#version 330 core

in VS_OUT {
    /* mat3 TBN; */
    vec3 frag_pos;
    vec3 tangent_light_pos;
    vec3 tangent_view_pos;
    vec3 tangent_frag_pos;
    vec2 tex_coords;
} fs_in;

out vec4 frag_color;

/* uniform vec3 light_pos; */
/* uniform vec3 view_pos; */

uniform sampler2D diffuse_texture;
uniform sampler2D normal_map;

void main(void)
{
    vec3 color = vec3(texture(diffuse_texture, fs_in.tex_coords));
    vec3 normal = vec3(texture(normal_map, fs_in.tex_coords));
    normal = normalize((normal*2.0)-1.0);
    /*
    normal = normalize(fs_in.TBN*normal);

    vec3 light_dir = fs_in.TBN * normalize(light_pos - fs_in.frag_pos);
    vec3 view_dir = fs_in.TBN * normalize(view_pos - fs_in.frag_pos);
    */

    vec3 light_color = vec3(1.0);

    float ambient = 0.01;

    /* vec3 light_dir = normalize(light_pos-fs_in.frag_pos); */
    vec3 light_dir = normalize(fs_in.tangent_light_pos - fs_in.tangent_frag_pos);
    float diff = max(dot(light_dir, normal), 0.0);
    vec3 diffuse = diff*light_color;

    /* vec3 view_dir = normalize(view_pos-fs_in.frag_pos); */
    vec3 view_dir = normalize(fs_in.tangent_view_pos-fs_in.frag_pos);
    vec3 halfway_dir = normalize(light_dir+view_dir); 
    float spec = pow(max(dot(halfway_dir, normal), 0.0), 64.0);
    float spec_strength = 1.0;
    vec3 specular = spec_strength*spec*light_color;

    vec3 result = (ambient+diffuse+specular)*color;

    frag_color = vec4(result, 1.0);
}