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

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

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

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

    let tls_conf = Arc::new(make_tls_config());
    let mut tls_conn = make_tls_connection(tls_conf, &host, port)
        .with_context(|| format!("Can't connect to {}:{}", host, port))?;

    // let uuid =// Uuid::new_v4();

    let uuid = [b'a'; 16];
    dbg!(&uuid);
    tls_conn.write_all(&uuid).context("Can't write UUID")?;

    let mut serv_uuid = [0; 16];
    tls_conn.read_exact(&mut serv_uuid)?;
    dbg!(serv_uuid);

    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 cert_dir = include_bytes!("../cert.der");

    assert_eq!(
        root_store.add_parsable_certificates(&[cert_dir.to_vec()]),
        (1, 0)
    );

    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)
}