/*
-----------------------------------------------------------------------------
This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright © 2000-2002 The OGRE Team
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.
-----------------------------------------------------------------------------
*/
#ifndef __Controller_H__
#define __Controller_H__

#include "OgrePrerequisites.h"

#include "OgreSharedPtr.h"

namespace Ogre {


	
	
	/** Subclasses of this class are responsible for performing a function on an input value for a Controller.
        @remarks
            This abstract class provides the interface that needs to be supported for a custom function which
            can be 'plugged in' to a Controller instance, which controls some object value based on an input value.
            For example, the WaveControllerFunction class provided by Ogre allows you to use various waveforms to
            translate an input value to an output value.
        @par
            You are free to create your own subclasses in order to define any function you wish.
    */
	template <typename T>
    class _OgreExport ControllerFunction
    {
    protected:
        /// If true, function will add imput values together and wrap at 1.0 before evaluating
        bool mDeltaInput;
        T mDeltaCount;

        /** Gets the input value as adjusted by any delta.
        */
        T getAdjustedInput(T input)
        {
            if (mDeltaInput)
            {
                mDeltaCount += input;
                // Wrap
                while (mDeltaCount >= 1.0)
                    mDeltaCount -= 1.0;

                return mDeltaCount;
            }
            else
			{
                return input;
            }
        }

    public:
        /** Constructor.
            @param
                deltaInput If true, signifies that the input will be a delta value such that the function should
                add it to an internal counter before calculating the output.
        */
        ControllerFunction(bool deltaInput)
        {
            mDeltaInput = deltaInput;
            mDeltaCount = 0;
        }

        virtual T calculate(T sourceValue) = 0;
    };


    /** Can either be used as an input or output value.
    */
	template <typename T>
    class _OgreExport ControllerValue
    {

    public:
        virtual ~ControllerValue() { }
        virtual T getValue(void) const = 0;
        virtual void setValue(T value) = 0;

    };

    /** Instances of this class 'control' the value of another object in the system.
        @remarks
            Controller classes are used to manage the values of object automatically based
            on the value of some input. For example, a Controller could animate a texture
            by controlling the current frame of the texture based on time, or a different Controller
            could change the colour of a material used for a spaceship shield mesh based on the remaining
            shield power level of the ship.
        @par
            The Controller is an intentionally abstract concept - it can generate values
            based on input and a function, which can either be one of the standard ones
            supplied, or a function can be 'plugged in' for custom behaviour - see the ControllerFunction class for details.
            Both the input and output values are via ControllerValue objects, meaning that any value can be both
            input and output of the controller.
        @par
            Whilst this is very flexible, it can be a little bit confusing so to make it simpler the most often used
            controller setups are available by calling methods on the ControllerManager object.
        @see
            ControllerFunction

    */
	template <typename T>
    class _OgreExport Controller
    {
    protected:
        /// Source value
        SharedPtr< ControllerValue<T> > mSource;
        /// Destination value
        SharedPtr< ControllerValue<T> > mDest;
        /// Function
        SharedPtr< ControllerFunction<T> > mFunc;
		/// Controller is enabled or not
        bool mEnabled;


    public:

        /** Usual constructor.
            @remarks
                Requires source and destination values, and a function object. None of these are destroyed
                with the Controller when it is deleted (they can be shared) so you must delete these as appropriate.
        */
        Controller(SharedPtr< ControllerValue<T> > src, 
			SharedPtr< ControllerValue<T> > dest, SharedPtr< ControllerFunction<T> > func)
			: mSource(src), mDest(dest), mFunc(func)
		{
			mEnabled = true;
		}

        /** Default d-tor.
        */
		virtual ~Controller() {}


		/// Sets the input controller value
        void setSource(SharedPtr< ControllerValue<T> > src)
		{
			mSource = src;
		}
		/// Gets the input controller value
        SharedPtr< ControllerValue<T> > getSource(void) const
		{
			return mSource;
		}
		/// Sets the output controller value
        void setDestination(SharedPtr< ControllerValue<T> > dest)
		{
			mDest = dest;
		}

		/// Gets the output controller value
        SharedPtr< ControllerValue<T> > getDestination(void) const
		{
			return mDest;
		}

        /// Returns true if this controller is currently enabled
        bool getEnabled(void) const
		{
			return mEnabled;
		}

        /// Sets whether this controller is enabled
        void setEnabled(bool enabled)
		{
			mEnabled = enabled;
		}

        /** Sets the function object to be used by this controller.
        */
        void setFunction(SharedPtr< ControllerFunction<T> > func)
		{
			mFunc = func;
		}

        /** Returns a pointer to the function object used by this controller.
        */
        SharedPtr< ControllerFunction<T> > getFunction(void) const
		{
			return mFunc;
		}

		/** Tells this controller to map it's input controller value
		    to it's output controller value, via the controller function. 
		@remarks
			This method is called automatically every frame by ControllerManager.
		*/
		void update(void)
		{
			if(mEnabled)
				mDest->setValue(mFunc->calculate(mSource->getValue()));
		}

    };


}

#endif
