use listenfd::ListenFd;
use thiserror::Error;
use tokio::net::TcpListener;

use backend::{get_router, init, InitError};

#[derive(Error, Debug)]
pub enum BackendError {
    #[error("Error while setting up or serving the TCP listener")]
    ServeTCPListener(#[from] std::io::Error),
    #[error("Error while initialising the backend")]
    InitError(#[from] InitError),
}

#[tokio::main]
async fn main() -> Result<(), BackendError> {
    init()?;

    let app = get_router();

    let mut listenfd = ListenFd::from_env();

    let listener = match listenfd.take_tcp_listener(0)? {
        // if we are given a tcp listener on listen fd 0, we use that one
        Some(listener) => {
            listener.set_nonblocking(true)?;
            TcpListener::from_std(listener)?
        }
        // otherwise fall back to local listening
        None => TcpListener::bind("0.0.0.0:8080").await?,
    };

    let local_addr = listener.local_addr()?;
    println!("Listening on {}", local_addr);
    axum::serve(listener, app).await?;

    Ok(())
}