#version 430

uniform mat4 model;
uniform mat4 view;
 
layout(binding=0) uniform sampler2D texture;

const int numberOfLights = 2;

uniform vec4 position[numberOfLights];
uniform vec4 specular[numberOfLights];
uniform vec4 diffuse[numberOfLights];
uniform float constantAttenuation[numberOfLights];
uniform float linearAttenuation[numberOfLights];
uniform float quadraticAttenuation[numberOfLights];
uniform float spotExponent[numberOfLights];

 in VertexData {
	vec3 Position;
	vec3 Normal;
	vec2 TextureCoord;
} Input;

vec3 scene_ambient = vec3(0.2, 0.2, 0.2);
 
out vec4 fragmentColor;

void main() {

	// Texture
	vec4 texel = texture2D(texture, Input.TextureCoord);
	//vec4 texel = (blend.x * texel0) + (blend.y * texel1) + (blend.z * texel2);

	//
	// Phong shading
	//

	// Ambient light
	vec3 La = scene_ambient;	// Ambient light
	vec3 Ks = vec3(0.3, 0.3, 0.3);	// Specular reflectance
	vec3 Kd = vec3(1.0, 1.0, 1.0);	// Diffuse reflectance
	vec3 Ka = vec3(1.0, 1.0, 1.0);	// Ambient reflectance

	vec3 totalLighting = La * Ka;

	float attenuation;

	for(int i = 0; i < numberOfLights; i++)
	{
	// Light
	//vec3 lightPosition = vec3(0, 0, 2);
	vec3 Ls = specular[i];	// Specular light
	vec3 Ld = diffuse[i];	// Diffuse light
	

	// Object
	
	vec3 lightPosView = vec3(view * vec4(LightPos[i], 1.0));
	vec3 surfacePosition = vec3(model * vec4(Input.Position, 1.0));
	vec3 surfacePosView = vec3(view * vec4(surfacePosition, 1.0));
	vec3 surfaceToLight = normalize(lightPosView - surfacePosView);
	mat3 normalMatrix = transpose(inverse(mat3(view * model)));
	vec3 surfaceNormal = normalize(normalMatrix * Input.Normal);
	
	float dist = length(LightPos[i] - surfacePosition);

	attenuation = 1.0 / (constantAttenuation
		+ linearAttenuation * dist
		+ quadraticAttenuation * pow(dist, 2.0));

	attenuation = attenuation * pow(clampedCosine, spotExponent[i]);
	
	// Diffuse light
	float dotProd = dot(surfaceToLight, surfaceNormal);
	dotProd = max(dotProd, 0.0);
	
	Id = Ld * Kd * abs(dotProd) * attenuation;
	
	// Specular light
	vec3 reflection = reflect(-surfaceToLight, surfaceNormal);
	float dotSpecular = dot(reflection, normalize(-surfacePosView));
	dotSpecular = max(dotSpecular, 0.0);
	float specularFactor = pow(dotSpecular, 30.0); // Specular factor
	
	Is = attenuation * Ls * Ks * specularFactor;

	totalLighting = totalLighting + Id + Is;
	}
	fragmentColor = vec4(totalLighting, 1.0) * texel;	
	

	//fragmentColor = vec4(Id, 1.0) * texel;

	//fragmentColor = texel;
}