/*
  SPDX-FileCopyrightText: 2006-2007 Volker Krause <vkrause@kde.org>

  SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include "transportmanager.h"
using namespace Qt::Literals::StringLiterals;

#include "mailtransport_defs.h"
#include "plugins/transportabstractplugin.h"
#include "plugins/transportpluginmanager.h"
#include "transport.h"
#include "transport_p.h"
#include "transportjob.h"
#include "transporttype_p.h"
#include "widgets/addtransportdialogng.h"
#include <MailTransport/TransportAbstractPlugin>

#include <QApplication>
#include <QDBusConnection>
#include <QDBusConnectionInterface>
#include <QDBusServiceWatcher>
#include <QPointer>
#include <QRandomGenerator>
#include <QRegularExpression>
#include <QStringList>

#include "mailtransport_debug.h"
#include <KConfig>
#include <KConfigGroup>
#include <KLocalizedString>
#include <KMessageBox>
#include <qt6keychain/keychain.h>

using namespace QKeychain;

using namespace MailTransport;

namespace MailTransport
{
/**
 * Private class that helps to provide binary compatibility between releases.
 * @internal
 */
class TransportManagerPrivate
{
public:
    TransportManagerPrivate(TransportManager *parent)
        : q(parent)
    {
    }

    ~TransportManagerPrivate()
    {
        delete config;
        qDeleteAll(transports);
    }

    KConfig *config = nullptr;
    QList<Transport *> transports;
    TransportType::List types;
    bool myOwnChange = false;
    bool appliedChange = false;
    bool walletAsyncOpen = false;
    int defaultTransportId = -1;
    bool isMainInstance = false;
    QList<TransportJob *> walletQueue;
    QMap<Transport *, QMetaObject::Connection> passwordConnections;
    TransportManager *const q;

    void readConfig();
    void writeConfig();
    void fillTypes();
    [[nodiscard]] Transport::Id createId() const;
    void prepareWallet();
    void validateDefault();
    void migrateToWallet();
    void updatePluginList();

    // Slots
    void slotTransportsChanged();
    void dbusServiceUnregistered();
    void startQueuedJobs();
    void jobResult(KJob *job);
};
}

class StaticTransportManager : public TransportManager
{
public:
    StaticTransportManager()
        : TransportManager()
    {
    }
};

StaticTransportManager *sSelf = nullptr;

static void destroyStaticTransportManager()
{
    delete sSelf;
}

TransportManager::TransportManager()
    : QObject()
    , d(new TransportManagerPrivate(this))
{
    qAddPostRoutine(destroyStaticTransportManager);
    d->config = new KConfig(QStringLiteral("mailtransports"));

    QDBusConnection::sessionBus().registerObject(DBUS_OBJECT_PATH, this, QDBusConnection::ExportScriptableSlots | QDBusConnection::ExportScriptableSignals);

    auto watcher = new QDBusServiceWatcher(DBUS_SERVICE_NAME, QDBusConnection::sessionBus(), QDBusServiceWatcher::WatchForUnregistration, this);
    connect(watcher, &QDBusServiceWatcher::serviceUnregistered, this, [this]() {
        d->dbusServiceUnregistered();
    });

    QDBusConnection::sessionBus().connect(QString(), QString(), DBUS_INTERFACE_NAME, DBUS_CHANGE_SIGNAL, this, SLOT(slotTransportsChanged()));

    d->isMainInstance = QDBusConnection::sessionBus().registerService(DBUS_SERVICE_NAME);

    d->fillTypes();
}

TransportManager::~TransportManager()
{
    qRemovePostRoutine(destroyStaticTransportManager);
}

TransportManager *TransportManager::self()
{
    if (!sSelf) {
        sSelf = new StaticTransportManager;
        sSelf->d->readConfig();
    }
    return sSelf;
}

Transport *TransportManager::transportById(Transport::Id id, bool def) const
{
    for (Transport *t : std::as_const(d->transports)) {
        if (t->id() == id) {
            return t;
        }
    }

    if (def || (id == 0 && d->defaultTransportId != id)) {
        return transportById(d->defaultTransportId, false);
    }
    return nullptr;
}

Transport *TransportManager::transportByName(const QString &name, bool def) const
{
    for (Transport *t : std::as_const(d->transports)) {
        if (t->name() == name) {
            return t;
        }
    }
    if (def) {
        return transportById(0, false);
    }
    return nullptr;
}

QList<Transport *> TransportManager::transports() const
{
    return d->transports;
}

TransportType::List TransportManager::types() const
{
    return d->types;
}

Transport *TransportManager::createTransport() const
{
    auto id = d->createId();
    auto t = new Transport(QString::number(id));
    t->setId(id);
    return t;
}

void TransportManager::addTransport(Transport *transport)
{
    if (d->transports.contains(transport)) {
        qCDebug(MAILTRANSPORT_LOG) << "Already have this transport.";
        return;
    }

    qCDebug(MAILTRANSPORT_LOG) << "Added transport" << transport;
    d->transports.append(transport);
    d->validateDefault();
    d->writeConfig();
    emitChangesCommitted();
}

void TransportManager::schedule(TransportJob *job)
{
    connect(job, &TransportJob::result, this, [this](KJob *job) {
        d->jobResult(job);
    });

    // check if the job is waiting for the wallet
    if (!job->transport()->isComplete()) {
        qCDebug(MAILTRANSPORT_LOG) << "job waits for wallet:" << job;
        d->walletQueue << job;
        loadPasswordsAsync();
        return;
    }

    job->start();
}

bool TransportManager::showTransportCreationDialog(QWidget *parent, ShowCondition showCondition)
{
    if (showCondition == IfNoTransportExists) {
        if (!isEmpty()) {
            return true;
        }

        const int response = KMessageBox::warningContinueCancel(parent,
                                                                i18n("You must create an outgoing account before sending."),
                                                                i18nc("@title:window", "Create Account Now?"),
                                                                KGuiItem(i18nc("@action:button", "Create Account Now")),
                                                                KStandardGuiItem::cancel());
        if (response != KMessageBox::Continue) {
            return false;
        }
    }

    QPointer<AddTransportDialogNG> dialog = new AddTransportDialogNG(parent);
    const bool accepted = (dialog->exec() == QDialog::Accepted);
    delete dialog;
    return accepted;
}

void TransportManager::initializeTransport(const QString &identifier, Transport *transport)
{
    TransportAbstractPlugin *plugin = TransportPluginManager::self()->plugin(identifier);
    if (plugin) {
        plugin->initializeTransport(transport, identifier);
    }
}

bool TransportManager::configureTransport(const QString &identifier, Transport *transport, QWidget *parent)
{
    TransportAbstractPlugin *plugin = TransportPluginManager::self()->plugin(identifier);
    if (plugin) {
        return plugin->configureTransport(identifier, transport, parent);
    }
    return false;
}

TransportJob *TransportManager::createTransportJob(int transportId)
{
    Transport *t = transportById(transportId, false);
    if (!t) {
        return nullptr;
    }
    t = t->clone(); // Jobs delete their transports.
    t->updatePasswordState();
    TransportAbstractPlugin *plugin = TransportPluginManager::self()->plugin(t->identifier());
    if (plugin) {
        return plugin->createTransportJob(t, t->identifier());
    }
    Q_ASSERT(false);
    return nullptr;
}

TransportJob *TransportManager::createTransportJob(const QString &transport)
{
    bool ok = false;
    Transport *t = nullptr;

    int transportId = transport.toInt(&ok);
    if (ok) {
        t = transportById(transportId);
    }

    if (!t) {
        t = transportByName(transport, false);
    }

    if (t) {
        return createTransportJob(t->id());
    }

    return nullptr;
}

bool TransportManager::isEmpty() const
{
    return d->transports.isEmpty();
}

QList<int> TransportManager::transportIds() const
{
    QList<int> rv;
    rv.reserve(d->transports.count());
    for (Transport *t : std::as_const(d->transports)) {
        rv << t->id();
    }
    return rv;
}

QStringList TransportManager::transportNames() const
{
    QStringList rv;
    rv.reserve(d->transports.count());
    for (Transport *t : std::as_const(d->transports)) {
        rv << t->name();
    }
    return rv;
}

QString TransportManager::defaultTransportName() const
{
    Transport *t = transportById(d->defaultTransportId, false);
    if (t) {
        return t->name();
    }
    return {};
}

int TransportManager::defaultTransportId() const
{
    return d->defaultTransportId;
}

void TransportManager::setDefaultTransport(Transport::Id id)
{
    if (id == d->defaultTransportId || !transportById(id, false)) {
        return;
    }
    d->defaultTransportId = id;
    d->writeConfig();
}

void TransportManager::removePasswordFromWallet(Transport::Id id)
{
    auto deleteJob = new DeletePasswordJob(WALLET_FOLDER);
    deleteJob->setKey(QString::number(id));
    deleteJob->start();
}

void TransportManager::removeTransport(Transport::Id id)
{
    Transport *t = transportById(id, false);
    if (!t) {
        return;
    }
    auto plugin = MailTransport::TransportPluginManager::self()->plugin(t->identifier());
    if (plugin) {
        plugin->cleanUp(t);
    }
    Q_EMIT transportRemoved(t->id(), t->name());

    d->transports.removeAll(t);
    d->validateDefault();
    const QString group = t->currentGroup();
    if (t->storePassword()) {
        auto deleteJob = new DeletePasswordJob(WALLET_FOLDER);
        deleteJob->setKey(QString::number(t->id()));
        deleteJob->start();
    }
    delete t;
    d->config->deleteGroup(group);
    d->writeConfig();
}

void TransportManagerPrivate::readConfig()
{
    QList<Transport *> oldTransports = transports;
    transports.clear();

    static QRegularExpression re(QStringLiteral("^Transport (.+)$"));
    const QStringList groups = config->groupList().filter(re);
    for (const QString &s : groups) {
        const QRegularExpressionMatch match = re.match(s);
        if (!match.hasMatch()) {
            continue;
        }
        Transport *t = nullptr;
        // see if we happen to have that one already
        const QString capturedString = match.captured(1);
        const QString checkString = "Transport "_L1 + capturedString;
        for (Transport *old : oldTransports) {
            if (old->currentGroup() == checkString) {
                qCDebug(MAILTRANSPORT_LOG) << "reloading existing transport:" << s;
                t = old;
                t->load();
                oldTransports.removeAll(old);
                break;
            }
        }

        if (!t) {
            t = new Transport(capturedString);
        }
        if (t->id() <= 0) {
            t->setId(createId());
            t->save();
        }
        transports.append(t);
    }

    qDeleteAll(oldTransports);
    oldTransports.clear();
    // read default transport
    KConfigGroup group(config, QStringLiteral("General"));
    defaultTransportId = group.readEntry("default-transport", 0);
    if (defaultTransportId == 0) {
        // migrated default transport contains the name instead
        QString name = group.readEntry("default-transport", QString());
        if (!name.isEmpty()) {
            Transport *t = q->transportByName(name, false);
            if (t) {
                defaultTransportId = t->id();
                writeConfig();
            }
        }
    }
    validateDefault();
    migrateToWallet();
    q->loadPasswordsAsync();
}

void TransportManagerPrivate::writeConfig()
{
    KConfigGroup group(config, QStringLiteral("General"));
    group.writeEntry("default-transport", defaultTransportId);
    config->sync();
    q->emitChangesCommitted();
}

void TransportManagerPrivate::fillTypes()
{
    Q_ASSERT(types.isEmpty());

    updatePluginList();
    QObject::connect(MailTransport::TransportPluginManager::self(), &TransportPluginManager::updatePluginList, q, &TransportManager::updatePluginList);
}

void TransportManagerPrivate::updatePluginList()
{
    types.clear();
    const QList<MailTransport::TransportAbstractPlugin *> lstPlugins = MailTransport::TransportPluginManager::self()->pluginsList();
    for (MailTransport::TransportAbstractPlugin *plugin : lstPlugins) {
        if (plugin->names().isEmpty()) {
            qCDebug(MAILTRANSPORT_LOG) << "Plugin " << plugin << " doesn't provide plugin";
        }
        const QList<TransportAbstractPluginInfo> lstInfos = plugin->names();
        for (const MailTransport::TransportAbstractPluginInfo &info : lstInfos) {
            TransportType type;
            type.d->mName = info.name;
            type.d->mDescription = info.description;
            type.d->mIdentifier = info.identifier;
            type.d->mIsAkonadiResource = info.isAkonadi;
            types << type;
        }
    }
}

void TransportManager::updatePluginList()
{
    d->updatePluginList();
}

void TransportManager::emitChangesCommitted()
{
    d->myOwnChange = true; // prevent us from reading our changes again
    d->appliedChange = false; // but we have to read them at least once
    Q_EMIT transportsChanged();
    Q_EMIT changesCommitted();
}

void TransportManagerPrivate::slotTransportsChanged()
{
    if (myOwnChange && appliedChange) {
        myOwnChange = false;
        appliedChange = false;
        return;
    }

    qCDebug(MAILTRANSPORT_LOG);
    config->reparseConfiguration();
    // FIXME: this deletes existing transport objects!
    readConfig();
    appliedChange = true; // to prevent recursion
    Q_EMIT q->transportsChanged();
}

Transport::Id TransportManagerPrivate::createId() const
{
    QList<int> usedIds;
    usedIds.reserve(transports.size());
    for (Transport *t : std::as_const(transports)) {
        usedIds << t->id();
    }
    int newId;
    do {
        // 0 is default for unknown, so use 1 as lower value accepted
        newId = QRandomGenerator::global()->bounded(1, RAND_MAX);
    } while (usedIds.contains(newId));
    return newId;
}

void TransportManager::loadPasswords()
{
    QEventLoop loop;
    for (Transport *t : std::as_const(d->transports)) {
        if (d->passwordConnections.contains(t)) {
            continue;
        }
        auto conn = connect(t, &Transport::passwordLoaded, this, [&]() {
            disconnect(d->passwordConnections[t]);
            d->passwordConnections.remove(t);
            if (d->passwordConnections.count() == 0) {
                loop.exit();
            }
        });
        d->passwordConnections[t] = conn;
        t->readPassword();
    }
    loop.exec();

    d->startQueuedJobs();
    Q_EMIT passwordsChanged();
}

void TransportManager::loadPasswordsAsync()
{
    for (Transport *t : std::as_const(d->transports)) {
        if (!t->isComplete()) {
            if (d->passwordConnections.contains(t)) {
                continue;
            }
            auto conn = connect(t, &Transport::passwordLoaded, this, [&]() {
                disconnect(d->passwordConnections[t]);
                d->passwordConnections.remove(t);
                if (d->passwordConnections.count() == 0) {
                    d->startQueuedJobs();
                    Q_EMIT passwordsChanged();
                }
            });
            d->passwordConnections[t] = conn;
            t->readPassword();
        }
    }
}

void TransportManagerPrivate::startQueuedJobs()
{
    QList<TransportJob *> jobsToDel;
    for (auto job : walletQueue) {
        if (job->transport()->isComplete()) {
            job->start();
            jobsToDel << job;
        }
    }

    for (auto job : jobsToDel) {
        walletQueue.removeAll(job);
    }
}

void TransportManagerPrivate::validateDefault()
{
    if (!q->transportById(defaultTransportId, false)) {
        if (q->isEmpty()) {
            defaultTransportId = -1;
        } else {
            defaultTransportId = transports.constFirst()->id();
            writeConfig();
        }
    }
}

void TransportManagerPrivate::migrateToWallet()
{
    // check if we tried this already
    static bool firstRun = true;
    if (!firstRun) {
        return;
    }
    firstRun = false;

    // check if we are the main instance
    if (!isMainInstance) {
        return;
    }

    // check if migration is needed
    QStringList names;
    for (Transport *t : std::as_const(transports)) {
        if (t->needsWalletMigration()) {
            names << t->name();
        }
    }
    if (names.isEmpty()) {
        return;
    }

    // ask user if he wants to migrate
    int result = KMessageBox::questionTwoActionsList(nullptr,
                                                     i18n("The following mail transports store their passwords in an "
                                                          "unencrypted configuration file.\nFor security reasons, "
                                                          "please consider migrating these passwords to KWallet, the "
                                                          "KDE Wallet management tool,\nwhich stores sensitive data "
                                                          "for you in a strongly encrypted file.\n"
                                                          "Do you want to migrate your passwords to KWallet?"),
                                                     names,
                                                     i18nc("@title:window", "Question"),
                                                     KGuiItem(i18nc("@action:button", "Migrate")),
                                                     KGuiItem(i18nc("@action:button", "Keep")),
                                                     QStringLiteral("WalletMigrate"));
    if (result != KMessageBox::ButtonCode::PrimaryAction) {
        return;
    }

    // perform migration
    for (Transport *t : std::as_const(transports)) {
        if (t->needsWalletMigration()) {
            t->migrateToWallet();
        }
    }
}

void TransportManagerPrivate::dbusServiceUnregistered()
{
    QDBusConnection::sessionBus().registerService(DBUS_SERVICE_NAME);
}

void TransportManagerPrivate::jobResult(KJob *job)
{
    walletQueue.removeAll(static_cast<TransportJob *>(job));
}

#include "moc_transportmanager.cpp"
