use std::error::Error;
use std::net::SocketAddr;
use std::sync::Arc;
use quinn::{ClientConfig, Endpoint};
use rustls::pki_types::CertificateDer;

/// 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: Option<&[&[u8]]>,
) -> Result<ClientConfig, Box<dyn Error + Send + Sync + 'static>> {
    if let Some(server_certs) = server_certs {
        let mut certs = rustls::RootCertStore::empty();
        for cert in server_certs {
            certs.add(CertificateDer::from(*cert))?;
        }

        Ok(ClientConfig::with_root_certificates(Arc::new(certs))?)
    } else {
        Ok(ClientConfig::with_platform_verifier())
    }
}

/// 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: Option<&[&[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)
}