use std::{fs::File, io::Read, path::Path};

use anyhow::Result;

use crate::{
  scene_data::{Object, Scene, Sphere},
  vec3::Vec3,
};

pub fn parse_input_file(path: impl AsRef<Path>) -> Result<Scene> {
  let contents = {
    let mut contents = String::new();
    let mut file = File::open(path.as_ref())?;
    file.read_to_string(&mut contents)?;
    contents
  };

  let mut scene = Scene::default();
  let mut material_color = None;

  for line in contents.lines() {
    let mut parts = line.split_whitespace();
    let keyword = match parts.next() {
      Some(v) => v,
      None => continue,
    };

    if keyword == "imsize" {
      let parts = parts
        .map(|s| s.parse::<usize>().map_err(|e| e.into()))
        .collect::<Result<Vec<_>>>()?;
      if let [width, height] = parts[..] {
        scene.image_width = width;
        scene.image_height = height;
      }
    }
    // Do float parsing instead
    else {
      let parts = parts
        .map(|s| s.parse::<f64>().map_err(|e| e.into()))
        .collect::<Result<Vec<_>>>()?;

      let read_vec3 = || {
        if parts.len() < 3 {
          bail!("Vec3 requires 3 components.");
        }
        Ok(Vec3::new(parts[0], parts[1], parts[2]))
      };

      match keyword {
        "eye" => scene.eye_pos = read_vec3()?,
        "viewdir" => scene.view_dir = read_vec3()?,
        "updir" => scene.up_dir = read_vec3()?,

        "hfov" => scene.hfov = parts[0],
        "bkgcolor" => scene.bkg_color = read_vec3()?,
        "mtlcolor" => material_color = Some(read_vec3()?),

        "sphere" => scene.objects.push(Object::Sphere(Sphere {
          center: read_vec3()?,
          radius: parts[3],
        })),
        _ => bail!("Unknown keyword {keyword}"),
      }
    }
  }

  Ok(scene)
}