use std::{future::Future, io, net::IpAddr};

pub trait Resolver: Send + Sync {
    fn resolve(
        &self,
        host: &str,
        port: u16,
    ) -> impl Future<Output = io::Result<Vec<IpAddr>>> + Send;
}

#[derive(Clone, Copy, Debug, Default)]
pub struct SystemResolver;

impl Resolver for SystemResolver {
    async fn resolve(&self, host: &str, port: u16) -> io::Result<Vec<IpAddr>> {
        let addresses = tokio::net::lookup_host((host, port)).await?;
        let mut unique = Vec::new();
        for address in addresses {
            if !unique.contains(&address.ip()) {
                unique.push(address.ip());
            }
        }
        Ok(unique)
    }
}