/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
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** file. Please review the following information to ensure the GNU General
** Public License version 3.0 requirements will be met:
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** Alternatively, this file may be used in accordance with the terms and
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** $QT_END_LICENSE$
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****************************************************************************/

#include "qplatformdefs.h"
#include "qfilesystemwatcher.h"
#include "qfilesystemwatcher_dnotify_p.h"

#ifndef QT_NO_FILESYSTEMWATCHER

#include <qsocketnotifier.h>
#include <qcoreapplication.h>
#include <qfileinfo.h>
#include <qtimer.h>
#include <qwaitcondition.h>
#include <qmutex.h>
#include <dirent.h>
#include <qdir.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>

#include "private/qcore_unix_p.h"

#ifdef QT_LINUXBASE

/* LSB doesn't standardize these */
#define F_NOTIFY       1026
#define DN_ACCESS      0x00000001
#define DN_MODIFY      0x00000002
#define DN_CREATE      0x00000004
#define DN_DELETE      0x00000008
#define DN_RENAME      0x00000010
#define DN_ATTRIB      0x00000020
#define DN_MULTISHOT   0x80000000

#endif

QT_BEGIN_NAMESPACE

static int qfswd_fileChanged_pipe[2];
static void (*qfswd_old_sigio_handler)(int) = 0;
static void (*qfswd_old_sigio_action)(int, siginfo_t *, void *) = 0;
static void qfswd_sigio_monitor(int signum, siginfo_t *i, void *v)
{
    qt_safe_write(qfswd_fileChanged_pipe[1], reinterpret_cast<char*>(&i->si_fd), sizeof(int));

    if (qfswd_old_sigio_handler && qfswd_old_sigio_handler != SIG_IGN)
        qfswd_old_sigio_handler(signum);
    if (qfswd_old_sigio_action)
        qfswd_old_sigio_action(signum, i, v);
}

class QDnotifySignalThread : public QThread
{
Q_OBJECT
public:
    QDnotifySignalThread();
    virtual ~QDnotifySignalThread();

    void startNotify();

    virtual void run();

signals:
    void fdChanged(int);

protected:
    virtual bool event(QEvent *);

private slots:
    void readFromDnotify();

private:
    QMutex mutex;
    QWaitCondition wait;
    bool isExecing;
};

Q_GLOBAL_STATIC(QDnotifySignalThread, dnotifySignal)

QDnotifySignalThread::QDnotifySignalThread()
: isExecing(false)
{
    moveToThread(this);

    qt_safe_pipe(qfswd_fileChanged_pipe, O_NONBLOCK);

    struct sigaction oldAction;
    struct sigaction action;
    memset(&action, 0, sizeof(action));
    action.sa_sigaction = qfswd_sigio_monitor;
    action.sa_flags = SA_SIGINFO;
    ::sigaction(SIGIO, &action, &oldAction);
    if (!(oldAction.sa_flags & SA_SIGINFO))
        qfswd_old_sigio_handler = oldAction.sa_handler;
    else
        qfswd_old_sigio_action = oldAction.sa_sigaction;
}

QDnotifySignalThread::~QDnotifySignalThread()
{
    if(isRunning()) {
        quit();
        QThread::wait();
    }
}

bool QDnotifySignalThread::event(QEvent *e)
{
    if(e->type() == QEvent::User) {
        QMutexLocker locker(&mutex);
        isExecing = true;
        wait.wakeAll();
        return true;
    } else {
        return QThread::event(e);
    }
}

void QDnotifySignalThread::startNotify()
{
    // Note: All this fancy waiting for the thread to enter its event
    // loop is to avoid nasty messages at app shutdown when the
    // QDnotifySignalThread singleton is deleted
    start();
    mutex.lock();
    while(!isExecing)
        wait.wait(&mutex);
    mutex.unlock();
}

void QDnotifySignalThread::run()
{
    QSocketNotifier sn(qfswd_fileChanged_pipe[0], QSocketNotifier::Read, this);
    connect(&sn, SIGNAL(activated(int)), SLOT(readFromDnotify()));

    QCoreApplication::instance()->postEvent(this, new QEvent(QEvent::User));
    (void) exec();
}

void QDnotifySignalThread::readFromDnotify()
{
    int fd;
    int readrv = qt_safe_read(qfswd_fileChanged_pipe[0], reinterpret_cast<char*>(&fd), sizeof(int));
    // Only expect EAGAIN or EINTR.  Other errors are assumed to be impossible.
    if(readrv != -1) {
        Q_ASSERT(readrv == sizeof(int));
        Q_UNUSED(readrv);

        if(0 == fd)
            quit();
        else
            emit fdChanged(fd);
    }
}

QDnotifyFileSystemWatcherEngine::QDnotifyFileSystemWatcherEngine()
{
    QObject::connect(dnotifySignal(), SIGNAL(fdChanged(int)),
                     this, SLOT(refresh(int)), Qt::DirectConnection);
}

QDnotifyFileSystemWatcherEngine::~QDnotifyFileSystemWatcherEngine()
{
    QMutexLocker locker(&mutex);

    for(QHash<int, Directory>::ConstIterator iter = fdToDirectory.constBegin();
            iter != fdToDirectory.constEnd();
            ++iter) {
        qt_safe_close(iter->fd);
        if(iter->parentFd)
            qt_safe_close(iter->parentFd);
    }
}

QDnotifyFileSystemWatcherEngine *QDnotifyFileSystemWatcherEngine::create()
{
    return new QDnotifyFileSystemWatcherEngine();
}

void QDnotifyFileSystemWatcherEngine::run()
{
    qFatal("QDnotifyFileSystemWatcherEngine thread should not be run");
}

QStringList QDnotifyFileSystemWatcherEngine::addPaths(const QStringList &paths, QStringList *files, QStringList *directories)
{
    QMutexLocker locker(&mutex);

    QStringList p = paths;
    QMutableListIterator<QString> it(p);

    while (it.hasNext()) {
        QString path = it.next();

        QFileInfo fi(path);

        if(!fi.exists()) {
            continue;
        }

        bool isDir = fi.isDir();

        if (isDir && directories->contains(path)) {
            continue; // Skip monitored directories
        } else if(!isDir && files->contains(path)) {
            continue; // Skip monitored files
        }

        if(!isDir)
            path = fi.canonicalPath();

        // Locate the directory entry (creating if needed)
        int fd = pathToFD[path];

        if(fd == 0) {

            QT_DIR *d = QT_OPENDIR(path.toUtf8().constData());
            if(!d) continue; // Could not open directory
            QT_DIR *parent = 0;

            QDir parentDir(path);
            if(!parentDir.isRoot()) {
                parentDir.cdUp();
                parent = QT_OPENDIR(parentDir.path().toUtf8().constData());
                if(!parent) {
                    QT_CLOSEDIR(d);
                    continue;
                }
            }

            fd = qt_safe_dup(::dirfd(d));
            int parentFd = parent ? qt_safe_dup(::dirfd(parent)) : 0;

            QT_CLOSEDIR(d);
            if(parent) QT_CLOSEDIR(parent);

            Q_ASSERT(fd);
            if(::fcntl(fd, F_SETSIG, SIGIO) ||
               ::fcntl(fd, F_NOTIFY, DN_MODIFY | DN_CREATE | DN_DELETE |
                                     DN_RENAME | DN_ATTRIB | DN_MULTISHOT) ||
               (parent && ::fcntl(parentFd, F_SETSIG, SIGIO)) ||
               (parent && ::fcntl(parentFd, F_NOTIFY, DN_DELETE | DN_RENAME |
                                            DN_MULTISHOT))) {
                continue; // Could not set appropriate flags
            }

            Directory dir;
            dir.path = path;
            dir.fd = fd;
            dir.parentFd = parentFd;

            fdToDirectory.insert(fd, dir);
            pathToFD.insert(path, fd);
            if(parentFd)
                parentToFD.insert(parentFd, fd);
        }

        Directory &directory = fdToDirectory[fd];

        if(isDir) {
            directory.isMonitored = true;
        } else {
            Directory::File file;
            file.path = fi.filePath();
            file.lastWrite = fi.lastModified();
            directory.files.append(file);
            pathToFD.insert(fi.filePath(), fd);
        }

        it.remove();

        if(isDir) {
            directories->append(path);
        } else {
            files->append(fi.filePath());
        }
    }

    dnotifySignal()->startNotify();

    return p;
}

QStringList QDnotifyFileSystemWatcherEngine::removePaths(const QStringList &paths, QStringList *files, QStringList *directories)
{
    QMutexLocker locker(&mutex);

    QStringList p = paths;
    QMutableListIterator<QString> it(p);
    while (it.hasNext()) {

        QString path = it.next();
        int fd = pathToFD.take(path);

        if(!fd)
            continue;

        Directory &directory = fdToDirectory[fd];
        bool isDir = false;
        if(directory.path == path) {
            isDir = true;
            directory.isMonitored = false;
        } else {
            for(int ii = 0; ii < directory.files.count(); ++ii) {
                if(directory.files.at(ii).path == path) {
                    directory.files.removeAt(ii);
                    break;
                }
            }
        }

        if(!directory.isMonitored && directory.files.isEmpty()) {
            // No longer needed
            qt_safe_close(directory.fd);
            pathToFD.remove(directory.path);
            fdToDirectory.remove(fd);
        }

        if(isDir) {
            directories->removeAll(path);
        } else {
            files->removeAll(path);
        }

        it.remove();
    }

    return p;
}

void QDnotifyFileSystemWatcherEngine::refresh(int fd)
{
    QMutexLocker locker(&mutex);

    bool wasParent = false;
    QHash<int, Directory>::Iterator iter = fdToDirectory.find(fd);
    if(iter == fdToDirectory.end()) {
        QHash<int, int>::Iterator pIter = parentToFD.find(fd);
        if(pIter == parentToFD.end())
            return;

        iter = fdToDirectory.find(*pIter);
        if (iter == fdToDirectory.end())
            return;
        wasParent = true;
    }

    Directory &directory = *iter;

    if(!wasParent) {
        for(int ii = 0; ii < directory.files.count(); ++ii) {
            Directory::File &file = directory.files[ii];
            if(file.updateInfo()) {
                // Emit signal
                QString filePath = file.path;
                bool removed = !QFileInfo(filePath).exists();

                if(removed) {
                    directory.files.removeAt(ii);
                    --ii;
                }

                emit fileChanged(filePath, removed);
            }
        }
    }

    if(directory.isMonitored) {
        // Emit signal
        bool removed = !QFileInfo(directory.path).exists();
        QString path = directory.path;

        if(removed)
            directory.isMonitored = false;

        emit directoryChanged(path, removed);
    }

    if(!directory.isMonitored && directory.files.isEmpty()) {
        qt_safe_close(directory.fd);
        if(directory.parentFd) {
            qt_safe_close(directory.parentFd);
            parentToFD.remove(directory.parentFd);
        }
        fdToDirectory.erase(iter);
    }
}

void QDnotifyFileSystemWatcherEngine::stop()
{
}

bool QDnotifyFileSystemWatcherEngine::Directory::File::updateInfo()
{
    QFileInfo fi(path);
    QDateTime nLastWrite = fi.lastModified();
    uint nOwnerId = fi.ownerId();
    uint nGroupId = fi.groupId();
    QFile::Permissions nPermissions = fi.permissions();

    if(nLastWrite != lastWrite ||
       nOwnerId != ownerId ||
       nGroupId != groupId ||
       nPermissions != permissions) {
        ownerId = nOwnerId;
        groupId = nGroupId;
        permissions = nPermissions;
        lastWrite = nLastWrite;
        return true;
    } else {
        return false;
    }
}

QT_END_NAMESPACE

#include "qfilesystemwatcher_dnotify.moc"

#endif // QT_NO_FILESYSTEMWATCHER