/*
 *  Copyright (C) 2012 Tobias Tangemann
 *  Copyright (C) 2012 Felix Geyer <debfx@fobos.de>
 *  Copyright (C) 2017 KeePassXC Team <team@keepassxc.org>
 *
 *  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 or (at your option)
 *  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 "Application.h"
#include "MainWindow.h"
#include "core/Config.h"

#include <QAbstractNativeEventFilter>
#include <QFileOpenEvent>
#include <QSocketNotifier>
#include <QLockFile>
#include <QStandardPaths>
#include <QtNetwork/QLocalSocket>

#include "autotype/AutoType.h"

#if defined(Q_OS_UNIX)
#include <signal.h>
#include <unistd.h>
#include <sys/socket.h>
#endif

#if defined(Q_OS_UNIX) && !defined(Q_OS_OSX)
class XcbEventFilter : public QAbstractNativeEventFilter
{
public:
    bool nativeEventFilter(const QByteArray& eventType, void* message, long* result) override
    {
        Q_UNUSED(result)

        if (eventType == QByteArrayLiteral("xcb_generic_event_t")) {
            int retCode = autoType()->callEventFilter(message);
            if (retCode == 1) {
                return true;
            }
        }

        return false;
    }
};
#elif defined(Q_OS_WIN)
class WinEventFilter : public QAbstractNativeEventFilter
{
public:
    bool nativeEventFilter(const QByteArray& eventType, void* message, long* result) override
    {
        Q_UNUSED(result);

        if (eventType == QByteArrayLiteral("windows_generic_MSG")
                || eventType == QByteArrayLiteral("windows_dispatcher_MSG")) {
            int retCode = autoType()->callEventFilter(message);
            if (retCode == 1) {
                return true;
            }
        }

        return false;
    }
};
#endif

Application::Application(int& argc, char** argv)
    : QApplication(argc, argv)
    , m_mainWindow(nullptr)
#ifdef Q_OS_UNIX
    , m_unixSignalNotifier(nullptr)
#endif
    , m_alreadyRunning(false)
    , m_lockFile(nullptr)
{
#if defined(Q_OS_UNIX) && !defined(Q_OS_OSX)
    installNativeEventFilter(new XcbEventFilter());
#elif defined(Q_OS_WIN)
    installNativeEventFilter(new WinEventFilter());
#endif
#if defined(Q_OS_UNIX)
    registerUnixSignals();
#endif

    QString userName = qgetenv("USER");
    if (userName.isEmpty()) {
        userName = qgetenv("USERNAME");
    }
    QString identifier = "keepassxc";
    if (!userName.isEmpty()) {
        identifier += "-" + userName;
    }
#ifdef QT_DEBUG
        // In DEBUG mode don't interfere with Release instances
        identifier += "-DEBUG";
#endif
    QString socketName = identifier + ".socket";
    QString lockName = identifier + ".lock";

    // According to documentation we should use RuntimeLocation on *nixes, but even Qt doesn't respect
    // this and creates sockets in TempLocation, so let's be consistent.
    m_lockFile = new QLockFile(QStandardPaths::writableLocation(QStandardPaths::TempLocation) + "/" + lockName);
    m_lockFile->setStaleLockTime(0);
    m_lockFile->tryLock();

    switch (m_lockFile->error()) {
    case QLockFile::NoError:
        // No existing lock was found, start listener
        m_lockServer.setSocketOptions(QLocalServer::UserAccessOption);
        m_lockServer.listen(socketName);
        connect(&m_lockServer, SIGNAL(newConnection()), this, SIGNAL(anotherInstanceStarted()));
        break;
    case QLockFile::LockFailedError: {
        if (config()->get("SingleInstance").toBool()) {
            // Attempt to connect to the existing instance
            QLocalSocket client;
            for (int i = 0; i < 3; i++) {
                client.connectToServer(socketName);
                if (client.waitForConnected(150)) {
                    // Connection succeeded, this will raise the existing window if minimized
                    client.abort();
                    m_alreadyRunning = true;
                    break;
                }
            }

            if (!m_alreadyRunning) {
                // If we get here then the original instance is likely dead
                qWarning() << QCoreApplication::translate("Main",
                                "Existing single-instance lock file is invalid. Launching new instance.")
                                .toUtf8().constData();

                // forceably reset the lock file
                m_lockFile->removeStaleLockFile();
                m_lockFile->tryLock();
                // start the listen server
                m_lockServer.setSocketOptions(QLocalServer::UserAccessOption);
                m_lockServer.listen(socketName);
                connect(&m_lockServer, SIGNAL(newConnection()), this, SIGNAL(anotherInstanceStarted()));
            }
        }
        break;
    }
    default:
        qWarning() << QCoreApplication::translate("Main",
                        "The lock file could not be created. Single-instance mode disabled.")
                        .toUtf8().constData();
    }
}

Application::~Application()
{
    m_lockServer.close();
    if (m_lockFile) {
        m_lockFile->unlock();
        delete m_lockFile;
    }
}

QWidget* Application::mainWindow() const
{
    return m_mainWindow;
}

void Application::setMainWindow(QWidget* mainWindow)
{
    m_mainWindow = mainWindow;
}

bool Application::event(QEvent* event)
{
    // Handle Apple QFileOpenEvent from finder (double click on .kdbx file)
    if (event->type() == QEvent::FileOpen) {
        emit openFile(static_cast<QFileOpenEvent*>(event)->file());
        return true;
    }
#ifdef Q_OS_MAC
    // restore main window when clicking on the docker icon
    else if ((event->type() == QEvent::ApplicationActivate) && m_mainWindow) {
        m_mainWindow->ensurePolished();
        m_mainWindow->setWindowState(m_mainWindow->windowState() & ~Qt::WindowMinimized);
        m_mainWindow->show();
        m_mainWindow->raise();
        m_mainWindow->activateWindow();
    }
#endif

    return QApplication::event(event);
}

#if defined(Q_OS_UNIX)
int Application::unixSignalSocket[2];

void Application::registerUnixSignals()
{
    int result = ::socketpair(AF_UNIX, SOCK_STREAM, 0, unixSignalSocket);
    Q_ASSERT(0 == result);
    if (0 != result) {
        // do not register handles when socket creation failed, otherwise
        // application will be unresponsive to signals such as SIGINT or SIGTERM
        return;
    }
    
    QVector<int> const handledSignals = { SIGQUIT, SIGINT, SIGTERM, SIGHUP };
    for (auto s: handledSignals) {
        struct sigaction sigAction;
        
        sigAction.sa_handler = handleUnixSignal;
        sigemptyset(&sigAction.sa_mask);
        sigAction.sa_flags = 0 | SA_RESTART;
        sigaction(s, &sigAction, nullptr);
    }
    
    m_unixSignalNotifier = new QSocketNotifier(unixSignalSocket[1], QSocketNotifier::Read, this);
    connect(m_unixSignalNotifier, SIGNAL(activated(int)), this, SLOT(quitBySignal()));
}

void Application::handleUnixSignal(int sig)
{
    switch (sig) {
        case SIGQUIT:
        case SIGINT:
        case SIGTERM:
        {
            char buf = 0;
            Q_UNUSED(::write(unixSignalSocket[0], &buf, sizeof(buf)));
            return;
        }
        case SIGHUP:
            return;
    }
}

void Application::quitBySignal()
{
    m_unixSignalNotifier->setEnabled(false);
    char buf;
    Q_UNUSED(::read(unixSignalSocket[1], &buf, sizeof(buf)));
    
    if (nullptr != m_mainWindow)
        static_cast<MainWindow*>(m_mainWindow)->appExit();
}
#endif

bool Application::isAlreadyRunning() const
{
#ifdef QT_DEBUG
    // In DEBUG mode we can run unlimited instances
    return false;
#endif
    return config()->get("SingleInstance").toBool() && m_alreadyRunning;
}