Add yesterday stats when day totals are not yet available

Fixes dsmrreader#1811

Author: RichieB2B

dsmr_stats/services.py

@@ -260,10 +260,7 @@ def clear_statistics() -> None:
 
 def electricity_tariff_percentage(start: date, end: date) -> Optional[Dict]:
     """Returns the total electricity consumption percentage by tariff (high/low tariff)."""
-    totals = DayStatistics.objects.filter(
-        day__gte=start,
-        day__lte=end,
-    ).aggregate(
+    totals = DayStatistics.objects.filter(day__gte=start, day__lte=end,).aggregate(
         electricity1=Sum("electricity1"),
         electricity2=Sum("electricity2"),
     )
@@ -419,7 +416,6 @@ def year_statistics(target_date: datetime.date):
     return range_statistics(start=start_of_year, end=end_of_year)
 
 
-# @TODO: Consider reworking this to meter positions in favor of https://github.com/dsmrreader/dsmr-reader/issues/1811
 def period_totals() -> Dict:
     """Retrieves year/month period totals and merges them with today's consumption."""
     today = timezone.localtime(timezone.now())
@@ -429,6 +425,17 @@ def period_totals() -> Dict:
     except LookupError:
         today_stats = {}
 
+    # also add yesterday stats if today totals are not available yet
+    # see https://github.com/dsmrreader/dsmr-reader/issues/1811
+    if not day_statistics(target_date=today):
+        try:
+            yesterday = today - timezone.timedelta(days=1)
+            yesterday_stats = dsmr_consumption.services.day_consumption(day=yesterday)
+        except LookupError:
+            yesterday_stats = {}
+    else:
+        yesterday_stats = {}
+
     month_stats = month_statistics(target_date=today)
     year_stats = year_statistics(target_date=today)
     excluded_keys = (
@@ -443,13 +450,15 @@ def period_totals() -> Dict:
             continue
 
         # Assumes same keys, zero value fallback.
+        month_stats[k] += yesterday_stats.get(k, 0)
         month_stats[k] += today_stats.get(k, 0)
 
     for k in year_stats.keys():
         if k in excluded_keys or year_stats[k] is None:
             continue
 
         # Assumes same keys, zero value fallback.
+        year_stats[k] += yesterday_stats.get(k, 0)
         year_stats[k] += today_stats.get(k, 0)
 
     return dict(