use std::convert::Infallible;

use rocket::{
    request::{self, FromRequest},
    Request,
};

macro_rules! header {
    ($name:ident, $header:expr) => {
        header!($name, $header, String, |header| header.to_owned());
    };
    ($name:ident, $header:expr, $type:ty, $handler:expr) => {
        pub struct $name(pub Option<$type>);

        #[rocket::async_trait]
        impl<'r> FromRequest<'r> for $name {
            type Error = Infallible;

            async fn from_request(req: &'r Request<'_>) -> request::Outcome<Self, Self::Error> {
                let header = req.headers().get_one($header);
                request::Outcome::Success(Self(header.map($handler)))
            }
        }
    };
}

header!(Referer, "Referer");
header!(AcceptLanguage, "Accept-Language", Vec<String>, |header| {
    accept_language::parse(header)
});