cookcli 0.38.1

A command-line interface for managing and working with Cooklang recipes
Documentation 
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//! SSE endpoint that streams `.shopping-list` / `.shopping-checked` change
//! pings to the browser. Each event names the file that changed, and the
//! client re-fetches what that file feeds via the existing JSON endpoints.

use crate::server::shopping_list_watcher::{ShoppingListChangeEvent, WatchedFile};
use crate::server::AppState;
use axum::{
    extract::State,
    response::sse::{Event, KeepAlive, Sse},
};
use futures_util::stream::{self, Stream};
use std::{convert::Infallible, sync::Arc, time::Duration};
use tokio_stream::wrappers::BroadcastStream;
use tokio_stream::StreamExt;

pub async fn shopping_list_events(
    State(state): State<Arc<AppState>>,
) -> Sse<impl Stream<Item = Result<Event, Infallible>>> {
    let stream: Box<dyn Stream<Item = Result<Event, Infallible>> + Send + Unpin> =
        match &state.shopping_list_events {
            Some(tx) => {
                let rx = tx.subscribe();
                // A receiver that fell behind has lost events it can't get
                // back, so it's told the list changed, which has the client
                // re-fetch everything. Channel close would end the stream,
                // but the sender is held by AppState for the life of the
                // process.
                let s = BroadcastStream::new(rx).map(|res| {
                    let evt = res.unwrap_or_else(|_lagged| {
                        tracing::debug!(
                            "SSE subscriber lagged — sending it a full-list change instead"
                        );
                        ShoppingListChangeEvent {
                            file: WatchedFile::List,
                        }
                    });
                    Ok(Event::default()
                        .event("change")
                        .json_data(evt)
                        .unwrap_or_else(|_| Event::default().event("change")))
                });
                Box::new(s)
            }
            None => {
                // Watcher failed to init; serve a well-formed but silent stream.
                Box::new(stream::pending::<Result<Event, Infallible>>())
            }
        };

    Sse::new(stream).keep_alive(
        KeepAlive::new()
            .interval(Duration::from_secs(30))
            .text("ping"),
    )
}