remove old platform admin billing query functions

these aren't going to be used in the future method, so to make the diffs
cleaner just delete them then re-add them. keep the column definitions
from the old query though just to make sure it's clear which things
we're changing/adding/removing

app/dao/fact_billing_dao.py

@@ -34,90 +34,19 @@ from app.models import (
 from app.utils import get_london_midnight_in_utc
 
 
-def fetch_sms_free_allowance_remainder_until_date(end_date):
-    # ASSUMPTION: AnnualBilling has been populated for year.
-    billing_year = get_financial_year_for_datetime(end_date)
-    start_of_year = date(billing_year, 4, 1)
-
-    billable_units = func.coalesce(func.sum(FactBilling.billable_units * FactBilling.rate_multiplier), 0)
-
-    query = db.session.query(
-        AnnualBilling.service_id.label("service_id"),
-        AnnualBilling.free_sms_fragment_limit,
-        billable_units.label('billable_units'),
-        func.greatest((AnnualBilling.free_sms_fragment_limit - billable_units).cast(Integer), 0).label('sms_remainder')
-    ).outerjoin(
-        # if there are no ft_billing rows for a service we still want to return the annual billing so we can use the
-        # free_sms_fragment_limit)
-        FactBilling, and_(
-            AnnualBilling.service_id == FactBilling.service_id,
-            FactBilling.bst_date >= start_of_year,
-            FactBilling.bst_date < end_date,
-            FactBilling.notification_type == SMS_TYPE,
-        )
-    ).filter(
-        AnnualBilling.financial_year_start == billing_year,
-    ).group_by(
-        AnnualBilling.service_id,
-        AnnualBilling.free_sms_fragment_limit,
-    )
-    return query
-
-
 def fetch_sms_billing_for_all_services(start_date, end_date):
-
-    # ASSUMPTION: AnnualBilling has been populated for year.
-    allowance_left_at_start_date_query = fetch_sms_free_allowance_remainder_until_date(start_date).subquery()
-
-    sms_billable_units = func.sum(FactBilling.billable_units * FactBilling.rate_multiplier)
-
-    # subtract sms_billable_units units accrued since report's start date to get up-to-date
-    # allowance remainder
-    sms_allowance_left = func.greatest(allowance_left_at_start_date_query.c.sms_remainder - sms_billable_units, 0)
-
-    # billable units here are for period between start date and end date only, so to see
-    # how many are chargeable, we need to see how much free allowance was used up in the
-    # period up until report's start date and then do a subtraction
-    chargeable_sms = func.greatest(sms_billable_units - allowance_left_at_start_date_query.c.sms_remainder, 0)
-    sms_cost = chargeable_sms * FactBilling.rate
-
-    query = db.session.query(
-        Organisation.name.label('organisation_name'),
-        Organisation.id.label('organisation_id'),
-        Service.name.label("service_name"),
-        Service.id.label("service_id"),
-        allowance_left_at_start_date_query.c.free_sms_fragment_limit,
-        FactBilling.rate.label('sms_rate'),
-        sms_allowance_left.label("sms_remainder"),
-        sms_billable_units.label('sms_billable_units'),
-        chargeable_sms.label("chargeable_billable_sms"),
-        sms_cost.label('sms_cost'),
-    ).select_from(
-        Service
-    ).outerjoin(
-        allowance_left_at_start_date_query, Service.id == allowance_left_at_start_date_query.c.service_id
-    ).outerjoin(
-        Service.organisation
-    ).join(
-        FactBilling, FactBilling.service_id == Service.id,
-    ).filter(
-        FactBilling.bst_date >= start_date,
-        FactBilling.bst_date <= end_date,
-        FactBilling.notification_type == SMS_TYPE,
-    ).group_by(
-        Organisation.name,
-        Organisation.id,
-        Service.id,
-        Service.name,
-        allowance_left_at_start_date_query.c.free_sms_fragment_limit,
-        allowance_left_at_start_date_query.c.sms_remainder,
-        FactBilling.rate,
-    ).order_by(
-        Organisation.name,
-        Service.name
-    )
-
-    return query.all()
+    # TODO: replace with new aggregate function containing the following columns:
+    # organisation_name
+    # organisation_id
+    # service_name
+    # service_id
+    # free_sms_fragment_limit
+    # sms_rate
+    # sms_remainder
+    # sms_billable_units
+    # chargeable_billable_sms
+    # sms_cost
+    raise NotImplementedError
 
 
 def fetch_letter_costs_and_totals_for_all_services(start_date, end_date):