Devices can now subscribe to specific topics.

- Device can now become (in)active
- Error alert makes sound
- Alerts now execute function on click

backend/endpoints/user.ts

@@ -232,7 +232,7 @@ export async function Resource(req: Request, res: Response) {
         return;
     }
 
-    // TODO: This has to change if we want to allow users to see the realtime movement of others.
+    // TODO: This has to change if we want to allow users to see the realtime movement of others. 
     if (resource.toString().startsWith('tracker-') && resource != 'tracker-' + username) {
         res.status(200).send('deny');
         return;
@@ -242,6 +242,34 @@ export async function Resource(req: Request, res: Response) {
 }
 
 export async function Topic(req: Request, res: Response) {
+    res.status(200);
+
+    const username = req.query.username;
+    const routingKey = req.query.routing_key;
+
+    if (routingKey === undefined || username === undefined) {
+        res.send('deny');
+        return;
+    }
+
+    // Check if it's us
+    if (username.toString() == 'backend') {
+        res.status(200).send('allow');
+        return;
+    }
+
+    // Check if user exists
+    const user = await User.findOne({ name: username.toString() });
+    if (user === null) {
+        res.send('deny');
+        return;
+    }
+
+    if (routingKey !== user.id) {
+        res.send('deny');
+        return;
+    }
+
     res.status(200).send('allow');
 }