Add a document download client

Allows uploading documents to the Document Download API.
The client is configured with an API host and auth token. There's
no need for a flag to disable the client in the test environments
at the moment since the upload is only triggered by a specific
payload which would only be sent with an explicit goal of using
document download.

app/__init__.py

@@ -16,6 +16,7 @@ from werkzeug.local import LocalProxy
 
 from app.celery.celery import NotifyCelery
 from app.clients import Clients
+from app.clients.document_download import DocumentDownloadClient
 from app.clients.email.aws_ses import AwsSesClient
 from app.clients.sms.firetext import FiretextClient
 from app.clients.sms.loadtesting import LoadtestingClient
@@ -39,6 +40,7 @@ deskpro_client = DeskproClient()
 statsd_client = StatsdClient()
 redis_store = RedisClient()
 performance_platform_client = PerformancePlatformClient()
+document_download_client = DocumentDownloadClient()
 
 clients = Clients()
 
@@ -71,6 +73,7 @@ def create_app(application):
     encryption.init_app(application)
     redis_store.init_app(application)
     performance_platform_client.init_app(application)
+    document_download_client.init_app(application)
     clients.init_app(sms_clients=[firetext_client, mmg_client, loadtest_client], email_clients=[aws_ses_client])
 
     register_blueprint(application)

app/clients/document_download.py

@@ -0,0 +1,27 @@
+import base64
+
+import requests
+
+
+class DocumentDownloadClient:
+
+    def init_app(self, app):
+        self.api_host = app.config['DOCUMENT_DOWNLOAD_API_HOST']
+        self.auth_token = app.config['DOCUMENT_DOWNLOAD_API_KEY']
+
+    def get_upload_url(self, service_id):
+        return "{}/services/{}/documents".format(self.api_host, service_id)
+
+    def upload_document(self, service_id, file_contents):
+        response = requests.post(
+            self.get_upload_url(service_id),
+            headers={
+                'Authorization': "Bearer {}".format(self.auth_token),
+            },
+            files={
+                'document': base64.b64decode(file_contents)
+            }
+        )
+        response.raise_for_status()
+
+        return response.json()['document']['url']

app/config.py

@@ -318,6 +318,9 @@ class Config(object):
     TEMPLATE_PREVIEW_API_HOST = os.environ.get('TEMPLATE_PREVIEW_API_HOST', 'http://localhost:6013')
     TEMPLATE_PREVIEW_API_KEY = os.environ.get('TEMPLATE_PREVIEW_API_KEY', 'my-secret-key')
 
+    DOCUMENT_DOWNLOAD_API_HOST = os.environ.get('DOCUMENT_DOWNLOAD_API_HOST', 'http://localhost:7000')
+    DOCUMENT_DOWNLOAD_API_KEY = os.environ.get('DOCUMENT_DOWNLOAD_API_KEY', 'auth-token')
+
     LETTER_PROCESSING_DEADLINE = time(17, 30)
 
     MMG_URL = "https://api.mmg.co.uk/json/api.php"