use std::error::Error;
use std::path::Path;

use engine::camera::Camera;
use engine::delta_time::DeltaTime;
use engine::ecs::sole::Single;
use engine::ecs::Query;
use engine::event::Update as UpdateEvent;
use engine::input::{Extension as InputExtension, Keys};
use engine::lighting::{LightSource, LightSourceBuilder};
use engine::material::Builder as MaterialBuilder;
use engine::renderer::Extension as RendererExtension;
use engine::shader::{Kind as ShaderKind, Program as ShaderProgram, Shader};
use engine::texture::{Id as TextureId, Map as TextureMap, Texture};
use engine::transform::Transform;
use engine::vector::{Vec2, Vec3};
use engine::vertex::Builder as VertexBuilder;
use engine::window::{Extension as WindowExtension, Key, KeyState};
use engine::Engine;
use tracing::Level;
use tracing_subscriber::FmtSubscriber;

use crate::cube::{create_cube_mesh, Corner as CubeCorner, Side as CubeSide};

mod cube;

const VERTEX_SHADER_FILE: &str = "vertex.glsl";
const FRAGMENT_SHADER_FILE: &str = "fragment.glsl";

const SHADER_DIR: &str = "engine";

const CAM_SPEED: f32 = 3.0;

const LIGHT_SOURCE_SPEED: f32 = 1.2;

fn lmao(
    camera_query: Query<(Camera,)>,
    light_source_query: Query<(LightSource,)>,
    keys: Single<Keys>,
    delta_time: Single<DeltaTime>,
)
{
    let (mut camera,) = camera_query.iter().next().expect("No camera");

    let (mut light_source,) = light_source_query.iter().next().expect("No light source");

    let delta_time = delta_time.duration;

    if matches!(keys.get_key_state(Key::W), KeyState::Pressed) {
        let cam_target_direction = camera.target_direction().clone();

        camera.position += cam_target_direction * CAM_SPEED * delta_time.as_secs_f32();
    }

    if matches!(keys.get_key_state(Key::S), KeyState::Pressed) {
        let rev_cam_target_direction = -camera.target_direction().clone();

        camera.position +=
            rev_cam_target_direction * CAM_SPEED * delta_time.as_secs_f32();
    }

    if matches!(keys.get_key_state(Key::A), KeyState::Pressed) {
        let cam_left = camera.left().clone();

        // Camera speed adjusted to be same no matter how far the distance is to the
        // camera target
        let cam_speed_dist_adj =
            CAM_SPEED * (camera.position.clone() - camera.target.clone()).length();

        camera.position += cam_left * cam_speed_dist_adj * delta_time.as_secs_f32();
    }

    if matches!(keys.get_key_state(Key::D), KeyState::Pressed) {
        let cam_right = camera.right().clone();

        // Camera speed adjusted to be same no matter how far the distance is to the
        // camera target
        let cam_speed_dist_adj =
            CAM_SPEED * (camera.position.clone() - camera.target.clone()).length();

        camera.position += cam_right * cam_speed_dist_adj * delta_time.as_secs_f32();
    }

    if matches!(keys.get_key_state(Key::K), KeyState::Pressed) {
        let cam_up = camera.up().clone();

        // Camera speed adjusted to be same no matter how far the distance is to the
        // camera target
        let cam_speed_dist_adj =
            CAM_SPEED * (camera.position.clone() - camera.target.clone()).length();

        camera.position += cam_up * cam_speed_dist_adj * delta_time.as_secs_f32();
    }

    if matches!(keys.get_key_state(Key::J), KeyState::Pressed) {
        let cam_up = camera.down().clone();

        // Camera speed adjusted to be same no matter how far the distance is to the
        // camera target
        let cam_speed_dist_adj =
            CAM_SPEED * (camera.position.clone() - camera.target.clone()).length();

        camera.position += cam_up * cam_speed_dist_adj * delta_time.as_secs_f32();
    }

    if matches!(keys.get_key_state(Key::O), KeyState::Pressed) {
        let front_right = Vec3 { x: 1.0, y: 0.0, z: 1.0 };

        light_source
            .translate(front_right * LIGHT_SOURCE_SPEED * delta_time.as_secs_f32());
    }

    if matches!(keys.get_key_state(Key::L), KeyState::Pressed) {
        let back_left = Vec3 { x: -1.0, y: 0.0, z: -1.0 };

        light_source.translate(back_left * LIGHT_SOURCE_SPEED * delta_time.as_secs_f32());
    }
}

fn main() -> Result<(), Box<dyn Error>>
{
    let subscriber = FmtSubscriber::builder()
        .with_max_level(Level::TRACE)
        .finish();

    tracing::subscriber::set_global_default(subscriber)?;

    let mut engine = Engine::new();

    let texture = Texture::open(Path::new("vent.png"))?;

    let material = MaterialBuilder::new()
        .ambient_map(TextureId::new(0))
        .diffuse_map(TextureId::new(0))
        .specular_map(TextureId::new(0))
        .build();

    /*
    let mut textured_cube = create_cube(cube_vertex_builder_cb)
        .texture(TextureId::new(0), texture.clone())
        .material(material.clone())
        .build(ObjectId::new(4))?;

    textured_cube.translate(Vec3 { x: 1.6, y: 0.0, z: 0.0 });

    engine.add_object(textured_cube);
    */

    let mut transform = Transform::new();

    transform.set_position(Vec3 { x: 1.6, y: 0.0, z: 0.0 });

    let mut shader_program = ShaderProgram::new();

    shader_program.push_shader(
        Shader::read_shader_file(
            ShaderKind::Vertex,
            &Path::new(SHADER_DIR).join(VERTEX_SHADER_FILE),
        )?
        .preprocess()?,
    );

    shader_program.push_shader(
        Shader::read_shader_file(
            ShaderKind::Fragment,
            &Path::new(SHADER_DIR).join(FRAGMENT_SHADER_FILE),
        )?
        .preprocess()?,
    );

    engine.spawn((
        create_cube_mesh(cube_vertex_builder_cb),
        TextureMap::from_iter([(TextureId::new(0), texture)]),
        material,
        transform,
        shader_program,
    ));

    let light_source = LightSourceBuilder::new()
        .position(Vec3 { x: 1.2, y: 1.0, z: 1.5 })
        .build();

    engine.spawn((light_source,));

    engine.spawn((Camera { current: true, ..Default::default() },));

    engine.register_system(UpdateEvent, lmao);

    engine.add_extension(RendererExtension::default());
    engine.add_extension(WindowExtension::default().window_title("Game"));
    engine.add_extension(InputExtension::default());

    engine.start();

    Ok(())
}

fn cube_vertex_builder_cb(
    vertex_builder: VertexBuilder,
    _side: CubeSide,
    corner: CubeCorner,
) -> VertexBuilder
{
    vertex_builder.texture_coords(match corner {
        CubeCorner::TopRight => Vec2 { x: 1.0, y: 1.0 },
        CubeCorner::TopLeft => Vec2 { x: 0.0, y: 1.0 },
        CubeCorner::BottomRight => Vec2 { x: 1.0, y: 0.0 },
        CubeCorner::BottomLeft => Vec2 { x: 0.0, y: 0.0 },
    })
}

trait CameraExt
{
    fn target_direction(&self) -> Vec3<f32>;

    fn right(&self) -> Vec3<f32>;

    fn left(&self) -> Vec3<f32>;

    fn up(&self) -> Vec3<f32>;

    fn down(&self) -> Vec3<f32>;
}

impl CameraExt for Camera
{
    fn target_direction(&self) -> Vec3<f32>
    {
        -(&self.position - &self.target).normalize()
    }

    fn right(&self) -> Vec3<f32>
    {
        let rev_target_direction = (&self.position - &self.target).normalize();

        Vec3::UP.cross(&rev_target_direction).normalize()
    }

    fn left(&self) -> Vec3<f32>
    {
        -self.right()
    }

    fn up(&self) -> Vec3<f32>
    {
        let rev_target_direction = (&self.position - &self.target).normalize();

        rev_target_direction.cross(&self.right())
    }

    fn down(&self) -> Vec3<f32>
    {
        -self.up()
    }
}