Update billable units for letters pdf task

app/celery/letters_pdf_tasks.py

@@ -1,4 +1,6 @@
+from datetime import datetime
 from flask import current_app
+import math
 from requests import (
     post as requests_post,
     RequestException
@@ -9,7 +11,11 @@ from botocore.exceptions import ClientError as BotoClientError
 from app import notify_celery
 from app.aws import s3
 from app.config import QueueNames
-from app.dao.notifications_dao import get_notification_by_id, update_notification_status_by_id
+from app.dao.notifications_dao import (
+    get_notification_by_id,
+    update_notification_status_by_id,
+    dao_update_notifications_by_reference
+)
 from app.statsd_decorators import statsd
 
 
@@ -19,7 +25,7 @@ def create_letters_pdf(self, notification_id):
     try:
         notification = get_notification_by_id(notification_id, _raise=True)
 
-        pdf_data = get_letters_pdf(
+        pdf_data, billable_units = get_letters_pdf(
             notification.template,
             contact_block=notification.reply_to_text,
             org_id=notification.service.dvla_organisation.id,
@@ -28,6 +34,24 @@ def create_letters_pdf(self, notification_id):
         current_app.logger.info("PDF Letter {} reference {} created at {}, {} bytes".format(
             notification.id, notification.reference, notification.created_at, len(pdf_data)))
         s3.upload_letters_pdf(reference=notification.reference, crown=notification.service.crown, filedata=pdf_data)
+
+        updated_count = dao_update_notifications_by_reference(
+            references=[notification.reference],
+            update_dict={
+                "billable_units": billable_units,
+                "updated_at": datetime.utcnow()
+            }
+        )
+
+        if not updated_count:
+            msg = "Update letter notification billing units failed: notification not found with reference {}".format(
+                notification.reference)
+            current_app.logger.error(msg)
+        else:
+            current_app.logger.info(
+                'Letter notification reference {reference}: billable units set to {billable_units}'.format(
+                    reference=str(notification.reference), billable_units=billable_units))
+
     except (RequestException, BotoClientError):
         try:
             current_app.logger.exception(
@@ -62,4 +86,7 @@ def get_letters_pdf(template, contact_block, org_id, values):
     )
     resp.raise_for_status()
 
-    return resp.content
+    pages_per_sheet = 2
+    billable_units = math.ceil(int(resp.headers.get("X-pdf-page-count", 0)) / pages_per_sheet)
+
+    return resp.content, billable_units

tests/app/celery/test_letters_pdf_tasks.py

@@ -10,6 +10,7 @@ from app.celery.letters_pdf_tasks import (
     create_letters_pdf,
     get_letters_pdf,
 )
+from app.models import Notification
 
 from tests.conftest import set_config_values
 
@@ -46,8 +47,36 @@ def test_get_letters_pdf_calls_notifications_template_preview_service_correctly(
     }
 
 
+@pytest.mark.parametrize('page_count,expected_billable_units', [
+    ('1', 1),
+    ('2', 1),
+    ('3', 2)
+])
+def test_get_letters_pdf_calculates_billing_units(
+        notify_api, mocker, client, sample_letter_template, page_count, expected_billable_units):
+    contact_block = 'Mr Foo,\n1 Test Street,\nLondon\nN1'
+    dvla_org_id = '002'
+
+    with set_config_values(notify_api, {
+        'TEMPLATE_PREVIEW_API_HOST': 'http://localhost/notifications-template-preview',
+        'TEMPLATE_PREVIEW_API_KEY': 'test-key'
+    }):
+        with requests_mock.Mocker() as request_mock:
+            request_mock.post(
+                'http://localhost/notifications-template-preview/print.pdf',
+                content=b'\x00\x01',
+                headers={'X-pdf-page-count': page_count},
+                status_code=200
+            )
+
+            _, billable_units = get_letters_pdf(
+                sample_letter_template, contact_block=contact_block, org_id=dvla_org_id, values=None)
+
+    assert billable_units == expected_billable_units
+
+
 def test_create_letters_pdf_calls_upload_letters_pdf(mocker, sample_letter_notification):
-    mocker.patch('app.celery.letters_pdf_tasks.get_letters_pdf', return_value=b'\x00\x01')
+    mocker.patch('app.celery.letters_pdf_tasks.get_letters_pdf', return_value=(b'\x00\x01', '1'))
     mock_s3 = mocker.patch('app.celery.tasks.s3.upload_letters_pdf')
 
     create_letters_pdf(sample_letter_notification.id)
@@ -59,6 +88,28 @@ def test_create_letters_pdf_calls_upload_letters_pdf(mocker, sample_letter_notif
     )
 
 
+def test_create_letters_pdf_sets_billable_units(mocker, sample_letter_notification):
+    mocker.patch('app.celery.letters_pdf_tasks.get_letters_pdf', return_value=(b'\x00\x01', 1))
+    mocker.patch('app.celery.tasks.s3.upload_letters_pdf')
+
+    create_letters_pdf(sample_letter_notification.id)
+    noti = Notification.query.filter(Notification.reference == sample_letter_notification.reference).one()
+    assert noti.billable_units == 1
+
+
+def test_create_letters_pdf_handles_update_failure(mocker, sample_letter_notification):
+    mocker.patch('app.celery.letters_pdf_tasks.get_letters_pdf', return_value=(b'\x00\x01', 1))
+    mocker.patch('app.celery.tasks.s3.upload_letters_pdf')
+    mocker.patch('app.celery.tasks.letters_pdf_tasks.dao_update_notifications_by_reference', return_value=0)
+    mock_error_logger = mocker.patch('app.celery.letters_pdf_tasks.current_app.logger.error')
+
+    create_letters_pdf(sample_letter_notification.id)
+
+    mock_error_logger.assert_called_once_with(
+        "Update letter notification billing units failed: notification not found with reference {}".format(
+            sample_letter_notification.reference))
+
+
 def test_create_letters_pdf_non_existent_notification(notify_api, mocker, fake_uuid):
     with pytest.raises(expected_exception=NoResultFound):
         create_letters_pdf(fake_uuid)
@@ -75,7 +126,7 @@ def test_create_letters_pdf_handles_request_errors(mocker, sample_letter_notific
 
 
 def test_create_letters_pdf_handles_s3_errors(mocker, sample_letter_notification):
-    mocker.patch('app.celery.letters_pdf_tasks.get_letters_pdf')
+    mocker.patch('app.celery.letters_pdf_tasks.get_letters_pdf', return_value=(b'\x00\x01', 1))
     mock_s3 = mocker.patch('app.celery.tasks.s3.upload_letters_pdf', side_effect=ClientError({}, 'operation_name'))
     mock_retry = mocker.patch('app.celery.letters_pdf_tasks.create_letters_pdf.retry')