Add dao method to get template stats per month in financial year for service

app/dao/services_dao.py

@@ -29,6 +29,7 @@ from app.models import (
     NOTIFICATION_STATUS_TYPES,
     TEMPLATE_TYPES,
 )
+from app.service.statistics import format_monthly_template_notification_stats
 from app.statsd_decorators import statsd
 from app.utils import get_london_month_from_utc_column
 
@@ -224,6 +225,38 @@ def _stats_for_service_query(service_id):
     )
 
 
+@statsd(namespace="dao")
+def dao_fetch_monthly_historical_stats_by_template_for_service(service_id, year):
+    month = get_london_month_from_utc_column(NotificationHistory.created_at)
+
+    sq = db.session.query(
+        NotificationHistory.template_id,
+        NotificationHistory.status,
+        month.label('month'),
+        func.count().label('count')
+    ).filter(
+        NotificationHistory.service_id == service_id,
+        NotificationHistory.created_at.between(*get_financial_year(year))
+    ).group_by(
+        month,
+        NotificationHistory.template_id,
+        NotificationHistory.status
+    ).subquery()
+
+    rows = db.session.query(
+        Template.id.label('template_id'),
+        Template.name,
+        sq.c.status,
+        sq.c.count.label('count'),
+        sq.c.month
+    ).join(
+        sq,
+        sq.c.template_id == Template.id
+    ).all()
+
+    return format_monthly_template_notification_stats(year, rows)
+
+
 @statsd(namespace="dao")
 def dao_fetch_monthly_historical_stats_for_service(service_id, year):
     month = get_london_month_from_utc_column(NotificationHistory.created_at)