It's clear that we need a way to track updates to a broadcast message.
It's also clear that we'll need some kind of audit log that captures
exactly what was sent out in a message.
This commit adds a new database table, `broadcast_event`, which maps 1:1
with CAP XML sent to the CBCs. We'll create one of these just before
sending out.
The main driver for this was that cancel and update messages need to
contain a list of references of all previous messages that they're
amending. This is of format `{sender},{identifier},{sent_timestamp}`,
and the identifier itself needs to be unique for each message.
task takes a brodcast_message_id, and makes a post to the cbc-proxy
for now, hardcode the url to the notify stub. the stub requires template
as the admin/api get it, so use the marshmallow schema to json dump it.
Note - this also required us to tweak the BroadcastMessage.serialize
function so that it converts uuids in to ids - flask's jsonify function
does that for free but requests.post doesn't sadly.
if the request fails (either 4xx or 5xx) just raise an exception and let
it bubble up for now - in the future we'll add retry logic
new blueprint `/service/<id>/broadcast-message` with the following
endpoints:
* GET / - get all broadcast messages for a service
* GET /<id> - get a single broadcast message
* POST / - create a new broadcast message
* POST /<id> - update an existing broadcast message's data
* POST /<id>/status - move a broadcast message to a new status
I've kept the regular data update (eg personalisation, start and end
times) separate from the status update, just to keep separation of
concerns a bit more rigid, especially around who can update.
I've included schemas for the three POSTs, they're pretty
straightforward.
