feat: implement real-time booking updates using Server-Sent Events (SSE) and add public booking URL sharing to the dashboard

apps/backend/src/lib/mailer.ts

@@ -1,5 +1,5 @@
-import nodemailer from 'nodemailer';
 import { MailtrapClientConfig, MailtrapTransport } from 'mailtrap';
+import nodemailer from 'nodemailer';
 
 const TOKEN = Bun.env.MAILTRAP_API_TOKEN;
 
@@ -16,13 +16,11 @@ function getTransporter() {
     token: TOKEN,
     sandbox: Bun.env.MAIL_SANDBOX === 'true',
     testInboxId: Bun.env.MAIL_INBOX_ID ? Number(Bun.env.MAIL_INBOX_ID) : undefined,
-  }
+  };
 
   console.log(JSON.stringify(config, null, 2));
 
-  cachedTransporter = nodemailer.createTransport(
-    MailtrapTransport(config)
-  );
+  cachedTransporter = nodemailer.createTransport(MailtrapTransport(config));
   return cachedTransporter;
 }
 

apps/backend/src/lib/sse.ts

@@ -0,0 +1,84 @@
+import type { AppEnv } from '@/types/hono';
+import { Hono } from 'hono';
+
+type EventCallback = (data: string) => void;
+
+class SSEManager {
+  private channels: Map<string, Set<EventCallback>> = new Map();
+
+  subscribe(channel: string, callback: EventCallback): () => void {
+    if (!this.channels.has(channel)) {
+      this.channels.set(channel, new Set());
+    }
+    this.channels.get(channel)!.add(callback);
+
+    return () => {
+      const subs = this.channels.get(channel);
+      if (subs) {
+        subs.delete(callback);
+        if (subs.size === 0) {
+          this.channels.delete(channel);
+        }
+      }
+    };
+  }
+
+  emit(channel: string, data: string): void {
+    const subs = this.channels.get(channel);
+    if (subs) {
+      for (const callback of subs) {
+        callback(data);
+      }
+    }
+  }
+}
+
+export const sseManager = new SSEManager();
+
+export function registerEventsRoutes(app: Hono<AppEnv>) {
+  app.get('/api/events/:channel', async (c) => {
+    const channel = c.req.param('channel');
+
+    const stream = new ReadableStream({
+      start(controller) {
+        const encoder = new TextEncoder();
+
+        const send = (data: string) => {
+          try {
+            controller.enqueue(encoder.encode(`data: ${data}\n\n`));
+          } catch {
+            // Controller closed
+          }
+        };
+
+        send('connected');
+
+        const unsubscribe = sseManager.subscribe(channel, send);
+
+        const keepAliveInterval = setInterval(() => {
+          send('ping');
+        }, 30000);
+
+        c.req.raw.signal.addEventListener('abort', () => {
+          console.log(`[SSE] Connection closed for channel: ${channel}`);
+          clearInterval(keepAliveInterval);
+          unsubscribe();
+          try {
+            controller.close();
+          } catch {
+            // Already closed
+          }
+        });
+      },
+    });
+
+    return new Response(stream, {
+      headers: {
+        'Content-Type': 'text/event-stream',
+        'Cache-Control': 'no-cache',
+        Connection: 'keep-alive',
+        'X-Accel-Buffering': 'no',
+      },
+    });
+  });
+}