#include "ogl.h"

#include <Kore/Graphics3/Graphics.h>
#include <Kore/Graphics3/Light.h>
#include <Kore/Math/Core.h>

using namespace Kore;

// OpenGL man pages for "glLight" function:
// see https://www.opengl.org/sdk/docs/man2/xhtml/glLight.xml

LightImpl::LightImpl()
    : myType(DirectionalLight), myAmbient(0, 0, 0, 1), myDiffuse(1, 1, 1, 1), mySpecular(1, 1, 1, 1), myPositionOrDirection(0, 0, 1, 0),
      mySpotDirection(0, 0, 1), // default point in +Z direction
      mySpotExponent(0.0f), mySpotCutoff(180.0f), myConstAttn(1.0f), myLinearAttn(0.0f), myQuadricAttn(0.0f) {}

LightImpl::~LightImpl() {}

void Light::setType(LightType type) {
	// Set new light type
	myType = type;

	// Update position/directior vector
	myPositionOrDirection[3] = (myType == DirectionalLight ? 0.0f : 1.0f);
}

void Light::setColors(const vec4 &ambient, const vec4 &diffuse, const vec4 &specular) {
	// Store light colors
	myAmbient = ambient;
	myDiffuse = diffuse;
	mySpecular = specular;
}

void Light::setPosition(const vec3 &position) {
	// Store position point (x, y, z, 1)
	myPositionOrDirection = vec4(position, 1);
}

void Light::setDirection(const vec3 &direction) {
	if (myType == SpotLight) {
		// Store spot direction vector (x, y, z)
		mySpotDirection = direction;
	}
	else {
		// Store direction vector (x, y, z, 0)
		myPositionOrDirection = vec4(direction, 0);
	}
}

void Light::setSpot(float exponent, float cutoff) {
	mySpotExponent = exponent;
	mySpotCutoff = cutoff;
}

void Light::setAttenuation(float constAttn, float linearAttn, float quadricAttn) {
	myConstAttn = constAttn;
	myLinearAttn = linearAttn;
	myQuadricAttn = quadricAttn;
}

/*
                                    1
GL Light Intensity = -----------------------------------
                     constant + d*linear + d^2*quadratic
*/
void Light::setAttenuationRadius(float radius) {
	setAttenuation(1.0f, 1.0f / radius, 1.0f / radius);
}

void LightImpl::submitLightParamsToGL(GLenum lightID) const {
	// Submit colors
	glLightfv(lightID, GL_AMBIENT, myAmbient.values);
	glLightfv(lightID, GL_DIFFUSE, myDiffuse.values);
	glLightfv(lightID, GL_SPECULAR, mySpecular.values);

	// Submit attenuation
	glLightf(lightID, GL_CONSTANT_ATTENUATION, myConstAttn);
	glLightf(lightID, GL_LINEAR_ATTENUATION, myLinearAttn);
	glLightf(lightID, GL_QUADRATIC_ATTENUATION, myQuadricAttn);

	// Submit spot parameters
	glLightfv(lightID, GL_SPOT_DIRECTION, mySpotDirection.values);
	glLightf(lightID, GL_SPOT_EXPONENT, mySpotExponent);
	glLightf(lightID, GL_SPOT_CUTOFF, mySpotCutoff);
}

void LightImpl::submitLightTransformToGL(GLenum lightID) const {
	glLightfv(lightID, GL_POSITION, myPositionOrDirection.values);
}

Light::Light(LightType type) : LightImpl() {
	setType(type);
}

void Light::_set(int num) {
	GLenum lightID = GL_LIGHT0 + num;
	glEnable(lightID);
	submitLightParamsToGL(lightID);
	submitLightTransformToGL(lightID);
}