hs-bindgen-attribute 0.9.2

use semver::{Version, VersionReq};
use serde::Deserialize;
use std::{env, fs, path::Path};

/// Struct that map the content of `hsbindgen.toml` config file
#[derive(Deserialize)]
pub(crate) struct Config {
    pub(crate) default: Option<String>,
    pub(crate) version: Option<String>,
}

/// Read `hsbindgen.toml` config file generated by `cargo-cabal`
pub(crate) fn config() -> Config {
    let cargo_manifest_dir = env::var("CARGO_MANIFEST_DIR")
        .expect("environment variable `CARGO_MANIFEST_DIR` must be set");
    let cfg_path = Path::new(&cargo_manifest_dir).join("hsbindgen.toml");
    let cfg = fs::read_to_string(cfg_path).expect(
        "fail to read content of `hsbindgen.toml` configuration file
n.b. you have to run the command `cargo-cabal` to generate it",
    );
    let cfg = toml::from_str(&cfg).expect("fail to parse TOML content of `hsbindgen.toml` file");
    check_version(&cfg);
    cfg
}

/// Compatibility constraints on `cargo-cabal` version used
fn check_version(config: &Config) {
    let req = VersionReq::parse("<=0.8").unwrap();
    let version = config
        .version
        .as_ref()
        .expect("a version field is required in `hsbindgen.toml`");
    let version = Version::parse(version)
        .expect("version field of `hsbindgen.toml` does not follow SemVer format");
    assert!(
        req.matches(&version),
        "incompatible versions of `cargo-cabal`/`hs-bindgen` used, please update"
    );
}