struct Environment {
    ambient: vec4<f32>,
    light: vec4<f32>,
    dir: vec4<f32>,
}

struct View {
    view: mat4x4<f32>,
    frame: mat4x4<f32>,
}

// Vertex shader
@group(0) @binding(0)
var<uniform> view: View;
@group(0) @binding(1)
var<uniform> environment: Environment;

struct VertexInput {
    @location(0) position: vec3<f32>,
    @location(1) normal: vec3<f32>,
    @location(2) tex_coords: vec2<f32>,
}

struct InstanceInput {
    @location(4) model_matrix_0: vec4<f32>,
    @location(5) model_matrix_1: vec4<f32>,
    @location(6) model_matrix_2: vec4<f32>,
    @location(7) model_matrix_3: vec4<f32>,
    @location(8) model_color: vec4<f32>,
}


struct VertexOutput {
    @builtin(position) clip_position: vec4<f32>,
    @location(0) tex_coords: vec2<f32>,
    @location(1) color: vec4<f32>,
    @location(2) world_normal: vec3<f32>,
    @location(3) world_position: vec3<f32>,
}

@vertex
fn vs_main(
    model: VertexInput,
    instance: InstanceInput,
) -> VertexOutput {
    var out: VertexOutput;
    let model_matrix = mat4x4<f32>(
        instance.model_matrix_0,
        instance.model_matrix_1,
        instance.model_matrix_2,
        instance.model_matrix_3,
    );
    let model_rot_matrix = mat3x3<f32>(
        instance.model_matrix_0.xyz,
        instance.model_matrix_1.xyz,
        instance.model_matrix_2.xyz,
    );
    out.tex_coords = model.tex_coords;
    out.color = instance.model_color;
    out.world_normal = model_rot_matrix * model.normal;
    var world_position: vec4<f32> = model_matrix * vec4<f32>(model.position, 1.0);
    out.world_position = world_position.xyz;
    out.clip_position = view.view * world_position;
    return out;
}

// Fragment shader

@group(1) @binding(0)
var s_diffuse: sampler;
@group(1) @binding(1)
var t_diffuse: texture_2d<f32>;
@group(1) @binding(2)
var t_normal: texture_2d<f32>;
@group(1) @binding(3)
var t_rough: texture_2d<f32>;

@fragment
fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
    let object_color: vec4<f32> = textureSample(t_diffuse, s_diffuse, in.tex_coords);
    let object_normal: vec4<f32> = textureSample(t_normal, s_diffuse, in.tex_coords);

    let tangent_normal = object_normal.xyz * 2.0 - 1.0;
    let light_dir = normalize(environment.dir.xyz);
    let view_dir = normalize(view.frame[3].xyz - in.world_position);
    let half_dir = normalize(view_dir + light_dir);

    let diffuse_strength = max(dot(tangent_normal, light_dir), 0.0);
    let diffuse_color = environment.light.xyz * diffuse_strength;

    let specular_strength = pow(max(dot(tangent_normal, half_dir), 0.0), 32.0);
    let specular_color = specular_strength * environment.light.xyz;

    let result = (environment.ambient.xyz + diffuse_color.xyz + specular_color.xyz) * object_color.xyz;

    return vec4<f32>(result.xyz,object_color.a);
}