Make set_as_broadcast_service use a single DB commit

We don't want things in a half state if there is an error during the
method. Therefore, we move it all into a single function that is wrapped
in a transaction.

Note, we copy the approach of
https://github.com/alphagov/notifications-api/blob/master/app/dao/services_dao.py#L293
by having a single new dao function that does all the DB work.

app/dao/broadcast_service_dao.py

@@ -0,0 +1,65 @@
+from datetime import datetime
+
+from flask import current_app
+
+from app import db
+from app.models import ServiceBroadcastSettings, ServicePermission, Organisation, BROADCAST_TYPE
+from app.dao.dao_utils import transactional
+
+
+@transactional
+def set_broadcast_service_type(service, service_mode, broadcast_channel, provider_restriction):
+    insert_or_update_service_broadcast_settings(
+        service, channel=broadcast_channel, provider_restriction=provider_restriction
+    )
+
+    # Remove all permissions and add broadcast permission
+    if not service.has_permission(BROADCAST_TYPE):
+        service_permission = ServicePermission(service_id=service.id, permission=BROADCAST_TYPE)
+        db.session.add(service_permission)
+
+    ServicePermission.query.filter(
+        ServicePermission.service_id == service.id,
+        ServicePermission.permission != BROADCAST_TYPE
+    ).delete()
+
+    # Refresh the service object as it has references to the service permissions but we don't yet
+    # want to commit the permission changes incase all of this needs to rollback
+    db.session.refresh(service)
+        
+    # Set service count as live false always
+    service.count_as_live = False
+
+    # Set service into training mode or live mode
+    if service_mode == "live":
+        if service.restricted == True:
+            # Only update the go live at timestamp if this if moving from training mode
+            # to live mode, not if it's moving from one type of live mode service to another
+            service.go_live_at = datetime.utcnow()
+        service.restricted = False
+    else:
+        service.restricted = True
+        service.go_live_at = None
+
+    # Add service to organisation 
+    organisation = Organisation.query.filter_by(
+        id=current_app.config['BROADCAST_ORGANISATION_ID']
+    ).one()
+    service.organisation_id = organisation.id
+    service.organisation_type = organisation.organisation_type
+    service.crown = organisation.crown
+
+    db.session.add(service)
+
+
+def insert_or_update_service_broadcast_settings(service, channel, provider_restriction=None):
+    if not service.service_broadcast_settings:
+        settings = ServiceBroadcastSettings()
+        settings.service = service
+        settings.channel = channel
+        settings.provider = provider_restriction
+        db.session.add(settings)
+    else:
+        service.service_broadcast_settings.channel = channel
+        service.service_broadcast_settings.provider = provider_restriction
+        db.session.add(service.service_broadcast_settings)

app/dao/service_broadcast_settings_dao.py

@@ -1,17 +0,0 @@
-from app import db
-from app.models import ServiceBroadcastSettings
-from app.dao.dao_utils import transactional
-
-
-@transactional
-def insert_or_update_service_broadcast_settings(service, channel, provider_restriction=None):
-    if not service.service_broadcast_settings:
-        settings = ServiceBroadcastSettings()
-        settings.service = service
-        settings.channel = channel
-        settings.provider = provider_restriction
-        db.session.add(settings)
-    else:
-        service.service_broadcast_settings.channel = channel
-        service.service_broadcast_settings.provider = provider_restriction
-        db.session.add(service.service_broadcast_settings)