zapamietanie akcji

app/vat.py

@@ -55,6 +55,51 @@ def effective_vat_rate(nominal_rate, on_date=None):
     return override["rate"]
 
 
+
+def vat_override_for_date(nominal_rate, on_date=None):
+    """Return a complete, immutable VAT-action snapshot for a date."""
+    override = global_vat_override()
+    if isinstance(on_date, datetime):
+        on_date = on_date.date()
+    on_date = on_date or date.today()
+    applies = bool(
+        override["enabled"]
+        and override["rate"] is not None
+        and (not override["start"] or on_date >= override["start"])
+        and (not override["end"] or on_date <= override["end"])
+    )
+    return {
+        "applied": applies,
+        "name": override["name"] if applies else None,
+        "rate": override["rate"] if applies else Decimal(str(nominal_rate)),
+        "start": override["start"] if applies else None,
+        "end": override["end"] if applies else None,
+    }
+
+
+def freeze_vat_action(entry, nominal_rate, previous_fueled_at=None):
+    """Attach VAT action conditions to an entry without rewriting valid history."""
+    fueled_date = entry.fueled_at.date() if isinstance(entry.fueled_at, datetime) else entry.fueled_at
+    previous_date = previous_fueled_at.date() if isinstance(previous_fueled_at, datetime) else previous_fueled_at
+    if entry.vat_action_frozen and (previous_date is None or previous_date == fueled_date):
+        return
+
+    snapshot = vat_override_for_date(nominal_rate, fueled_date)
+    entry.vat_action_frozen = True
+    entry.vat_action_applied = snapshot["applied"]
+    entry.vat_action_name = snapshot["name"]
+    entry.vat_action_rate = snapshot["rate"] if snapshot["applied"] else None
+    entry.vat_action_start = snapshot["start"]
+    entry.vat_action_end = snapshot["end"]
+
+
+def entry_vat_rate(entry, nominal_rate):
+    if entry.vat_action_frozen:
+        if entry.vat_action_applied and entry.vat_action_rate is not None:
+            return Decimal(str(entry.vat_action_rate))
+        return Decimal(str(nominal_rate))
+    return effective_vat_rate(nominal_rate, entry.fueled_at)
+
 def save_global_vat_override(form):
     enabled = "enabled" in form
     name = (form.get("name") or "Projekt rządowy").strip()