#version 330

// TODO: get color value from vertex shader
in vec3 world_position;
in vec3 world_normal;

// Uniforms for light properties
uniform vec3 light_direction;
uniform vec3 light_position;
uniform vec3 eye_position;

uniform float material_kd;
uniform float material_ks;
uniform int material_shininess;

uniform vec3 object_color;

uniform int spotlight;
uniform float cut_off;

layout(location = 0) out vec4 out_color;

void main()
{
	vec3 V = normalize(eye_position - world_position);
	vec3 L = normalize(light_position - world_position);
	vec3 H = normalize(L + V);

	// TODO: define ambient light component
	float ambient_light = 0.25;

	// TODO: compute diffuse light component
	float diffuse_light = material_kd*max(0,(dot(world_normal, L)));

	// TODO: compute specular light component
	float specular_light = 0;
	if(diffuse_light > 0)
		specular_light = material_ks * pow(max(dot(world_normal, H), 0), material_shininess);

	// TODO: compute light
	float light_att_factor;
	if(spotlight == 1) {
		float cut_off = radians(30);
		float spot_light = dot(L, light_direction);
		float spot_light_limit = cos(radians(cut_off));

		if (spot_light > spot_light_limit)
		{
			float linear_att = (spot_light - spot_light_limit) / (1 - spot_light_limit);
			light_att_factor = pow(linear_att, 2);

			diffuse_light *= light_att_factor;
			specular_light *= light_att_factor;
		}
	}
	else {
		light_att_factor = 1 / pow(distance(light_position, world_position), 2);
	}
	vec3 color = object_color * (ambient_light + light_att_factor * (diffuse_light + specular_light));

	// TODO: write pixel out color
	out_color = vec4(color, 1);
}