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.

app/v2/notifications/post_notifications.py

@@ -7,7 +7,7 @@ from flask import request, jsonify, current_app, abort
 from notifications_utils.pdf import pdf_page_count, PdfReadError
 from notifications_utils.recipients import try_validate_and_format_phone_number
 
-from app import api_user, authenticated_service, notify_celery
+from app import api_user, authenticated_service, notify_celery, document_download_client
 from app.config import QueueNames, TaskNames
 from app.dao.notifications_dao import dao_update_notification, update_notification_status_by_reference
 from app.dao.templates_dao import dao_create_template
@@ -19,6 +19,7 @@ from app.models import (
     EMAIL_TYPE,
     LETTER_TYPE,
     PRECOMPILED_LETTER,
+    UPLOAD_DOCUMENT,
     PRIORITY,
     KEY_TYPE_TEST,
     KEY_TYPE_TEAM,
@@ -136,7 +137,7 @@ def post_notification(notification_type):
             reply_to_text=reply_to
         )
     else:
-        notification = process_sms_or_email_notification(
+        notification, personalisation = process_sms_or_email_notification(
             form=form,
             notification_type=notification_type,
             api_key=api_user,
@@ -145,6 +146,8 @@ def post_notification(notification_type):
             reply_to_text=reply_to
         )
 
+        template_with_content.values = personalisation
+
     if notification_type == SMS_TYPE:
         create_resp_partial = functools.partial(
             create_post_sms_response_from_notification,
@@ -182,12 +185,14 @@ def process_sms_or_email_notification(*, form, notification_type, api_key, templ
     # Do not persist or send notification to the queue if it is a simulated recipient
     simulated = simulated_recipient(send_to, notification_type)
 
+    personalisation = process_document_uploads(form.get('personalisation'), service, simulated=simulated)
+
     notification = persist_notification(
         template_id=template.id,
         template_version=template.version,
         recipient=form_send_to,
         service=service,
-        personalisation=form.get('personalisation', None),
+        personalisation=personalisation,
         notification_type=notification_type,
         api_key_id=api_key.id,
         key_type=api_key.key_type,
@@ -210,7 +215,27 @@ def process_sms_or_email_notification(*, form, notification_type, api_key, templ
         else:
             current_app.logger.debug("POST simulated notification for id: {}".format(notification.id))
 
-    return notification
+    return notification, personalisation
+
+
+def process_document_uploads(personalisation_data, service, simulated=False):
+    file_keys = [k for k, v in (personalisation_data or {}).items() if isinstance(v, dict) and 'file' in v]
+    if not file_keys:
+        return personalisation_data
+
+    personalisation_data = personalisation_data.copy()
+
+    check_service_has_permission(UPLOAD_DOCUMENT, authenticated_service.permissions)
+
+    for key in file_keys:
+        if simulated:
+            personalisation_data[key] = document_download_client.get_upload_url(service.id) + '/test-document'
+        else:
+            personalisation_data[key] = document_download_client.upload_document(
+                service.id, personalisation_data[key]['file']
+            )
+
+    return personalisation_data
 
 
 def process_letter_notification(*, letter_data, api_key, template, reply_to_text, precompiled=False):