Spry/website/Endpoints/CounterSseEndpoint.vala

using Astralis;
using Invercargill;
using Invercargill.DataStructures;
using Inversion;
using Spry;

/**
 * CounterSseEndpoint - Singleton SSE endpoint for counter updates
 * 
 * Broadcasts counter value updates to all connected clients
 * when counter actions are triggered (Increment, Decrement, Reset)
 * 
 * Uses the Astralis SseEndpoint pattern - NOT continuations.
 */
public class CounterSseEndpoint : SseEndpoint {
    
    private AuroraState aurora_state;
    
    public CounterSseEndpoint(AuroraState aurora_state) {
        this.aurora_state = aurora_state;
    }
    
    /// Retry interval: clients should wait 2 seconds before reconnecting
    public override uint retry_interval { get { return 2000; } }
    
    /// Called when a new client connects - send current counter value
    public override async void new_connection(HttpContext http_context, RouteContext route_context, SseStream stream) {
        print(@"Counter SSE client connected (total: $(get_open_streams().length))\n");
        
        // Send current counter value to new client
        try {
            yield send_counter_update(stream);
        } catch (Error e) {
            print(@"Failed to send counter update: $(e.message)\n");
        }
        
        stream.disconnected.connect(() => {
            print(@"Counter SSE client disconnected\n");
        });
    }
    
    /// Increment counter and broadcast update
    public async void increment() {
        aurora_state.counter++;
        yield broadcast_counter_update();
    }
    
    /// Decrement counter and broadcast update
    public async void decrement() {
        aurora_state.counter--;
        yield broadcast_counter_update();
    }
    
    /// Reset counter and broadcast update
    public async void reset() {
        aurora_state.counter = 0;
        yield broadcast_counter_update();
    }
    
    /// Broadcast counter update to all connected clients
    private async void broadcast_counter_update() {
        try {
            string counter_html = build_counter_html();
            var counter_event = new SseEvent.with_type("counter-value", counter_html);
            yield broadcast_event(counter_event);
        } catch (Error e) {
            printerr(@"Failed to broadcast counter update: $(e.message)\n");
        }
    }
    
    /// Send counter update to a single stream (for new connections)
    private async void send_counter_update(SseStream stream) throws Error {
        string counter_html = build_counter_html();
        yield stream.send_event(new SseEvent.with_type("counter-value", counter_html));
    }
    
    /// Build the counter value HTML
    private string build_counter_html() {
        return aurora_state.counter.to_string();
    }
}