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use axum::{
extract::State,
http::{HeaderName, HeaderValue},
response::{
sse::{self, Sse},
IntoResponse,
},
routing::get,
Router,
};
use axum_extra::{extract::Query, typed_header::TypedHeader};
use chrono::{format::SecondsFormat, DateTime};
use futures::{
future,
stream::{self, StreamExt as _, TryStreamExt as _},
};
use crate::{
app::App,
channel::repo::{channels::Id as ChannelId, messages::BroadcastMessage},
error::BoxedError,
error::InternalError,
login::repo::logins::Login,
};
pub fn router() -> Router<App> {
Router::new().route("/events", get(on_events))
}
#[derive(serde::Deserialize)]
struct EventsQuery {
#[serde(default, rename = "channel")]
channels: Vec<ChannelId>,
}
async fn on_events(
State(app): State<App>,
_: Login, // requires auth, but doesn't actually care who you are
last_event_id: Option<TypedHeader<LastEventId>>,
Query(query): Query<EventsQuery>,
) -> Result<impl IntoResponse, InternalError> {
let resume_at = last_event_id
.map(|TypedHeader(header)| header)
.map(|LastEventId(header)| header)
.map(|header| DateTime::parse_from_rfc3339(&header))
.transpose()?
.map(|ts| ts.to_utc());
let streams = stream::iter(query.channels)
.then(|channel| {
let app = app.clone();
async move { app.channels().events(&channel, resume_at.as_ref()).await }
})
.try_collect::<Vec<_>>()
.await?;
let stream = stream::select_all(streams).and_then(|msg| future::ready(to_event(msg)));
let sse = Sse::new(stream).keep_alive(sse::KeepAlive::default());
Ok(sse)
}
fn to_event(msg: BroadcastMessage) -> Result<sse::Event, BoxedError> {
let data = serde_json::to_string(&msg)?;
let event = sse::Event::default()
.id(msg
.sent_at
.to_rfc3339_opts(SecondsFormat::AutoSi, /* use_z */ true))
.data(&data);
Ok(event)
}
pub struct LastEventId(pub String);
static LAST_EVENT_ID: HeaderName = HeaderName::from_static("last-event-id");
impl headers::Header for LastEventId {
fn name() -> &'static HeaderName {
&LAST_EVENT_ID
}
fn decode<'i, I>(values: &mut I) -> Result<Self, headers::Error>
where
I: Iterator<Item = &'i HeaderValue>,
{
let value = values.next().ok_or_else(headers::Error::invalid)?;
if let Ok(value) = value.to_str() {
Ok(Self(value.into()))
} else {
Err(headers::Error::invalid())
}
}
fn encode<E>(&self, values: &mut E)
where
E: Extend<HeaderValue>,
{
let Self(value) = self;
// Must panic or suppress; the trait provides no other options.
let value = HeaderValue::from_str(value).expect("LastEventId is a valid header value");
values.extend(std::iter::once(value));
}
}
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