use std::{
    env,
    fs::{self, DirEntry},
    path::Path,
};

fn include_dir(d: &DirEntry) -> bool {
    d.metadata().map(|m| m.is_dir()).unwrap_or(false)
        && d.path()
            .iter()
            .nth(2)
            .map_or(false, |c| c.to_str().map_or(false, |x| !x.starts_with("_")))
}

fn generate_header<P: AsRef<Path>>(config_path: P) {
    let config_path = config_path.as_ref();
    let relative_path = config_path
        .strip_prefix("src/header")
        .ok()
        .and_then(|p| p.parent())
        .and_then(|p| p.to_str())
        .unwrap()
        .replace("_", "/");
    // TODO use outer workspace's target directory?
    let header_path = Path::new("target/include")
        .join(&relative_path)
        .with_extension("h");
    let mod_path = config_path.with_file_name("mod.rs");

    let config = cbindgen::Config::from_file(config_path).unwrap();

    cbindgen::Builder::new()
        .with_config(config)
        .with_src(mod_path)
        .generate()
        .unwrap()
        .write_to_file(header_path);
}

fn main() {
    fs::read_dir("src/header")
        .unwrap()
        .into_iter()
        .filter_map(Result::ok)
        .filter(|d| include_dir(d))
        .map(|d| d.path().as_path().join("cbindgen.toml"))
        .filter(|p| p.exists())
        .for_each(|p| {
            println!("cargo:rerun-if-changed={:?}", p.parent().unwrap());
            println!("cargo:rerun-if-changed={:?}", p);
            println!("cargo:rerun-if-changed={:?}", p.with_file_name("mod.rs"));
            generate_header(&p);
        });
}