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#include <windows.h>

#include "qwaitcondition.h"

#include "qmutex.h"

#include "qinternallist.h"

//***********************************************************************

// QWaitConditionPrivate

// **********************************************************************

class QWaitConditionEvent

{

public:

    QWaitConditionEvent() : priority(0), wokenUp(false)

    {

        event = CreateEvent(NULL, TRUE, FALSE, NULL);

    }

    ~QWaitConditionEvent() { CloseHandle(event); }

    int priority;

    bool wokenUp;

    HANDLE event;

};

class EventQueue : public QInternalList<QWaitConditionEvent>

{

  public:

    EventQueue() { setAutoDelete(TRUE); }

   ~EventQueue() {}

};

class QWaitConditionPrivate

{

public:

    QMutex mtx;

    EventQueue queue;

    EventQueue freeQueue;

    QWaitConditionEvent *pre();

    void wait(QWaitConditionEvent *wce);

    void post(QWaitConditionEvent *wce);

};

QWaitConditionEvent *QWaitConditionPrivate::pre()

{

    mtx.lock();

    QWaitConditionEvent *wce =

        freeQueue.isEmpty() ? new QWaitConditionEvent : freeQueue.take(0);

    wce->priority = GetThreadPriority(GetCurrentThread());

    wce->wokenUp = FALSE;

    // insert 'wce' into the queue (sorted by priority)

    uint index = 0;

    for (; index < queue.count(); ++index)

    {

        QWaitConditionEvent *current = queue.at(index);

        if (current->priority < wce->priority)

            break;

    }

    queue.insert(index, wce);

    mtx.unlock();

    return wce;

}

void QWaitConditionPrivate::wait(QWaitConditionEvent *wce)

{

    WaitForSingleObject(wce->event, INFINITE);

}

void QWaitConditionPrivate::post(QWaitConditionEvent *wce)

{

    mtx.lock();

    // remove 'wce' from the queue

    int idx = queue.find(wce);

    ASSERT(idx!=-1);

    queue.take(idx);

    ResetEvent(wce->event);

    freeQueue.append(wce);

    // wakeups delivered after the timeout should be forwarded to the next waiter

    if (wce->wokenUp && !queue.isEmpty())

    {

        QWaitConditionEvent *other = queue.getFirst();

        SetEvent(other->event);

        other->wokenUp = TRUE;

    }

    mtx.unlock();

}

//***********************************************************************

// QWaitCondition implementation

//***********************************************************************

QWaitCondition::QWaitCondition()

{

    d = new QWaitConditionPrivate;

}

QWaitCondition::~QWaitCondition()

{

    if (!d->queue.isEmpty())

    {

        qWarning("QWaitCondition: Destroyed while threads are still waiting");

    }

    delete d;

}

void QWaitCondition::wait(QMutex *mutex)

{

    if (!mutex) return;

    QWaitConditionEvent *wce = d->pre();

    mutex->unlock();

    d->wait(wce);

    mutex->lock();

    d->post(wce);

}

void QWaitCondition::wakeOne()

{

    // wake up the first waiting thread in the queue

    QMutexLocker locker(&d->mtx);

    for (uint i = 0; i < d->queue.count(); ++i)

    {

        QWaitConditionEvent *current = d->queue.at(i);

        if (current->wokenUp) continue;

        SetEvent(current->event);

        current->wokenUp = TRUE;

        break;

    }

}

void QWaitCondition::wakeAll()

{

    // wake up the all threads in the queue

    QMutexLocker locker(&d->mtx);

    for (uint i = 0; i < d->queue.count(); ++i) 

    {

        QWaitConditionEvent *current = d->queue.at(i);

        SetEvent(current->event);

        current->wokenUp = TRUE;

    }

}