add flag to return pdf content via api

this is only applicable when getting a single notification by id. it's
also ignored if the notification isn't a letter.

Otherwise, it overwrites the 'body' field in the response.

If the notification's pdf is available, it returns that, base64
encoded. If the pdf is not available, it returns an empty string.

The pdf won't be available if the notification's status is:
* pending-virus-scan
* virus-scan-failed
* validation-failed
* technical-failure

The pdf will be retrieved from the correct s3 bucket based on its type

app/models.py

@@ -1547,7 +1547,7 @@ class Notification(db.Model):
         elif self.status in [NOTIFICATION_DELIVERED, NOTIFICATION_RETURNED_LETTER]:
             return NOTIFICATION_STATUS_LETTER_RECEIVED
         else:
-            # Currently can only be technical-failure
+            # Currently can only be technical-failure OR pending-virus-check OR validation-failed
             return self.status
 
     def get_created_by_name(self):

app/v2/notifications/get_notifications.py

@@ -1,9 +1,14 @@
+import base64
+
 from flask import jsonify, request, url_for, current_app
+
 from app import api_user, authenticated_service
 from app.dao import notifications_dao
+from app.letters.utils import get_letter_pdf
 from app.schema_validation import validate
 from app.v2.notifications import v2_notification_blueprint
 from app.v2.notifications.notification_schemas import get_notifications_request, notification_by_id
+from app.models import NOTIFICATION_CREATED, NOTIFICATION_STATUS_TYPES_BILLABLE_FOR_LETTERS, LETTER_TYPE
 
 
 @v2_notification_blueprint.route("/<notification_id>", methods=['GET'])
@@ -14,7 +19,17 @@ def get_notification_by_id(notification_id):
         authenticated_service.id, notification_id, key_type=None
     )
 
-    return jsonify(notification.serialize()), 200
+    response = notification.serialize()
+
+    if request.args.get('return_pdf_content') and notification.notification_type == LETTER_TYPE:
+        if notification.status in (NOTIFICATION_CREATED, *NOTIFICATION_STATUS_TYPES_BILLABLE_FOR_LETTERS):
+            pdf_data = get_letter_pdf(notification)
+        else:
+            # precompiled letters that are still being virus scanned, or that failed validation/virus scan
+            pdf_data = b''
+        response['body'] = base64.b64encode(pdf_data).decode('utf-8')
+
+    return jsonify(response), 200
 
 
 @v2_notification_blueprint.route("", methods=['GET'])

tests/app/letters/test_letter_utils.py

@@ -80,6 +80,16 @@ def test_get_bucket_name_and_prefix_for_notification_precompiled_letter_using_te
         sample_precompiled_letter_notification_using_test_key.reference).upper()
 
 
+@freeze_time(FROZEN_DATE_TIME)
+def test_get_bucket_name_and_prefix_for_notification_templated_letter_using_test_key(sample_letter_notification):
+    sample_letter_notification.key_type = KEY_TYPE_TEST
+
+    bucket, bucket_prefix = get_bucket_name_and_prefix_for_notification(sample_letter_notification)
+
+    assert bucket == current_app.config['TEST_LETTERS_BUCKET_NAME']
+    assert bucket_prefix == 'NOTIFY.{}'.format(sample_letter_notification.reference).upper()
+
+
 @freeze_time(FROZEN_DATE_TIME)
 def test_get_bucket_name_and_prefix_for_failed_validation(sample_precompiled_letter_notification):
     sample_precompiled_letter_notification.status = NOTIFICATION_VALIDATION_FAILED

tests/app/v2/notifications/test_get_notifications.py

@@ -649,3 +649,38 @@ def test_get_notifications_renames_letter_statuses(client, sample_letter_templat
     json_response = json.loads(response.get_data(as_text=True))
     assert response.status_code == 200
     assert json_response['status'] == expected_status
+
+
+@pytest.mark.parametrize('status,expected_body,mock_called', [
+    ('created', 'Zm9v', True),
+    ('sending', 'Zm9v', True),
+    ('pending-virus-check', '', False),
+    ('virus-scan-failed', '', False),
+    ('validation-failed', '', False),
+    ('technical-failure', '', False),
+])
+def test_get_notification_only_returns_pdf_content_if_right_status(
+    client,
+    sample_letter_notification,
+    mocker,
+    status,
+    expected_body,
+    mock_called
+):
+    mock_get_letter_pdf = mocker.patch('app.v2.notifications.get_notifications.get_letter_pdf', return_value=b'foo')
+    sample_letter_notification.status = status
+
+    auth_header = create_authorization_header(service_id=sample_letter_notification.service_id)
+    response = client.get(
+        path=url_for(
+            'v2_notifications.get_notification_by_id',
+            notification_id=sample_letter_notification.id,
+            return_pdf_content='true'
+        ),
+        headers=[('Content-Type', 'application/json'), auth_header]
+    )
+
+    json_response = json.loads(response.get_data(as_text=True))
+    assert response.status_code == 200
+    assert json_response['body'] == expected_body
+    assert mock_get_letter_pdf.called == mock_called