use libc;

pub fn getfullhostname() -> Option<String> {
    const MAX_HOSTNAME_LENGTH: usize = 255; // Max possible size as specified by POSIX
    let mut dest = [0 as i8; MAX_HOSTNAME_LENGTH];

    unsafe {
        let err = libc::gethostname(&mut dest[0] as *mut libc::c_char, MAX_HOSTNAME_LENGTH as libc::size_t);

        if err == 0 {
            match String::from_utf8(dest.into_iter()
                .filter(|c| **c > 0)
                .map(|c| *c as u8)
                .collect()) {
                Ok(s) => Some(s),
                Err(_) => None,
            }
        } else {
            None
        }
    }
}

pub fn gethostname() -> Option<String> {
    getfullhostname().and_then(|s| s.split('.').next().map(|s| s.to_string()))
}

#[cfg(test)]
mod tests {
    #[test]
    fn test_util_gethostname() {
        println!("{:?}", super::gethostname());
        println!("{:?}", super::getfullhostname());
    }
}