Upload files from personalisation data to document download

Adds support for a new personalisation value type: file upload.

File uploads are represented as a dictionary with a "file" key and
a base64-encoded file data as the key's value:

```
personalisation={
  'field1': {'file': '<base64-encoded file contents>'}
}
```

Post notification endpoint checks the request personalisation data
looking for the file uploads in personalisation data. If any are
found and the service has permissions to upload documents the files
are sent to document download API and personalisation values are
replaced with the URLs returned in the document download response.

A fake document URL is returned for simulated notifications, no
documents are stored in Document Download.

Multiple files can be uploaded for one notification by providing
a file upload in more than one personalisation field.

tests/app/v2/notifications/test_post_notifications.py

@@ -9,7 +9,8 @@ from app.models import (
     EMAIL_TYPE,
     NOTIFICATION_CREATED,
     SCHEDULE_NOTIFICATIONS,
-    SMS_TYPE
+    SMS_TYPE,
+    UPLOAD_DOCUMENT
 )
 from flask import json, current_app
 
@@ -697,3 +698,96 @@ def test_post_email_notification_with_invalid_reply_to_id_returns_400(client, sa
     assert 'email_reply_to_id {} does not exist in database for service id {}'. \
         format(fake_uuid, sample_email_template.service_id) in resp_json['errors'][0]['message']
     assert 'BadRequestError' in resp_json['errors'][0]['error']
+
+
+def test_post_notification_with_document_upload(client, notify_db, notify_db_session, mocker):
+    service = sample_service(notify_db, notify_db_session, permissions=[EMAIL_TYPE, UPLOAD_DOCUMENT])
+    template = create_sample_template(
+        notify_db, notify_db_session, service=service,
+        template_type='email',
+        content="Document: ((document))"
+    )
+
+    mocker.patch('app.celery.provider_tasks.deliver_email.apply_async')
+    document_download_mock = mocker.patch('app.v2.notifications.post_notifications.document_download_client')
+    document_download_mock.upload_document.return_value = 'https://document-url/'
+
+    data = {
+        "email_address": service.users[0].email_address,
+        "template_id": template.id,
+        "personalisation": {"document": {"file": "abababab"}}
+    }
+
+    auth_header = create_authorization_header(service_id=service.id)
+    response = client.post(
+        path="v2/notifications/email",
+        data=json.dumps(data),
+        headers=[('Content-Type', 'application/json'), auth_header])
+
+    assert response.status_code == 201, response.get_data(as_text=True)
+    resp_json = json.loads(response.get_data(as_text=True))
+    assert validate(resp_json, post_email_response) == resp_json
+
+    notification = Notification.query.one()
+    assert notification.status == NOTIFICATION_CREATED
+    assert notification.personalisation == {'document': 'https://document-url/'}
+
+    assert resp_json['content']['body'] == 'Document: https://document-url/'
+
+
+def test_post_notification_with_document_upload_simulated(client, notify_db, notify_db_session, mocker):
+    service = sample_service(notify_db, notify_db_session, permissions=[EMAIL_TYPE, UPLOAD_DOCUMENT])
+    template = create_sample_template(
+        notify_db, notify_db_session, service=service,
+        template_type='email',
+        content="Document: ((document))"
+    )
+
+    mocker.patch('app.celery.provider_tasks.deliver_email.apply_async')
+    document_download_mock = mocker.patch('app.v2.notifications.post_notifications.document_download_client')
+    document_download_mock.get_upload_url.return_value = 'https://document-url'
+
+    data = {
+        "email_address": 'simulate-delivered@notifications.service.gov.uk',
+        "template_id": template.id,
+        "personalisation": {"document": {"file": "abababab"}}
+    }
+
+    auth_header = create_authorization_header(service_id=service.id)
+    response = client.post(
+        path="v2/notifications/email",
+        data=json.dumps(data),
+        headers=[('Content-Type', 'application/json'), auth_header])
+
+    assert response.status_code == 201, response.get_data(as_text=True)
+    resp_json = json.loads(response.get_data(as_text=True))
+    assert validate(resp_json, post_email_response) == resp_json
+
+    assert resp_json['content']['body'] == 'Document: https://document-url/test-document'
+
+
+def test_post_notification_without_document_upload_permission(client, notify_db, notify_db_session, mocker):
+    service = sample_service(notify_db, notify_db_session, permissions=[EMAIL_TYPE])
+    template = create_sample_template(
+        notify_db, notify_db_session, service=service,
+        template_type='email',
+        content="Document: ((document))"
+    )
+
+    mocker.patch('app.celery.provider_tasks.deliver_email.apply_async')
+    document_download_mock = mocker.patch('app.v2.notifications.post_notifications.document_download_client')
+    document_download_mock.upload_document.return_value = 'https://document-url/'
+
+    data = {
+        "email_address": service.users[0].email_address,
+        "template_id": template.id,
+        "personalisation": {"document": {"file": "abababab"}}
+    }
+
+    auth_header = create_authorization_header(service_id=service.id)
+    response = client.post(
+        path="v2/notifications/email",
+        data=json.dumps(data),
+        headers=[('Content-Type', 'application/json'), auth_header])
+
+    assert response.status_code == 400, response.get_data(as_text=True)