add: apps api

crates/core/src/model/auth.rs

@@ -403,6 +403,14 @@ impl User {
         self.stripe_id = String::new();
         self.connections = HashMap::new();
     }
+
+    /// Get a grant from the user given the grant's `app` ID.
+    ///
+    /// Should be used **before** adding another grant (to ensure the app doesn't
+    /// already have a grant for this user).
+    pub fn get_grant_by_app_id(&self, id: usize) -> Option<&AuthGrant> {
+        self.grants.iter().find(|x| x.app == id)
+    }
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord, Hash)]