/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

pub mod dns;

use std::{
    net::SocketAddr,
    task::{self, Poll},
};

use futures::Future;
use hyper::client::connect::dns::Name;
use tower_service::Service;

pub trait Resolve {
    type Addrs: Iterator<Item = SocketAddr>;
    type Error: Into<Box<dyn std::error::Error + Send + Sync>>;
    type Future: Future<Output = Result<Self::Addrs, Self::Error>>;

    fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>>;
    fn resolve(&mut self, name: Name) -> Self::Future;
}

impl<S> Resolve for S
where
    S: Service<String>,
    S::Response: Iterator<Item = SocketAddr>,
    S::Error: Into<Box<dyn std::error::Error + Send + Sync>>,
{
    type Addrs = S::Response;

    type Error = S::Error;

    type Future = S::Future;

    fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), Self::Error>> {
        S::poll_ready(self, cx)
    }

    fn resolve(&mut self, name: Name) -> Self::Future {
        S::call(self, name.to_string())
    }
}