#version 440

in vec3 f_color;
out vec4 FragColors;

uniform vec3 Kd;
uniform vec3 Ka;
uniform vec3 Ks;
uniform float Shininess;

struct LightInfo {
  vec4 Position; 
  vec3 Intensity;
  float SpotCutoff;
  float SpotInnerCutoff;
  float SpotExponent;
  vec3 SpotDirection;  
};

uniform LightInfo Light[64];
uniform int LightCount;

in vec3 fNormal;
in vec3 pos;

void main()
{ 

	vec3 ambient_sum;
	vec3 diffuse_sum;
	vec3 specular_sum;
	vec3 ambient;
	float D;
	float attenuation;

	
	for (int i=0; i<LightCount; i++) 
	{
		D = distance(Light[i].Position.xyz, pos);
		attenuation = 1 / (1 + 0.01 * D + 0.001 * D * D);
		vec3 L = normalize(Light[i].Position.xyz - pos);
		vec3 N = fNormal;
		vec3 V = normalize(-pos);	
		//vec3 R = normalize(reflect(-L, N));
		vec3 H = normalize(V + L);
		float SpotAttenuation = 1.0;		
		float spotDot = dot(-L, normalize(Light[i].SpotDirection));		

		if (spotDot > cos(radians(Light[i].SpotInnerCutoff)))
		{
			//Fragment is outside the Cone
			//Interpolate between cos(Innercutoff )and cos(cutoff) with cos(theta)
			float spotValue = smoothstep(cos(radians(Light[i].SpotCutoff)),
									cos(radians(Light[i].SpotInnerCutoff)),
									spotDot);		
			SpotAttenuation = pow(spotValue, Light[i].SpotExponent);
		}

		attenuation *= SpotAttenuation;

		vec3 ambient = Ka * Light[i].Intensity * attenuation;
		vec3 diffuse = Kd * Light[i].Intensity * max(dot(L, N), 0.0) * attenuation;	
		vec3 specular = Ks * Light[i].Intensity * pow(max(dot(H, N), 0.0), Shininess) * attenuation;	

		ambient_sum += ambient;
		diffuse_sum += diffuse;
		specular_sum += specular;
    }
		
      FragColors = vec4(diffuse_sum + specular_sum + ambient_sum / LightCount, 1);   
}