#![cfg(any(feature = "rustls-aws-lc-rs", feature = "rustls-ring"))]
//! Commonly used code in most examples.

use quinn::{ClientConfig, Endpoint, ServerConfig};
use rustls::pki_types::{CertificateDer, PrivatePkcs8KeyDer};

use std::{error::Error, net::SocketAddr, sync::Arc};

/// Constructs a QUIC endpoint configured for use a client only.
///
/// ## Args
///
/// - server_certs: list of trusted certificates.
#[allow(unused)]
pub fn make_client_endpoint(
    bind_addr: SocketAddr,
    server_certs: &[&[u8]],
) -> Result<Endpoint, Box<dyn Error + Send + Sync + 'static>> {
    let client_cfg = configure_client(server_certs)?;
    let mut endpoint = Endpoint::client(bind_addr)?;
    endpoint.set_default_client_config(client_cfg);
    Ok(endpoint)
}

/// Constructs a QUIC endpoint configured to listen for incoming connections on a certain address
/// and port.
///
/// ## Returns
///
/// - a stream of incoming QUIC connections
/// - server certificate serialized into DER format
#[allow(unused)]
pub fn make_server_endpoint(
    bind_addr: SocketAddr,
) -> Result<(Endpoint, CertificateDer<'static>), Box<dyn Error + Send + Sync + 'static>> {
    let (server_config, server_cert) = configure_server()?;
    let endpoint = Endpoint::server(server_config, bind_addr)?;
    Ok((endpoint, server_cert))
}

/// Builds default quinn client config and trusts given certificates.
///
/// ## Args
///
/// - server_certs: a list of trusted certificates in DER format.
fn configure_client(
    server_certs: &[&[u8]],
) -> Result<ClientConfig, Box<dyn Error + Send + Sync + 'static>> {
    let mut certs = rustls::RootCertStore::empty();
    for cert in server_certs {
        certs.add(CertificateDer::from(*cert))?;
    }

    Ok(ClientConfig::with_root_certificates(Arc::new(certs))?)
}

/// Returns default server configuration along with its certificate.
fn configure_server()
-> Result<(ServerConfig, CertificateDer<'static>), Box<dyn Error + Send + Sync + 'static>> {
    let cert = rcgen::generate_simple_self_signed(vec!["localhost".into()]).unwrap();
    let cert_der = CertificateDer::from(cert.cert);
    let priv_key = PrivatePkcs8KeyDer::from(cert.key_pair.serialize_der());

    let mut server_config =
        ServerConfig::with_single_cert(vec![cert_der.clone()], priv_key.into())?;
    let transport_config = Arc::get_mut(&mut server_config.transport).unwrap();
    transport_config.max_concurrent_uni_streams(0_u8.into());

    Ok((server_config, cert_der))
}

#[allow(unused)]
pub const ALPN_QUIC_HTTP: &[&[u8]] = &[b"hq-29"];
