/****************************************************************************
Copyright (c) 2008-2010 Ricardo Quesada
Copyright (c) 2010-2012 cocos2d-x.org
Copyright (c) 2011      Zynga Inc.
Copyright (c) 2013-2016 Chukong Technologies Inc.
Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

http://www.cocos2d-x.org

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
****************************************************************************/
#include "base/CCScheduler.h"
#include "base/ccMacros.h"
#include "base/utlist.h"
#include "base/ccCArray.h"

#define CC_REPEAT_FOREVER (UINT_MAX -1)

NS_CC_BEGIN

// data structures

// A list double-linked list used for "updates with priority"
typedef struct _listEntry
{
    struct _listEntry   *prev, *next;
    ccSchedulerFunc     callback;
    void                *target;
    int                 priority;
    bool                paused;
    bool                markedForDeletion; // selector will no longer be called and entry will be removed at end of the next tick
} tListEntry;

typedef struct _hashUpdateEntry
{
    tListEntry          **list;        // Which list does it belong to ?
    tListEntry          *entry;        // entry in the list
    void                *target;
    ccSchedulerFunc     callback;
    UT_hash_handle      hh;
} tHashUpdateEntry;

// Hash Element used for "selectors with interval"
typedef struct _hashSelectorEntry
{
    ccArray             *timers;
    void                *target;
    int                 timerIndex;
    Timer               *currentTimer;
    bool                currentTimerSalvaged;
    bool                paused;
    UT_hash_handle      hh;
} tHashTimerEntry;

// implementation Timer

Timer::Timer()
{
}

void Timer::setupTimerWithInterval(float seconds, unsigned int repeat, float delay)
{
    _elapsed = -1;
    _interval = seconds;
    _delay = delay;
    _useDelay = (_delay > 0.0f) ? true : false;
    _repeat = repeat;
    _runForever = (_repeat == CC_REPEAT_FOREVER) ? true : false;
}

void Timer::update(float dt)
{
    if (_elapsed == -1)
    {
        _elapsed = 0;
        _timesExecuted = 0;
        return;
    }

    // accumulate elapsed time
    _elapsed += dt;

    // deal with delay
    if (_useDelay)
    {
        if (_elapsed < _delay)
        {
            return;
        }
        trigger(_delay);
        _elapsed = _elapsed - _delay;
        _timesExecuted += 1;
        _useDelay = false;
        // after delay, the rest time should compare with interval
        if (!_runForever && _timesExecuted > _repeat)
        {    //unschedule timer
            cancel();
            return;
        }
    }

    // if _interval == 0, should trigger once every frame
    float interval = (_interval > 0) ? _interval : _elapsed;
    while (_elapsed >= interval)
    {
        trigger(interval);
        _elapsed -= interval;
        _timesExecuted += 1;

        if (!_runForever && _timesExecuted > _repeat)
        {
            cancel();
            break;
        }

        if (_elapsed <= 0.f)
        {
            break;
        }
        
        if (_scheduler->isCurrentTargetSalvaged())
        {
            break;
        }
    }
}

// TimerTargetCallback

TimerTargetCallback::TimerTargetCallback()
{
}

bool TimerTargetCallback::initWithCallback(Scheduler* scheduler, const ccSchedulerFunc& callback, void *target, const std::string& key, float seconds, unsigned int repeat, float delay)
{
    _scheduler = scheduler;
    _target = target;
    _callback = callback;
    _key = key;
    setupTimerWithInterval(seconds, repeat, delay);
    return true;
}

void TimerTargetCallback::trigger(float dt)
{
    if (_callback)
    {
        _callback(dt);
    }
}

void TimerTargetCallback::cancel()
{
    _scheduler->unschedule(_key, _target);
}

// implementation of Scheduler

Scheduler::Scheduler()
{
    // I don't expect to have more than 30 functions to all per frame
    _functionsToPerform.reserve(30);
}

Scheduler::~Scheduler(void)
{
    unscheduleAll();
}

void Scheduler::removeHashElement(_hashSelectorEntry *element)
{
    ccArrayFree(element->timers);
    HASH_DEL(_hashForTimers, element);
    free(element);
}

void Scheduler::schedule(const ccSchedulerFunc& callback, void *target, float interval, bool paused, const std::string& key)
{
    this->schedule(callback, target, interval, CC_REPEAT_FOREVER, 0.0f, paused, key);
}

void Scheduler::schedule(const ccSchedulerFunc& callback, void *target, float interval, unsigned int repeat, float delay, bool paused, const std::string& key)
{
    CCASSERT(target, "Argument target must be non-nullptr");
    CCASSERT(!key.empty(), "key should not be empty!");

    tHashTimerEntry *element = nullptr;
    HASH_FIND_PTR(_hashForTimers, &target, element);

    if (! element)
    {
        element = (tHashTimerEntry *)calloc(sizeof(*element), 1);
        element->target = target;

        HASH_ADD_PTR(_hashForTimers, target, element);

        // Is this the 1st element ? Then set the pause level to all the selectors of this target
        element->paused = paused;
    }
    else
    {
        CCASSERT(element->paused == paused, "element's paused should be paused!");
    }

    if (element->timers == nullptr)
    {
        element->timers = ccArrayNew(10);
    }
    else
    {
        for (int i = 0; i < element->timers->num; ++i)
        {
            TimerTargetCallback *timer = dynamic_cast<TimerTargetCallback*>(element->timers->arr[i]);

            if (timer && key == timer->getKey())
            {
                CCLOG("CCScheduler#scheduleSelector. Selector already scheduled. Updating interval from: %.4f to %.4f", timer->getInterval(), interval);
                timer->setInterval(interval);
                return;
            }
        }
        ccArrayEnsureExtraCapacity(element->timers, 1);
    }

    TimerTargetCallback *timer = new (std::nothrow) TimerTargetCallback();
    timer->initWithCallback(this, callback, target, key, interval, repeat, delay);
    ccArrayAppendObject(element->timers, timer);
    timer->release();
}

void Scheduler::unschedule(const std::string &key, void *target)
{
    // explicit handle nil arguments when removing an object
    if (target == nullptr || key.empty())
    {
        return;
    }

    //CCASSERT(target);
    //CCASSERT(selector);

    tHashTimerEntry *element = nullptr;
    HASH_FIND_PTR(_hashForTimers, &target, element);

    if (element)
    {
        for (int i = 0; i < element->timers->num; ++i)
        {
            TimerTargetCallback *timer = dynamic_cast<TimerTargetCallback*>(element->timers->arr[i]);

            if (timer && key == timer->getKey())
            {
                if (timer == element->currentTimer && (! element->currentTimerSalvaged))
                {
                    element->currentTimer->retain();
                    element->currentTimerSalvaged = true;
                }

                ccArrayRemoveObjectAtIndex(element->timers, i, true);

                // update timerIndex in case we are in tick:, looping over the actions
                if (element->timerIndex >= i)
                {
                    element->timerIndex--;
                }

                if (element->timers->num == 0)
                {
                    if (_currentTarget == element)
                    {
                        _currentTargetSalvaged = true;
                    }
                    else
                    {
                        removeHashElement(element);
                    }
                }

                return;
            }
        }
    }
}

bool Scheduler::isScheduled(const std::string& key, void *target)
{
    CCASSERT(!key.empty(), "Argument key must not be empty");
    CCASSERT(target, "Argument target must be non-nullptr");

    tHashTimerEntry *element = nullptr;
    HASH_FIND_PTR(_hashForTimers, &target, element);

    if (!element)
    {
        return false;
    }

    if (element->timers == nullptr)
    {
        return false;
    }
    else
    {
        for (int i = 0; i < element->timers->num; ++i)
        {
            TimerTargetCallback *timer = dynamic_cast<TimerTargetCallback*>(element->timers->arr[i]);

            if (timer && key == timer->getKey())
            {
                return true;
            }
        }

        return false;
    }

    return false;  // should never get here
}

void Scheduler::unscheduleAll()
{
    for (tHashTimerEntry *element = _hashForTimers, *nextElement = nullptr; element != nullptr;)
    {
        // element may be removed in unscheduleAllSelectorsForTarget
        nextElement = (tHashTimerEntry *)element->hh.next;
        unscheduleAllForTarget(element->target);
        
        element = nextElement;
    }
}

void Scheduler::unscheduleAllForTarget(void *target)
{
    // explicit nullptr handling
    if (target == nullptr)
    {
        return;
    }

    // Custom Selectors
    tHashTimerEntry *element = nullptr;
    HASH_FIND_PTR(_hashForTimers, &target, element);

    if (element)
    {
        if (ccArrayContainsObject(element->timers, element->currentTimer)
            && (! element->currentTimerSalvaged))
        {
            element->currentTimer->retain();
            element->currentTimerSalvaged = true;
        }
        ccArrayRemoveAllObjects(element->timers);

        if (_currentTarget == element)
        {
            _currentTargetSalvaged = true;
        }
        else
        {
            removeHashElement(element);
        }
    }
}

void Scheduler::resumeTarget(void *target)
{
    CCASSERT(target != nullptr, "target can't be nullptr!");

    // custom selectors
    tHashTimerEntry *element = nullptr;
    HASH_FIND_PTR(_hashForTimers, &target, element);
    if (element)
    {
        element->paused = false;
    }
}

void Scheduler::pauseTarget(void *target)
{
    CCASSERT(target != nullptr, "target can't be nullptr!");

    // custom selectors
    tHashTimerEntry *element = nullptr;
    HASH_FIND_PTR(_hashForTimers, &target, element);
    if (element)
    {
        element->paused = true;
    }
}

bool Scheduler::isTargetPaused(void *target)
{
    CCASSERT( target != nullptr, "target must be non nil" );

    // Custom selectors
    tHashTimerEntry *element = nullptr;
    HASH_FIND_PTR(_hashForTimers, &target, element);
    if( element )
    {
        return element->paused;
    }

    return false;  // should never get here
}

std::set<void*> Scheduler::pauseAllTargets()
{
    std::set<void*> idsWithSelectors;
    
    // Custom Selectors
    for(tHashTimerEntry *element = _hashForTimers; element != nullptr;
        element = (tHashTimerEntry*)element->hh.next)
    {
        element->paused = true;
        idsWithSelectors.insert(element->target);
    }
    
    return idsWithSelectors;
}

void Scheduler::resumeTargets(const std::set<void*>& targetsToResume)
{
    for(const auto &obj : targetsToResume) {
        this->resumeTarget(obj);
    }
}

void Scheduler::performFunctionInCocosThread(const std::function<void ()> &function)
{
    _performMutex.lock();
    _functionsToPerform.push_back(function);
    _performMutex.unlock();
}

void Scheduler::removeAllFunctionsToBePerformedInCocosThread()
{
    std::unique_lock<std::mutex> lock(_performMutex);
    _functionsToPerform.clear();
}

// main loop
void Scheduler::update(float dt)
{
    _updateHashLocked = true;

    // Iterate over all the custom selectors
    for (tHashTimerEntry *elt = _hashForTimers; elt != nullptr; )
    {
        _currentTarget = elt;
        _currentTargetSalvaged = false;

        if (! _currentTarget->paused)
        {
            // The 'timers' array may change while inside this loop
            for (elt->timerIndex = 0; elt->timerIndex < elt->timers->num; ++(elt->timerIndex))
            {
                elt->currentTimer = (Timer*)(elt->timers->arr[elt->timerIndex]);
                elt->currentTimerSalvaged = false;

                elt->currentTimer->update(dt);

                if (elt->currentTimerSalvaged)
                {
                    // The currentTimer told the remove itself. To prevent the timer from
                    // accidentally deallocating itself before finishing its step, we retained
                    // it. Now that step is done, it's safe to release it.
                    elt->currentTimer->release();
                }

                elt->currentTimer = nullptr;
            }
        }

        // elt, at this moment, is still valid
        // so it is safe to ask this here (issue #490)
        elt = (tHashTimerEntry *)elt->hh.next;

        // only delete currentTarget if no actions were scheduled during the cycle (issue #481)
        if (_currentTargetSalvaged && _currentTarget->timers->num == 0)
        {
            removeHashElement(_currentTarget);
        }
    }

    _updateHashLocked = false;
    _currentTarget = nullptr;

    //
    // Functions allocated from another thread
    //

    // Testing size is faster than locking / unlocking.
    // And almost never there will be functions scheduled to be called.
    if( !_functionsToPerform.empty() ) {
        _performMutex.lock();
        // fixed #4123: Save the callback functions, they must be invoked after '_performMutex.unlock()', otherwise if new functions are added in callback, it will cause thread deadlock.
        auto temp = _functionsToPerform;
        _functionsToPerform.clear();
        _performMutex.unlock();
        for( const auto &function : temp ) {
            function();
        }

    }
}

NS_CC_END