/*  This file is part of the KDE libraries
    Copyright (C) 2022 Ivailo Monev <xakepa10@gmail.com>

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License version 2, as published by the Free Software Foundation.

    This library 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
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public License
    along with this library; see the file COPYING.LIB.  If not, write to
    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
    Boston, MA 02110-1301, USA.
*/

#include "klauncher_adaptor.h"
#include "kprotocolmanager.h"
#include "krun.h"
#include "kstandarddirs.h"
#include "kautostart.h"
#include "kdebug.h"

#include <QDir>
#include <QApplication>
#include <QThread>
#include <QElapsedTimer>
#include <QDBusConnection>
#include <QDBusConnectionInterface>
#include <QDBusReply>

#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>

static const int s_eventstime = 250;
static const int s_sleeptime = 50;
static const qint64 s_servicetimeout = 10000; // 10sec

static bool isPIDAlive(const pid_t pid)
{
    return (::kill(pid, 0) >= 0);
}

static int getExitStatus(const pid_t pid)
{
    int pidstate = 0;
    ::waitpid(pid, &pidstate, WNOHANG);
    return WEXITSTATUS(pidstate);
}

KLauncherAdaptor::KLauncherAdaptor(QObject *parent)
    : QDBusAbstractAdaptor(parent),
    m_dbusconnectioninterface(nullptr)
{
    m_environment = QProcessEnvironment::systemEnvironment();
    m_dbusconnectioninterface = QDBusConnection::sessionBus().interface();
}

KLauncherAdaptor::~KLauncherAdaptor()
{
    kDebug() << "terminating processes" << m_processes.size();
    while (!m_processes.isEmpty()) {
        QProcess* process = m_processes.takeLast();
        disconnect(process, 0, this, 0);
        process->terminate();
        process->waitForFinished();
    }
}

void KLauncherAdaptor::autoStart(int phase)
{
    if (m_autostart.isEmpty()) {
        m_autostart = KGlobal::dirs()->findAllResources(
            "autostart",
            QString::fromLatin1("*.desktop"),
            KStandardDirs::NoDuplicates
        );
    }

    kDebug() << "autostart, phase" << phase;
    foreach(const QString &it, m_autostart) {
        KAutostart kautostart(it);
        if (!kautostart.autostarts(QString::fromLatin1("KDE"), KAutostart::CheckAll)) {
            continue;
        }
        if (kautostart.startPhase() != phase) {
            continue;
        }
        KService kservice(it);
        QStringList programandargs = KRun::processDesktopExec(kservice, KUrl::List());
        if (programandargs.isEmpty()) {
            kWarning() << "could not process service" << kservice.entryPath();
            continue;
        }
        const QString program = programandargs.takeFirst();
        const QStringList programargs = programandargs;
        exec_blind(program, programargs);
    }
    switch (phase) {
        case 0: {
            emit autoStart0Done();
            break;
        }
        case 1: {
            emit autoStart1Done();
            break;
        }
        case 2: {
            emit autoStart2Done();
            break;
        }
    }
}

void KLauncherAdaptor::exec_blind(const QString &name, const QStringList &arg_list)
{
    const QString appexe = findExe(name);
    if (appexe.isEmpty()) {
        kWarning() << "Could not find" << name;
        return;
    }

    kDebug() << "blind starting" << appexe << arg_list << m_environment.toStringList();
    const QString envexe = findExe("env");
    if (envexe.isEmpty()) {
        kWarning() << "env program not found";
        QProcess::startDetached(appexe, arg_list);
        return;
    }

    QStringList envargs = m_environment.toStringList();
    envargs += appexe;
    envargs += arg_list;
    QProcess::startDetached(envexe, envargs);
}

int KLauncherAdaptor::kdeinit_exec(const QString &app, const QStringList &args, const QStringList &env, const QString& startup_id,
                                   const QDBusMessage &msg, QString &dbusServiceName, QString &error, qint64 &pid)
{
    return kdeinit_exec_with_workdir(app, args, QDir::currentPath(), env, startup_id, msg, dbusServiceName, error, pid);
}

int KLauncherAdaptor::kdeinit_exec_wait(const QString &app, const QStringList &args, const QStringList &env, const QString& startup_id,
                                        const QDBusMessage &msg, QString &dbusServiceName, QString &error, qint64 &pid)
{
    int result = kdeinit_exec(app, args, env, startup_id, msg, dbusServiceName, error, pid);
    if (result != KLauncherAdaptor::NoError) {
        return result;
    }
    kDebug() << "waiting for" << pid;
    while (isPIDAlive(pid)) {
        QApplication::processEvents(QEventLoop::AllEvents, s_eventstime);
        QThread::msleep(s_sleeptime);
    }
    result = getExitStatus(pid);
    kDebug() << "done waiting for" << pid << ", exit status" << result;
    return result;
}

int KLauncherAdaptor::kdeinit_exec_with_workdir(const QString &app, const QStringList &args, const QString& workdir, const QStringList &env, const QString& startup_id,
                                                const QDBusMessage &msg, QString &dbusServiceName, QString &error, qint64 &pid)
{
    const QString appexe = findExe(app);
    if (appexe.isEmpty()) {
        error = i18n("Could not find: %1", app);
        return KLauncherAdaptor::FindError;
    }

    QProcess* process = new QProcess(this);
    connect(process, SIGNAL(stateChanged(QProcess::ProcessState)), this, SLOT(slotProcessStateChanged(QProcess::ProcessState)));
    connect(process, SIGNAL(finished(int)), this, SLOT(slotProcessFinished(int)));
    m_processes.append(process);
    QProcessEnvironment processenv = m_environment;
    foreach (const QString &it, env) {
        const int equalindex = it.indexOf(QLatin1Char('='));
        if (equalindex <= 0) {
            kWarning() << "invalid environment variable" << it;
            continue;
        }
        const QString environmentvar = it.mid(0, equalindex);
        const QString environmentvalue = it.mid(equalindex + 1, it.size() - equalindex - 1);
        kDebug() << "adding to environment" << environmentvar << environmentvalue;
        processenv.insert(environmentvar, environmentvalue);
    }
    process->setProcessEnvironment(processenv);
    process->setWorkingDirectory(workdir);
    kDebug() << "starting" << appexe << args << env << processenv.toStringList();
    m_kstartupinfoid = KStartupInfoId();
    m_kstartupinfoid.initId(startup_id.toLatin1());
    m_kstartupinfodata = KStartupInfoData();
    m_kstartupinfodata.setBin(QFileInfo(appexe).fileName());
    sendSIStart();
    process->start(appexe, args);
    while (process->state() == QProcess::Starting) {
        QApplication::processEvents(QEventLoop::AllEvents, s_eventstime);
        QThread::msleep(s_sleeptime);
    }
    if (process->error() == QProcess::FailedToStart || process->error() == QProcess::Crashed) {
        sendSIFinish();
        error = i18n("Could not start: %1", appexe);
        return KLauncherAdaptor::ExecError;
    }
    if (dbusServiceName.isEmpty()) {
        // if service name is not empty it will be send when the service is up
        sendSIFinish();
    }

    error.clear();
    pid = process->pid();
    return KLauncherAdaptor::NoError;
}

void KLauncherAdaptor::reparseConfiguration()
{
    kDebug() << "reparsing configuration";
    KProtocolManager::reparseConfiguration();
}

void KLauncherAdaptor::setLaunchEnv(const QString &name, const QString &value)
{
    kDebug() << "setting environment variable" << name << "to" << value;
    m_environment.insert(name, value);
}

int KLauncherAdaptor::start_service_by_desktop_name(const QString &serviceName, const QStringList &urls, const QStringList &envs, const QString &startup_id, bool blind,
                                                    const QDBusMessage &msg, QString &dbusServiceName, QString &error, qint64 &pid)
{
    KService::Ptr kservice = KService::serviceByDesktopName(serviceName);
    if (!kservice) {
        error = i18n("Invalid service name: %1", serviceName);
        return KLauncherAdaptor::ServiceError;
    }
    return start_service_by_desktop_path(kservice->entryPath(), urls, envs, startup_id, blind, msg, dbusServiceName, error, pid);
}

int KLauncherAdaptor::start_service_by_desktop_path(const QString &serviceName, const QStringList &urls, const QStringList &envs, const QString &startup_id, bool blind,
                                                    const QDBusMessage &msg, QString &dbusServiceName, QString &error, qint64 &pid)
{
    KService::Ptr kservice = KService::serviceByStorageId(serviceName);
    if (!kservice) {
        error = i18n("Invalid service path: %1", serviceName);
        return KLauncherAdaptor::ServiceError;
    }
    const KService::DBusStartupType dbusstartuptype = kservice->dbusStartupType();
    dbusServiceName = kservice->property(QString::fromLatin1("X-DBUS-ServiceName"), QVariant::String).toString();
    if (dbusstartuptype == KService::DBusUnique) {
        QDBusReply<bool> sessionreply = m_dbusconnectioninterface->isServiceRegistered(dbusServiceName);
        if (!sessionreply.isValid()) {
            sendSIFinish();
            error = i18n("Invalid D-Bus reply for: %1", dbusServiceName);
            return KLauncherAdaptor::DBusError;
        }
        if (sessionreply.value() == true) {
            kDebug() << "service already started" << dbusServiceName;
            return KLauncherAdaptor::NoError;
        }
    }
    if (urls.size() > 1 && !kservice->allowMultipleFiles()) {
        // TODO: start multiple instances for each URL
        error = i18n("Service does not support multiple files: %1", serviceName);
        return KLauncherAdaptor::ServiceError;
    }
    QStringList programandargs = KRun::processDesktopExec(*kservice, urls);
    if (programandargs.isEmpty()) {
        error = i18n("Could not process service: %1", kservice->entryPath());
        return KLauncherAdaptor::ArgumentsError;
    }
    const QString program = programandargs.takeFirst();
    const QStringList programargs = programandargs;
    int result = kdeinit_exec(program, programargs, envs, startup_id, msg, dbusServiceName, error, pid);
    if (result != KLauncherAdaptor::NoError) {
        // sendSIFinish() is called on exec error
        return result;
    }
    // blind means do not wait, even if its type is wait
    if (blind || dbusstartuptype == KService::DBusNone) {
        sendSIFinish();
        return result;
    } else if (dbusstartuptype != KService::DBusNone && dbusServiceName.isEmpty()) {
        // not going to guess what service to wait for, bud
        kWarning() << "X-DBUS-ServiceName not specified in" << kservice->entryPath();
        sendSIFinish();
        return result;
    } else if (dbusstartuptype == KService::DBusMulti) {
        dbusServiceName.append(QLatin1Char('-'));
        dbusServiceName.append(QString::number(pid));
    }
    kDebug() << "waiting for" << pid << dbusServiceName;
    QElapsedTimer elapsedtime;
    elapsedtime.start();
    while (true) {
        QDBusReply<bool> sessionreply = m_dbusconnectioninterface->isServiceRegistered(dbusServiceName);
        if (!sessionreply.isValid()) {
            sendSIFinish();
            error = i18n("Invalid D-Bus reply for: %1", dbusServiceName);
            return KLauncherAdaptor::DBusError;
        }
        // the service unregistered
        if (sessionreply.value() == false && dbusstartuptype == KService::DBusWait) {
            break;
        }
        // the service registered
        if (sessionreply.value() == true && dbusstartuptype != KService::DBusWait) {
            break;
        }
        // or the program is just not registering the service at all
        if (elapsedtime.elapsed() >= s_servicetimeout && dbusstartuptype != KService::DBusWait) {
            kWarning() << "timed out for" << pid << ", service name" << dbusServiceName;
            break;
        }
        // or the program is not even running
        if (!isPIDAlive(pid)) {
            result = getExitStatus(pid);
            kWarning() << "not running" << pid << ", exit status" << result;
            break;
        }
        QApplication::processEvents(QEventLoop::AllEvents, s_eventstime);
        QThread::msleep(s_sleeptime);
    }
    kDebug() << "done waiting for" << pid << ", service name" << dbusServiceName;
    sendSIFinish();
    return result;
}

void KLauncherAdaptor::slotProcessStateChanged(QProcess::ProcessState state)
{
    QProcess* process = qobject_cast<QProcess*>(sender());
    kDebug() << "process state changed" << process << state;
    if (state == QProcess::Starting && !m_kstartupinfoid.none()) {
        m_kstartupinfodata.addPid(process->pid());
        sendSIUpdate();
    } else if (state == QProcess::NotRunning && m_kstartupinfodata.is_pid(process->pid())) {
        sendSIFinish();
    }
}

void KLauncherAdaptor::slotProcessFinished(int exitcode)
{
    QProcess* process = qobject_cast<QProcess*>(sender());
    kDebug() << "process finished" << process << exitcode;
    m_processes.removeAll(process);
}

QString KLauncherAdaptor::findExe(const QString &app) const
{
    if (QDir::isAbsolutePath(app)) {
        if (!QFile::exists(app)) {
            // return empty string if it does not exists (like KStandardDirs::findExe())
            return QString();
        }
        return app;
    }
    const QString environmentpath = m_environment.value(QString::fromLatin1("PATH"), QString());
    return KStandardDirs::findExe(app, environmentpath);
}

void KLauncherAdaptor::sendSIStart() const
{
    kDebug() << "sending ASN start";
    KStartupInfo::sendStartup(m_kstartupinfoid, m_kstartupinfodata);
}

void KLauncherAdaptor::sendSIUpdate()
{
    if (m_kstartupinfoid.none()) {
        return;
    }
    kDebug() << "sending ASN update";
    KStartupInfo::sendChange(m_kstartupinfoid, m_kstartupinfodata);
}

void KLauncherAdaptor::sendSIFinish()
{
    if (m_kstartupinfoid.none()) {
        return;
    }
    kDebug() << "sending ASN finish";
    KStartupInfo::sendFinish(m_kstartupinfoid, m_kstartupinfodata);
    m_kstartupinfoid = KStartupInfoId();
    m_kstartupinfodata = KStartupInfoData();
}

#include "moc_klauncher_adaptor.cpp"