use std::net::{Ipv4Addr, SocketAddr};

use axum::{routing::get, Router};
use axum_server::tls_rustls::RustlsConfig;
use color_eyre::{eyre::Context, Result};
use http::StatusCode;
use tower_http::trace::TraceLayer;
use tracing::{info, level_filters::LevelFilter};
use webfinger_rs::{Link, Rel, WebFingerRequest, WebFingerResponse, WELL_KNOWN_PATH};

const SUBJECT: &str = "acct:carol@localhost";

#[tokio::main]
async fn main() -> Result<()> {
    color_eyre::install()?;
    tracing_subscriber::fmt()
        .with_max_level(LevelFilter::DEBUG)
        .init();

    let addr = SocketAddr::new(Ipv4Addr::LOCALHOST.into(), 3000);
    let router = Router::new()
        .route(WELL_KNOWN_PATH, get(webfinger))
        .route_layer(TraceLayer::new_for_http())
        .into_make_service();
    let config = tls_config().await?;

    info!("Listening at https://{addr:?}{WELL_KNOWN_PATH}?resource={SUBJECT}");
    axum_server::bind_rustls(addr, config).serve(router).await?;

    Ok(())
}

/// Generate a self-signed certificate for localhost
async fn tls_config() -> Result<RustlsConfig> {
    let self_signed_cert = rcgen::generate_simple_self_signed(vec!["localhost".to_string()])
        .wrap_err("failed to generate self signed certificat for localhost")?;
    let cert = self_signed_cert.cert.der().to_vec();
    let key = self_signed_cert.key_pair.serialize_der();
    RustlsConfig::from_der(vec![cert], key)
        .await
        .wrap_err("failed to create tls config")
}

async fn webfinger(request: WebFingerRequest) -> axum::response::Result<WebFingerResponse> {
    info!("fetching webfinger resource: {:?}", request);
    let subject = request.resource.to_string();
    if subject != SUBJECT {
        let message = format!("{subject} does not exist");
        return Err((StatusCode::NOT_FOUND, message).into());
    }
    let rel = Rel::new("http://webfinger.net/rel/profile-page");
    let response = if request.rels.is_empty() || request.rels.contains(&rel) {
        let link = Link::builder(rel).href(format!("https://example.com/profile/{subject}"));
        WebFingerResponse::builder(subject).link(link).build()
    } else {
        WebFingerResponse::builder(subject).build()
    };
    Ok(response)
}