Write some pseudo code for ft billing

app/dao/fact_billing_dao.py

@@ -1,7 +1,8 @@
+from datetime import datetime, timedelta
 from sqlalchemy import func
 
 from app import db
-from app.dao.date_util import get_month_start_and_end_date_in_utc
+from app.dao.date_util import get_month_start_and_end_date_in_utc, get_financial_year
 from app.models import FactBilling
 from app.utils import convert_utc_to_bst
 
@@ -32,3 +33,52 @@ def fetch_annual_billing_by_month(service_id, billing_month, notification_type):
     ).all()
 
     return monthly_data, start_date
+
+
+def need_deltas(start_date, end_date, service_id, notification_type):
+    max_fact_billing_date = db.session.query(
+        func.max(FactBilling.bst_date)
+    ).filter(
+        FactBilling.notification_type == notification_type,
+        FactBilling.service_id == service_id,
+        FactBilling.bst_date >= start_date,
+        FactBilling.bst_date <= end_date
+    ).one()
+    print(max_fact_billing_date)
+    return max_fact_billing_date < end_date
+
+
+def fetch_annual_billing_for_year(service_id, year):
+    year_start_date, year_end_date = get_financial_year(year)
+    utcnow = datetime.utcnow()
+    today = convert_utc_to_bst(utcnow)
+    last_2_days = utcnow - timedelta(days=2)
+    last_bst_date_for_ft = convert_utc_to_bst(last_2_days)
+    # if year end date is less than today, we are calculating for data in the past and have no need for deltas.
+    if year_end_date >= today:
+        todays_data = get_deltas(service_id, last_2_days, today)
+        year_end_date = last_bst_date_for_ft
+
+
+    yearly_data = db.session.query(
+        FactBilling.notifications_sent,
+        FactBilling.billable_units,
+        FactBilling.service_id,
+        FactBilling.notification_type,
+        FactBilling.rate,
+        FactBilling.rate_multiplier,
+        FactBilling.international
+    ).filter(
+        FactBilling.service_id == service_id,
+        FactBilling.bst_date >= year_start_date,
+        FactBilling.bst_date <= last_bst_date_for_ft
+    ).all()
+
+    # today_data + yearly_data and aggregate by month
+
+
+def get_deltas(service_id, start_date_end_date):
+    # query ft_billing data using queries from create_nightly_billing
+    return []
+
+