/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
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** accordance with the Qt Commercial License Agreement provided with the
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** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
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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 and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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****************************************************************************/

#include <qplatformdefs.h>

#include "qfilesystemwatcher.h"
#include "qfilesystemwatcher_kqueue_p.h"
#include "private/qcore_unix_p.h"

#include <qdebug.h>
#include <qfile.h>
#include <qsocketnotifier.h>
#include <qvarlengtharray.h>

#include <sys/types.h>
#include <sys/event.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <fcntl.h>

QT_BEGIN_NAMESPACE

// #define KEVENT_DEBUG
#ifdef KEVENT_DEBUG
#  define DEBUG qDebug
#else
#  define DEBUG if(false)qDebug
#endif

QKqueueFileSystemWatcherEngine *QKqueueFileSystemWatcherEngine::create()
{
    int kqfd = kqueue();
    if (kqfd == -1)
        return 0;
    return new QKqueueFileSystemWatcherEngine(kqfd);
}

QKqueueFileSystemWatcherEngine::QKqueueFileSystemWatcherEngine(int kqfd)
    : kqfd(kqfd)
{
    fcntl(kqfd, F_SETFD, FD_CLOEXEC);

    if (pipe(kqpipe) == -1) {
        perror("QKqueueFileSystemWatcherEngine: cannot create pipe");
        kqpipe[0] = kqpipe[1] = -1;
        return;
    }
    fcntl(kqpipe[0], F_SETFD, FD_CLOEXEC);
    fcntl(kqpipe[1], F_SETFD, FD_CLOEXEC);

    struct kevent kev;
    EV_SET(&kev,
           kqpipe[0],
           EVFILT_READ,
           EV_ADD | EV_ENABLE,
           0,
           0,
           0);
    if (kevent(kqfd, &kev, 1, 0, 0, 0) == -1) {
        perror("QKqueueFileSystemWatcherEngine: cannot watch pipe, kevent returned");
        return;
    }
}

QKqueueFileSystemWatcherEngine::~QKqueueFileSystemWatcherEngine()
{
    stop();
    wait();

    close(kqfd);
    close(kqpipe[0]);
    close(kqpipe[1]);

    foreach (int id, pathToID)
        ::close(id < 0 ? -id : id);
}

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

        QMutableListIterator<QString> it(p);
        while (it.hasNext()) {
            QString path = it.next();
            int fd;
#if defined(O_EVTONLY)
            fd = qt_safe_open(QFile::encodeName(path), O_EVTONLY);
#else
            fd = qt_safe_open(QFile::encodeName(path), O_RDONLY);
#endif
            if (fd == -1) {
                perror("QKqueueFileSystemWatcherEngine::addPaths: open");
                continue;
            }
            if (fd >= (int)FD_SETSIZE / 2 && fd < (int)FD_SETSIZE) {
                int fddup = fcntl(fd, F_DUPFD, FD_SETSIZE);
                if (fddup != -1) {
                    ::close(fd);
                    fd = fddup;
                }
            }
            fcntl(fd, F_SETFD, FD_CLOEXEC);

            QT_STATBUF st;
            if (QT_FSTAT(fd, &st) == -1) {
                perror("QKqueueFileSystemWatcherEngine::addPaths: fstat");
                ::close(fd);
                continue;
            }
            int id = (S_ISDIR(st.st_mode)) ? -fd : fd;
            if (id < 0) {
                if (directories->contains(path)) {
                    ::close(fd);
                    continue;
                }
            } else {
                if (files->contains(path)) {
                    ::close(fd);
                    continue;
                }
            }

            struct kevent kev;
            EV_SET(&kev,
                   fd,
                   EVFILT_VNODE,
                   EV_ADD | EV_ENABLE | EV_CLEAR,
                   NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE,
                   0,
                   0);
            if (kevent(kqfd, &kev, 1, 0, 0, 0) == -1) {
                perror("QKqueueFileSystemWatcherEngine::addPaths: kevent");
                ::close(fd);
                continue;
            }

            it.remove();
            if (id < 0) {
                DEBUG() << "QKqueueFileSystemWatcherEngine: added directory path" << path;
                directories->append(path);
            } else {
                DEBUG() << "QKqueueFileSystemWatcherEngine: added file path" << path;
                files->append(path);
            }

            pathToID.insert(path, id);
            idToPath.insert(id, path);
        }
    }

    if (!isRunning())
        start();
    else
        write(kqpipe[1], "@", 1);

    return p;
}

QStringList QKqueueFileSystemWatcherEngine::removePaths(const QStringList &paths,
                                                        QStringList *files,
                                                        QStringList *directories)
{
    bool isEmpty;
    QStringList p = paths;
    {
        QMutexLocker locker(&mutex);
        if (pathToID.isEmpty())
            return p;

        QMutableListIterator<QString> it(p);
        while (it.hasNext()) {
            QString path = it.next();
            int id = pathToID.take(path);
            QString x = idToPath.take(id);
            if (x.isEmpty() || x != path)
                continue;

            ::close(id < 0 ? -id : id);

            it.remove();
            if (id < 0)
                directories->removeAll(path);
            else
                files->removeAll(path);
        }
        isEmpty = pathToID.isEmpty();
    }

    if (isEmpty) {
        stop();
        wait();
    } else {
        write(kqpipe[1], "@", 1);
    }

    return p;
}

void QKqueueFileSystemWatcherEngine::stop()
{
    write(kqpipe[1], "q", 1);
}

void QKqueueFileSystemWatcherEngine::run()
{
    forever {
        int r;
        struct kevent kev;
        DEBUG() << "QKqueueFileSystemWatcherEngine: waiting for kevents...";
        EINTR_LOOP(r, kevent(kqfd, 0, 0, &kev, 1, 0));
        if (r < 0) {
            perror("QKqueueFileSystemWatcherEngine: error during kevent wait");
            return;
        } else {
            int fd = kev.ident;

            DEBUG() << "QKqueueFileSystemWatcherEngine: processing kevent" << kev.ident << kev.filter;
            if (fd == kqpipe[0]) {
                // read all pending data from the pipe
                QByteArray ba;
                ba.resize(kev.data);
                if (read(kqpipe[0], ba.data(), ba.size()) != ba.size()) {
                    perror("QKqueueFileSystemWatcherEngine: error reading from pipe");
                    return;
                }
                // read the command from the buffer (but break and return on 'q')
                char cmd = 0;
                for (int i = 0; i < ba.size(); ++i) {
                    cmd = ba.constData()[i];
                    if (cmd == 'q')
                        break;
                }
                // handle the command
                switch (cmd) {
                case 'q':
                    DEBUG() << "QKqueueFileSystemWatcherEngine: thread received 'q', exiting...";
                    return;
                case '@':
                    DEBUG() << "QKqueueFileSystemWatcherEngine: thread received '@', continuing...";
                    break;
                default:
                    DEBUG() << "QKqueueFileSystemWatcherEngine: thread received unknow message" << cmd;
                    break;
                }
            } else {
                QMutexLocker locker(&mutex);

                int id = fd;
                QString path = idToPath.value(id);
                if (path.isEmpty()) {
                    // perhaps a directory?
                    id = -id;
                    path = idToPath.value(id);
                    if (path.isEmpty()) {
                        DEBUG() << "QKqueueFileSystemWatcherEngine: received a kevent for a file we're not watching";
                        continue;
                    }
                }
                if (kev.filter != EVFILT_VNODE) {
                    DEBUG() << "QKqueueFileSystemWatcherEngine: received a kevent with the wrong filter";
                    continue;
                }

                if ((kev.fflags & (NOTE_DELETE | NOTE_REVOKE | NOTE_RENAME)) != 0) {
                    DEBUG() << path << "removed, removing watch also";

                    pathToID.remove(path);
                    idToPath.remove(id);
                    ::close(fd);

                    if (id < 0)
                        emit directoryChanged(path, true);
                    else
                        emit fileChanged(path, true);
                } else {
                    DEBUG() << path << "changed";

                    if (id < 0)
                        emit directoryChanged(path, false);
                    else
                        emit fileChanged(path, false);
                }
            }
        }
    }
}

QT_END_NAMESPACE