use std::{
	env,
	fs::{self, DirEntry, File},
	io::{self, Write},
	path::{Path, PathBuf},
};

fn main() -> Result<(), Box<dyn std::error::Error>> {
	let out_dir = env::var("OUT_DIR").unwrap();
	compile(
		PathBuf::from("scss/index.scss"),
		PathBuf::from(out_dir).join("styles.css"),
	)?;

	let here = Path::new(".").canonicalize()?;

	visit_dirs(&here, &handle_dir)?;

	Ok(())
}

fn handle_dir(e: &DirEntry) -> Result<(), Box<dyn std::error::Error>> {
	let path = e.path();

	if path.extension().is_some() && path.extension().unwrap().eq("scss") {
		let mut output = path.clone();
		output.set_extension("css");

		compile(path, output)?;
	}

	Ok(())
}

fn compile(input: PathBuf, output: PathBuf) -> Result<(), Box<dyn std::error::Error>> {
	if PathBuf::from("scss/index.scss").canonicalize()?.eq(&input) {
		return Ok(());
	}

	let out_dir = env::var("OUT_DIR").unwrap();
	let output = PathBuf::from(out_dir).join(output.file_name().unwrap());

	let mut output = File::create(output)?;

	let opts = grass::Options::default();
	let opts = opts.style(grass::OutputStyle::Compressed);

	let css_text = grass::from_path(input, &opts).unwrap_or_else(|e| {
		panic!("Sass Error: {e:#?}");
	});

	output.write_all(css_text.as_bytes())?;

	Ok(())
}

#[allow(clippy::type_complexity)]
fn visit_dirs(
	dir: &Path,
	cb: &dyn Fn(&DirEntry) -> Result<(), Box<dyn std::error::Error>>,
) -> io::Result<()> {
	let ignore = |pattern: &str| -> bool { dir.file_name().unwrap().eq(pattern) };

	if dir.is_dir() && !ignore(".git") && !ignore("target") && !ignore("scss") {
		for entry in fs::read_dir(dir)? {
			let entry = entry?;
			let path = entry.path();
			if path.is_dir() {
				visit_dirs(&path, cb)?;
			} else {
				cb(&entry).unwrap();
			}
		}
	}
	Ok(())
}