reintroduce rooms::alias::Serivce struct

We're going to need it.

src/service.rs

@@ -61,7 +61,7 @@ impl Services {
                 db,
             },
             rooms: rooms::Service {
-                alias: db,
+                alias: rooms::alias::Service::new(db),
                 auth_chain: rooms::auth_chain::Service {
                     db,
                 },

src/service/rooms/alias.rs

@@ -1,4 +1,52 @@
+use ruma::{OwnedRoomAliasId, OwnedRoomId, RoomAliasId, RoomId};
+
+use crate::Result;
+
 mod data;
 
 pub(crate) use data::Data;
-pub(crate) type Service = &'static dyn Data;
+
+pub(crate) struct Service {
+    db: &'static dyn Data,
+}
+
+impl Service {
+    pub(crate) fn new<D>(db: &'static D) -> Self
+    where
+        D: Data,
+    {
+        Self {
+            db,
+        }
+    }
+
+    /// Creates or updates the alias to the given room id.
+    pub(crate) fn set_alias(
+        &self,
+        alias: &RoomAliasId,
+        room_id: &RoomId,
+    ) -> Result<()> {
+        self.db.set_alias(alias, room_id)
+    }
+
+    /// Forgets about an alias. Returns an error if the alias did not exist.
+    pub(crate) fn remove_alias(&self, alias: &RoomAliasId) -> Result<()> {
+        self.db.remove_alias(alias)
+    }
+
+    /// Looks up the roomid for the given alias.
+    pub(crate) fn resolve_local_alias(
+        &self,
+        alias: &RoomAliasId,
+    ) -> Result<Option<OwnedRoomId>> {
+        self.db.resolve_local_alias(alias)
+    }
+
+    /// Returns all local aliases that point to the given room
+    pub(crate) fn local_aliases_for_room<'a>(
+        &'a self,
+        room_id: &RoomId,
+    ) -> Box<dyn Iterator<Item = Result<OwnedRoomAliasId>> + 'a> {
+        self.db.local_aliases_for_room(room_id)
+    }
+}