use std::{fmt::Display, str::FromStr};

macro_rules! header {
    ($hname:literal, struct $name:ident($type:ty)) => {
        pub struct $name(pub $type);
        impl Header for $name {
            const NAME: &'static str = $hname;
        }
        impl Display for $name {
            fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
                write!(f, "{}", self.0)
            }
        }
        impl FromStr for $name {
            type Err = anyhow::Error;
            fn from_str(s: &str) -> Result<Self, Self::Err> {
                Ok($name(<$type>::from_str(s)?))
            }
        }
    };
}

pub trait Header: FromStr<Err = anyhow::Error> + Display {
    const NAME: &'static str;
}

header!("Content-Length", struct ContentLength(usize));
header!("Call-ID", struct CallID(String));
header!("CSeq", struct CSeq(String));
header!("Via", struct Via(String));
header!("Contact", struct Contact(String));
header!("Max-Forwards", struct MaxForwards(usize));
header!("From", struct From(String));
header!("To", struct To(String));
header!("User-Agent", struct UserAgent(String));
header!("Allow", struct Allow(String));