[Plugin] balance: Fix with reversed transaction and improvement on shortcuts.

* Raise exception if transaction is already reversed.
* Sort shortcuts

flaschengeist/plugins/balance/__init__.py

@@ -67,6 +67,7 @@ def get_shortcuts(userid, current_session: Session):
         data = request.get_json()
         if not isinstance(data, list) or not all(isinstance(n, (int, float)) for n in data):
             raise BadRequest
+        data.sort()
         user.set_attribute("balance_shortcuts", data)
         userController.persist()
         return no_content()

flaschengeist/plugins/balance/balance_controller.py

@@ -5,7 +5,7 @@
 
 from sqlalchemy import func
 from datetime import datetime, timezone
-from werkzeug.exceptions import BadRequest, NotFound
+from werkzeug.exceptions import BadRequest, NotFound, Conflict
 
 from flaschengeist.database import db
 from flaschengeist.models.user import User
@@ -109,6 +109,8 @@ def reverse_transaction(transaction: Transaction, author: User):
         transaction: Transaction to reverse
         author: User that wants the transaction to be reverted
     """
+    if transaction.reversal:
+        raise Conflict
     reversal = send(transaction.receiver_, transaction.sender_, transaction.amount, author)
     reversal.reversal = transaction
     transaction.reversal = reversal