// SPDX-FileCopyrightText: Copyright (C) 2014 swift Project Community / Contributors
// SPDX-License-Identifier: GPL-3.0-or-later OR LicenseRef-swift-pilot-client-1

#include "misc/worker.h"

#include <future>

#include <QPointer>
#include <QTimer>

#include "misc/logmessage.h"
#include "misc/threadutils.h"
#include "misc/verify.h"

#ifdef Q_OS_WIN32
#    include <Windows.h>
#endif

namespace swift::misc
{
    QSet<CWorkerBase *> CWorkerBase::s_allWorkers;

    void CRegularThread::run()
    {
#ifdef Q_OS_WIN32
        m_handle = GetCurrentThread();
        QThread::run();
        m_handle = nullptr;
#else
        QThread::run();
#endif
    }

    CRegularThread::~CRegularThread()
    {
        const QString name = this->objectName();

#ifdef Q_OS_WIN32
        auto handle = m_handle.load();
        if (handle)
        {
            const auto status = WaitForSingleObject(handle, 0);
            if (isRunning())
            {
                switch (status)
                {
                default:
                case WAIT_FAILED: qWarning() << "Thread" << name << "unspecified error"; break;
                case WAIT_OBJECT_0: qWarning() << "Thread" << name << "unsafely terminated by program shutdown"; break;
                case WAIT_TIMEOUT: break;
                }
            }
        }
#endif
        quit();

        // the wait avoids: QThread: Destroyed while thread is still running
        const unsigned long timeoutMs = 5 * 1000;
        const bool ok = wait(timeoutMs); //! \todo KB 2017-10 temp workaround: in T145 this will be fixed, sometimes
                                         //! (very rarely) hanging here during shutdown
        const QString as = QStringLiteral("Wait timeout after %1ms for '%2'").arg(timeoutMs).arg(name);
        const QByteArray asBA = as.toLatin1();
        SWIFT_AUDIT_X(ok, Q_FUNC_INFO,
                      asBA); // MS 2018-09 assert because we want a stack trace of all threads, via breakpad
        Q_UNUSED(ok)
    }

    CWorker *CWorker::fromTaskImpl(QObject *owner, const QString &name, int typeId,
                                   const std::function<QVariant()> &task)
    {
        auto *worker = new CWorker(task);
        emit worker->aboutToStart();
        worker->setStarted();
        auto *thread = new CRegularThread(owner);

        if (typeId != QMetaType::Void) { worker->m_result = QVariant(QMetaType(typeId), nullptr); }

        const QString ownerName =
            owner->objectName().isEmpty() ? owner->metaObject()->className() : owner->objectName();
        thread->setObjectName(ownerName + ":" + name);
        worker->setObjectName(name);

        worker->moveToThread(thread);
        const bool s = QMetaObject::invokeMethod(worker, &CWorker::ps_runTask);
        Q_ASSERT_X(s, Q_FUNC_INFO, "cannot invoke");
        Q_UNUSED(s)
        thread->start();
        return worker;
    }

    void CWorker::ps_runTask()
    {
        m_result = m_task();

        this->setFinished();

        QThread *workerThread = this->thread();
        Q_ASSERT_X(workerThread->thread()->isRunning(), Q_FUNC_INFO, "Owner thread's event loop already ended");

        // MS 2018-09 Now we post the DeferredDelete event from within the worker thread, but rely on it being
        // dispatched
        //            by the owner thread. Posted events are moved along with the object when moveToThread is called.
        this->deleteLater();

        this->moveToThread(
            workerThread
                ->thread()); // move worker back to the thread which constructed it, so there is no race on deletion
        // must not access the worker beyond this point, as it now lives in the owner's thread and could be deleted at
        // any moment

        QMetaObject::invokeMethod(workerThread, [workerThread] {
            // quit and wait is redundant as the CRegularThread dtor will do that anyway, but put here for debugging
            workerThread->quit();
            const bool ok = workerThread->wait(5000);
            const QString as = QStringLiteral("Worker thread '%2' refuses to stop after worker finished")
                                   .arg(workerThread->objectName());
            const QByteArray asBA = as.toLatin1();
            SWIFT_AUDIT_X(ok, Q_FUNC_INFO, asBA);

            workerThread->deleteLater();
        });
    }

    CWorkerBase::CWorkerBase() { s_allWorkers.insert(this); }

    CWorkerBase::~CWorkerBase() { s_allWorkers.remove(this); }

    const QStringList &CWorkerBase::getLogCategories()
    {
        static const QStringList cats { CLogCategories::worker() };
        return cats;
    }

    void CWorkerBase::waitForFinished() noexcept
    {
        std::promise<void> promise;
        then([&] { promise.set_value(); });
        promise.get_future().wait();
    }

    void CWorkerBase::abandon() noexcept
    {
        if (thread() != thread()->thread()) { thread()->requestInterruption(); }
        quit();
    }

    void CWorkerBase::abandonAndWait() noexcept
    {
        if (thread() != thread()->thread()) { thread()->requestInterruption(); }
        quitAndWait();
    }

    bool CWorkerBase::isAbandoned() const
    {
        Q_ASSERT(thread() == QThread::currentThread());
        return thread()->isInterruptionRequested();
    }

    CContinuousWorker::CContinuousWorker(QObject *owner, const QString &name) : m_owner(owner), m_name(name)
    {
        Q_ASSERT_X(!name.isEmpty(), Q_FUNC_INFO, "Empty name");
        this->setObjectName(m_name);
    }

    void CContinuousWorker::start(QThread::Priority priority)
    {
        SWIFT_VERIFY_X(!hasStarted(), Q_FUNC_INFO, "Tried to start a worker that was already started");
        if (hasStarted()) { return; }

        // avoid message "QObject: Cannot create children for a parent that is in a different thread"
        Q_ASSERT_X(CThreadUtils::isInThisThread(m_owner), Q_FUNC_INFO, "Needs to be started in owner thread");
        emit this->aboutToStart();
        setStarted();
        auto *thread = new CRegularThread(m_owner);

        Q_ASSERT(m_owner); // must not be null
        if (m_owner)
        {
            const QString ownerName =
                m_owner->objectName().isEmpty() ? m_owner->metaObject()->className() : m_owner->objectName();
            thread->setObjectName(ownerName + ": " + m_name);
        }

        moveToThread(thread);
        connect(thread, &QThread::started, this, &CContinuousWorker::initialize);
        connect(thread, &QThread::finished, this, &CContinuousWorker::cleanup);
        connect(thread, &QThread::finished, this, &CContinuousWorker::finish);
        thread->start(priority);
    }

    void CContinuousWorker::quit() noexcept
    {
        this->setEnabled(false);

        // already in owner's thread? then return
        if (this->thread() == m_owner->thread()) { return; }

        // remark: cannot stop timer here, as I am normally not in the correct thread
        this->beforeQuit();
        thread()->quit();
    }

    void CContinuousWorker::quitAndWait() noexcept
    {
        this->setEnabled(false);

        // already in owner's thread? then return
        if (this->thread() == m_owner->thread()) { return; }

        // called by own thread, will deadlock, return
        if (CThreadUtils::isInThisThread(this)) { return; }

        QThread *workerThread = thread(); // must be before quit()
        this->quit();

        // T647, discussed here:
        // https://discordapp.com/channels/539048679160676382/539925070550794240/573260844004016148
        const unsigned long waitTimeoutMs = this->waitTimeoutMs();
        const QString name(this->getName());
        qint64 waitTime = QDateTime::currentMSecsSinceEpoch();
        const bool ok = workerThread->wait(waitTimeoutMs);
        waitTime = QDateTime::currentMSecsSinceEpoch() - waitTime;
        const QString msg = QStringLiteral("Waiting for quitAndWait of '%1' for %2ms").arg(name).arg(waitTime);
        const QByteArray msgBA = msg.toLatin1();
        SWIFT_AUDIT_X(ok, Q_FUNC_INFO,
                      msgBA); // MS 2019-05 AUDIT because we want a stack trace of all threads, via breakpad
        CLogMessage(this).info(msg);
        Q_UNUSED(ok)
    }

    void CContinuousWorker::finish()
    {
        this->setFinished();

        QThread *workerThread = this->thread();
        Q_ASSERT_X(m_owner->thread()->isRunning(), Q_FUNC_INFO, "Owner thread's event loop already ended");

        // MS 2018-09 Now we post the DeferredDelete event from within the worker thread, but rely on it being
        // dispatched
        //            by the owner thread. Posted events are moved along with the object when moveToThread is called.
        this->deleteLater();

        this->moveToThread(
            m_owner->thread()); // move worker back to the thread which constructed it, so there is no race on deletion
        // must not access the worker beyond this point, as it now lives in the owner's thread and could be deleted at
        // any moment

        QMetaObject::invokeMethod(workerThread, [workerThread] {
            // quit and wait is redundant as the CRegularThread dtor will do that anyway, but put here for debugging
            workerThread->quit();
            const bool ok = workerThread->wait(5000);
            const QString as = QStringLiteral("Worker thread '%2' refuses to stop after worker finished")
                                   .arg(workerThread->objectName());
            const QByteArray asBA = as.toLatin1();
            SWIFT_AUDIT_X(ok, Q_FUNC_INFO, asBA);

            workerThread->deleteLater();
        });
    }
} // namespace swift::misc