/*
    This file is part of the KDE libraries

    SPDX-FileCopyrightText: 2009 David Faure <faure@kde.org>

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

#include <kdirwatch.h>

#include <QDebug>
#include <QDir>
#include <QFileInfo>
#include <QSignalSpy>
#include <QTemporaryDir>
#include <QTest>
#include <QThread>
#include <sys/stat.h>
#ifdef Q_OS_UNIX
#include <unistd.h> // ::link()
#endif

#include "config-tests.h"
#include "kcoreaddons_debug.h"

// Debugging notes: to see which inotify signals are emitted, either set s_verboseDebug=true
// at the top of kdirwatch.cpp, or use the command-line tool "inotifywait -m /path"

// Note that kdirlistertest and kdirmodeltest also exercise KDirWatch quite a lot.

static const char *methodToString(KDirWatch::Method method)
{
    switch (method) {
    case KDirWatch::FAM:
        return "Fam";
    case KDirWatch::INotify:
        return "INotify";
    case KDirWatch::Stat:
        return "Stat";
    case KDirWatch::QFSWatch:
        return "QFSWatch";
    }
    return "ERROR!";
}

class StaticObject
{
public:
    KDirWatch m_dirWatch;
};
Q_GLOBAL_STATIC(StaticObject, s_staticObject)

class StaticObjectUsingSelf // like KSambaShare does, bug 353080
{
public:
    StaticObjectUsingSelf()
    {
        KDirWatch::self();
    }
    ~StaticObjectUsingSelf()
    {
        if (KDirWatch::exists() && KDirWatch::self()->contains(QDir::homePath())) {
            KDirWatch::self()->removeDir(QDir::homePath());
        }
    }
};
Q_GLOBAL_STATIC(StaticObjectUsingSelf, s_staticObjectUsingSelf)

class KDirWatch_UnitTest : public QObject
{
    Q_OBJECT
public:
    KDirWatch_UnitTest()
    {
        // Speed up the test by making the kdirwatch timer (to compress changes) faster
        qputenv("KDIRWATCH_POLLINTERVAL", "50");
        qputenv("KDIRWATCH_METHOD", KDIRWATCH_TEST_METHOD);
        s_staticObjectUsingSelf();

        m_path = m_tempDir.path() + QLatin1Char('/');
        KDirWatch *dirW = &s_staticObject()->m_dirWatch;
        m_stat = dirW->internalMethod() == KDirWatch::Stat;
        m_slow = (dirW->internalMethod() == KDirWatch::FAM || m_stat);
        qCDebug(KCOREADDONS_DEBUG) << "Using method" << methodToString(dirW->internalMethod());
    }

private Q_SLOTS: // test methods
    void initTestCase()
    {
        QFileInfo pathInfo(m_path);
        QVERIFY(pathInfo.isDir() && pathInfo.isWritable());

        // By creating the files upfront, we save waiting a full second for an mtime change
        createFile(m_path + QLatin1String("ExistingFile"));
        createFile(m_path + QLatin1String("TestFile"));
        createFile(m_path + QLatin1String("nested_0"));
        createFile(m_path + QLatin1String("nested_1"));

        s_staticObject()->m_dirWatch.addFile(m_path + QLatin1String("ExistingFile"));
    }
    void touchOneFile();
    void touch1000Files();
    void watchAndModifyOneFile();
    void removeAndReAdd();
    void watchNonExistent();
    void watchNonExistentWithSingleton();
    void testDelete();
    void testDeleteAndRecreateFile();
    void testDeleteAndRecreateDir();
    void testMoveTo();
    void nestedEventLoop();
    void testHardlinkChange();
    void stopAndRestart();
    void benchCreateTree();
    void benchCreateWatcher();
    void benchNotifyWatcher();
    void testRefcounting();

protected Q_SLOTS: // internal slots
    void nestedEventLoopSlot();

private:
    void waitUntilMTimeChange(const QString &path);
    void waitUntilNewSecond();
    void waitUntilAfter(const QDateTime &ctime);
    QList<QVariantList> waitForDirtySignal(KDirWatch &watch, int expected);
    QList<QVariantList> waitForDeletedSignal(KDirWatch &watch, int expected);
    bool waitForOneSignal(KDirWatch &watch, const char *sig, const QString &path);
    bool waitForRecreationSignal(KDirWatch &watch, const QString &path);
    bool verifySignalPath(QSignalSpy &spy, const char *sig, const QString &expectedPath);
    void createFile(const QString &path);
    QString createFile(int num);
    void removeFile(int num);
    void appendToFile(const QString &path);
    void appendToFile(int num);
    int createDirectoryTree(const QString &path, int depth = 4);

    QTemporaryDir m_tempDir;
    QString m_path;
    bool m_slow;
    bool m_stat;
};

QTEST_MAIN(KDirWatch_UnitTest)

// Just to make the inotify packets bigger
static const char s_filePrefix[] = "This_is_a_test_file_";

static const int s_maxTries = 50;

// helper method: create a file
void KDirWatch_UnitTest::createFile(const QString &path)
{
    QFile file(path);
    QVERIFY(file.open(QIODevice::WriteOnly));
#ifdef Q_OS_FREEBSD
    // FreeBSD has inotify implemented as user-space library over native kevent API.
    // When using it, one has to open() a file to start watching it, so workaround
    // test breakage by giving inotify time to react to file creation.
    // Full context: https://github.com/libinotify-kqueue/libinotify-kqueue/issues/10
    if (!m_slow)
        QThread::msleep(1);
#endif
    file.write(QByteArray("foo"));
    file.close();
}

// helper method: create a file (identified by number)
QString KDirWatch_UnitTest::createFile(int num)
{
    const QString fileName = QLatin1String(s_filePrefix) + QString::number(num);
    createFile(m_path + fileName);
    return m_path + fileName;
}

// helper method: delete a file (identified by number)
void KDirWatch_UnitTest::removeFile(int num)
{
    const QString fileName = QLatin1String(s_filePrefix) + QString::number(num);
    QFile::remove(m_path + fileName);
}

int KDirWatch_UnitTest::createDirectoryTree(const QString &basePath, int depth)
{
    int filesCreated = 0;

    const int numFiles = 10;
    for (int i = 0; i < numFiles; ++i) {
        createFile(basePath + QLatin1Char('/') + QLatin1String(s_filePrefix) + QString::number(i));
        ++filesCreated;
    }

    if (depth <= 0) {
        return filesCreated;
    }

    const int numFolders = 5;
    for (int i = 0; i < numFolders; ++i) {
        const QString childPath = basePath + QLatin1String("/subdir") + QString::number(i);
        QDir().mkdir(childPath);
        filesCreated += createDirectoryTree(childPath, depth - 1);
    }

    return filesCreated;
}

void KDirWatch_UnitTest::waitUntilMTimeChange(const QString &path)
{
    // Wait until the current second is more than the file's mtime
    // otherwise this change will go unnoticed

    QFileInfo fi(path);
    QVERIFY(fi.exists());
    const QDateTime ctime = fi.lastModified();
    waitUntilAfter(ctime);
}

void KDirWatch_UnitTest::waitUntilNewSecond()
{
    QDateTime now = QDateTime::currentDateTime();
    waitUntilAfter(now);
}

void KDirWatch_UnitTest::waitUntilAfter(const QDateTime &ctime)
{
    int totalWait = 0;
    QDateTime now;
    Q_FOREVER {
        now = QDateTime::currentDateTime();
        if (now.toMSecsSinceEpoch() / 1000 == ctime.toMSecsSinceEpoch() / 1000) // truncate milliseconds
        {
            totalWait += 50;
            QTest::qWait(50);
        } else {
            QVERIFY(now > ctime); // can't go back in time ;)
            QTest::qWait(50); // be safe
            break;
        }
    }
    // if (totalWait > 0)
    qCDebug(KCOREADDONS_DEBUG) << "Waited" << totalWait << "ms so that now" << now.toString(Qt::ISODate) << "is >" << ctime.toString(Qt::ISODate);
}

// helper method: modifies a file
void KDirWatch_UnitTest::appendToFile(const QString &path)
{
    QVERIFY(QFile::exists(path));
    waitUntilMTimeChange(path);

    QFile file(path);
    QVERIFY(file.open(QIODevice::Append | QIODevice::WriteOnly));
    file.write(QByteArray("foobar"));
    file.close();
}

// helper method: modifies a file (identified by number)
void KDirWatch_UnitTest::appendToFile(int num)
{
    const QString fileName = QLatin1String(s_filePrefix) + QString::number(num);
    appendToFile(m_path + fileName);
}

static QString removeTrailingSlash(const QString &path)
{
    if (path.endsWith(QLatin1Char('/'))) {
        return path.left(path.length() - 1);
    } else {
        return path;
    }
}

// helper method
QList<QVariantList> KDirWatch_UnitTest::waitForDirtySignal(KDirWatch &watch, int expected)
{
    QSignalSpy spyDirty(&watch, &KDirWatch::dirty);
    int numTries = 0;
    // Give time for KDirWatch to notify us
    while (spyDirty.count() < expected) {
        if (++numTries > s_maxTries) {
            qWarning() << "Timeout waiting for KDirWatch. Got" << spyDirty.count() << "dirty() signals, expected" << expected;
            return std::move(spyDirty);
        }
        spyDirty.wait(50);
    }
    return std::move(spyDirty);
}

bool KDirWatch_UnitTest::waitForOneSignal(KDirWatch &watch, const char *sig, const QString &path)
{
    const QString expectedPath = removeTrailingSlash(path);
    while (true) {
        QSignalSpy spyDirty(&watch, sig);
        int numTries = 0;
        // Give time for KDirWatch to notify us
        while (spyDirty.isEmpty()) {
            if (++numTries > s_maxTries) {
                qWarning() << "Timeout waiting for KDirWatch signal" << QByteArray(sig).mid(1) << "(" << path << ")";
                return false;
            }
            spyDirty.wait(50);
        }
        return verifySignalPath(spyDirty, sig, expectedPath);
    }
}

bool KDirWatch_UnitTest::verifySignalPath(QSignalSpy &spy, const char *sig, const QString &expectedPath)
{
    for (int i = 0; i < spy.count(); ++i) {
        const QString got = spy[i][0].toString();
        if (got == expectedPath) {
            return true;
        }
        if (got.startsWith(expectedPath + QLatin1Char('/'))) {
            qCDebug(KCOREADDONS_DEBUG) << "Ignoring (inotify) notification of" << (sig + 1) << '(' << got << ')';
            continue;
        }
        qWarning() << "Expected" << sig << '(' << expectedPath << ')' << "but got" << sig << '(' << got << ')';
        return false;
    }
    return false;
}

bool KDirWatch_UnitTest::waitForRecreationSignal(KDirWatch &watch, const QString &path)
{
    // When watching for a deleted + created signal pair, the two might come so close that
    // using waitForOneSignal will miss the created signal.  This function monitors both all
    // the time to ensure both are received.
    //
    // In addition, it allows dirty() to be emitted (for that same path) as an alternative

    const QString expectedPath = removeTrailingSlash(path);
    QSignalSpy spyDirty(&watch, &KDirWatch::dirty);
    QSignalSpy spyDeleted(&watch, &KDirWatch::deleted);
    QSignalSpy spyCreated(&watch, &KDirWatch::created);

    int numTries = 0;
    while (spyDeleted.isEmpty() && spyDirty.isEmpty()) {
        if (++numTries > s_maxTries) {
            return false;
        }
        spyDeleted.wait(50);
        while (!spyDirty.isEmpty()) {
            if (spyDirty.at(0).at(0).toString() != expectedPath) { // unrelated
                spyDirty.removeFirst();
            }
        }
    }
    if (!spyDirty.isEmpty()) {
        return true;
    }

    // Don't bother waiting for the created signal if the signal spy already received a signal.
    if (spyCreated.isEmpty() && !spyCreated.wait(50 * s_maxTries)) {
        qWarning() << "Timeout waiting for KDirWatch signal created(QString) (" << path << ")";
        return false;
    }

    return verifySignalPath(spyDeleted, "deleted(QString)", expectedPath) && verifySignalPath(spyCreated, "created(QString)", expectedPath);
}

QList<QVariantList> KDirWatch_UnitTest::waitForDeletedSignal(KDirWatch &watch, int expected)
{
    QSignalSpy spyDeleted(&watch, &KDirWatch::created);
    int numTries = 0;
    // Give time for KDirWatch to notify us
    while (spyDeleted.count() < expected) {
        if (++numTries > s_maxTries) {
            qWarning() << "Timeout waiting for KDirWatch. Got" << spyDeleted.count() << "deleted() signals, expected" << expected;
            return std::move(spyDeleted);
        }
        spyDeleted.wait(50);
    }
    return std::move(spyDeleted);
}

void KDirWatch_UnitTest::touchOneFile() // watch a dir, create a file in it
{
    KDirWatch watch;
    watch.addDir(m_path);
    watch.startScan();

    waitUntilMTimeChange(m_path);

    // dirty(the directory) should be emitted.
    QSignalSpy spyCreated(&watch, &KDirWatch::created);
    createFile(0);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), m_path));
    QCOMPARE(spyCreated.count(), 0); // "This is not emitted when creating a file is created in a watched directory."

    removeFile(0);
}

void KDirWatch_UnitTest::touch1000Files()
{
    KDirWatch watch;
    watch.addDir(m_path);
    watch.startScan();

    waitUntilMTimeChange(m_path);

    const int fileCount = 100;
    for (int i = 0; i < fileCount; ++i) {
        createFile(i);
    }

    QList<QVariantList> spy = waitForDirtySignal(watch, fileCount);
    if (watch.internalMethod() == KDirWatch::INotify) {
        QVERIFY(spy.count() >= fileCount);
    } else {
        // More stupid backends just see one mtime change on the directory
        QVERIFY(spy.count() >= 1);
    }

    for (int i = 0; i < fileCount; ++i) {
        removeFile(i);
    }
}

void KDirWatch_UnitTest::watchAndModifyOneFile() // watch a specific file, and modify it
{
    KDirWatch watch;
    const QString existingFile = m_path + QLatin1String("ExistingFile");
    watch.addFile(existingFile);
    watch.startScan();
    if (m_slow) {
        waitUntilNewSecond();
    }
    appendToFile(existingFile);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), existingFile));
}

void KDirWatch_UnitTest::removeAndReAdd()
{
    KDirWatch watch;
    watch.addDir(m_path);
    // This triggers bug #374075.
    watch.addDir(QStringLiteral(":/kio5/newfile-templates"));
    watch.startScan();
    if (watch.internalMethod() != KDirWatch::INotify) {
        waitUntilNewSecond(); // necessary for mtime checks in scanEntry
    }
    createFile(0);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), m_path));

    // Just like KDirLister does: remove the watch, then re-add it.
    watch.removeDir(m_path);
    watch.addDir(m_path);
    if (watch.internalMethod() != KDirWatch::INotify) {
        waitUntilMTimeChange(m_path); // necessary for FAM and QFSWatcher
    }
    createFile(1);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), m_path));
}

void KDirWatch_UnitTest::watchNonExistent()
{
    KDirWatch watch;
    // Watch "subdir", that doesn't exist yet
    const QString subdir = m_path + QLatin1String("subdir");
    QVERIFY(!QFile::exists(subdir));
    watch.addDir(subdir);
    watch.startScan();

    if (m_slow) {
        waitUntilNewSecond();
    }

    // Now create it, KDirWatch should emit created()
    qCDebug(KCOREADDONS_DEBUG) << "Creating" << subdir;
    QDir().mkdir(subdir);

    QVERIFY(waitForOneSignal(watch, SIGNAL(created(QString)), subdir));

    KDirWatch::statistics();

    // Play with addDir/removeDir, just for fun
    watch.addDir(subdir);
    watch.removeDir(subdir);
    watch.addDir(subdir);

    // Now watch files that don't exist yet
    const QString file = subdir + QLatin1String("/0");
    watch.addFile(file); // doesn't exist yet
    const QString file1 = subdir + QLatin1String("/1");
    watch.addFile(file1); // doesn't exist yet
    watch.removeFile(file1); // forget it again

    KDirWatch::statistics();

    QVERIFY(!QFile::exists(file));
    // Now create it, KDirWatch should emit created
    qCDebug(KCOREADDONS_DEBUG) << "Creating" << file;
    createFile(file);
    QVERIFY(waitForOneSignal(watch, SIGNAL(created(QString)), file));

    appendToFile(file);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), file));

    // Create the file after all; we're not watching for it, but the dir will emit dirty
    createFile(file1);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), subdir));
}

void KDirWatch_UnitTest::watchNonExistentWithSingleton()
{
    const QString file = QLatin1String("/root/.ssh/authorized_keys");
    KDirWatch::self()->addFile(file);
    // When running this test in KDIRWATCH_METHOD=QFSWatch, or when FAM is not available
    // and we fallback to qfswatch when inotify fails above, we end up creating the fsWatch
    // in the kdirwatch singleton. Bug 261541 discovered that Qt hanged when deleting fsWatch
    // once QCoreApp was gone, this is what this test is about.
}

void KDirWatch_UnitTest::testDelete()
{
    const QString file1 = m_path + QLatin1String("del");
    if (!QFile::exists(file1)) {
        createFile(file1);
    }
    waitUntilMTimeChange(file1);

    // Watch the file, then delete it, KDirWatch will emit deleted (and possibly dirty for the dir, if mtime changed)
    KDirWatch watch;
    watch.addFile(file1);

    KDirWatch::statistics();

    QSignalSpy spyDirty(&watch, &KDirWatch::dirty);
    QFile::remove(file1);
    QVERIFY(waitForOneSignal(watch, SIGNAL(deleted(QString)), file1));
    QTest::qWait(40); // just in case delayed processing would emit it
    QCOMPARE(spyDirty.count(), 0);
}

void KDirWatch_UnitTest::testDeleteAndRecreateFile() // Useful for /etc/localtime for instance
{
    const QString subdir = m_path + QLatin1String("subdir");
    QDir().mkdir(subdir);
    const QString file1 = subdir + QLatin1String("/1");
    if (!QFile::exists(file1)) {
        createFile(file1);
    }
    waitUntilMTimeChange(file1);

    // Watch the file, then delete it, KDirWatch will emit deleted (and possibly dirty for the dir, if mtime changed)
    KDirWatch watch;
    watch.addFile(file1);

    // Make sure this even works multiple times, as needed for ksycoca
    for (int i = 0; i < 5; ++i) {
        if (m_slow || watch.internalMethod() == KDirWatch::QFSWatch) {
            waitUntilNewSecond();
        }

        qCDebug(KCOREADDONS_DEBUG) << "Attempt #" << (i + 1) << "removing+recreating" << file1;

        // When watching for a deleted + created signal pair, the two might come so close that
        // using waitForOneSignal will miss the created signal.  This function monitors both all
        // the time to ensure both are received.
        //
        // In addition, allow dirty() to be emitted (for that same path) as an alternative

        const QString expectedPath = file1;
        QSignalSpy spyDirty(&watch, &KDirWatch::dirty);
        QSignalSpy spyDeleted(&watch, &KDirWatch::deleted);
        QSignalSpy spyCreated(&watch, &KDirWatch::created);

        // WHEN
        QFile::remove(file1);
        // And recreate immediately, to try and fool KDirWatch with unchanged ctime/mtime ;)
        // (This emulates the /etc/localtime case)
        createFile(file1);

        // THEN
        int numTries = 0;
        while (spyDeleted.isEmpty() && spyDirty.isEmpty()) {
            if (++numTries > s_maxTries) {
                QFAIL("Failed to detect file deletion and recreation through either a deleted/created signal pair or through a dirty signal!");
                return;
            }
            spyDeleted.wait(50);
            while (!spyDirty.isEmpty()) {
                if (spyDirty.at(0).at(0).toString() != expectedPath) { // unrelated
                    spyDirty.removeFirst();
                } else {
                    break;
                }
            }
        }
        if (!spyDirty.isEmpty()) {
            continue; // all ok
        }

        // Don't bother waiting for the created signal if the signal spy already received a signal.
        if (spyCreated.isEmpty() && !spyCreated.wait(50 * s_maxTries)) {
            qWarning() << "Timeout waiting for KDirWatch signal created(QString) (" << expectedPath << ")";
            QFAIL("Timeout waiting for KDirWatch signal created, after deleted was emitted");
            return;
        }

        QVERIFY(verifySignalPath(spyDeleted, "deleted(QString)", expectedPath) && verifySignalPath(spyCreated, "created(QString)", expectedPath));
    }

    waitUntilMTimeChange(file1);

    appendToFile(file1);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), file1));
}

void KDirWatch_UnitTest::testDeleteAndRecreateDir()
{
    // Like KDirModelTest::testOverwriteFileWithDir does at the end.
    // The linux-2.6.31 bug made kdirwatch emit deletion signals about the -new- dir!
    QTemporaryDir *tempDir1 = new QTemporaryDir(QDir::tempPath() + QLatin1Char('/') + QLatin1String("olddir-"));
    KDirWatch watch;
    const QString path1 = tempDir1->path() + QLatin1Char('/');
    watch.addDir(path1);

    delete tempDir1;
    QTemporaryDir *tempDir2 = new QTemporaryDir(QDir::tempPath() + QLatin1Char('/') + QLatin1String("newdir-"));
    const QString path2 = tempDir2->path() + QLatin1Char('/');
    watch.addDir(path2);

    QVERIFY(waitForOneSignal(watch, SIGNAL(deleted(QString)), path1));

    delete tempDir2;
}

void KDirWatch_UnitTest::testMoveTo()
{
    // This reproduces the famous digikam crash, #222974
    // A watched file was being rewritten (overwritten by ksavefile),
    // which gives inotify notifications "moved_to" followed by "delete_self"
    //
    // What happened then was that the delayed slotRescan
    // would adjust things, making it status==Normal but the entry was
    // listed as a "non-existent sub-entry" for the parent directory.
    // That's inconsistent, and after removeFile() a dangling sub-entry would be left.

    // Initial data: creating file subdir/1
    const QString file1 = m_path + QLatin1String("moveTo");
    createFile(file1);

    KDirWatch watch;
    watch.addDir(m_path);
    watch.addFile(file1);
    watch.startScan();

    if (watch.internalMethod() != KDirWatch::INotify) {
        waitUntilMTimeChange(m_path);
    }

    // Atomic rename of "temp" to "file1", much like KAutoSave would do when saving file1 again
    // ### TODO: this isn't an atomic rename anymore. We need ::rename for that, or API from Qt.
    const QString filetemp = m_path + QLatin1String("temp");
    createFile(filetemp);
    QFile::remove(file1);
    QVERIFY(QFile::rename(filetemp, file1)); // overwrite file1 with the tempfile
    qCDebug(KCOREADDONS_DEBUG) << "Overwrite file1 with tempfile";

    QSignalSpy spyCreated(&watch, &KDirWatch::created);
    QSignalSpy spyDirty(&watch, &KDirWatch::dirty);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), m_path));

    // Getting created() on an unwatched file is an inotify bonus, it's not part of the requirements.
    if (watch.internalMethod() == KDirWatch::INotify) {
        QCOMPARE(spyCreated.count(), 1);
        QCOMPARE(spyCreated[0][0].toString(), file1);

        QCOMPARE(spyDirty.size(), 2);
        QCOMPARE(spyDirty[1][0].toString(), filetemp);
    }

    // make sure we're still watching it
    appendToFile(file1);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), file1));

    watch.removeFile(file1); // now we remove it

    // Just touch another file to trigger a findSubEntry - this where the crash happened
    waitUntilMTimeChange(m_path);
    createFile(filetemp);
#ifdef Q_OS_WIN
    if (watch.internalMethod() == KDirWatch::QFSWatch) {
        QEXPECT_FAIL(nullptr, "QFSWatch fails here on Windows!", Continue);
    }
#endif
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), m_path));
}

void KDirWatch_UnitTest::nestedEventLoop() // #220153: watch two files, and modify 2nd while in slot for 1st
{
    KDirWatch watch;

    const QString file0 = m_path + QLatin1String("nested_0");
    watch.addFile(file0);
    const QString file1 = m_path + QLatin1String("nested_1");
    watch.addFile(file1);
    watch.startScan();

    if (m_slow) {
        waitUntilNewSecond();
    }

    appendToFile(file0);

    // use own spy, to connect it before nestedEventLoopSlot, otherwise it reverses order
    QSignalSpy spyDirty(&watch, &KDirWatch::dirty);
    connect(&watch, &KDirWatch::dirty, this, &KDirWatch_UnitTest::nestedEventLoopSlot);
    waitForDirtySignal(watch, 1);
    QVERIFY(spyDirty.count() >= 2);
    QCOMPARE(spyDirty[0][0].toString(), file0);
    QCOMPARE(spyDirty[spyDirty.count() - 1][0].toString(), file1);
}

void KDirWatch_UnitTest::nestedEventLoopSlot()
{
    const KDirWatch *const_watch = qobject_cast<const KDirWatch *>(sender());
    KDirWatch *watch = const_cast<KDirWatch *>(const_watch);
    // let's not come in this slot again
    disconnect(watch, &KDirWatch::dirty, this, &KDirWatch_UnitTest::nestedEventLoopSlot);

    const QString file1 = m_path + QLatin1String("nested_1");
    appendToFile(file1);
    // The nested event processing here was from a messagebox in #220153
    QList<QVariantList> spy = waitForDirtySignal(*watch, 1);
    QVERIFY(spy.count() >= 1);
    QCOMPARE(spy[spy.count() - 1][0].toString(), file1);

    // Now the user pressed reload...
    const QString file0 = m_path + QLatin1String("nested_0");
    watch->removeFile(file0);
    watch->addFile(file0);
}

void KDirWatch_UnitTest::testHardlinkChange()
{
#ifdef Q_OS_UNIX

    // The unittest for the "detecting hardlink change to /etc/localtime" problem
    // described on kde-core-devel (2009-07-03).
    // It shows that watching a specific file doesn't inform us that the file is
    // being recreated. Better watch the directory, for that.
    // Well, it works with inotify (and fam - which uses inotify I guess?)

    const QString existingFile = m_path + QLatin1String("ExistingFile");
    KDirWatch watch;
    watch.addFile(existingFile);
    watch.startScan();

    QFile::remove(existingFile);
    const QString testFile = m_path + QLatin1String("TestFile");
    QVERIFY(::link(QFile::encodeName(testFile).constData(), QFile::encodeName(existingFile).constData()) == 0); // make ExistingFile "point" to TestFile
    QVERIFY(QFile::exists(existingFile));

    QVERIFY(waitForRecreationSignal(watch, existingFile));

    // The mtime of the existing file is the one of "TestFile", so it's old.
    // We won't detect the change then, if we use that as baseline for waiting.
    // We really need msec granularity, but that requires using statx which isn't available everywhere...
    waitUntilNewSecond();
    appendToFile(existingFile);
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), existingFile));
#else
    QSKIP("Unix-specific");
#endif
}

void KDirWatch_UnitTest::stopAndRestart()
{
    KDirWatch watch;
    watch.addDir(m_path);
    watch.startScan();

    waitUntilMTimeChange(m_path);

    watch.stopDirScan(m_path);

    qCDebug(KCOREADDONS_DEBUG) << "create file 2 at" << QDateTime::currentDateTime().toMSecsSinceEpoch();
    const QString file2 = createFile(2);
    QSignalSpy spyDirty(&watch, &KDirWatch::dirty);
    QTest::qWait(200);
    QCOMPARE(spyDirty.count(), 0); // suspended -> no signal

    watch.restartDirScan(m_path);

    QTest::qWait(200);

#ifndef Q_OS_WIN
    QCOMPARE(spyDirty.count(), 0); // as documented by restartDirScan: no signal
    // On Windows, however, signals will get emitted, due to the ifdef Q_OS_WIN in the timestamp
    // comparison ("trust QFSW since the mtime of dirs isn't modified")
#endif

    KDirWatch::statistics();

    waitUntilMTimeChange(m_path); // necessary for the mtime comparison in scanEntry

    qCDebug(KCOREADDONS_DEBUG) << "create file 3 at" << QDateTime::currentDateTime().toMSecsSinceEpoch();
    const QString file3 = createFile(3);
#ifdef Q_OS_WIN
    if (watch.internalMethod() == KDirWatch::QFSWatch) {
        QEXPECT_FAIL(nullptr, "QFSWatch fails here on Windows!", Continue);
    }
#endif
    QVERIFY(waitForOneSignal(watch, SIGNAL(dirty(QString)), m_path));

    QFile::remove(file2);
    QFile::remove(file3);
}

void KDirWatch_UnitTest::benchCreateTree()
{
#if !ENABLE_BENCHMARKS
    QSKIP("Benchmarks are disabled in debug mode");
#endif
    QTemporaryDir dir;

    QBENCHMARK {
        createDirectoryTree(dir.path());
    }
}

void KDirWatch_UnitTest::benchCreateWatcher()
{
#if !ENABLE_BENCHMARKS
    QSKIP("Benchmarks are disabled in debug mode");
#endif
    QTemporaryDir dir;
    createDirectoryTree(dir.path());

    QBENCHMARK {
        KDirWatch watch;
        watch.addDir(dir.path(), KDirWatch::WatchSubDirs | KDirWatch::WatchFiles);
    }
}

void KDirWatch_UnitTest::benchNotifyWatcher()
{
#if !ENABLE_BENCHMARKS
    QSKIP("Benchmarks are disabled in debug mode");
#endif
    QTemporaryDir dir;
    // create the dir once upfront
    auto numFiles = createDirectoryTree(dir.path());
    waitUntilMTimeChange(dir.path());

    KDirWatch watch;
    watch.addDir(dir.path(), KDirWatch::WatchSubDirs | KDirWatch::WatchFiles);

    // now touch all the files repeatedly and wait for the dirty updates to come in
    QSignalSpy spy(&watch, &KDirWatch::dirty);
    QBENCHMARK {
        createDirectoryTree(dir.path());
        QTRY_COMPARE_WITH_TIMEOUT(spy.count(), numFiles, 30000);
        spy.clear();
    }
}

void KDirWatch_UnitTest::testRefcounting()
{
#if QT_CONFIG(cxx11_future)
    bool initialExists = false;
    bool secondExists = true; // the expectation is it will be set false
    auto thread = QThread::create([&] {
        QTemporaryDir dir;
        {
            KDirWatch watch;
            watch.addFile(dir.path());
            initialExists = KDirWatch::exists();
        } // out of scope, the internal private should have been unset
        secondExists = KDirWatch::exists();
    });
    thread->start();
    thread->wait();
    delete thread;
    QVERIFY(initialExists);
    QVERIFY(!secondExists);
#endif
}

#include "kdirwatch_unittest.moc"
