#version 330 core

in vec3 frag_pos;
in vec3 frag_normal;
in vec2 frag_uv;

out vec4 color;

uniform sampler2D sampler;

const vec4 ambient_color = vec4(0.1, 0.1, 0.1, 1);
const uint NUM_LIGHTS = 32u;

layout (std140) uniform lights
{
	uint buf_size;
	uint max_p_lights;
	uint active_p_lights;
	uint max_d_lights;
	uint active_d_lights;

	vec4 pl_positions[NUM_LIGHTS];
	vec4 pl_colors[NUM_LIGHTS];
	uint pl_intensities[NUM_LIGHTS]; // NOTE: 16 bytes * NUM_LIGHTS

	vec4 dl_directions[NUM_LIGHTS];
	vec4 dl_colors[NUM_LIGHTS];
	uint dl_intensities[NUM_LIGHTS]; // NOTE: 16 bytes * NUM_LIGHTS
};


void main()
{
	// NOTE: directional lights
	vec4 diffuse_color = vec4(0);

	for (uint i = 0u; i < active_d_lights; i++) {
		vec4 light_direction = normalize(dl_directions[i]);
		float diffuse_factor =
			clamp(dot(vec4(frag_normal, 1), light_direction), 0, 1);
		diffuse_color = diffuse_color +
			dl_intensities[i] * diffuse_factor * dl_colors[i];
	}

//#else // point light
//	vec4 light_direction = pl1.pos - frag_pos;
//	float len = length(light_direction);
//	light_direction = normalize(light_direction);
//	float diffuse_factor = dot(frag_normal, light_direction) / pow(len, 2);
//	diffuse_factor = clamp(diffuse_factor, 0, 1);
//	vec4 diffuse_color = pl1.intensity * vec4(pl1.color * diffuse_factor);
//#endif

	color = (ambient_color + diffuse_color) * texture(sampler, frag_uv.st);
}