def customer_pubsub()

in services/customer-async/main.py [0:0]

• 68 lines of code
• 12 McCabe index (conditional complexity)

def customer_pubsub():
    envelope = request.get_json()
    if not isinstance(envelope, dict) or 'message' not in envelope:
        return error500()
    message = envelope['message']
    if 'data' not in message or 'attributes' not in message:
        return error500()
    attributes = message['attributes']
    if 'event_id' not in attributes or 'event_type' not in attributes:
        return error500()

    order = json.loads(base64.b64decode(message['data']).decode('utf-8'))
    event_id = attributes['event_id']
    event_type = attributes['event_type']

    query = ds_client.query(kind='ProcessedEvent')
    query.keys_only()
    query.add_filter('event_id', '=', event_id)
    if list(query.fetch()): # duplicate
        print('Duplicate event {}'.format(event_id))
        return 'Finished.', 200

    if event_type != 'order_create':
        print('Unknown event type {}.format(event_type)')
        return 'Finished.', 200

    customer_id = order['customer_id']
    number = order['number']

    query = ds_client.query(kind='Customer')
    query.add_filter('customer_id', '=', customer_id)
    customer = None
    for result in query.fetch(): # This should return a single entity.
        customer = result
        break
    if not customer: # Non existing customer_id
        return error500()

    accept = None
    credit = customer['credit']
    limit = customer['limit']
    credit += number * 100

    with ds_client.transaction():
        if credit > limit: # Reject order
            accept = False
        else: # Accept order
            accept = True
            customer['credit'] = credit
            ds_client.put(customer)

        check_result = {
            'customer_id': customer_id,
            'order_id': order['order_id'],
            'accepted': accept
        }
        event = {
            'event_id': str(uuid.uuid4()),
            'topic': 'customer-service-event',
            'type': 'order_checked',
            'timestamp': datetime.datetime.utcnow(),
            'published': False,
            'body': json.dumps(check_result)
        }

        incomplete_key = ds_client.key('Event')
        event_entity = datastore.Entity(key=incomplete_key)
        event_entity.update(event)
        ds_client.put(event_entity)

        incomplete_key = ds_client.key('ProcessedEvent')
        entity = datastore.Entity(key=incomplete_key)
        entity.update({
            'event_id': event_id,
            'timestamp': datetime.datetime.utcnow()
        })
        ds_client.put(entity)

    return 'Finished.', 200