/****************************************************************************
**
** Copyright (C) 1992-2005 Trolltech AS. All rights reserved.
**
** This file is part of the core module of the Qt Toolkit.
**
** This file may be distributed and/or modified under the terms of the
** GNU General Public License version 2 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.
**
** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
**   information about Qt Commercial License Agreements.
** See http://www.trolltech.com/gpl/ for GPL licensing information.
**
** Contact info@trolltech.com if any conditions of this licensing are
** not clear to you.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "qplatformdefs.h"

#include "qbitarray.h"
#include "qcoreapplication.h"
#include "qsocketnotifier.h"
#include "qthread.h"

#include "qeventdispatcher_unix_p.h"
#include <private/qthread_p.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>

bool qt_disable_lowpriority_timers=false;

// Internal operator functions for timevals
static inline bool operator<(const timeval &t1, const timeval &t2)
{ return t1.tv_sec < t2.tv_sec || (t1.tv_sec == t2.tv_sec && t1.tv_usec < t2.tv_usec); }
static inline bool operator==(const timeval &t1, const timeval &t2)
{ return t1.tv_sec == t2.tv_sec && t1.tv_usec == t2.tv_usec; }
static inline timeval &operator+=(timeval &t1, const timeval &t2)
{
    t1.tv_sec += t2.tv_sec;
    if ((t1.tv_usec += t2.tv_usec) >= 1000000l) {
        ++t1.tv_sec;
        t1.tv_usec -= 1000000l;
    }
    return t1;
}
static inline timeval operator+(const timeval &t1, const timeval &t2)
{
    timeval tmp;
    tmp.tv_sec = t1.tv_sec + t2.tv_sec;
    if ((tmp.tv_usec = t1.tv_usec + t2.tv_usec) >= 1000000l) {
        ++tmp.tv_sec;
        tmp.tv_usec -= 1000000l;
    }
    return tmp;
}
static inline timeval operator-(const timeval &t1, const timeval &t2)
{
    timeval tmp;
    tmp.tv_sec = t1.tv_sec - t2.tv_sec;
    if ((tmp.tv_usec = t1.tv_usec - t2.tv_usec) < 0l) {
        --tmp.tv_sec;
        tmp.tv_usec += 1000000l;
    }
    return tmp;
}

// get time of day
static inline void getTime(timeval &t)
{
    gettimeofday(&t, 0);
    // NTP-related fix
    while (t.tv_usec >= 1000000l) {
        t.tv_usec -= 1000000l;
        ++t.tv_sec;
    }
    while (t.tv_usec < 0l) {
        if (t.tv_sec > 0l) {
            t.tv_usec += 1000000l;
            --t.tv_sec;
        } else {
            t.tv_usec = 0l;
            break;
        }
    }
}

struct QTimerInfo {
    int id;           // - timer identifier
    timeval interval; // - timer interval
    timeval timeout;  // - when to sent event
    QObject *obj;     // - object to receive event
};




/*****************************************************************************
 UNIX signal handling
 *****************************************************************************/

static sig_atomic_t signal_received;
static sig_atomic_t signals_fired[NSIG];

static void signalHandler(int sig)
{
    signals_fired[sig] = 1;
    signal_received = 1;
}




QEventDispatcherUNIXPrivate::QEventDispatcherUNIXPrivate()
{
    extern Qt::HANDLE qt_application_thread_id;
    mainThread = (QThread::currentThreadId() == qt_application_thread_id);

    // initialize the common parts of the event loop
    pipe(thread_pipe);
    fcntl(thread_pipe[0], F_SETFD, FD_CLOEXEC);
    fcntl(thread_pipe[1], F_SETFD, FD_CLOEXEC);
    fcntl(thread_pipe[0], F_SETFL, fcntl(thread_pipe[0], F_GETFL) | O_NONBLOCK);
    fcntl(thread_pipe[1], F_SETFL, fcntl(thread_pipe[1], F_GETFL) | O_NONBLOCK);

    sn_highest = -1;

    timerBitVec.fill(false, 128);

    interrupt = false;

    getTime(watchtime);
}

QEventDispatcherUNIXPrivate::~QEventDispatcherUNIXPrivate()
{
    // cleanup the common parts of the event loop
    close(thread_pipe[0]);
    close(thread_pipe[1]);

    // cleanup timers
    qDeleteAll(timerList);
}

int QEventDispatcherUNIXPrivate::doSelect(QEventLoop::ProcessEventsFlags flags, timeval *timeout)
{
    Q_Q(QEventDispatcherUNIX);

    // Process timers and socket notifiers - the common UNIX stuff
    int highest = 0;
    FD_ZERO(&sn_vec[0].select_fds);
    FD_ZERO(&sn_vec[1].select_fds);
    FD_ZERO(&sn_vec[2].select_fds);
    if (! (flags & QEventLoop::ExcludeSocketNotifiers) && (sn_highest >= 0)) {
        // return the highest fd we can wait for input on
        if (!sn_vec[0].list.isEmpty())
            sn_vec[0].select_fds = sn_vec[0].enabled_fds;
        if (!sn_vec[1].list.isEmpty())
            sn_vec[1].select_fds = sn_vec[1].enabled_fds;
        if (!sn_vec[2].list.isEmpty())
            sn_vec[2].select_fds = sn_vec[2].enabled_fds;
        highest = sn_highest;
    }

    FD_SET(thread_pipe[0], &sn_vec[0].select_fds);
    highest = qMax(highest, thread_pipe[0]);

    int nsel;
    do {
        if (mainThread) {
            while (signal_received) {
                signal_received = 0;
                for (int i = 0; i < NSIG; ++i) {
                    if (signals_fired[i]) {
                        signals_fired[i] = 0;
                        emit QCoreApplication::instance()->unixSignal(i);
                    }
                }
            }
        }
        nsel = q->select(highest + 1,
                         &sn_vec[0].select_fds,
                         &sn_vec[1].select_fds,
                         &sn_vec[2].select_fds,
                         timeout);
    } while (nsel == -1 && (errno == EINTR || errno == EAGAIN));

    if (nsel == -1) {
        if (errno == EBADF) {
            // it seems a socket notifier has a bad fd... find out
            // which one it is and disable it
            fd_set fdset;
            timeval tm;
            tm.tv_sec = tm.tv_usec = 0l;

            for (int type = 0; type < 3; ++type) {
                QList<QSockNot *> &list = sn_vec[type].list;
                if (list.size() == 0)
                    continue;

                for (int i = 0; i < list.size(); ++i) {
                    QSockNot *sn = list.at(i);

                    FD_ZERO(&fdset);
                    FD_SET(sn->fd, &fdset);

                    int ret = -1;
                    do {
                        switch (type) {
                        case 0: // read
                            ret = select(sn->fd + 1, &fdset, 0, 0, &tm);
                            break;
                        case 1: // write
                            ret = select(sn->fd + 1, 0, &fdset, 0, &tm);
                            break;
                        case 2: // except
                            ret = select(sn->fd + 1, 0, 0, &fdset, &tm);
                            break;
                        }
                    } while (ret == -1 && (errno == EINTR || errno == EAGAIN));

                    if (ret == -1 && errno == EBADF) {
                        // disable the invalid socket notifier
                        static const char *t[] = { "Read", "Write", "Exception" };
                        qWarning("QSocketNotifier: invalid socket %d and type '%s', disabling...",
                                 sn->fd, t[type]);
                        sn->obj->setEnabled(false);
                    }
                }
            }
        } else {
            // EINVAL... shouldn't happen, so let's complain to stderr
            // and hope someone sends us a bug report
            perror("select");
        }
    }

    // some other thread woke us up... consume the data on the thread pipe so that
    // select doesn't immediately return next time
    int nevents = 0;
    if (nsel > 0 && FD_ISSET(thread_pipe[0], &sn_vec[0].select_fds)) {
        char c[16];
        while (::read(thread_pipe[0], c, sizeof(c)) > 0)
            ;
        ++nevents;
    }

    // activate socket notifiers
    if (! (flags & QEventLoop::ExcludeSocketNotifiers) && nsel > 0 && sn_highest >= 0) {
        // if select says data is ready on any socket, then set the socket notifier
        // to pending
        for (int i=0; i<3; i++) {
            QList<QSockNot *> &list = sn_vec[i].list;
            for (int j = 0; j < list.size(); ++j) {
                QSockNot *sn = list.at(j);
                if (FD_ISSET(sn->fd, &sn_vec[i].select_fds))
                    q->setSocketNotifierPending(sn->obj);
            }
        }
    }
    return (nevents + q->activateSocketNotifiers());
}

/*
 * Internal functions for manipulating timer data structures.  The
 * timerBitVec array is used for keeping track of timer identifiers.
 */

/*
  insert timer info into list
*/ void QEventDispatcherUNIXPrivate::timerInsert(QTimerInfo *ti)
{
    int index = 0;
#if defined(QT_DEBUG)
    int dangerCount = 0;
#endif
    for (; index < timerList.size(); ++index) {
        register const QTimerInfo * const t = timerList.at(index);
#if defined(QT_DEBUG)
        if (t->obj == ti->obj) ++dangerCount;
#endif
        if (ti->timeout < t->timeout) break;
    }
    timerList.insert(index, ti);

#if defined(QT_DEBUG)
    if (dangerCount > 16)
        qDebug("QObject: %d timers now exist for object %s::%s",
               dangerCount, ti->obj->metaObject()->className(),
               ti->obj->objectName().toLocal8Bit().data());
#endif
}

/*
  repair broken timer
*/
void QEventDispatcherUNIXPrivate::timerRepair(const timeval &time)
{
    timeval diff = watchtime - time;
    // repair all timers
    for (int i = 0; i < timerList.size(); ++i) {
        register QTimerInfo *t = timerList.at(i);
        t->timeout = t->timeout - diff;
    }
}

/*
  Returns the time to wait for the next timer, or null if no timers
  are waiting.
*/
bool QEventDispatcherUNIXPrivate::timerWait(timeval &tm)
{
    timeval currentTime;
    getTime(currentTime);
    if (currentTime < watchtime)        // clock was turned back
        timerRepair(currentTime);
    watchtime = currentTime;

    if (timerList.isEmpty())
        return false;

    QTimerInfo *t = timerList.first();        // first waiting timer
    if (currentTime < t->timeout) {
        // time to wait
        tm = t->timeout - currentTime;
    } else {
        // no time to wait
        tm.tv_sec  = 0;
        tm.tv_usec = 0;
    }

    return true;
}

QEventDispatcherUNIX::QEventDispatcherUNIX(QObject *parent)
    : QAbstractEventDispatcher(*new QEventDispatcherUNIXPrivate, parent)
{ }

QEventDispatcherUNIX::QEventDispatcherUNIX(QEventDispatcherUNIXPrivate &dd, QObject *parent)
    : QAbstractEventDispatcher(dd, parent)
{ }

QEventDispatcherUNIX::~QEventDispatcherUNIX()
{ }

int QEventDispatcherUNIX::select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
                                 timeval *timeout)
{
    Q_D(QEventDispatcherUNIX);
    if (timeout) {
        // handle the case where select returns with a timeout, too
        // soon.
        timeval tvStart = d->watchtime;
        timeval tvCurrent = tvStart;
        timeval originalTimeout = *timeout;

        int nsel;
        do {
            timeval tvRest = originalTimeout + tvStart - tvCurrent;
            nsel = ::select(nfds, readfds, writefds, exceptfds, &tvRest);
            getTime(tvCurrent);
        } while (nsel == 0 && (tvCurrent - tvStart) < originalTimeout);

        return nsel;
    }

    return ::select(nfds, readfds, writefds, exceptfds, timeout);
}

/*!
    \internal
*/
int QEventDispatcherUNIX::registerTimer(int interval, QObject *obj)
{
    Q_ASSERT_X(obj->thread() == thread() && thread() == QThread::currentThread(),
               "QEventDispatcherUNIX::registerTimer",
               "timers cannot be started from another thread");

    Q_D(QEventDispatcherUNIX);

    int id = 0;
    {
        int i = d->timerBitVec.size()-1;
        while (i >= 0 && d->timerBitVec[i])
            i--;
        if (i < 0) {
            i = d->timerBitVec.size();
            d->timerBitVec.resize(4 * i);
            for(int j=d->timerBitVec.size()-1; j > i; j--)
                d->timerBitVec.clearBit(j);
        }
        d->timerBitVec.setBit(i);
        id = i+1;
    }
    if (id <= 0 ||
         id > (int)d->timerBitVec.size() || !obj)// cannot create timer
        return 0;
    d->timerBitVec.setBit(id-1);                // set timer active
    QTimerInfo *t = new QTimerInfo;                // create timer
    t->id = id;
    t->interval.tv_sec  = interval / 1000;
    t->interval.tv_usec = (interval % 1000) * 1000;
    timeval currentTime;
    getTime(currentTime);
    t->timeout = currentTime + t->interval;
    t->obj = obj;
    d->timerInsert(t);                                // put timer in list
    return id;
}

/*!
    \internal
*/
bool QEventDispatcherUNIX::unregisterTimer(int id)
{
    Q_D(QEventDispatcherUNIX);
    if (d->timerList.isEmpty()
        || id <= 0 || id > (int)d->timerBitVec.size() || !d->timerBitVec.testBit(id-1)) {
        // invalid timer
        return false;
    }
    // set timer inactive
    for (int i = 0; i < d->timerList.size(); ++i) {
        register QTimerInfo *t = d->timerList.at(i);
        if (t->id == id) {
            d->timerBitVec.clearBit(id - 1);
            d->timerList.removeAt(i);
            delete t;
            return true;
        }
    }
    // id not found
    return false;
}

/*!
    \internal
*/
bool QEventDispatcherUNIX::unregisterTimers(QObject *obj)
{
    Q_ASSERT_X(obj->thread() == thread() && thread() == QThread::currentThread(),
               "QEventDispatcherUNIX::unregisterTimers",
               "timers cannot be stopped from another thread");

    Q_D(QEventDispatcherUNIX);
    if (d->timerList.isEmpty())
        return false;
    for (int i = 0; i < d->timerList.size(); ++i) {
        register QTimerInfo *t = d->timerList.at(i);
        if (t->obj == obj) {
            // object found
            d->timerBitVec.clearBit(t->id - 1);
            d->timerList.removeAt(i);
            delete t;
            // move back one so that we don't skip the new current item
            --i;
        }
    }
    return true;
}

/*****************************************************************************
 Socket notifier type
 *****************************************************************************/
QSockNotType::QSockNotType()
{
    FD_ZERO(&select_fds);
    FD_ZERO(&enabled_fds);
    FD_ZERO(&pending_fds);
}

QSockNotType::~QSockNotType()
{
    while (!list.isEmpty())
        delete list.takeFirst();
}

/*****************************************************************************
 QEventDispatcher implementations for UNIX
 *****************************************************************************/

void QEventDispatcherUNIX::registerSocketNotifier(QSocketNotifier *notifier)
{
    Q_ASSERT(notifier->thread() == thread() && thread() == QThread::currentThread());

    int sockfd = notifier->socket();
    int type = notifier->type();
    if (sockfd < 0 || sockfd >= FD_SETSIZE || type < 0 || type > 2 || notifier == 0) {
        qWarning("QSocketNotifier: Internal error");
        return;
    }

    Q_D(QEventDispatcherUNIX);
    QList<QSockNot *> &list = d->sn_vec[type].list;
    fd_set *fds  = &d->sn_vec[type].enabled_fds;
    QSockNot *sn;

    sn = new QSockNot;
    sn->obj = notifier;
    sn->fd = sockfd;
    sn->queue = &d->sn_vec[type].pending_fds;

    int i;
    for (i = 0; i < list.size(); ++i) {
        QSockNot *p = list.at(i);
        if (p->fd < sockfd)
            break;
        if (p->fd == sockfd) {
            static const char *t[] = { "read", "write", "exception" };
            qWarning("QSocketNotifier: Multiple socket notifiers for "
                      "same socket %d and type %s", sockfd, t[type]);
        }
    }
    list.insert(i, sn);

    FD_SET(sockfd, fds);
    d->sn_highest = qMax(d->sn_highest, sockfd);
}

void QEventDispatcherUNIX::unregisterSocketNotifier(QSocketNotifier *notifier)
{
    Q_ASSERT(notifier->thread() == thread() && thread() == QThread::currentThread());

    int sockfd = notifier->socket();
    int type = notifier->type();
    if (sockfd < 0 || type < 0 || type > 2 || notifier == 0) {
        qWarning("QSocketNotifier: Internal error");
        return;
    }

    Q_D(QEventDispatcherUNIX);
    QList<QSockNot *> &list = d->sn_vec[type].list;
    fd_set *fds  =  &d->sn_vec[type].enabled_fds;
    QSockNot *sn;
    int i;
    for (i = 0; i < list.size(); ++i) {
        sn = list.at(i);
        if(sn->obj == notifier && sn->fd == sockfd)
            break;
    }
    if (i == list.size()) // not found
        return;

    FD_CLR(sockfd, fds);                        // clear fd bit
    FD_CLR(sockfd, sn->queue);
    d->sn_pending_list.removeAll(sn);                // remove from activation list
    list.removeAt(i);                                // remove notifier found above
    delete sn;

    if (d->sn_highest == sockfd) {                // find highest fd
        d->sn_highest = -1;
        for (int i=0; i<3; i++) {
            if (!d->sn_vec[i].list.isEmpty())
                d->sn_highest = qMax(d->sn_highest,  // list is fd-sorted
                                      d->sn_vec[i].list.first()->fd);
        }
    }
}

void QEventDispatcherUNIX::setSocketNotifierPending(QSocketNotifier *notifier)
{
    Q_ASSERT(notifier->thread() == thread() && thread() == QThread::currentThread());

    int sockfd = notifier->socket();
    int type = notifier->type();
    if (sockfd < 0 || type < 0 || type > 2 || notifier == 0) {
        qWarning("QSocketNotifier: Internal error");
        return;
    }

    Q_D(QEventDispatcherUNIX);
    QList<QSockNot *> &list = d->sn_vec[type].list;
    QSockNot *sn = 0;
    int i;
    for (i = 0; i < list.size(); ++i) {
        sn = list.at(i);
        if(sn->obj == notifier && sn->fd == sockfd)
            break;
    }
    if (i == list.size()) // not found
        return;

    // We choose a random activation order to be more fair under high load.
    // If a constant order is used and a peer early in the list can
    // saturate the IO, it might grab our attention completely.
    // Also, if we're using a straight list, the callback routines may
    // delete other entries from the list before those other entries are
    // processed.
    if (! FD_ISSET(sn->fd, sn->queue)) {
        d->sn_pending_list.insert((rand() & 0xff) %
                                   (d->sn_pending_list.size()+1), sn);
        FD_SET(sn->fd, sn->queue);
    }
}

int QEventDispatcherUNIX::activateTimers()
{
    Q_ASSERT(thread() == QThread::currentThread());

    Q_D(QEventDispatcherUNIX);
    if (qt_disable_lowpriority_timers || d->timerList.isEmpty())
        return 0; // nothing to do

    bool first = true;
    timeval currentTime;
    int n_act = 0, maxCount = d->timerList.size();
    QTimerInfo *begin = 0;

    while (maxCount--) {
        getTime(currentTime);
        if (first) {
            if (currentTime < d->watchtime)
                d->timerRepair(currentTime); // clock was turned back

            first = false;
            d->watchtime = currentTime;
        }

        if (d->timerList.isEmpty()) break;
        register QTimerInfo *t = d->timerList.first();
        if (currentTime < t->timeout)
            break; // no timer has expired

        if (!begin) {
            begin = t;
        } else if (begin == t) {
            // avoid sending the same timer multiple times
            break;
        } else if (t->interval <  begin->interval || t->interval == begin->interval) {
            begin = t;
        }

        // remove from list
        d->timerList.removeFirst();
        t->timeout += t->interval;
        if (t->timeout < currentTime)
            t->timeout = currentTime + t->interval;

        // reinsert timer
        d->timerInsert(t);
        if (t->interval.tv_usec > 0 || t->interval.tv_sec > 0)
            n_act++;

        // send event
        QTimerEvent e(t->id);
        QCoreApplication::sendEvent(t->obj, &e);

        if (!d->timerList.contains(begin)) begin = 0;
    }
    return n_act;
}

int QEventDispatcherUNIX::activateSocketNotifiers()
{
    Q_D(QEventDispatcherUNIX);
    if (d->sn_pending_list.isEmpty())
        return 0;

    // activate entries
    int n_act = 0;
    QEvent event(QEvent::SockAct);
    while (!d->sn_pending_list.isEmpty()) {
        QSockNot *sn = d->sn_pending_list.takeFirst();
        if (FD_ISSET(sn->fd, sn->queue)) {
            FD_CLR(sn->fd, sn->queue);
            QCoreApplication::sendEvent(sn->obj, &event);
            n_act++;
        }
    }

    return n_act;
}

bool QEventDispatcherUNIX::processEvents(QEventLoop::ProcessEventsFlags flags)
{
    Q_D(QEventDispatcherUNIX);

    // we are awake, broadcast it
    emit awake();

    QCoreApplication::sendPostedEvents();

    int nevents = 0;
    QThreadData *data = QThreadData::current();
    const bool canWait = (data->postEventList.size() == 0
                          && !d->interrupt
                          && (flags & QEventLoop::WaitForMoreEvents));

    if (canWait)
        emit aboutToBlock();

    if (!d->interrupt) {
        // return the maximum time we can wait for an event.
        timeval *tm = 0;
        timeval wait_tm = { 0l, 0l };
        if (!(flags & 0x08)) {                        // 0x08 == ExcludeTimers for X11 only
            if (d->timerWait(wait_tm))
                tm = &wait_tm;

            if (!canWait) {
                if (!tm)
                    tm = &wait_tm;

                // no time to wait
                tm->tv_sec  = 0l;
                tm->tv_usec = 0l;
            }
        }

        nevents = d->doSelect(flags, tm);

        // activate timers
        if (! (flags & 0x08)) {
            // 0x08 == ExcludeTimers for X11 only
            nevents += activateTimers();
        }
    } else {
        d->interrupt = false;
    }
    // return true if we handled events, false otherwise
    return (nevents > 0);
}

bool QEventDispatcherUNIX::hasPendingEvents()
{
    extern uint qGlobalPostedEventsCount(); // from qapplication.cpp
    return qGlobalPostedEventsCount();
}

void QEventDispatcherUNIX::wakeUp()
{
    char c = 0;
    Q_D(QEventDispatcherUNIX);
    ::write( d->thread_pipe[1], &c, 1 );
}

void QEventDispatcherUNIX::interrupt()
{
    Q_D(QEventDispatcherUNIX);
    d->interrupt = true;
    wakeUp();
}

void QEventDispatcherUNIX::flush()
{ }




void QCoreApplication::watchUnixSignal(int sig, bool watch)
{
    if (sig < NSIG) {
        struct sigaction sa;
        sigemptyset(&(sa.sa_mask));
        sa.sa_flags = 0;
        if (watch)
            sa.sa_handler = signalHandler;
        else
            sa.sa_handler = SIG_DFL;
        sigaction(sig, &sa, 0);
    }
}
