use futures::{SinkExt, StreamExt};
use std::net::SocketAddr;
use std::sync::atomic::AtomicUsize;
use std::sync::Arc;
use std::{collections::HashMap, env};
use tokio::sync::mpsc::{unbounded_channel, UnboundedSender};
use tokio::sync::RwLock;
use tokio_stream::wrappers::UnboundedReceiverStream;
use warp::ws::Message;
use warp::Filter;
/// A representation of the clients to the server. These are only the clients
/// that will be told about reloads, any user can command a reload over the HTTP
/// endpoint (unauthenticated because this is a development server).
type Clients = Arc<RwLock<HashMap<usize, UnboundedSender<Message>>>>;
/// A simple counter that can be incremented from anywhere. This will be used as
/// the source of the next user ID. This is an atomic `usize` for maximum
/// platform portability (see the Rust docs on atomic primitives).
static NEXT_UID: AtomicUsize = AtomicUsize::new(0);
/// Runs the reload server, which is used to instruct the browser on when to
/// reload for updates.
pub async fn run_reload_server(host: String, port: u16) {
// Parse `localhost` into `127.0.0.1` (picky Rust `std`)
let host = if host == "localhost" {
"127.0.0.1".to_string()
} else {
host
};
// Parse the host and port into an address
let addr: SocketAddr = format!("{}:{}", host, port).parse().unwrap();
let clients = Clients::default();
let clients = warp::any().map(move || clients.clone());
// This will be used by the CLI to order reloads
let command = warp::path("send")
.and(clients.clone())
.then(|clients: Clients| async move {
// Iterate through all the clients and tell them all to reload
for (_id, tx) in clients.read().await.iter() {
// We don't care if this fails, that means the client has disconnected and the
// disconnection code will be running
let _ = tx.send(Message::text("reload"));
}
"sent".to_string()
});
// This will be used by the browser to listen for reload orders
let receive = warp::path("receive").and(warp::ws()).and(clients).map(
|ws: warp::ws::Ws, clients: Clients| {
// This code will run once the WS handshake completes
ws.on_upgrade(|ws| async move {
// Assign a new ID to this user
// This nifty operation just gets the current value and then increments
let id = NEXT_UID.fetch_add(1, std::sync::atomic::Ordering::Relaxed);
// Split out their sender/receiver
let (mut ws_tx, mut ws_rx) = ws.split();
// Use an unbounded channel as an intermediary to the WebSocket
let (tx, rx) = unbounded_channel();
let mut rx = UnboundedReceiverStream::new(rx);
tokio::task::spawn(async move {
// Whenever a message come sin on that intermediary channel, we'll just relay it
// to the client
while let Some(message) = rx.next().await {
let _ = ws_tx.send(message).await;
}
});
// Save the sender and their intermediary channel
clients.write().await.insert(id, tx);
// Because we don't accept messages from listening clients, we'll just hold a
// loop until the client disconnects Then, this will become
// `None` and we'll move on
while ws_rx.next().await.is_some() {
continue;
}
// Once we're here, the client has disconnected
clients.write().await.remove(&id);
})
},
);
let routes = command.or(receive);
warp::serve(routes).run(addr).await
}
/// Orders all connected browsers to reload themselves. This spawns a blocking
/// task through Tokio under the hood. Note that this will only do anything if
/// `PERSEUS_USE_RELOAD_SERVER` is set to `true`.
pub fn order_reload(host: String, port: u16) {
// This environment variable is only for use by the CLI internally
if env::var("PERSEUS_USE_RELOAD_SERVER").is_ok() {
tokio::task::spawn(async move {
// We don't care if this fails because we have no guarantees that the server is
// actually up
let _ = reqwest::get(&format!("http://{}:{}/send", host, port)).await;
});
}
}