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use futures_util::{Stream, StreamExt};
use std::collections::HashMap;
use std::sync::{
atomic::{AtomicUsize, Ordering},
Arc, Mutex,
};
use tokio::sync::mpsc;
use tokio_stream::wrappers::UnboundedReceiverStream;
use warp::{sse::Event, Filter};
#[tokio::main]
async fn main() {
pretty_env_logger::init();
// Keep track of all connected users, key is usize, value
// is an event stream sender.
let users = Arc::new(Mutex::new(HashMap::new()));
// Turn our "state" into a new Filter...
let users = warp::any().map(move || users.clone());
// POST /chat -> send message
let chat_send = warp::path("chat")
.and(warp::post())
.and(warp::path::param::<usize>())
.and(warp::body::content_length_limit(500))
.and(
warp::body::bytes().and_then(|body: bytes::Bytes| async move {
std::str::from_utf8(&body)
.map(String::from)
.map_err(|_e| warp::reject::custom(NotUtf8))
}),
)
.and(users.clone())
.map(|my_id, msg, users| {
user_message(my_id, msg, &users);
warp::reply()
});
// GET /chat -> messages stream
let chat_recv = warp::path("chat").and(warp::get()).and(users).map(|users| {
// reply using server-sent events
let stream = user_connected(users);
warp::sse::reply(warp::sse::keep_alive().stream(stream))
});
// GET / -> index html
let index = warp::path::end().map(|| {
warp::http::Response::builder()
.header("content-type", "text/html; charset=utf-8")
.body(INDEX_HTML)
});
let routes = index.or(chat_recv).or(chat_send);
warp::serve(routes).run(([127, 0, 0, 1], 3030)).await;
}
/// Our global unique user id counter.
static NEXT_USER_ID: AtomicUsize = AtomicUsize::new(1);
/// Message variants.
#[derive(Debug)]
enum Message {
UserId(usize),
Reply(String),
}
#[derive(Debug)]
struct NotUtf8;
impl warp::reject::Reject for NotUtf8 {}
/// Our state of currently connected users.
///
/// - Key is their id
/// - Value is a sender of `Message`
type Users = Arc<Mutex<HashMap<usize, mpsc::UnboundedSender<Message>>>>;
fn user_connected(users: Users) -> impl Stream<Item = Result<Event, warp::Error>> + Send + 'static {
// Use a counter to assign a new unique ID for this user.
let my_id = NEXT_USER_ID.fetch_add(1, Ordering::Relaxed);
eprintln!("new chat user: {}", my_id);
// Use an unbounded channel to handle buffering and flushing of messages
// to the event source...
let (tx, rx) = mpsc::unbounded_channel();
let rx = UnboundedReceiverStream::new(rx);
tx.send(Message::UserId(my_id))
// rx is right above, so this cannot fail
.unwrap();
// Save the sender in our list of connected users.
users.lock().unwrap().insert(my_id, tx);
// Convert messages into Server-Sent Events and return resulting stream.
rx.map(|msg| match msg {
Message::UserId(my_id) => Ok(Event::default().event("user").data(my_id.to_string())),
Message::Reply(reply) => Ok(Event::default().data(reply)),
})
}
fn user_message(my_id: usize, msg: String, users: &Users) {
let new_msg = format!("<User#{}>: {}", my_id, msg);
// New message from this user, send it to everyone else (except same uid)...
//
// We use `retain` instead of a for loop so that we can reap any user that
// appears to have disconnected.
users.lock().unwrap().retain(|uid, tx| {
if my_id == *uid {
// don't send to same user, but do retain
true
} else {
// If not `is_ok`, the SSE stream is gone, and so don't retain
tx.send(Message::Reply(new_msg.clone())).is_ok()
}
});
}
static INDEX_HTML: &str = r#"
<!DOCTYPE html>
<html>
<head>
<title>Warp Chat</title>
</head>
<body>
<h1>warp chat</h1>
<div id="chat">
<p><em>Connecting...</em></p>
</div>
<input type="text" id="text" />
<button type="button" id="send">Send</button>
<script type="text/javascript">
var uri = 'http://' + location.host + '/chat';
var sse = new EventSource(uri);
function message(data) {
var line = document.createElement('p');
line.innerText = data;
chat.appendChild(line);
}
sse.onopen = function() {
chat.innerHTML = "<p><em>Connected!</em></p>";
}
var user_id;
sse.addEventListener("user", function(msg) {
user_id = msg.data;
});
sse.onmessage = function(msg) {
message(msg.data);
};
send.onclick = function() {
var msg = text.value;
var xhr = new XMLHttpRequest();
xhr.open("POST", uri + '/' + user_id, true);
xhr.send(msg);
text.value = '';
message('<You>: ' + msg);
};
</script>
</body>
</html>
"#;