forbid editing after broadcast message goes live

only allow editing while in:

* draft
* pending-approval
* rejected (not too sure if/how this'll be used, so easier to include it
 for now)

app/broadcast_message/rest.py

@@ -1,7 +1,7 @@
 from datetime import datetime
 
 import iso8601
-from flask import Blueprint, jsonify, request, current_app
+from flask import Blueprint, jsonify, request, current_app, abort
 
 from app.config import QueueNames
 from app.dao.templates_dao import dao_get_template_by_id_and_service_id
@@ -85,6 +85,12 @@ def update_broadcast_message(service_id, broadcast_message_id):
 
     broadcast_message = dao_get_broadcast_message_by_id_and_service_id(broadcast_message_id, service_id)
 
+    if broadcast_message.status not in BroadcastStatusType.PRE_BROADCAST_STATUSES:
+        abort(
+            400,
+            f'Cannot update broadcast_message {broadcast_message.id} while it has status {broadcast_message.status}'
+        )
+
     if 'personalisation' in data:
         broadcast_message.personalisation = data['personalisation']
     if 'starts_at' in data:

app/models.py

@@ -2172,6 +2172,10 @@ class BroadcastStatusType(db.Model):
 
     STATUSES = [DRAFT, PENDING_APPROVAL, REJECTED, BROADCASTING, COMPLETED, CANCELLED, TECHNICAL_FAILURE]
 
+    # a broadcast message can be edited while in one of these states
+    PRE_BROADCAST_STATUSES = [DRAFT, PENDING_APPROVAL, REJECTED]
+    LIVE_STATUSES = [BROADCASTING, COMPLETED, CANCELLED]
+
     name = db.Column(db.String, primary_key=True)