use std::{
    io::{Read, Write},
    net::TcpStream,
    str::FromStr,
    sync::Arc,
};

use anyhow::{bail, Result};
use rustls::{ClientConfig, ClientConnection, OwnedTrustAnchor, RootCertStore, StreamOwned};
use trust_dns_resolver::{
    config::{ResolverConfig, ResolverOpts},
    Resolver,
};

fn main() -> Result<()> {
    let (port, host) = resolve_dns("daeken.dev")?;

    dbg!(port);
    dbg!(host);

    let (port, host) = (443, "example.com".to_owned());

    let tls_conf = Arc::new(make_tls_config());
    let mut tls_conn = make_tls_connection(tls_conf, &host, port)?;

    tls_conn.write_all(
        concat!(
            "GET / HTTP/1.1\r\n",
            "Host: example.com\r\n",
            "Connection: close\r\n",
            "\r\n"
        )
        .as_bytes(),
    )?;

    let mut pt = Vec::new();
    tls_conn.read_to_end(&mut pt)?;
    println!("{}", String::from_utf8(pt)?);

    Ok(())
}

// TODO: How to cache this?
fn resolve_dns(server: &str) -> Result<(u16, String)> {
    let name = format!("_hypercosm._tls.{}", server);

    let resp = make_dns_client()?
        .srv_lookup(name)?
        .into_iter()
        .collect::<Vec<_>>();

    // TODO: Ensure exactly 1 result: I think.
    let srv = &resp[0];

    // TODO: Handle priority and weight.
    let port = srv.port();
    // TODO: Should this be ascii or utf8
    let name = srv.target().to_ascii();

    Ok((port, name))
}

fn make_dns_client() -> Result<Resolver> {
    Ok(Resolver::new(
        ResolverConfig::cloudflare_tls(),
        ResolverOpts::default(),
    )?)
}

fn make_tls_config() -> ClientConfig {
    let mut root_store = RootCertStore::empty();
    root_store.add_server_trust_anchors(webpki_roots::TLS_SERVER_ROOTS.0.iter().map(|ta| {
        OwnedTrustAnchor::from_subject_spki_name_constraints(
            ta.subject,
            ta.spki,
            ta.name_constraints,
        )
    }));
    let config = rustls::ClientConfig::builder()
        .with_safe_defaults()
        .with_root_certificates(root_store)
        .with_no_client_auth();

    config
}

fn make_tls_connection(
    config: Arc<ClientConfig>,
    server: &str,
    port: u16,
) -> Result<impl Read + Write> {
    let server_name = server.try_into()?;

    let conn = ClientConnection::new(config, server_name)?;
    let sock = TcpStream::connect((server, port))?;

    let stream = StreamOwned::new(conn, sock);

    Ok(stream)
}