use std::ops::RangeInclusive;

const PORT_RANGE: RangeInclusive<usize> = 1..=65535;

pub fn port_in_range(s: &str) -> Result<u16, String> {
    let port = s
        .parse()
        .map_err(|_| format!("{s} is not a valid port number"))?;

    if PORT_RANGE.contains(&port) {
        Ok(port as u16)
    } else {
        Err(format!(
            "port not in range {}-{}",
            PORT_RANGE.start(),
            PORT_RANGE.end()
        ))
    }
}

#[cfg(test)]
mod tests {
    use rand::Rng;

    use super::*;

    #[test]
    fn in_port_range() {
        let mut rng = rand::rng();
        let num = rng.random_range(PORT_RANGE);

        assert!(port_in_range(&num.to_string()).is_ok());
    }

    #[test]
    fn outside_port_range() {
        let mut rng = rand::rng();
        let num = rng.random_range((65535 + 1)..=usize::MAX);

        assert!(port_in_range(&num.to_string()).is_err());
    }
}