/*
 *  EventLoop.h
 *
 *  Created by Lou Amadio on 9/17/08.
 *  Copyright 2008 OoeyGUI. All rights reserved.
 *     Provided under GPLv3 per gpl-3.0.txt
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
 *  FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 *  COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 *  BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 *  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
 *  ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 *  POSSIBILITY OF SUCH DAMAGE. *
 */
#ifndef EventLoop_h
#define EventLoop_h

typedef unsigned long milliclock_t;
extern const unsigned long MILLICLOCK_MAX;

//
// Periodic Event Callback
//  Derive from this class to implement a periodic servicing
//
class PeriodicCallback
{
public:
  // NOTE: This is a harmless warning: 
  //  alignment of 'PeriodicCallback::_ZTV16PeriodicCallback' 
  // is greater than maximum object file alignment.
  // Bug in avr-g++. 
  // See http://www.mail-archive.com/avr-chat@nongnu.org/msg00982.html
    PeriodicCallback();
    virtual ~PeriodicCallback();
    
    virtual void service() = 0;
};

//
// Timer
//  Derive from this class to implement a periodic timer.
//  This class also contains information needed for 
//  maintianing a timer, designed to be memory efficient.
//
class EventLoopTimer
{
private:
    milliclock_t _lastTimeout;
    milliclock_t _period;
protected:
    inline void setPeriod(milliclock_t period) 
        { _period = period; }
        
public:
    EventLoopTimer(unsigned long period);
    virtual ~EventLoopTimer();
    
    virtual void fire() = 0;
    
    inline milliclock_t period() const 
    { return _period; }
    inline milliclock_t lastTimeout() const 
        { return _lastTimeout; }
    milliclock_t nextTimeout() const;
    
    inline void setLastTimeout(milliclock_t nextTimeout) 
        { _lastTimeout = nextTimeout; }
};

//
// Event Loop
//  This class implements the main loop. 
//  It allows clients to register for periodic 
//      servicing, or timed servicing.
//  
class EventLoop
{
private:
    DArray _periodicEvents;
    DArray _timers;
    milliclock_t _lastTimeout;
    bool _running;
    
    void sortTimers();
    DArray* findFiringTimers();
public:
    EventLoop();
    ~EventLoop();
    
    void addPeriodicCallback(PeriodicCallback* callback);
    void removePeriodicCallback(PeriodicCallback* callback);
    
    int periodicCallbacks() { return _periodicEvents.count(); }

    void addTimer(EventLoopTimer* timer);
    void removeTimer(EventLoopTimer* timer);
    int timers() { return _timers.count(); }
    
    bool running() { return _running; }
    void exit() { _running = false; }

    void run();
    
    static EventLoop* current();
};

#endif