Revert "Letter preview use api not template preview"

app/main/views/notifications.py

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

app/notify_client/notification_api_client.py

@@ -73,14 +73,3 @@ 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

@@ -1,11 +1,9 @@
-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_python_client.errors import APIError
+from notifications_utils.template import LetterImageTemplate
 from tests.conftest import (
     SERVICE_ONE_ID,
     mock_get_notification,
@@ -165,11 +163,9 @@ def test_should_show_image_of_letter_notification(
 
     mock_get_notification(mocker, fake_uuid, template_type='letter')
 
-    mocker.patch(
-        'app.notify_client.notification_api_client.NotificationApiClient.get',
-        return_value={
-            'content': base64.b64encode(b'foo').decode('utf-8')
-        }
+    mocked_preview = mocker.patch(
+        'app.main.views.templates.TemplatePreview.from_utils_template',
+        return_value='foo'
     )
 
     response = logged_in_client.get(url_for(
@@ -181,32 +177,8 @@ def test_should_show_image_of_letter_notification(
 
     assert response.status_code == 200
     assert response.get_data(as_text=True) == 'foo'
-
-
-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'
+    assert isinstance(mocked_preview.call_args[0][0], LetterImageTemplate)
+    assert mocked_preview.call_args[0][1] == filetype
 
 
 def test_should_404_for_unknown_extension(