use image::{DynamicImage, ImageReader};
use log::trace;

use crate::{
    objects::{hit::Hit, materials::traits::Material},
    ray::Ray,
    vec3::Vec3,
};

// TODO: overhaul texture implementation so we can support textures for arbitrary materials.
// Basically remove this struct, and instead make lambertian/metal/dielectric/take either a texture
// or a flat colour
// I think we can use an enum ColourSource with a function to fetch a specific colour depending on
// if we have a texture/flat colour. and yeah.
#[derive(Debug)]
pub struct Texture {
    source: DynamicImage,
    width: u32,
    height: u32,
    stride: usize,
}

impl Texture {
    pub fn new(texture: &str) -> Self {
        let img = ImageReader::open(texture).unwrap().decode().unwrap(); // FIXME: unwraps
        trace!(
            "texture '{}' is {} by {} pixels, with {} bytes total",
            texture,
            img.width(),
            img.height(),
            img.as_bytes().len()
        );
        let stride = match img.color() {
            // TODO: support other types of image
            image::ColorType::L8 => todo!(),
            image::ColorType::La8 => todo!(),
            image::ColorType::Rgb8 => 3,
            image::ColorType::Rgba8 => 4,
            image::ColorType::L16 => todo!(),
            image::ColorType::La16 => todo!(),
            image::ColorType::Rgb16 => todo!(),
            image::ColorType::Rgba16 => todo!(),
            image::ColorType::Rgb32F => todo!(),
            image::ColorType::Rgba32F => todo!(),
            _ => 3,
        };
        Self {
            width: img.width(),
            height: img.height(),
            source: img,
            stride,
        }
    }

    fn _idx(&self, u: f32, v: f32) -> usize {
        let x: usize = (u * ((self.width - 1) as f32)) as usize; 
        let y: usize = (v * ((self.height - 1) as f32)) as usize;

        y * self.width as usize + x
    }

    fn _at(&self, u: f32, v: f32) -> Vec3 {
        let b = self.source.as_bytes();
        let idx = self._idx(u, v);

        Vec3::from_u8(
            b[self.stride * idx],
            b[self.stride * idx + 2],
            b[self.stride * idx + 1],
        )
    }
}

impl Material for Texture {
    fn scatter(&self, hit: &Hit, _ray: &Ray) -> Option<(Option<Ray>, Vec3)> {
        let (u, v) = hit.uv();
        let col = self._at(u, 1. - v);
        Some((None, col))
    }
}