Refactor codebase

app/auth.py

@@ -1,5 +1,5 @@
 from functools import wraps
-from flask import session, redirect, url_for, request
+from flask import session, redirect, url_for, request, jsonify
 from app.db import query_one
 
 
@@ -19,3 +19,19 @@ def get_current_user():
     if user_id is None:
         return None
     return query_one("SELECT * FROM users WHERE id = %s", (user_id,))
+
+
+def privacy_guard(f):
+    """Decorator for API endpoints that take a user_id parameter.
+
+    If the requested user is private and is not the current session user,
+    returns an empty JSON response instead of the actual data.
+    """
+    @wraps(f)
+    def decorated_function(user_id, *args, **kwargs):
+        if user_id != session.get("user_id"):
+            target = query_one("SELECT is_private FROM users WHERE id = %s", (user_id,))
+            if target and target["is_private"]:
+                return jsonify({})
+        return f(user_id, *args, **kwargs)
+    return decorated_function