/*! 
    \file light.h
    \brief Handles Lights.

    A Light is one of the more important things in a 3D-environment,
    without it one sees nothing :)
    It is here for diffuse-, specular- and Bump-Mappings.
*/

#ifndef _LIGHT_H
#define _LIGHT_H

#include "world_entity.h"
#include "glincl.h"

//! The maximum number of Lights this OpenGL-implementation supports
#define NUMBEROFLIGHTS GL_MAX_LIGHTS

// FORWARD DEFINITIONS //
class Vector;

//! A struct that holds information about a Light
class Light : public WorldEntity
{
 public:
  Light(int lightNumber);
  ~Light(void);

  void setPosition(Vector position);
  void setPosition(GLfloat x, GLfloat y, GLfloat z);
  void setDiffuseColor(GLfloat r, GLfloat g, GLfloat b);
  void setSpecularColor(GLfloat r, GLfloat g, GLfloat b);
  void setAttenuation(float constantAttenuation, float linearAttenuation, float quadraticAttenuation);
  void setSpotDirection(Vector direction);
  void setSpotCutoff(GLfloat cutoff);

  virtual void draw();

  // attributes

  int lightNumber;            //!< The number of this Light.
  GLfloat lightPosition[4];   //!< The Position of this Light.
  GLfloat diffuseColor[4];    //!< The Diffuse Color this Light emmits.
  GLfloat specularColor[4];   //!< The specular Color of this Light.
  float constantAttenuation;  //!< The Factor of the the Constant Attenuation.
  float linearAttenuation;    //!< The Factor of the the Linear Attenuation.
  float quadraticAttenuation; //!< The Factor of the the Quadratic Attenuation.
  GLfloat spotDirection[4];   //!< The direction of the Spot Light.
  GLfloat spotCutoff;         //!< The cutoff Angle of the Light Source

  void debug(void);
};

//! A class that handles Lights
/**
   A Light is a source that emits light rays (photons)
*/
class LightManager : public BaseObject
{
 private:
  LightManager(void);
  void initLight(int LightNumber);
  
  static LightManager* singletonRef;    //!< This is the LightHandlers Reference.
  GLfloat ambientColor[4];       //!< The ambient Color of the scene.

  Light** lights;                //!< An array of Lenght NUMBEROFLIGHTS, that holds pointers to all LightValues.
  Light* currentLight;           //!< The current Light, we are working with.
  
 public:
  static LightManager* getInstance();
  virtual ~LightManager(void);

  // set Attributes
  int addLight(void);
  int addLight(int lightNumber);
  void editLightNumber(int lightNumber);
  void deleteLight(void);
  void deleteLight(int lightNumber);

  void setAmbientColor(GLfloat r, GLfloat g, GLfloat b);

  //set Attributes
  void setPosition(Vector position);
  void setPosition(GLfloat x, GLfloat y, GLfloat z);
  void setDiffuseColor(GLfloat r, GLfloat g, GLfloat b);
  void setSpecularColor(GLfloat r, GLfloat g, GLfloat b);
  void setAttenuation(float constantAttenuation, float linearAttenuation, float quadraticAttenuation);
  void setSpotDirection(Vector direction);
  void setSpotCutoff(GLfloat cutoff);

  // get Attributes
  Vector getPosition(void);
  /**
     \returns the Position of Light 
     \param lightNumber lightnumber
  */
  inline Vector getPosition(int lightNumber)
    {
      if (!this->lights[lightNumber])
	return Vector(.0,.0,.0);
      return Vector(this->lights[lightNumber]->lightPosition[0],
		    this->lights[lightNumber]->lightPosition[1],
		    this->lights[lightNumber]->lightPosition[2]);
    }

  void debug(void);
};

#endif /* _LIGHT_H */