chore: initialize public repository

app/services/public_holidays.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+from datetime import date
+
+import holidays
+
+
+GERMAN_STATE_OPTIONS: list[dict[str, str]] = [
+    {"code": "BW", "label": "Baden-Württemberg"},
+    {"code": "BY", "label": "Bayern"},
+    {"code": "BE", "label": "Berlin"},
+    {"code": "BB", "label": "Brandenburg"},
+    {"code": "HB", "label": "Bremen"},
+    {"code": "HH", "label": "Hamburg"},
+    {"code": "HE", "label": "Hessen"},
+    {"code": "MV", "label": "Mecklenburg-Vorpommern"},
+    {"code": "NI", "label": "Niedersachsen"},
+    {"code": "NW", "label": "Nordrhein-Westfalen"},
+    {"code": "RP", "label": "Rheinland-Pfalz"},
+    {"code": "SL", "label": "Saarland"},
+    {"code": "SN", "label": "Sachsen"},
+    {"code": "ST", "label": "Sachsen-Anhalt"},
+    {"code": "SH", "label": "Schleswig-Holstein"},
+    {"code": "TH", "label": "Thüringen"},
+]
+GERMAN_STATE_CODES = {item["code"] for item in GERMAN_STATE_OPTIONS}
+
+
+def normalize_german_state_code(value: str | None) -> str | None:
+    if value is None:
+        return None
+    normalized = value.strip().upper()
+    if not normalized:
+        return None
+    if normalized not in GERMAN_STATE_CODES:
+        return None
+    return normalized
+
+
+def list_public_holiday_dates(
+    *,
+    federal_state: str,
+    from_date: date,
+    to_date: date,
+) -> set[date]:
+    if to_date < from_date:
+        return set()
+    years = list(range(from_date.year, to_date.year + 1))
+    holiday_map = holidays.country_holidays("DE", subdiv=federal_state, years=years)
+    result: set[date] = set()
+    for holiday_date in holiday_map.keys():
+        if from_date <= holiday_date <= to_date:
+            result.add(holiday_date)
+    return result