use rand::Rng;
use ray_tracing_core::{light::AreaLight, prelude::*, scene::Scene};
use ray_tracing_material::{
    microfacet::{BeckmannDistribution, Microfacet},
    oren_nayar::OrenNayar,
};
use std::cell::OnceCell;

use crate::{
    acceleration_structure::{
        triangle_bvh::{Triangle, TriangleBVH},
        ASMaterial, AccelerationStructureScene,
    },
    parse_obj::ObjData,
};

use super::ExampleScene;

pub struct StanfordDragon<R: Rng> {
    scene: OnceCell<AccelerationStructureScene<TriangleBVH<u32>, R>>,
}

impl<R: Rng> StanfordDragon<R> {
    pub fn new() -> Self {
        Self {
            scene: OnceCell::new(),
        }
    }
}

impl<R: Rng + 'static> ExampleScene<R> for StanfordDragon<R> {
    fn get_scene(&self) -> Box<dyn Scene<R> + Sync> {
        let s = self.scene.get_or_init(|| {
            let obj = ObjData::new("ray-tracing-scene/obj/stanford_dragon.obj").unwrap();

            let mut triangles = obj
                .triangle_faces()
                .map(|t| Triangle::new(t.v, 0))
                .collect::<Vec<_>>();

            let color = Color::new(0.2, 0.2, 0.9);
            let materials = vec![
                ASMaterial::new_material(Microfacet::new(BeckmannDistribution::new(0.01), color)),
                ASMaterial::new_material(OrenNayar::new(0.5, Color::new(0.8, 0.8, 0.8))),
                ASMaterial::new_material(OrenNayar::new(0.5, Color::new(0.9, 0.0, 0.0))),
                ASMaterial::new_material(OrenNayar::new(0.5, Color::new(0.0, 0.9, 0.0))),
                ASMaterial::new_light(AreaLight::new(Color::white() * 30.0)),
            ];

            let mut vertices = obj.vertices;
            for v in &mut vertices {
                *v = Pos3::new(v.x(), v.z() + 60.0, -v.y());
            }

            let side_length = 400.0;
            let light_size = 150.0;
            let light_offset = 0.01;
            let offset = vertices.len() as u32;
            vertices.extend_from_slice(&[
                Pos3::new(side_length, 2.0 * side_length, side_length),
                Pos3::new(side_length, 2.0 * side_length, -side_length),
                Pos3::new(side_length, 0.0, side_length),
                Pos3::new(side_length, 0.0, -side_length),
                Pos3::new(-side_length, 2.0 * side_length, side_length),
                Pos3::new(-side_length, 2.0 * side_length, -side_length),
                Pos3::new(-side_length, 0.0, side_length),
                Pos3::new(-side_length, 0.0, -side_length),
                Pos3::new(light_size, 2.0 * side_length - light_offset, light_size),
                Pos3::new(light_size, 2.0 * side_length - light_offset, -light_size),
                Pos3::new(-light_size, 2.0 * side_length - light_offset, light_size),
                Pos3::new(-light_size, 2.0 * side_length - light_offset, -light_size),
            ]);

            triangles.extend_from_slice(&[
                Triangle::new([offset, 1 + offset, 2 + offset], 1),
                Triangle::new([1 + offset, 3 + offset, 2 + offset], 1),
                Triangle::new([offset, 4 + offset, 1 + offset], 1),
                Triangle::new([1 + offset, 4 + offset, 5 + offset], 1),
                Triangle::new([2 + offset, 3 + offset, 6 + offset], 1),
                Triangle::new([3 + offset, 7 + offset, 6 + offset], 1),
                Triangle::new([offset, 2 + offset, 4 + offset], 2),
                Triangle::new([6 + offset, 4 + offset, 2 + offset], 2),
                Triangle::new([1 + offset, 5 + offset, 3 + offset], 3),
                Triangle::new([7 + offset, 3 + offset, 5 + offset], 3),
                Triangle::new([8 + offset, 10 + offset, 9 + offset], 4),
                Triangle::new([11 + offset, 9 + offset, 10 + offset], 4),
            ]);

            let lights: Vec<_> = triangles
                .iter()
                .filter(|f| materials[f.data as usize].light.is_some())
                .map(|t| {
                    (
                        t.data as usize,
                        [
                            vertices[t.vertices[0] as usize],
                            vertices[t.vertices[1] as usize],
                            vertices[t.vertices[2] as usize],
                        ],
                    )
                })
                .collect();
            let a = TriangleBVH::new(vertices, triangles);
            AccelerationStructureScene::new(a, materials.into(), lights)
        });

        let n: AccelerationStructureScene<_, _> = s.clone();
        Box::new(n)
    }

    fn get_camera_pos(&self) -> Pos3 {
        Pos3::new(-150.0, 160.0, 250.0)
    }

    fn get_camera_look_at(&self) -> Pos3 {
        Pos3::new(0.0, 60.0, 0.0)
    }

    fn get_camera_up(&self) -> Dir3 {
        Dir3::up()
    }

    fn get_horizontal_fov(&self) -> Float {
        Float::to_radians(90.0)
    }
}