use color_eyre::eyre::{anyhow, bail, Context, Result};
use color_eyre::owo_colors::OwoColorize;
use mumble_web2_common::GuiConfig;
use once_cell::sync::OnceCell;
use rcgen::date_time_ymd;
use salvo::conn::rustls::{Keycert, RustlsConfig};
use salvo::cors::{AllowOrigin, Cors};
use salvo::logging::Logger;
use salvo::prelude::*;
use salvo::proto::quic::BidiStream;
use serde::{Deserialize, Serialize};
use std::net::{SocketAddr, ToSocketAddrs};
use std::path::PathBuf;
use std::sync::{Arc, Mutex};
use tokio::fs;
use tokio::io::{AsyncRead, AsyncReadExt, AsyncWrite, AsyncWriteExt};
use tokio::net::TcpStream;
use tokio::pin;
use tokio_rustls::rustls::client::danger::{HandshakeSignatureValid, ServerCertVerifier};
use tokio_rustls::rustls::pki_types::{CertificateDer, ServerName, UnixTime};
use tokio_rustls::rustls::{ClientConfig, DigitallySignedStruct};
use tokio_rustls::{rustls, TlsConnector};
use tracing::info;
use tracing::info_span;
use tracing::Instrument;
use tracing::{error, instrument};
use tracing_subscriber::filter::LevelFilter;
use tracing_subscriber::EnvFilter;

fn default_cert_alt_names() -> Vec<String> {
    vec!["localhost".into()]
}

#[derive(Deserialize)]
struct Config {
    https_listen_address: SocketAddr,
    http_listen_address: Option<SocketAddr>,
    cert_path: Option<PathBuf>,
    key_path: Option<PathBuf>,
    #[serde(default = "default_cert_alt_names")]
    cert_alt_names: Vec<String>,
    mumble_server_url: String,
    mumble_server_address: Option<SocketAddr>,
    gui_path: PathBuf,
    gui: Mutex<GuiConfig>,
}

static CONFIG: OnceCell<Config> = OnceCell::new();

#[handler]
#[instrument]
async fn serve_gui_index_html(req: &Request, res: &mut Response) {
    let config = CONFIG.get().unwrap();

    // Load the HTML file
    let path = config.gui_path.join("index.html");
    let html = match fs::read_to_string(&path).await {
        Ok(content) => content,
        Err(err) => {
            error!("could not load {}: {:?}", path.display(), err);
            res.status_code(StatusCode::INTERNAL_SERVER_ERROR);
            return;
        }
    };

    // Insert the script tag with configuration
    let modified_html = html.replace(
        "</head>",
        &format!(
            "<script>window.config = {}</script>\n</head>",
            serde_json::to_string(&config.gui).unwrap(),
        ),
    );
    res.render(Text::Html(modified_html));
}

async fn init_config() -> Result<()> {
    let mut config: Config = toml::from_str(
        &fs::read_to_string("./config.toml")
            .await
            .context("reading config.toml (try making a copy of config.toml.example)")?,
    )?;
    let mumble_server_addr = config
        .mumble_server_url
        .to_socket_addrs()
        .context(format!(
            "parsing mumble_server_url={}",
            config.mumble_server_url
        ))?
        .next()
        .ok_or(anyhow!(
            "no socket addrs in mumble_server_url={}",
            config.mumble_server_url
        ))?;
    config.mumble_server_address = Some(mumble_server_addr);
    CONFIG
        .set(config)
        .map_err(|_| anyhow!("config already initialized"))?;
    Ok(())
}

#[tokio::main]
async fn main() -> Result<()> {
    init_logging();
    init_config().await?;
    let config = CONFIG.get().unwrap();
    info!("config\n{}", toml::to_string_pretty(&config.gui)?);
    info!("gui config\n{}", serde_json::to_string_pretty(&config.gui)?);

    rustls::crypto::aws_lc_rs::default_provider()
        .install_default()
        .map_err(|e| anyhow!("could not install crypto provider {e:?}"))?;

    let (cert, key) = match (&config.cert_path, &config.key_path) {
        (None, None) => {
            info!("generating self-signed cert");

            // FIXME: redo every <14 days
            let mut dname = rcgen::DistinguishedName::new();
            dname.push(rcgen::DnType::CommonName, "mumble-web self-signed");
            let key_pair = rcgen::KeyPair::generate_for(&rcgen::PKCS_ECDSA_P256_SHA256)?;
            let mut cert_params = rcgen::CertificateParams::new(config.cert_alt_names.clone())?;
            cert_params.distinguished_name = dname;
            cert_params.not_before = time::OffsetDateTime::now_utc();
            cert_params.not_after = cert_params.not_before + time::Duration::days(12);
            let cert = cert_params.self_signed(&key_pair)?;

            let hash = hmac_sha256::Hash::hash(cert.der().as_ref());
            {
                let mut gui_config = config.gui.lock().unwrap();
                gui_config.cert_hash = Some(hash.into());
            }

            (cert.pem().into(), key_pair.serialize_pem().into())
        }
        (Some(cert_path), Some(key_path)) => {
            // Read server certs
            let cert = fs::read(cert_path)
                .await
                .context(format!("reading cert {}", cert_path.display()))?;
            let key = fs::read(key_path)
                .await
                .context(format!("reading key {}", key_path.display()))?;
            (cert, key)
        }
        _ => {
            bail!("please supply both cert_path and key_path (or neither to generate a self-signed cert)")
        }
    };
    let rustls_config = RustlsConfig::new(Keycert::new().cert(cert.as_slice()).key(key.as_slice()));

    let config_craft = ConfigCraft {
        client_config: MumbleClientConfig {
            force_proxy: true,
            proxy_url: "https://localhost:4433".to_string(),
            cert_hash: config.gui.lock().unwrap().cert_hash.clone().unwrap(),
        },
    };

    // Server routing
    let router = Router::new()
        .get(serve_gui_index_html)
        .push(Router::with_path("/proxy").goal(connect_proxy))
        .push(Router::with_path("/config").get(config_craft.get_config()))
        .push(Router::with_path("/<*+rest>").get(StaticDir::new(config.gui_path.clone())))
        .hoop(Logger::new());

    let cors = Cors::new().allow_origin(AllowOrigin::any()).into_handler();

    let service = Service::new(router).hoop(cors);

    // Create http listeners
    let http_listener = config.http_listen_address.map(TcpListener::new);
    let https_listener =
        TcpListener::new(config.https_listen_address).rustls(rustls_config.clone());
    let http3_listener = QuinnListener::new(rustls_config, config.https_listen_address);

    // Start server
    match (http_listener, https_listener, http3_listener) {
        (Some(a), b, c) => {
            let accepter = a.join(b).join(c).bind().await;
            Server::new(accepter).serve(service).await;
        }
        (None, b, c) => {
            let accepter = b.join(c).bind().await;
            Server::new(accepter).serve(service).await;
        }
    }

    Ok(())
}

#[derive(Serialize, Clone)]
struct MumbleClientConfig {
    force_proxy: bool,
    proxy_url: String,
    cert_hash: Vec<u8>,
}

#[derive(Clone)]
pub struct ConfigCraft {
    client_config: MumbleClientConfig,
}

#[craft]
impl ConfigCraft {
    #[craft(handler)]
    async fn get_config(&self) -> Json<MumbleClientConfig> {
        Json(self.client_config.clone())
    }
}

#[handler]
#[instrument]
async fn connect_proxy(req: &mut Request, res: &mut Response) {
    info!("received proxy request");
    let mumble_server_address = CONFIG.get().unwrap().mumble_server_address.unwrap();

    let wt = match req.web_transport_mut().await {
        Ok(wt) => wt,
        Err(err) => {
            res.status_code(StatusCode::BAD_REQUEST);
            res.render(format!("error with webtransport: {err:?}"));
            return;
        }
    };
    info!("got webtransport for connection");

    use salvo::webtransport::server::AcceptedBi;
    let (id, bi) = match wt.accept_bi().await {
        Ok(Some(AcceptedBi::BidiStream(id, bi))) => (id, bi),
        Ok(Some(AcceptedBi::Request(req, _))) => {
            res.status_code(StatusCode::BAD_REQUEST);
            res.render(format!(
                "expected webtransport stream but got request {req:?}"
            ));
            return;
        }
        Ok(None) => {
            res.status_code(StatusCode::BAD_REQUEST);
            res.render(format!("no bidirectional connection requested"));
            return;
        }
        Err(err) => {
            res.status_code(StatusCode::INTERNAL_SERVER_ERROR);
            res.render(format!("error with bidirectional connection: {err:?}"));
            return;
        }
    };

    /*
    let id = wt.session_id();
    let bi = match wt.open_bi(id).await {
        Ok(bi) => bi,
        Err(err) => {
            res.status_code(StatusCode::BAD_REQUEST);
            res.render(format!("could not open bidirectional stream: {err:?}"));
            return;
        }
    };
    */

    let (outgoing, incoming) = bi.split();
    let res = tokio::spawn(async move {
        if let Err(error) = connect_proxy_impl(mumble_server_address, incoming, outgoing).await {
            error!("error connecting proxy {error:?}")
        }
    })
    .await;
    if let Err(err) = res {
        error!("crash in connected proxy {err:?}");
    }
}

#[instrument(skip(incoming, outgoing))]
async fn connect_proxy_impl(
    mumble_server_address: SocketAddr,
    incoming: impl AsyncRead + Send + Sync + 'static,
    outgoing: impl AsyncWrite + Send + Sync + 'static,
) -> Result<()> {
    info!("connecting to Mumble server...");

    let config = ClientConfig::builder()
        .dangerous()
        .with_custom_certificate_verifier(Arc::new(NoCertificateVerification))
        .with_no_client_auth();

    let connector = TlsConnector::from(Arc::new(config));

    let server_tcp = TcpStream::connect(mumble_server_address).await?;
    let server_stream = connector
        .connect("example.com".try_into()?, server_tcp)
        .await?;
    let (read_server, write_server) = tokio::io::split(server_stream);

    info!("connected to Mumble server");

    // Spawn tasks to handle transmitting data between the WebTransport client and Mumble TCP Server
    let c2s = tokio::spawn(
        pass_bytes_loop(incoming, write_server)
            .instrument(info_span!("Handler", "Client to server")),
    );
    let s2c = tokio::spawn(
        pass_bytes_loop(read_server, outgoing)
            .instrument(info_span!("Handler", "Server to client")),
    );

    tokio::select! {
        res = c2s => res??,
        res = s2c => res??,
    };
    Ok(())
}

#[derive(Debug)]
struct NoCertificateVerification;

impl ServerCertVerifier for NoCertificateVerification {
    fn verify_server_cert(
        &self,
        _end_entity: &CertificateDer<'_>,
        _intermediates: &[CertificateDer<'_>],
        _server_name: &ServerName<'_>,
        _ocsp: &[u8],
        _now: UnixTime,
    ) -> Result<rustls::client::danger::ServerCertVerified, rustls::Error> {
        Ok(rustls::client::danger::ServerCertVerified::assertion())
    }

    fn verify_tls12_signature(
        &self,
        _message: &[u8],
        _cert: &CertificateDer<'_>,
        _dss: &DigitallySignedStruct,
    ) -> Result<HandshakeSignatureValid, rustls::Error> {
        Ok(HandshakeSignatureValid::assertion())
    }

    fn verify_tls13_signature(
        &self,
        _message: &[u8],
        _cert: &CertificateDer<'_>,
        _dss: &DigitallySignedStruct,
    ) -> Result<HandshakeSignatureValid, rustls::Error> {
        Ok(HandshakeSignatureValid::assertion())
    }

    fn supported_verify_schemes(&self) -> Vec<rustls::SignatureScheme> {
        vec![
            rustls::SignatureScheme::RSA_PKCS1_SHA1,
            rustls::SignatureScheme::ECDSA_SHA1_Legacy,
            rustls::SignatureScheme::RSA_PKCS1_SHA256,
            rustls::SignatureScheme::ECDSA_NISTP256_SHA256,
            rustls::SignatureScheme::RSA_PKCS1_SHA384,
            rustls::SignatureScheme::ECDSA_NISTP384_SHA384,
            rustls::SignatureScheme::RSA_PKCS1_SHA512,
            rustls::SignatureScheme::ECDSA_NISTP521_SHA512,
            rustls::SignatureScheme::RSA_PSS_SHA256,
            rustls::SignatureScheme::RSA_PSS_SHA384,
            rustls::SignatureScheme::RSA_PSS_SHA512,
            rustls::SignatureScheme::ED25519,
            rustls::SignatureScheme::ED448,
        ]
    }
}

async fn pass_bytes_loop(
    client_stream: impl AsyncRead + Sync + Send + 'static,
    server_stream: impl AsyncWrite + Send + Sync + 'static,
) -> Result<()> {
    let mut buffer = vec![0; 65536].into_boxed_slice();
    pin!(client_stream);
    pin!(server_stream);
    loop {
        let bytes_read = client_stream.read(&mut buffer).await?;
        if bytes_read == 0 {
            break Ok(());
        }

        server_stream.write_all(&buffer[..bytes_read]).await?;
        server_stream.flush().await?;
    }
}

fn init_logging() {
    let env_filter = EnvFilter::builder()
        .with_default_directive(LevelFilter::DEBUG.into())
        .from_env_lossy();

    tracing_subscriber::fmt()
        .with_target(true)
        .with_level(true)
        .with_env_filter(env_filter)
        .init();
}