use crate::{
    bvh_triangles::BVHTriangles,
    camera::Camera,
    cuboid::Cuboid,
    hitable::Hit,
    hitable_list::HitableList,
    material::{Dielectric, DiffuseLight, Isotropic, Lambertian, Material, Metal},
    renderer::Scene,
    sphere::Sphere,
    texture::{EnvMap, Texture},
};
use chrono::IsoWeek;
use serde::Deserialize;
use std::{collections::HashMap, fs::File, io::BufReader, path::PathBuf, sync::Arc};
use stl::STL;
use thiserror::Error;
use vec3::Vec3;

#[derive(Debug, Deserialize)]
pub struct Config {
    scene: SceneConfig,
    camera: CameraConfig,
    materials: Vec<MaterialConfig>,
    hitables: Vec<HitableConfig>,
    envmap: Option<EnvMapConfig>,
}

#[derive(Error, Debug)]
pub enum ConfigError {
    #[error("failed to load image")]
    ImageError(#[from] image::ImageError),
    #[error("failed to parser STL")]
    STLError(#[from] stl::ParseError),
    #[error("I/O error")]
    IOError(#[from] std::io::Error),
    #[error("duplication material named '{0}'")]
    DuplicateMaterial(String),
    #[error("unkown material named '{0}'")]
    UnknownMaterial(String),
}

impl TryFrom<Config> for Scene {
    type Error = ConfigError;

    fn try_from(c: Config) -> Result<Scene, Self::Error> {
        let mut materials = HashMap::new();
        for mc in c.materials {
            let v: Arc<dyn Material> = match mc.material {
                Materials::Metal { albedo, fuzzy } => Arc::new(Metal::new(albedo, fuzzy)),
                Materials::Dielectric { ref_idx } => Arc::new(Dielectric::new(ref_idx)),
                Materials::DiffuseLight { texture } => Arc::new(DiffuseLight::new(texture)),
                Materials::Isotropic { texture } => Arc::new(Isotropic::new(texture)),
                Materials::Lambertian { texture } => Arc::new(Lambertian::new(texture)),
            };
            if materials.insert(mc.name.clone(), v).is_some() {
                return Err(ConfigError::DuplicateMaterial(mc.name));
            }
        }

        let hitables: Result<Vec<Box<dyn Hit>>, Self::Error> = c
            .hitables
            .into_iter()
            .map(|hc| -> Result<Box<dyn Hit>, Self::Error> {
                match hc.hitable {
                    Hitables::Sphere { center, radius } => Ok(Box::new(Sphere::new(
                        center,
                        radius,
                        Arc::clone(
                            materials
                                .get(&hc.material_name)
                                .ok_or(ConfigError::UnknownMaterial(hc.material_name))?,
                        ),
                    ))),
                    Hitables::Cuboid { min, max } => Ok(Box::new(Cuboid::new(
                        min.into(),
                        max.into(),
                        Arc::clone(
                            materials
                                .get(&hc.material_name)
                                .ok_or(ConfigError::UnknownMaterial(hc.material_name))?,
                        ),
                    ))),
                    Hitables::STL { path, scale } => {
                        let r = BufReader::new(File::open(path)?);
                        let stl = STL::parse(r, false)?;
                        Ok(Box::new(BVHTriangles::new(
                            &stl,
                            Arc::clone(
                                materials
                                    .get(&hc.material_name)
                                    .ok_or(ConfigError::UnknownMaterial(hc.material_name))?,
                            ),
                            scale.unwrap_or(1.),
                        )))
                    }
                }
            })
            .collect();
        let hitables = hitables?;

        let world: Box<dyn Hit> = Box::new(HitableList::new(hitables));
        let mut env_map: Option<EnvMap> = None;

        if let Some(em) = c.envmap {
            let im = image::open(em.path)?.into_rgb();
            env_map = Some(EnvMap::new(im));
        };

        let camera = make_camera(&c.camera, c.scene.width, c.scene.height);

        let scene = Scene {
            world,
            camera,
            env_map,
            subsamples: c.scene.subsamples.unwrap_or(8),
            adaptive_subsampling: c.scene.adaptive_subsampling,
            num_threads: c.scene.num_threads,
            width: c.scene.width,
            height: c.scene.height,
            global_illumination: c.scene.global_illumination.unwrap_or(true),
        };
        Ok(scene)
    }
}

fn make_camera(cfg: &CameraConfig, width: usize, height: usize) -> Camera {
    Camera::new(
        cfg.lookfrom.into(),
        cfg.lookat.into(),
        Vec3::new(0., 1., 0.),
        cfg.fov,
        width as f32 / height as f32,
        cfg.aperture,
        cfg.focus_dist,
        cfg.time_min,
        cfg.time_max,
    )
}

#[derive(Debug, Deserialize)]
struct SceneConfig {
    subsamples: Option<usize>,
    adaptive_subsampling: Option<f32>,
    num_threads: Option<usize>,
    width: usize,
    height: usize,
    global_illumination: Option<bool>,
}

#[derive(Debug, Deserialize)]
#[serde(tag = "type")]
struct HitableConfig {
    material_name: String,
    #[serde(flatten)]
    hitable: Hitables,
}

#[derive(Debug, Deserialize)]
#[serde(tag = "type")]
enum Hitables {
    #[serde(rename = "sphere")]
    Sphere { center: [f32; 3], radius: f32 },
    #[serde(rename = "cuboid")]
    Cuboid { min: [f32; 3], max: [f32; 3] },
    #[serde(rename = "stl")]
    STL { path: PathBuf, scale: Option<f32> },
}

#[derive(Debug, Deserialize)]
struct MaterialConfig {
    name: String,
    #[serde(flatten)]
    material: Materials,
}

#[derive(Debug, Deserialize)]
#[serde(tag = "type")]
enum Materials {
    #[serde(rename = "metal")]
    Metal { albedo: [f32; 3], fuzzy: f32 },
    #[serde(rename = "dielectric")]
    Dielectric { ref_idx: f32 },
    // TODO(wathiede): these all take Textures, for now, only support RGB
    #[serde(rename = "diffuse_light")]
    DiffuseLight { texture: [f32; 3] },
    #[serde(rename = "isotropic")]
    Isotropic { texture: [f32; 3] },
    #[serde(rename = "lambertian")]
    Lambertian { texture: [f32; 3] },
}

#[derive(Debug, Deserialize)]
pub struct CameraConfig {
    lookfrom: [f32; 3],
    lookat: [f32; 3],
    fov: f32,
    aperture: f32,
    focus_dist: f32,
    time_min: f32,
    time_max: f32,
}

#[derive(Debug, Deserialize)]
struct EnvMapConfig {
    path: PathBuf,
}