And an endpoint to get uploaded letters for a day

Because we won’t be showing uploaded letters individually on the uploads
page any more we need a way of listing them. This should be by printing
day, to match how we’re grouping them on the uploads page.

The response matches a normal `get_notifications` response so we can
reuse the same code in the admin app.

app/upload/rest.py

@@ -1,5 +1,7 @@
+from datetime import datetime
 from flask import (
     Blueprint,
+    abort,
     jsonify,
     request,
     current_app
@@ -9,10 +11,14 @@ from app.dao.fact_notification_status_dao import fetch_notification_statuses_for
 from app.dao.jobs_dao import (
     dao_get_notification_outcomes_for_job
 )
-from app.dao.uploads_dao import dao_get_uploads_by_service_id
+from app.dao.uploads_dao import (
+    dao_get_uploaded_letters_by_print_date,
+    dao_get_uploads_by_service_id,
+)
 from app.errors import (
     register_errors,
 )
+from app.schemas import notification_with_template_schema
 from app.utils import pagination_links, midnight_n_days_ago
 
 upload_blueprint = Blueprint('upload', __name__, url_prefix='/service/<uuid:service_id>/upload')
@@ -74,3 +80,31 @@ def get_paginated_uploads(service_id, limit_days, page):
             service_id=service_id
         )
     }
+
+
+@upload_blueprint.route('/uploaded-letters/<letter_print_date>', methods=['GET'])
+def get_uploaded_letter_by_service_and_print_day(service_id, letter_print_date):
+    try:
+        letter_print_datetime = datetime.strptime(letter_print_date, '%Y-%m-%d')
+    except ValueError:
+        abort(404)
+    pagination = dao_get_uploaded_letters_by_print_date(
+        service_id,
+        letter_print_date=letter_print_datetime,
+        page=request.args.get('page', type=int),
+        page_size=current_app.config['PAGE_SIZE']
+    )
+    return jsonify({
+        'notifications': notification_with_template_schema.dump(
+            pagination.items,
+            many=True,
+        ).data,
+        'page_size': pagination.per_page,
+        'total': pagination.total,
+        'links': pagination_links(
+            pagination,
+            '.get_uploaded_letter_by_service_and_print_day',
+            service_id=service_id,
+            letter_print_date=letter_print_date,
+        ),
+    })