Merge pull request #1938 from alphagov/letter_preview_use_api_not_template_preview

Letter preview use api not template preview

app/main/views/notifications.py

@@ -1,4 +1,6 @@
 # -*- coding: utf-8 -*-
+import base64
+import os
 from datetime import datetime
 
 from flask import (
@@ -11,6 +13,7 @@ from flask import (
     url_for,
 )
 from flask_login import login_required
+from notifications_python_client.errors import APIError
 
 from app import (
     current_service,
@@ -19,7 +22,7 @@ from app import (
     notification_api_client,
 )
 from app.main import main
-from app.template_previews import TemplatePreview, get_page_count_for_letter
+from app.template_previews import get_page_count_for_letter
 from app.utils import (
     DELIVERED_STATUSES,
     FAILURE_STATUSES,
@@ -83,6 +86,12 @@ def view_notification(service_id, notification_id):
     )
 
 
+def get_preview_error_image():
+    path = os.path.join(os.path.dirname(__file__), "..", "..", "static", "images", "preview_error.png")
+    with open(path, "rb") as file:
+        return file.read()
+
+
 @main.route("/services/<service_id>/notification/<uuid:notification_id>.<filetype>")
 @login_required
 @user_has_permissions('view_activity')
@@ -91,23 +100,19 @@ def view_letter_notification_as_preview(service_id, notification_id, filetype):
     if filetype not in ('pdf', 'png'):
         abort(404)
 
-    notification = notification_api_client.get_notification(service_id, notification_id)
-    notification['template'].update({'reply_to_text': notification['reply_to_text']})
+    try:
+        preview = notification_api_client.get_notification_letter_preview(
+            service_id,
+            notification_id,
+            filetype,
+            page=request.args.get('page')
+        )
 
-    template = get_template(
-        notification['template'],
-        current_service,
-        letter_preview_url=url_for(
-            '.view_letter_notification_as_preview',
-            service_id=service_id,
-            notification_id=notification_id,
-            filetype='png',
-        ),
-    )
+        display_file = base64.b64decode(preview['content'])
+    except APIError:
+        display_file = get_preview_error_image()
 
-    template.values = notification['personalisation']
-
-    return TemplatePreview.from_utils_template(template, filetype, page=request.args.get('page'))
+    return display_file
 
 
 @main.route("/services/<service_id>/notification/<notification_id>.json")

app/notify_client/notification_api_client.py

@@ -73,3 +73,14 @@ class NotificationApiClient(NotifyAdminAPIClient):
             if notification['notification_type'] == 'letter' and notification['status'] in ('created', 'sending'):
                 notification['status'] = 'accepted'
         return notifications
+
+    def get_notification_letter_preview(self, service_id, notification_id, file_type, page=None):
+
+        get_url = '/service/{}/template/preview/{}/{}{}'.format(
+            service_id,
+            notification_id,
+            file_type,
+            '?page={}'.format(page) if page else ''
+        )
+
+        return self.get(url=get_url)

tests/app/main/views/test_notifications.py

@@ -1,9 +1,11 @@
+import base64
 from functools import partial
+from unittest.mock import mock_open
 
 import pytest
 from flask import url_for
 from freezegun import freeze_time
-from notifications_utils.template import LetterImageTemplate
+from notifications_python_client.errors import APIError
 from tests.conftest import (
     SERVICE_ONE_ID,
     mock_get_notification,
@@ -163,9 +165,11 @@ def test_should_show_image_of_letter_notification(
 
     mock_get_notification(mocker, fake_uuid, template_type='letter')
 
-    mocked_preview = mocker.patch(
-        'app.main.views.templates.TemplatePreview.from_utils_template',
-        return_value='foo'
+    mocker.patch(
+        'app.notify_client.notification_api_client.NotificationApiClient.get',
+        return_value={
+            'content': base64.b64encode(b'foo').decode('utf-8')
+        }
     )
 
     response = logged_in_client.get(url_for(
@@ -177,8 +181,32 @@ def test_should_show_image_of_letter_notification(
 
     assert response.status_code == 200
     assert response.get_data(as_text=True) == 'foo'
-    assert isinstance(mocked_preview.call_args[0][0], LetterImageTemplate)
-    assert mocked_preview.call_args[0][1] == filetype
+
+
+def test_should_show_preview_error_image_letter_notification_on_preview_error(
+    logged_in_client,
+    fake_uuid,
+    mocker,
+):
+
+    mock_get_notification(mocker, fake_uuid, template_type='letter')
+
+    mocker.patch(
+        'app.notify_client.notification_api_client.NotificationApiClient.get',
+        side_effect=APIError
+    )
+
+    mocker.patch("builtins.open", mock_open(read_data="preview error image"))
+
+    response = logged_in_client.get(url_for(
+        'main.view_letter_notification_as_preview',
+        service_id=SERVICE_ONE_ID,
+        notification_id=fake_uuid,
+        filetype='png'
+    ))
+
+    assert response.status_code == 200
+    assert response.get_data(as_text=True) == 'preview error image'
 
 
 def test_should_404_for_unknown_extension(