return entry.isValid(); });
    const auto resources = kTransform<QVector<AbstractResource*>>(filtered, [this](const KNSCore::EntryInternal& entry){ return resourceForEntry(entry); });

    if (!resources.isEmpty()) {
        Q_EMIT receivedResources(resources);
    } else {
        Q_EMIT searchFinished();
        Q_EMIT availableForQueries();
        setFetching(false);
        return;
    }
//     qDebug() << "received" << objectName() << this << m_resourcesByName.count();
    if (m_onePage) {
        Q_EMIT availableForQueries();
        setFetching(false);
    }
}

void KNSBackend::fetchMore()
{
    if (m_responsePending)
        return;

    // We _have_ to set this first. If we do not, we may run into a situation where the
    // data request will conclude immediately, causing m_responsePending to remain true
    // for perpetuity as the slots will be called before the function returns.
    m_responsePending = true;
    m_engine->requestMoreData();
}

void KNSBackend::statusChanged(const KNSCore::EntryInternal& entry)
{
    resourceForEntry(entry);
}

void KNSBackend::signalErrorCode(const KNSCore::ErrorCode& errorCode, const QString& message, const QVariant& metadata)
{
    QString error = message;
    qDebug() << "KNS error in" << m_displayName << ":" << errorCode << message << metadata;
    bool invalidFile = false;
    switch(errorCode) {
        case KNSCore::ErrorCode::UnknownError:
            // This is not supposed to be hit, of course, but any error coming to this point should be non-critical and safely ignored.
            break;
        case KNSCore::ErrorCode::NetworkError:
            // If we have a network error, we need to tell the user about it. This is almost always fatal, so mark invalid and tell the user.
            error = i18n("Network error in backend %1: %2", m_displayName, metadata.toInt());
            markInvalid(error);
            invalidFile = true;
            break;
        case KNSCore::ErrorCode::OcsError:
            if(metadata.toInt() == 200) {
                // Too many requests, try again in a couple of minutes - perhaps we can simply postpone it automatically, and give a message?
                error = i18n("Too many requests sent to the server for backend %1. Please try again in a few minutes.", m_displayName);
            } else {
                // Unknown API error, usually something critical, mark as invalid and cry a lot
                error = i18n("Invalid %1 backend, contact your distributor.", m_displayName);
                markInvalid(error);
                invalidFile = true;
            }
            break;
        case KNSCore::ErrorCode::ConfigFileError:
            error = i18n("Invalid %1 backend, contact your distributor.", m_displayName);
            markInvalid(error);
            invalidFile = true;
            break;
        case KNSCore::ErrorCode::ProviderError:
            error = i18n("Invalid %1 backend, contact your distributor.", m_displayName);
            markInvalid(error);
            invalidFile = true;
            break;
        case KNSCore::ErrorCode::InstallationError:
            // This error is handled already, by forwarding the KNS engine's installer error message.
            break;
        case KNSCore::ErrorCode::ImageError:
            // Image fetching errors are not critical as such, but may lead to weird layout issues, might want handling...
            error = i18n("Could not fetch screenshot for the entry %1 in backend %2", metadata.toList().at(0).toString(), m_displayName);
            break;
        default:
            // Having handled all current error values, we should by all rights never arrive here, but for good order and future safety...
            error = i18n("Unhandled error in %1 backend. Contact your distributor.", m_displayName);
            break;
    }
    m_responsePending = false;
    Q_EMIT searchFinished();
    Q_EMIT availableForQueries();
    // Setting setFetching to false when we get an error ensures we don't end up in an eternally-fetching state
    this->setFetching(false);
    qWarning() << "kns error" << objectName() << error;
    if (!invalidFile)
        Q_EMIT passiveMessage(i18n("%1: %2", name(), error));
}

class KNSTransaction : public Transaction
{
public:
    KNSTransaction(QObject* parent, KNSResource* res, Transaction::Role role)
        : Transaction(parent, res, role)
        , m_id(res->entry().uniqueId())
    {
        setCancellable(false);

        auto manager = res->knsBackend()->engine();
        connect(manager, &KNSCore::Engine::signalEntryChanged, this, &KNSTransaction::anEntryChanged);
        TransactionModel::global()->addTransaction(this);

        std::function<void()> actionFunction;
        auto engine = res->knsBackend()->engine();
        if(role == RemoveRole)
            actionFunction = [res, engine]() {
                engine->uninstall(res->entry());
            };
        else if (res->entry().status() == KNS3::Entry::Updateable)
            actionFunction = [res, engine]() {
                engine->install(res->entry(), -1);
            };
        else if (res->linkIds().isEmpty())
            actionFunction = [res]() {
                qWarning() << "No installable candidates in the KNewStuff entry" << res->entry().name() << "with id" << res->entry().uniqueId() << "on the backend" << res->backend()->name() << "There should always be at least one downloadable item in an OCS entry, and if there isn't, we should consider it broken. OCS can technically show them, but if there is nothing to install, it cannot be installed.";
            };
        else
            actionFunction = [res, engine]() {
                engine->install(res->entry());
            };
        QTimer::singleShot(0, res, actionFunction);
    }

    void anEntryChanged(const KNSCore::EntryInternal& entry) {
        if (entry.uniqueId() == m_id) {
            switch (entry.status()) {
                case KNS3::Entry::Invalid:
                    qWarning() << "invalid status for" << entry.uniqueId() << entry.status();
                    break;
                case KNS3::Entry::Installing:
                case KNS3::Entry::Updating:
                    setStatus(CommittingStatus);
                    break;
                case KNS3::Entry::Downloadable:
                case KNS3::Entry::Installed:
                case KNS3::Entry::Deleted:
                case KNS3::Entry::Updateable:
                    if (status() != DoneStatus) {
                        setStatus(DoneStatus);
                    }
                    break;
            }
        }
    }

    void cancel() override {}

private:
    const QString m_id;
};

Transaction* KNSBackend::removeApplication(AbstractResource* app)
{
    auto res = qobject_cast<KNSResource*>(app);
    return new KNSTransaction(this, res, Transaction::RemoveRole);
}

Transaction* KNSBackend::installApplication(AbstractResource* app)
{
    auto res = qobject_cast<KNSResource*>(app);
    return new KNSTransaction(this, res, Transaction::InstallRole);
}

Transaction* KNSBackend::installApplication(AbstractResource* app, const AddonList& /*addons*/)
{
    return installApplication(app);
}

int KNSBackend::updatesCount() const
{
    return m_updater->updatesCount();
}

AbstractReviewsBackend* KNSBackend::reviewsBackend() const
{
    return m_reviews;
}

static ResultsStream* voidStream()
{
    return new ResultsStream(QStringLiteral("KNS-void"), {});
}

ResultsStream* KNSBackend::search(const AbstractResourcesBackend::Filters& filter)
{
    if (!m_isValid || (!filter.resourceUrl.isEmpty() && filter.resourceUrl.scheme() != QLatin1String("kns")) || !filter.mimetype.isEmpty())
        return voidStream();

    if (filter.resourceUrl.scheme() == QLatin1String("kns")) {
        return findResourceByPackageName(filter.resourceUrl);
    } else if (filter.state >= AbstractResource::Installed) {
        auto stream = new ResultsStream(QStringLiteral("KNS-installed"));

        const auto start = [this, stream, filter]() {
            if (m_isValid) {
                auto filterFunction = [&filter](AbstractResource* r) { return r->state()>=filter.state && (r->name().contains(filter.search, Qt::CaseInsensitive) || r->comment().contains(filter.search, Qt::CaseInsensitive)); };
                const auto ret = kFilter<QVector<AbstractResource*>>(m_resourcesByName, filterFunction);

                if (!ret.isEmpty())
                    Q_EMIT stream->resourcesFound(ret);
            }
            stream->finish();
        };
        if (isFetching()) {
            connect(this, &KNSBackend::initialized, stream, start);
        } else {
            QTimer::singleShot(0, stream, start);
        }

        return stream;
    } else if ((!filter.category && !filter.search.isEmpty()) // Accept global searches
              // If there /is/ a category, make sure we actually are one of those requested before searching
           || (filter.category && kContains(m_categories, [&filter](const QString& cat) { return filter.category->matchesCategoryName(cat); }))) {
        auto r = new ResultsStream(QLatin1String("KNS-search-")+name());
        searchStream(r, filter.search);
        return r;
    }
    return voidStream();
}

void KNSBackend::searchStream(ResultsStream* stream, const QString &searchText)
{
    Q_EMIT startingSearch();

    auto start = [this, stream, searchText]() {
        Q_ASSERT(!isFetching());
        if (!m_isValid) {
            stream->finish();
            return;
        }
        // No need to explicitly launch a search, setting the search term already does that for us
        m_engine->setSearchTerm(searchText);
        m_onePage = false;
        m_responsePending = true;

        connect(stream, &ResultsStream::fetchMore, this, &KNSBackend::fetchMore);
        connect(this, &KNSBackend::receivedResources, stream, &ResultsStream::resourcesFound);
        connect(this, &KNSBackend::searchFinished, stream, &ResultsStream::finish);
        connect(this, &KNSBackend::startingSearch, stream, &ResultsStream::finish);
    };

    if (m_responsePending) {
        connect(this, &KNSBackend::availableForQueries, stream, start, Qt::QueuedConnection);
    } else if (isFetching()) {
        connect(this, &KNSBackend::initialized, stream, start);
    } else {
        QTimer::singleShot(0, stream, start);
    }
}

ResultsStream * KNSBackend::findResourceByPackageName(const QUrl& search)
{
    if (search.scheme() != QLatin1String("kns") || search.host() != name())
        return voidStream();

#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
    const auto pathParts = search.path().split(QLatin1Char('/'), QString::SkipEmptyParts);
#else
    const auto pathParts = search.path().split(QLatin1Char('/'), Qt::SkipEmptyParts);
#endif
    if (pathParts.size() != 2) {
        Q_EMIT passiveMessage(i18n("Wrong KNewStuff URI: %1", search.toString()));
        return voidStream();
    }
    const auto providerid = pathParts.at(0);
    const auto entryid = pathParts.at(1);

    auto stream = new ResultsStream(QLatin1String("KNS-byname-")+entryid);
    auto start = [this, entryid, stream, providerid]() {
        m_responsePending = true;
        m_engine->fetchEntryById(entryid);
        m_onePage = false;

        connect(m_engine, &KNSCore::Engine::signalErrorCode, stream, &ResultsStream::finish);
        connect(m_engine, &KNSCore::Engine::signalEntryDetailsLoaded, stream, [this, stream, entryid, providerid](const KNSCore::EntryInternal &entry) {
            if (entry.uniqueId() == entryid && providerid == QUrl(entry.providerId()).host()) {
                Q_EMIT stream->resourcesFound({resourceForEntry(entry)});
            } else
                qWarning() << "found invalid" << entryid << entry.uniqueId() << providerid << QUrl(entry.providerId()).host();
            m_responsePending = false;
            QTimer::singleShot(0, this, &KNSBackend::availableForQueries);
            stream->finish();
        });
    };
    if (m_responsePending) {
        connect(this, &KNSBackend::availableForQueries, stream, start);
    } else {
        start();
    }
    return stream;
}

bool KNSBackend::isFetching() const
{
    return m_fetching;
}

AbstractBackendUpdater* KNSBackend::backendUpdater() const
{
    return m_updater;
}

QString KNSBackend::displayName() const
{
    return QStringLiteral("KNewStuff");
}

void KNSBackend::detailsLoaded(const KNSCore::EntryInternal& entry)
{
    auto res = resourceForEntry(entry);
    Q_EMIT res->longDescriptionChanged();
}

#include "KNSBackend.moc"
