/**
 * Copyright 2013 Albert Vaca <albertvaka@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) 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 <http://www.gnu.org/licenses/>.
 */

#include "device.h"

#ifdef interface // MSVC language extension, QDBusConnection uses this as a variable name
#undef interface
#endif

#include <QDBusConnection>
#include <QFile>
#include <QStandardPaths>

#include <KSharedConfig>
#include <KConfigGroup>
#include <KLocalizedString>
#include <QIcon>
#include <QDir>
#include <QJsonArray>

#include "core_debug.h"
#include "kdeconnectplugin.h"
#include "pluginloader.h"
#include "backends/devicelink.h"
#include "backends/linkprovider.h"
#include "networkpackage.h"
#include "kdeconnectconfig.h"
#include "daemon.h"

Q_LOGGING_CATEGORY(KDECONNECT_CORE, "kdeconnect.core")

Device::Device(QObject* parent, const QString& id)
    : QObject(parent)
    , m_deviceId(id)
    , m_pairStatus(Device::Paired)
    , m_protocolVersion(NetworkPackage::ProtocolVersion) //We don't know it yet
{
    KdeConnectConfig::DeviceInfo info = KdeConnectConfig::instance()->getTrustedDevice(id);

    m_deviceName = info.deviceName;
    m_deviceType = str2type(info.deviceType);
    m_publicKey = QCA::RSAPublicKey::fromPEM(info.publicKey);

    m_pairingTimeut.setSingleShot(true);
    m_pairingTimeut.setInterval(30 * 1000);  //30 seconds of timeout
    connect(&m_pairingTimeut, SIGNAL(timeout()),
            this, SLOT(pairingTimeout()));

    //Register in bus
    QDBusConnection::sessionBus().registerObject(dbusPath(), this, QDBusConnection::ExportScriptableContents | QDBusConnection::ExportAdaptors);
}

Device::Device(QObject* parent, const NetworkPackage& identityPackage, DeviceLink* dl)
    : QObject(parent)
    , m_deviceId(identityPackage.get<QString>("deviceId"))
    , m_deviceName(identityPackage.get<QString>("deviceName"))
    , m_deviceType(str2type(identityPackage.get<QString>("deviceType")))
    , m_pairStatus(Device::NotPaired)
    , m_protocolVersion(identityPackage.get<int>("protocolVersion", -1))
{
    addLink(identityPackage, dl);

    //Register in bus
    QDBusConnection::sessionBus().registerObject(dbusPath(), this, QDBusConnection::ExportScriptableContents | QDBusConnection::ExportAdaptors);

    //Implement deprecated signals
    connect(this, &Device::pairingChanged, this, [this](bool newPairing) {
        if (newPairing)
            Q_EMIT pairingSuccesful();
        else
            Q_EMIT unpaired();
    });
}

Device::~Device()
{
    qDeleteAll(m_deviceLinks);
}

bool Device::hasPlugin(const QString& name) const
{
    return m_plugins.contains(name);
}

QStringList Device::loadedPlugins() const
{
    return m_plugins.keys();
}

void Device::reloadPlugins()
{
    QHash<QString, KdeConnectPlugin*> newPluginMap;
    QMultiMap<QString, KdeConnectPlugin*> newPluginsByIncomingInterface;
    QMultiMap<QString, KdeConnectPlugin*> newPluginsByOutgoingInterface;
    QSet<QString> supportedIncomingInterfaces;
    QStringList unsupportedPlugins;

    if (isPaired() && isReachable()) { //Do not load any plugin for unpaired devices, nor useless loading them for unreachable devices

        KConfigGroup pluginStates = KSharedConfig::openConfig(pluginsConfigFile())->group("Plugins");

        PluginLoader* loader = PluginLoader::instance();

        //Code borrowed from KWin
        foreach (const QString& pluginName, loader->getPluginList()) {
            const KPluginMetaData service = loader->getPluginInfo(pluginName);
            const QSet<QString> incomingInterfaces = KPluginMetaData::readStringList(service.rawData(), "X-KdeConnect-SupportedPackageType").toSet();
            const QSet<QString> outgoingInterfaces = KPluginMetaData::readStringList(service.rawData(), "X-KdeConnect-OutgoingPackageType").toSet();

            const bool pluginEnabled = isPluginEnabled(pluginName);

            if (pluginEnabled) {
                supportedIncomingInterfaces += incomingInterfaces;
            }

            //If we don't find intersection with the received on one end and the sent on the other, we don't
            //let the plugin stay
            //Also, if no capabilities are specified on the other end, we don't apply this optimizaton, as
            //we assume that the other client doesn't know about capabilities.
            if ((!m_incomingCapabilities.isEmpty() || !m_outgoingCapabilities.isEmpty())
                && (m_incomingCapabilities & outgoingInterfaces).isEmpty()
                && (m_outgoingCapabilities & incomingInterfaces).isEmpty()
                && !incomingInterfaces.isEmpty() && !outgoingInterfaces.isEmpty()
            ) {
                qCWarning(KDECONNECT_CORE) << "not loading " << pluginName << "because of unmatched capabilities";
                unsupportedPlugins.append(pluginName);
                continue;
            }

            if (pluginEnabled) {
                KdeConnectPlugin* plugin = m_plugins.take(pluginName);

                if (!plugin) {
                    plugin = loader->instantiatePluginForDevice(pluginName, this);
                }

                foreach(const QString& interface, incomingInterfaces) {
                    newPluginsByIncomingInterface.insert(interface, plugin);
                }
                foreach(const QString& interface, outgoingInterfaces) {
                    newPluginsByOutgoingInterface.insert(interface, plugin);
                }
                newPluginMap[pluginName] = plugin;
            }
        }
    }

    //Erase all left plugins in the original map (meaning that we don't want
    //them anymore, otherwise they would have been moved to the newPluginMap)
    const QStringList newSupportedIncomingInterfaces = supportedIncomingInterfaces.toList();
    const bool capabilitiesChanged = (m_pluginsByOutgoingInterface != newPluginsByOutgoingInterface
                                     || m_supportedIncomingInterfaces != newSupportedIncomingInterfaces);
    qDeleteAll(m_plugins);
    m_plugins = newPluginMap;
    m_pluginsByOutgoingInterface = newPluginsByOutgoingInterface;
    m_supportedIncomingInterfaces = newSupportedIncomingInterfaces;
    m_pluginsByIncomingInterface = newPluginsByIncomingInterface;
    m_unsupportedPlugins = unsupportedPlugins;

    Q_FOREACH(KdeConnectPlugin* plugin, m_plugins) {
        plugin->connected();
    }
    Q_EMIT pluginsChanged();

    if (capabilitiesChanged && isReachable() && isPaired())
    {
        NetworkPackage np(PACKAGE_TYPE_CAPABILITIES);
        np.set<QStringList>("SupportedIncomingInterfaces", newSupportedIncomingInterfaces);
        np.set<QStringList>("SupportedOutgoingInterfaces", newPluginsByOutgoingInterface.keys());
        sendPackage(np);
    }
}

QString Device::pluginsConfigFile() const
{
    return KdeConnectConfig::instance()->deviceConfigDir(id()).absoluteFilePath("config");
}

void Device::requestPair()
{
    switch(m_pairStatus) {
        case Device::Paired:
            Q_EMIT pairingFailed(i18n("Already paired"));
            return;
        case Device::Requested:
            Q_EMIT pairingFailed(i18n("Pairing already requested for this device"));
            return;
        case Device::RequestedByPeer:
            qCDebug(KDECONNECT_CORE) << "Pairing already started by the other end, accepting their request.";
            acceptPairing();
            return;
        case Device::NotPaired:
            ;
    }

    if (!isReachable()) {
        Q_EMIT pairingFailed(i18n("Device not reachable"));
        return;
    }

    m_pairStatus = Device::Requested;

    //Send our own public key
    bool success = sendOwnPublicKey();

    if (!success) {
        m_pairStatus = Device::NotPaired;
        Q_EMIT pairingFailed(i18n("Error contacting device"));
        return;
    }

    if (m_pairStatus == Device::Paired) {
        return;
    }

    m_pairingTimeut.start();
}

void Device::unpair()
{

    NetworkPackage np(PACKAGE_TYPE_PAIR);
    np.set("pair", false);
    sendPackage(np);

    unpairInternal();
}

void Device::unpairInternal()
{
    bool alreadyUnpaired = (m_pairStatus != Device::Paired);
    m_pairStatus = Device::NotPaired;
    KdeConnectConfig::instance()->removeTrustedDevice(id());
    reloadPlugins(); //Will unload the plugins
    if (!alreadyUnpaired) {
        Q_EMIT pairingChanged(false);
    }
}

void Device::pairingTimeout()
{
    NetworkPackage np(PACKAGE_TYPE_PAIR);
    np.set("pair", false);
    sendPackage(np);
    m_pairStatus = Device::NotPaired;
    Q_EMIT pairingFailed(i18n("Timed out"));
}

static bool lessThan(DeviceLink* p1, DeviceLink* p2)
{
    return p1->provider()->priority() > p2->provider()->priority();
}

void Device::addLink(const NetworkPackage& identityPackage, DeviceLink* link)
{
    //qCDebug(KDECONNECT_CORE) << "Adding link to" << id() << "via" << link->provider();

    m_protocolVersion = identityPackage.get<int>("protocolVersion", -1);
    if (m_protocolVersion != NetworkPackage::ProtocolVersion) {
        qCWarning(KDECONNECT_CORE) << m_deviceName << "- warning, device uses a different protocol version" << m_protocolVersion << "expected" << NetworkPackage::ProtocolVersion;
    }

    connect(link, SIGNAL(destroyed(QObject*)),
            this, SLOT(linkDestroyed(QObject*)));

    m_deviceLinks.append(link);

    //re-read the device name from the identityPackage because it could have changed
    setName(identityPackage.get<QString>("deviceName"));
    m_deviceType = str2type(identityPackage.get<QString>("deviceType"));

    //Theoretically we will never add two links from the same provider (the provider should destroy
    //the old one before this is called), so we do not have to worry about destroying old links.
    //-- Actually, we should not destroy them or the provider will store an invalid ref!

    connect(link, SIGNAL(receivedPackage(NetworkPackage)),
            this, SLOT(privateReceivedPackage(NetworkPackage)));

    qSort(m_deviceLinks.begin(), m_deviceLinks.end(), lessThan);

    if (m_deviceLinks.size() == 1) {
        m_incomingCapabilities = identityPackage.get<QStringList>("SupportedIncomingInterfaces", QStringList()).toSet();
        m_outgoingCapabilities = identityPackage.get<QStringList>("SupportedOutgoingInterfaces", QStringList()).toSet();
        reloadPlugins(); //Will load the plugins
        Q_EMIT reachableStatusChanged();
    } else {
        Q_FOREACH(KdeConnectPlugin* plugin, m_plugins) {
            plugin->connected();
        }
    }
}

void Device::linkDestroyed(QObject* o)
{
    removeLink(static_cast<DeviceLink*>(o));
}

void Device::removeLink(DeviceLink* link)
{
    m_deviceLinks.removeOne(link);

    //qCDebug(KDECONNECT_CORE) << "RemoveLink" << m_deviceLinks.size() << "links remaining";

    if (m_deviceLinks.isEmpty()) {
        reloadPlugins();
        Q_EMIT reachableStatusChanged();
    }
}

bool Device::sendPackage(NetworkPackage& np)
{
    if (np.type() != PACKAGE_TYPE_PAIR && isPaired()) {
        Q_FOREACH(DeviceLink* dl, m_deviceLinks) {
            if (dl->sendPackageEncrypted(m_publicKey, np)) return true;
        }
    } else {
        //Maybe we could block here any package that is not an identity or a pairing package to prevent sending non encrypted data
        Q_FOREACH(DeviceLink* dl, m_deviceLinks) {
            if (dl->sendPackage(np)) return true;
        }
    }

    return false;
}

void Device::privateReceivedPackage(const NetworkPackage& np)
{
    if (np.type() == PACKAGE_TYPE_PAIR) {

        //qCDebug(KDECONNECT_CORE) << "Pair package";

        bool wantsPair = np.get<bool>("pair");

        if (wantsPair == isPaired()) {
            qCDebug(KDECONNECT_CORE) << m_deviceName << "already" << (wantsPair? "paired":"unpaired");
            if (m_pairStatus == Device::Requested) {
                m_pairStatus = Device::NotPaired;
                m_pairingTimeut.stop();
                Q_EMIT pairingFailed(i18n("Canceled by other peer"));
            }
            return;
        }

        if (wantsPair) {

            //Retrieve their public key
            const QString& key = np.get<QString>("publicKey");
            m_publicKey = QCA::RSAPublicKey::fromPEM(key);
            if (m_publicKey.isNull()) {
                qCDebug(KDECONNECT_CORE) << "ERROR decoding key";
                if (m_pairStatus == Device::Requested) {
                    m_pairStatus = Device::NotPaired;
                    m_pairingTimeut.stop();
                }
                Q_EMIT pairingFailed(i18n("Received incorrect key"));
                return;
            }

            if (m_pairStatus == Device::Requested)  { //We started pairing

                qCDebug(KDECONNECT_CORE) << "Pair answer";
                setAsPaired();

            } else {
                qCDebug(KDECONNECT_CORE) << "Pair request";

                Daemon::instance()->requestPairing(this);

                m_pairStatus = Device::RequestedByPeer;
            }

        } else {

            qCDebug(KDECONNECT_CORE) << "Unpair request";

            PairStatus prevPairStatus = m_pairStatus;
            m_pairStatus = Device::NotPaired;

            if (prevPairStatus == Device::Requested) {
                m_pairingTimeut.stop();
                Q_EMIT pairingFailed(i18n("Canceled by other peer"));
            } else if (prevPairStatus == Device::Paired) {
                unpairInternal();
            }

        }

    } else if (np.type() == PACKAGE_TYPE_CAPABILITIES) {
        QSet<QString> newIncomingCapabilities = np.get<QStringList>("SupportedIncomingInterfaces", QStringList()).toSet();
        QSet<QString> newOutgoingCapabilities = np.get<QStringList>("SupportedOutgoingInterfaces", QStringList()).toSet();

        if (newOutgoingCapabilities != m_outgoingCapabilities || newIncomingCapabilities != m_incomingCapabilities) {
            m_incomingCapabilities = newIncomingCapabilities;
            m_outgoingCapabilities = newOutgoingCapabilities;
            reloadPlugins();
        }
    } else if (isPaired()) {
        QList<KdeConnectPlugin*> plugins = m_pluginsByIncomingInterface.values(np.type());
        foreach(KdeConnectPlugin* plugin, plugins) {
            plugin->receivePackage(np);
        }
    } else {
        qCDebug(KDECONNECT_CORE) << "device" << name() << "not paired, ignoring package" << np.type();
        if (m_pairStatus != Device::Requested)
            unpair();
    }

}

bool Device::sendOwnPublicKey()
{
    NetworkPackage np(PACKAGE_TYPE_PAIR);
    np.set("pair", true);
    np.set("publicKey", KdeConnectConfig::instance()->publicKey().toPEM());
    bool success = sendPackage(np);
    return success;
}

void Device::rejectPairing()
{
    qCDebug(KDECONNECT_CORE) << "Rejected pairing";

    m_pairStatus = Device::NotPaired;

    NetworkPackage np(PACKAGE_TYPE_PAIR);
    np.set("pair", false);
    sendPackage(np);

    Q_EMIT pairingFailed(i18n("Canceled by the user"));

}

void Device::acceptPairing()
{
    if (m_pairStatus != Device::RequestedByPeer) return;

    qCDebug(KDECONNECT_CORE) << "Accepted pairing";

    bool success = sendOwnPublicKey();

    if (!success) {
        m_pairStatus = Device::NotPaired;
        return;
    }

    setAsPaired();

}

void Device::setAsPaired()
{

    bool alreadyPaired = (m_pairStatus == Device::Paired);

    m_pairStatus = Device::Paired;

    m_pairingTimeut.stop(); //Just in case it was started

    //Save device info in the config
    KdeConnectConfig::instance()->addTrustedDevice(id(), name(), type2str(m_deviceType), m_publicKey.toPEM());

    reloadPlugins(); //Will actually load the plugins

    if (!alreadyPaired) {
        Q_EMIT pairingChanged(true);
    }

}

QStringList Device::availableLinks() const
{
    QStringList sl;
    Q_FOREACH(DeviceLink* dl, m_deviceLinks) {
        sl.append(dl->provider()->name());
    }
    return sl;
}

Device::DeviceType Device::str2type(QString deviceType) {
    if (deviceType == "desktop") return Desktop;
    if (deviceType == "laptop") return Laptop;
    if (deviceType == "smartphone" || deviceType == "phone") return Phone;
    if (deviceType == "tablet") return Tablet;
    return Unknown;
}

QString Device::type2str(Device::DeviceType deviceType) {
    if (deviceType == Desktop) return "desktop";
    if (deviceType == Laptop) return "laptop";
    if (deviceType == Phone) return "smartphone";
    if (deviceType == Tablet) return "tablet";
    return "unknown";
}

QString Device::statusIconName() const
{
    return iconForStatus(isReachable(), isPaired());
}

QString Device::iconName() const
{

    return iconForStatus(true, false);
}

QString Device::iconForStatus(bool reachable, bool paired) const
{
    Device::DeviceType deviceType = m_deviceType;
    if (deviceType == Device::Unknown) {
        deviceType = Device::Phone; //Assume phone if we don't know the type
    } else if (deviceType == Device::Desktop) {
        deviceType = Device::Device::Laptop; // We don't have desktop icon yet
    }

    QString status = (reachable? (paired? QStringLiteral("connected") : QStringLiteral("disconnected")) : QStringLiteral("trusted"));
    QString type = type2str(deviceType);

    return type+'-'+status;
}

void Device::setName(const QString &name)
{
    if (m_deviceName != name) {
        m_deviceName = name;
        Q_EMIT nameChanged(name);
    }
}

KdeConnectPlugin* Device::plugin(const QString& pluginName) const
{
    return m_plugins[pluginName];
}

void Device::setPluginEnabled(const QString& pluginName, bool enabled)
{
    KConfigGroup pluginStates = KSharedConfig::openConfig(pluginsConfigFile())->group("Plugins");

    const QString enabledKey = pluginName + QStringLiteral("Enabled");
    pluginStates.writeEntry(enabledKey, enabled);
    reloadPlugins();
}

bool Device::isPluginEnabled(const QString& pluginName) const
{
    const QString enabledKey = pluginName + QStringLiteral("Enabled");
    KConfigGroup pluginStates = KSharedConfig::openConfig(pluginsConfigFile())->group("Plugins");

    return (pluginStates.hasKey(enabledKey) ? pluginStates.readEntry(enabledKey, false)
                                            : PluginLoader::instance()->getPluginInfo(pluginName).isEnabledByDefault());
}