/*!
    @file Timer.h
    @brief Definition and Implementation of the Timer class.

    The Timer is a callback-object, calling a given function after a given time-interval.

    Usage:
    header.h:
        class ClassName
        {
            public:
                ClassName();
                void functionName();
                Timer myTimer;
        };

    source.cc:
        ClassName::ClassName()
        {
            myTimer.setTimer(interval_in_seconds, bLoop, this, &ClassName::functionName);
        }

        void ClassName::functionName()
        {
            whateveryouwant();
            something(else);
        }
*/

#ifndef _Timer_H__
#define _Timer_H__

#include "../core/CoreIncludes.h"
#include "OgreFrameListener.h"

namespace orxonox
{
    //! TimerBase is the parent of the Timer class.
    class TimerBase : public OrxonoxClass
    {
        friend class TimerFrameListener;

        public:
            /** @brief Constructor: Sets the default-values. */
            TimerBase()
            {
                RegisterRootObject(TimerBase);

                this->interval_ = 0;
                this->bLoop_ = false;
                this->bActive_ = false;

                this->time_ = 0;
            }

            virtual void run() const = 0;

            /** @brief Starts the Timer: Function-call after 'interval' seconds. */
            inline void startTimer() { this->bActive_ = true; this->time_ = this->interval_; }
            /** @brief Stops the Timer. */
            inline void stopTimer() { this->bActive_ = false; this->time_ = this->interval_; }
            /** @brief Pauses the Timer - it will continue with the actual state if you unpause it. */
            inline void pauseTimer() { this->bActive_ = false; }
            /** @brief Unpauses the Timer - continues with the given state. */
            inline void unpauseTimer() { this->bActive_ = true; }
            /** @returns true if the Timer is active (= not stoped, not paused). */
            inline bool isActive() const { return this->bActive_; }

        protected:
            float interval_;    //!< The time-interval in seconds
            bool bLoop_;        //!< If true, the function gets called every 'interval' seconds
            bool bActive_;      //!< If true, the Timer ticks and calls the function if the time's up

            float time_;        //!< Internal variable, counting the time till the next function-call
    };

    //! The Timer is a callback-object, calling a given function after a given time-interval.
    template <class T = BaseObject>
    class Timer : public TimerBase
    {
        public:
            /** @brief Constructor: Sets the default-values. */
            Timer()
            {
                this->timerFunction_ = 0;
                this->object_ = 0;
            }

            /**
                @brief Constructor: Initializes the Timer with given values.
                @param interval The timer-interval in seconds
                @param bLoop If true, the function gets called every 'interval' seconds
                @param object The object owning the timer and the function
                @param timerFunction A function pointer to the function to call
            */
            Timer(float interval, bool bLoop, T* object, void (T::*timerFunction)())
            {
                this->setTimer(interval, bLoop, timerFunction, object);
            }

            /**
                @brief Initializes the Timer with given values.
                @param interval The timer-interval in seconds
                @param bLoop If true, the function gets called every 'interval' seconds
                @param object The object owning the timer and the function
                @param timerFunction A function pointer to the function to call
            */
            void setTimer(float interval, bool bLoop, T* object, void (T::*timerFunction)())
            {
                this->interval_ = interval;
                this->bLoop_ = bLoop;
                this->timerFunction_ = timerFunction;
                this->object_ = object;
                this->bActive_ = true;

                this->time_ = interval;
            }

            /** @brief Calls the given function of the given object. */
            void run() const
            {
                ((*this->object_).*timerFunction_)();
            }

        private:
            void (T::*timerFunction_)();
            T* object_;
    };

    //! The TimerFrameListener manages all Timers in the game.
    class TimerFrameListener : public Ogre::FrameListener
    {
        private:
            /** @brief Gets called before a frame gets rendered. */
            bool frameStarted(const Ogre::FrameEvent &evt)
            {
                // Iterate through all Timers
                for (Iterator<TimerBase> it = ObjectList<TimerBase>::start(); it; ++it)
                {
                    if (it->isActive())
                    {
                        // If active: Decrease the timer by the duration of the last frame
                        it->time_ -= evt.timeSinceLastFrame;

                        if (it->time_ <= 0)
                        {
                            // It's time to call the function
                            if (it->bLoop_)
                                it->time_ += it->interval_; // Q: Why '+=' and not '='? A: Think about it. It's more accurate like that. Seriously.
                            else
                                it->stopTimer(); // Stop the timer if we don't want to loop

                            it->run();
                        }
                    }
                }

                return FrameListener::frameStarted(evt);
            }
    };
}

#endif