New pages to show a summary of all the reports the services has for its returned letters

app/main/__init__.py

@@ -29,6 +29,7 @@ from app.main.views import (  # noqa isort:skip
     platform_admin,
     providers,
     register,
+    returned_letters,
     send,
     service_settings,
     sign_in,

app/main/views/returned_letters.py

@@ -0,0 +1,22 @@
+from flask import render_template, request
+
+from app import service_api_client
+from app.main import main
+from app.utils import user_has_permissions
+
+
+@main.route("/services/<uuid:service_id>/returned-letter-summary", methods=["GET", "POST"])
+@user_has_permissions('manage_service')
+def returned_letter_summary(service_id):
+    summary = service_api_client.get_returned_letter_summary(service_id)
+    return render_template(
+        'views/returned-letter-summary.html',
+        data=summary,
+    )
+
+
+@main.route("/services/<uuid:service_id>/returned-letters-csv/<reported_at>", methods=["GET", "POST"])
+@user_has_permissions('manage_service')
+def returned_letters_report(service_id, reported_at):
+
+    return str(service_api_client.get_returned_letters(service_id, reported_at))