#version 330 core

in vec2 tex_coords;
in vec3 normal;
in vec3 frag_pos;

out vec4 frag_color;

uniform sampler2D texture_diffuse;
uniform sampler2D texture_specular;

uniform vec3 light_pos;
uniform vec3 view_pos;

uniform float ambient_strength;
uniform float specular_strength;
uniform float shininess;

vec4
spotlight(vec3 light_dir, vec3 view_dir)
{
    vec3 tex_color_diff = texture(texture_diffuse, tex_coords);
    float ambient_strength = 0.1f;
    vec4 ambient = tex_color_diff*ambient_strength;
    vec4 diffuse = tex_color_diff*dot(-light_dir, )
    return(color);
}

vec4
blinn_phong()
{
    // Sample the diffuse color from the texture
    vec3 diffuse_color = texture(texture_diffuse, tex_coords).rgb;

    // Sample the specular color from the texture (if available)
    vec3 specular_color = texture(texture_specular, tex_coords).rgb;

    // Ambient lighting
    vec3 ambient = ambient_strength*diffuse_color;

    // Diffuse lighting
    vec3 norm = normalize(normal);
    vec3 light_dir = normalize(light_pos-frag_pos);
    float diff = max(dot(norm, light_dir), 0.0);
    vec3 diffuse = diff * diffuse_color;

    // Specular lighting
    vec3 view_dir = normalize(view_pos-frag_pos);
    vec3 halfway_dir = normalize(light_dir+view_dir); // Halfway vector
    float spec = pow(max(dot(norm, halfway_dir), 0.0), shininess);
    vec3 specular = specular_strength*spec*specular_color;

    // Combine all components
    vec3 result = (ambient+diffuse+specular);
    return((result, 1.0));
}

void
main(void)
{
    frag_color = blinn_phong();
}