/**
 * SPDX-FileCopyrightText: 2016 Saikrishna Arcot <saiarcot895@gmail.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
 */

#include "bluetoothlinkprovider.h"
#include "bluetoothdevicelink.h"
#include "connectionmultiplexer.h"
#include "core_debug.h"
#include "kdeconnectconfig.h"
#include "multiplexchannel.h"

#include <QBluetoothServiceInfo>

BluetoothLinkProvider::BluetoothLinkProvider()
    : mServiceUuid(QBluetoothUuid(QStringLiteral("185f3df4-3268-4e3f-9fca-d4d5059915bd")))
    , mServiceDiscoveryAgent(new QBluetoothServiceDiscoveryAgent(this))
    , connectTimer(new QTimer(this))
{
    connectTimer->setInterval(30000);
    connectTimer->setSingleShot(false);

    mServiceDiscoveryAgent->setUuidFilter(mServiceUuid);
    connect(connectTimer, &QTimer::timeout, this, [this]() {
        mServiceDiscoveryAgent->start();
    });

    connect(mServiceDiscoveryAgent, &QBluetoothServiceDiscoveryAgent::serviceDiscovered, this, &BluetoothLinkProvider::serviceDiscovered);
}

void BluetoothLinkProvider::onStart()
{
    QBluetoothLocalDevice localDevice;
    if (!localDevice.isValid()) {
        qCWarning(KDECONNECT_CORE) << "No local bluetooth adapter found";
        return;
    }

    mBluetoothServer = new QBluetoothServer(QBluetoothServiceInfo::RfcommProtocol, this);
    mBluetoothServer->setSecurityFlags(QBluetooth::Security::Encryption | QBluetooth::Security::Secure);
    connect(mBluetoothServer, &QBluetoothServer::newConnection, this, &BluetoothLinkProvider::serverNewConnection);

    mServiceDiscoveryAgent->start();

    connectTimer->start();
    mKdeconnectService = mBluetoothServer->listen(mServiceUuid, QStringLiteral("KDE Connect"));
}

void BluetoothLinkProvider::onStop()
{
    if (!mBluetoothServer) {
        return;
    }

    connectTimer->stop();

    mKdeconnectService.unregisterService();
    mBluetoothServer->close();
    mBluetoothServer->deleteLater();
}

// I'm in a new network, let's be polite and introduce myself
void BluetoothLinkProvider::onNetworkChange()
{
}

void BluetoothLinkProvider::connectError()
{
    QBluetoothSocket *socket = qobject_cast<QBluetoothSocket *>(sender());
    if (!socket)
        return;

    qCWarning(KDECONNECT_CORE) << "Couldn't connect to socket:" << socket->errorString();

    disconnect(socket, &QBluetoothSocket::connected, this, nullptr);
    disconnect(socket, &QBluetoothSocket::readyRead, this, nullptr);
    disconnect(socket, QOverload<QBluetoothSocket::SocketError>::of(&QBluetoothSocket::error), this, nullptr);

    mSockets.remove(socket->peerAddress());
    socket->deleteLater();
}

void BluetoothLinkProvider::addLink(BluetoothDeviceLink *deviceLink, const QString &deviceId)
{
    QMap<QString, DeviceLink *>::iterator oldLinkIterator = mLinks.find(deviceId);
    delete oldLinkIterator.value(); // not calling deleteLater because this triggers onLinkDestroyed
    mLinks[deviceId] = deviceLink;
}

void BluetoothLinkProvider::serviceDiscovered(const QBluetoothServiceInfo &old_info)
{
    auto info = old_info;
    info.setServiceUuid(mServiceUuid);
    if (mSockets.contains(info.device().address())) {
        return;
    }

    QBluetoothSocket *socket = new QBluetoothSocket(QBluetoothServiceInfo::RfcommProtocol);

    // Delay before sending data
    QPointer<QBluetoothSocket> deleteableSocket = socket;
    connect(socket, &QBluetoothSocket::connected, this, [this, deleteableSocket]() {
        QTimer::singleShot(500, this, [this, deleteableSocket]() {
            clientConnected(deleteableSocket);
        });
    });
    connect(socket, QOverload<QBluetoothSocket::SocketError>::of(&QBluetoothSocket::error), this, &BluetoothLinkProvider::connectError);

    socket->connectToService(info);

    qCDebug(KDECONNECT_CORE) << "Connecting to" << info.device().address();

    if (socket->error() != QBluetoothSocket::SocketError::NoSocketError) {
        qCWarning(KDECONNECT_CORE) << "Socket connection error:" << socket->errorString();
    }
}

// I'm the new device and I'm connected to the existing device. Time to get data.
void BluetoothLinkProvider::clientConnected(QPointer<QBluetoothSocket> socket)
{
    if (!socket)
        return;

    auto peer = socket->peerAddress();

    qCDebug(KDECONNECT_CORE) << "Connected to" << peer;

    if (mSockets.contains(socket->peerAddress())) {
        qCWarning(KDECONNECT_CORE) << "Duplicate connection to" << peer;
        socket->close();
        socket->deleteLater();
        return;
    }

    ConnectionMultiplexer *multiplexer = new ConnectionMultiplexer(socket, this);

    mSockets.insert(peer, multiplexer);
    disconnect(socket, nullptr, this, nullptr);

    auto channel = QSharedPointer<MultiplexChannel>{multiplexer->getDefaultChannel().release()};
    connect(channel.data(), &MultiplexChannel::readyRead, this, [this, peer, channel]() {
        clientIdentityReceived(peer, channel);
    });
    connect(channel.data(), &MultiplexChannel::aboutToClose, this, [this, peer, channel]() {
        socketDisconnected(peer, channel.data());
    });

    if (channel->bytesAvailable())
        clientIdentityReceived(peer, channel);
    if (!channel->isOpen())
        socketDisconnected(peer, channel.data());
}

// I'm the new device and the existing device sent me data.
void BluetoothLinkProvider::clientIdentityReceived(const QBluetoothAddress &peer, QSharedPointer<MultiplexChannel> socket)
{
    socket->startTransaction();

    QByteArray identityArray = socket->readLine();
    if (identityArray.isEmpty()) {
        socket->rollbackTransaction();
        return;
    }
    socket->commitTransaction();

    disconnect(socket.data(), &MultiplexChannel::readyRead, this, nullptr);

    NetworkPacket receivedPacket;
    bool success = NetworkPacket::unserialize(identityArray, &receivedPacket);

    if (!success || receivedPacket.type() != PACKET_TYPE_IDENTITY) {
        qCWarning(KDECONNECT_CORE) << "Not an identity packet";
        mSockets.remove(peer);
        socket->close();
        socket->deleteLater();
        return;
    }

    qCDebug(KDECONNECT_CORE) << "Received identity packet from" << peer;

    // TODO?
    // disconnect(socket, &QAbstractSocket::error, this, &BluetoothLinkProvider::connectError);

    QSslCertificate receivedCertificate(receivedPacket.get<QString>(QStringLiteral("certificate")).toLatin1());
    DeviceInfo deviceInfo = deviceInfo.FromIdentityPacketAndCert(receivedPacket, receivedCertificate);
    BluetoothDeviceLink *deviceLink = new BluetoothDeviceLink(deviceInfo, this, mSockets[peer], socket);

    DeviceInfo myDeviceInfo = KdeConnectConfig::instance().deviceInfo();
    NetworkPacket myIdentity = myDeviceInfo.toIdentityPacket();
    myIdentity.set(QStringLiteral("certificate"), QString::fromLatin1(myDeviceInfo.certificate.toPem()));
    success = deviceLink->sendPacket(myIdentity);

    if (success) {
        qCDebug(KDECONNECT_CORE) << "Handshaking done (I'm the new device)";

        Q_EMIT onConnectionReceived(deviceLink);

        // We kill any possible link from this same device
        addLink(deviceLink, deviceInfo.id);

    } else {
        // Connection might be lost. Delete it.
        delete deviceLink;
    }

    // We don't delete the socket because now it's owned by the BluetoothDeviceLink
}

// I'm the existing device, a new device is kindly introducing itself.
void BluetoothLinkProvider::serverNewConnection()
{
    QBluetoothSocket *socket = mBluetoothServer->nextPendingConnection();

    qCDebug(KDECONNECT_CORE) << "Received connection from" << socket->peerAddress();

    QBluetoothAddress peer = socket->peerAddress();

    if (mSockets.contains(peer)) {
        qCDebug(KDECONNECT_CORE) << "Duplicate connection from" << peer;
        socket->close();
        socket->deleteLater();
        return;
    }

    ConnectionMultiplexer *multiplexer = new ConnectionMultiplexer(socket, this);

    mSockets.insert(peer, multiplexer);
    disconnect(socket, nullptr, this, nullptr);

    auto channel = QSharedPointer<MultiplexChannel>{multiplexer->getDefaultChannel().release()};
    connect(channel.data(), &MultiplexChannel::readyRead, this, [this, peer, channel]() {
        serverDataReceived(peer, channel);
    });
    connect(channel.data(), &MultiplexChannel::aboutToClose, this, [this, peer, channel]() {
        socketDisconnected(peer, channel.data());
    });

    if (!channel->isOpen()) {
        socketDisconnected(peer, channel.data());
        return;
    }

    DeviceInfo myDeviceInfo = KdeConnectConfig::instance().deviceInfo();
    NetworkPacket myIdentity = myDeviceInfo.toIdentityPacket();
    myIdentity.set(QStringLiteral("certificate"), QString::fromLatin1(myDeviceInfo.certificate.toPem()));
    socket->write(myIdentity.serialize());

    qCDebug(KDECONNECT_CORE) << "Sent identity packet to" << socket->peerAddress();
}

// I'm the existing device and this is the answer to my identity packet (data received)
void BluetoothLinkProvider::serverDataReceived(const QBluetoothAddress &peer, QSharedPointer<MultiplexChannel> socket)
{
    QByteArray identityArray;
    socket->startTransaction();
    identityArray = socket->readLine();

    if (identityArray.isEmpty()) {
        socket->rollbackTransaction();
        return;
    }
    socket->commitTransaction();

    disconnect(socket.data(), &MultiplexChannel::readyRead, this, nullptr);

    NetworkPacket receivedPacket;
    bool success = NetworkPacket::unserialize(identityArray, &receivedPacket);

    if (!success || receivedPacket.type() != PACKET_TYPE_IDENTITY) {
        qCWarning(KDECONNECT_CORE) << "Not an identity packet.";
        mSockets.remove(peer);
        socket->close();
        socket->deleteLater();
        return;
    }

    qCDebug(KDECONNECT_CORE) << "Received identity packet from" << peer;

    QSslCertificate receivedCertificate(receivedPacket.get<QString>(QStringLiteral("certificate")).toLatin1());
    DeviceInfo deviceInfo = deviceInfo.FromIdentityPacketAndCert(receivedPacket, receivedCertificate);
    BluetoothDeviceLink *deviceLink = new BluetoothDeviceLink(deviceInfo, this, mSockets[peer], socket);

    Q_EMIT onConnectionReceived(deviceLink);

    addLink(deviceLink, deviceInfo.id);
}

void BluetoothLinkProvider::onLinkDestroyed(const QString &deviceId, DeviceLink *oldPtr)
{
    qCDebug(KDECONNECT_CORE) << "BluetoothLinkProvider deviceLinkDestroyed" << deviceId;
    DeviceLink *link = mLinks.take(deviceId);
    Q_ASSERT(link == oldPtr);
}

void BluetoothLinkProvider::socketDisconnected(const QBluetoothAddress &peer, MultiplexChannel *socket)
{
    qCDebug(KDECONNECT_CORE) << "Disconnected";
    disconnect(socket, nullptr, this, nullptr);

    mSockets.remove(peer);
}

BluetoothLinkProvider::~BluetoothLinkProvider()
{
}

#include "moc_bluetoothlinkprovider.cpp"